混凝土外文翻译---混凝土的收缩
外文翻译--混凝土结构使用的可靠性
Electronic Journal of Structural Engineering, 1 ( 2001)15 Shrinkage, Cracking and Deflection-the Serviceability of Concrete Structures R.I. GilbertProfessor and Head, School of Civil and Environmental EngineeringThe University of New South Wales, Sydney, NSW, 2052Email: ******************.auABSTRACT This paper addresses the effects of shrinkage on the serviceability of concrete structures. It outlines why shrinkage is important, its major influence on the final extent of cracking and the magnitude of deflection in structures, and what to do about it in design. A model is presented for predicting the shrinkage strain in normal and high strength concrete and the time-dependent behaviour of plain concrete and reinforced concrete, with and without external restraints, is explained. Analytical procedures are described for estimating the final width and spacing of both flexural cracks and direct tension cracks and a simplified procedure is presented for including the effects of shrinkage when calculating long-term deflection. The paper also contains an overview of the considerations currently being made by the working group established by Standards Australia to revise the serviceability provisions of AS3600-1994, particularly those clauses related to shrinkage.KEYWORDSCreep; Cracking; Deflection; Reinforced concrete; Serviceability; Shrinkage.1. IntroductionFor a concrete structure to be serviceable, cracking must be controlled and deflections must not be excessive. It must also not vibrate excessively. Concrete shrinkage plays a major role in each of these aspects of the service load behaviour of concrete structures.The design for serviceability is possibility the most difficult and least well understood aspect of the design of concrete structures. Service load behaviour depends primarily on the properties of the concrete and these are often not known reliably at the design stage. Moreover, concrete behaves in a non-linear and inelastic manner at service loads. The non-linear behaviour that complicates serviceability calculations is due to cracking, tension stiffening, creep, and shrinkage. Of these, shrinkage is the most problematic. Restraint to shrinkage causes time-dependent cracking and gradually reduces the beneficial effects of tension stiffening. It results in a gradual widening of existing cracks and, in flexural members, a significant increase in deflections with time.The control of cracking in a reinforced or prestressed concrete structure is usually achieved by limiting the stress increment in the bonded reinforcement to some appropriately low value and ensuring that the bonded reinforcement is suitably distributed. Many codes of practice specify maximum steel stress increments after cracking and maximum spacing requirements for the bonded reinforcement. However, few existing code procedures, if any, account adequately for the gradual increase in existing crack widths with time, due primarily to shrinkage, or the time-dependent development of new cracks resulting from tensile stresses caused by restraint to shrinkage.For deflection control, the structural designer should select maximum deflection limits that are appropriate to the structure and its intended use. The calculated deflection (or camber) must not exceed these limits. Codes of practice give general guidance for both the selection of the maximum deflection limits and the calculation of deflection. However, the simplified procedures for calculating e J S E Internationaldeflection in most codes were developed from tests on simply-supported reinforced concrete beams and often produce grossly inaccurate predictions when applied to more complex structures. Again, the existing code procedures do not provide real guidance on how to adequately model the time-dependent effects of creep and shrinkage in deflection calculations.Serviceability failures of concrete structures involving excessive cracking and/or excessive deflection are relatively common. Numerous cases have been reported, in Australia and elsewhere, of structures that complied with code requirements but still deflected or cracked excessively. In a large majority of these failures, shrinkage of concrete is primarily responsible. Clearly, the serviceability provisions embodied in our codes do not adequately model the in-service behaviour of structures and, in particular, fail to account adequately for shrinkage.The quest for serviceable concrete structures must involve the development of more reliable design procedures. It must also involve designers giving more attention to the specification of an appropriate concrete mix, particularly with regard to the creep and shrinkage characteristics of the mix, and sound engineering input is required in the construction procedures. High performance concrete structures require the specification of high performance concrete (not necessarily high strength concrete, but concrete with relatively low shrinkage, not prone to plastic shrinkage cracking) and a high standard of construction, involving suitably long stripping times, adequate propping, effective curing procedures and rigorous on-site supervision.This paper addresses some of these problems, particularly those related to designing for the effects of shrinkage. It outlines how shrinkage affects the in-service behaviour of structures and what to do about it in design. It also provides an overview of the considerations currently being made by the working group established by Standards Australia to revise the serviceability provisions of AS3600-1994 [1], particularly those clauses related to shrinkage.2. Designing for ServiceabilityWhen designing for serviceability, the designer must ensure that the structure can perform its intended function under the day to day service loads. Deflection must not be excessive, cracks must be adequately controlled and no portion of the structure should suffer excessive vibration. Shrinkage causes time-dependent cracking, thereby reducing the stiffness of a concrete structure, and is therefore a detrimental factor in all aspects of the design for serviceability.Deflection problems that may affect the serviceability of concrete structures can be classified into three main types:(a)Where excessive deflection causes either aesthetic or functional problems.(b)Where excessive deflection results in damage to either structural or non-structural elementattached to the member.(c)Where dynamics effects due to insufficient stiffness cause discomfort to occupants.3. Effects of ShrinkageIf concrete members were free to shrink, without restraint, shrinkage of concrete would not be a major concern to structural engineers. However, this is not the case. The contraction of a concrete member is often restrained by its supports or by the adjacent structure. Bonded reinforcement also restrains shrinkage. Each of these forms of restraint involve the imposition of a gradually increasing tensile force on the concrete which may lead to time-dependent cracking (in previously uncracked regions), increases in deflection and a widening of existing cracks. Restraint to shrinkage is probably the most common cause of unsightly cracking in concrete structures. In many cases, these problemsarise because shrinkage has not been adequately considered by the structural designer and the effects of shrinkage are not adequately modelled in the design procedures specified in codes of practice for crack control and deflection calculation.The advent of shrinkage cracking depends on the degree of restraint to shrinkage, the extensibility and strength of the concrete in tension, tensile creep and the load induced tension existing in the member. Cracking can only be avoided if the gradually increasing tensile stress induced by shrinkage, and reduced by creep, is at all times less than the tensile strength of the concrete. Although the tensile strength of concrete increases with time, so too does the elastic modulus and, therefore, so too does the tensile stress induced by shrinkage. Furthermore, the relief offered by creep decreases with age. The existence of load induced tension in uncracked regions accelerates the formation of time-dependent cracking. In many cases, therefore, shrinkage cracking is inevitable. The control of such cracking requires two important steps. First, the shrinkage-induced tension and the regions where shrinkage cracks are likely to develop must be recognised by the structural designer. Second, an adequate quantity and distribution of anchored reinforcement must be included in these regions to ensure that the cracks remain fine and the structure remains serviceable.3.1 What is Shrinkage?Shrinkage of concrete is the time-dependent strain measured in an unloaded and unrestrained specimen at constant temperature. It is important from the outset to distinguish between plastic shrinkage, chemical shrinkage and drying shrinkage. Some high strength concretes are prone to plastic shrinkage, which occurs in the wet concrete, and may result in significant cracking during the setting process. This cracking occurs due to capillary tension in the pore water. Since the bond between the plastic concrete and the reinforcement has not yet developed, the steel is ineffective in controlling such cracks. This problem may be severe in the case of low water content, silica fume concrete and the use of such concrete in elements such as slabs with large exposed surfaces is not recommended.Drying shrinkage is the reduction in volume caused principally by the loss of water during the drying process. Chemical (or endogenous) shrinkage results from various chemical reactions within the cement paste and includes hydration shrinkage, which is related to the degree of hydration of the binder in a sealed specimen. Concrete shrinkage strain, which is usually considered to be the sum of the drying and chemical shrinkage components, continues to increase with time at a decreasing rate.Shrinkage is assumed to approach a final value, *sc ε, as time approaches infinity and is dependent onall the factors which affect the drying of concrete, including the relative humidity and temperature, the mix characteristics (in particular, the type and quantity of the binder, the water content and water-to-cement ratio, the ratio of fine to coarse aggregate, and the type of aggregate), and the size and shape of the member.Drying shrinkage in high strength concrete is smaller than in normal strength concrete due to the smaller quantities of free water after hydration. However, endogenous shrinkage is significantly higher.For normal strength concrete (50≤'c f MPa), AS3600 suggests that the design shrinkage (which includes both drying and endogenous shrinkage) at any time after the commencement of drying may be estimated fromb cs cs k .1εε=(1)where b cs .ε is a basic shrinkage strain which, in the absence of measurements, may be taken to be 850 x 10-6 (note that this value was increased from 700 x 10-6 in the recent Amendment 2 of the Standard); k 1 is obtained by interpolation from Figure 6.1.7.2 in the Standard and depends on the time since the commencement of drying, the environment and the concrete surface area to volume ratio. A hypothetical thickness, t h = 2A / u e , is used to take this into account, where A is the cross-sectional area of the member and u e is that portion of the section perimeter exposed to the atmosphere plus half the total perimeter of any voids contained within the section.AS3600 states that the actual shrinkage strain may be within a range of plus or minus 40% of the value predicted (increased from ± 30% in Amendment 2 to AS3600-1994). In the writer’s opin ion, this range is still optimistically narrow, particularly when one considers the size of the country and the wide variation in shrinkage measured in concretes from the various geographical locations. Equation 1 does not include any of the effects related to the composition and quality of the concrete. The same value of εcs is predicted irrespective of the concrete strength, the water-cement ratio, the aggregate type and quantity, the type of admixtures, etc. In addition, the factor k 1 tends to overestimate the effect of member size and significantly underestimate the rate of shrinkage development at early ages.The method should be used only as a guide for concrete with a low water-cement ratio (<0.4) and with a well graded, good quality aggregate. Where a higher water-cement ratio is expected or when doubts exist concerning the type of aggregate to be used, the value of εcs predicted by AS3600 should be increased by at least 50%. The method in the Standard for the prediction of shrinkage strain is currently under revision and it is quite likely that significant changes will be proposed with the inclusion of high strength concretes.A proposal currently being considered by Standards Australia, and proposed by Gilbert (1998) [9], involves the total shrinkage strain, εcs , being divided into two components, endogenous shrinkage, εcse , (which is assumed to develop relatively rapidly and increases with concrete strength) and drying shrinkage, εcsd (which develops more slowly, but decreases with concrete strength). At any time t (in days) after pouring, the endogenous shrinkage is given byεcse = ε*cse (1.0 - e -0.1t ) (2) where ε*cse is the final endogenous shrinkage and may be taken as ε*cse 610)503(-⨯-'=c f , wherec f ' is in MPa. The basic drying shrinkage *csd ε is given by66*1025010)81100(--⨯≥⨯'-=c csd f ε(3) and at any time t (in days) after the commencement of drying, the drying shrinkage may be taken as*1csd csd k εε= (4)The variable 1k is given by )7/(8.08.0541h t t t k k k += (5) where h t e k 005.042.18.0-+= and 5k is equal to 0.7 for an arid environment, 0.6 for a temperate environment and 0.5 for a tropical/coastal environment. For an interior environment, k 5 may be taken as 0.65. The value of k 1 given by Equation 5 has the same general shape as that given in Figure6.1.7.2 in AS3600, except that shrinkage develops more rapidly at early ages and the reduction in drying shrinkage with increasing values of t h is not as great.The final shrinkage at any time is therefore the sum of the endogenous shrinkage (Equation 2) and the drying shrinkage (Equation 4). For example, for specimens in an interior environment with hypothetical thicknesses t h = 100 mm and t h = 400 mm, the shrinkage strains predicted by the above model are given in Table 1. Table 1 Design shrinkage strains predicted by proposed model for an interior environment. h t c f ' *cse ε (x 10-6)*csd ε(x 10-6) Strain at 28 days (x 10-6) Strain at 10000 days (x 10-6) cse ε csd ε cs ε cse ε csd ε cs ε 100 2525 900 23 449 472 25 885 910 50100 700 94 349 443 100 690 790 75175 500 164 249 413 175 493 668 100250 300 235 150 385 250 296 546 4002525 900 23 114 137 25 543 568 50100 700 94 88 182 100 422 522 75175 500 164 63 227 175 303 478 100 250 300 235 38 273 250 182 4323.2 Shrinkage in Unrestrained and Unreinforced Concrete (Gilbert, 1988) [7]Drying shrinkage is greatest at the surfaces exposed to drying and decreases towards the interior of a concrete member. In Fig.1a , the shrinkage strains through the thickness of a plain concrete slab, drying on both the top and bottom surfaces, are shown. The slab is unloaded and unrestrained.The mean shrinkage strain, εcs in Fig. 1, is the average contraction. The non-linear strain labelled ∆εcs is that portion of the shrinkage strain that causes internal stresses to develop. These self-equilibrating stresses (called eigenstresses) produce the elastic and creep strains required to restore compatibility (ie. to ensure that plane sections remain plane). These stresses occur in all concrete structures and are tensile near the drying surfaces and compressive in the interior of the member. Because the shrinkage-induced stresses develop gradually with time, they are relieved by creep. Nevertheless, the tensile stresses near the drying surfaces often overcome the tensile strength of the immature concrete and result in surface cracking, soon after the commencement of drying. Moist curing delays the commencement of drying and may provide the concrete time to develop sufficient tensile strength to avoid unsightly surface cracking.Fig. 1 - Strain components caused by shrinkage in a plain concrete slab.The elastic plus creep strains caused by the eigenstresses are equal and opposite to ∆εcs and are shown in Fig. 1b. The total strain distribution, obtained by summing the elastic, creep and shrinkage strain components, is linear (Fig. 1c) thus satisfying compatibility. If the drying conditions are the same at both the top and bottom surfaces, the total strain is uniform over the depth of the slab and equal to the mean shrinkage strain, εcs . It is this quantity that is usually of significance in the analysis of concrete structures. If drying occurs at a different rate from the top and bottom surfaces, the total strain distribution becomes inclined and a warping of the member results.4. Control of deflectionThe control of deflections may be achieved by limiting the calculated deflection to an acceptably small value. Two alternative general approaches for deflection calculation are specified in AS3600 (1), namely ‘deflection by refined calculation’ (Clause 9.5.2 for beams and Clause 9.3.2 for slabs) and ‘deflection by simplified calculation’ (Clause 9.5.3 for beams and Clause 9.3.3 for slabs). The former is not specified in detail but allowance should be made for cracking and tension stiffening, the shrinkage and creep properties of the concrete, the expected load history and, for slabs, the two-way action of the slab. 呵呵The long-term or time-dependent behaviour of a beam or slab under sustained service loads can be determined using a variety of analytical procedures (Gilbert, 1988) [7], including the Age-Adjusted Effective Modulus Method (AEMM), described in detail by Gilbert and Mickleborough (1997) [12]. The use of the AEMM to determine the instantaneous and time-dependent deformation of the critical cross-sections in a beam or slab and then integrating the curvatures to obtain deflection, is a refined calculation method and is recommended.Using the AEMM, the strain and curvature on individual cross-sections at any time can be calculated, as can the stress in the concrete and bonded reinforcement or tendons. The routine use of the AEMM in the design of concrete structures for the serviceability limit states is strongly encouraged.5. Control of flexural crackingIn AS3600-1994, the control of flexural cracking is deemed to be satisfactory, providing the designer satisfies certain detailing requirements. These involve maximum limits on the centre-to-centre spacing of bars and on the distance from the side or soffit of the beam to the nearest longitudinal bar. These limits do not depend on the stress in the tensile steel under service loads and have been found to be unreliable when the steel stress exceeds about 240 MPa. The provisions of AS3600-1994 over-simplify the problem and do not always ensure adequate control of cracking.With the current move to higher strength reinforcing steels (characteristic strengths of 500 MPa and above), there is an urgent need to review the crack-control design rules in AS3600 for reinforced concrete beams and slabs. The existing design rules for reinforced concrete flexural elements are intended for use in the design of elements containing 400 MPa bars and are sometimes unconservative. They are unlikely to be satisfactory for members in which higher strength steels are used, where steel stresses at service loads are likely to be higher due to the reduced steel area required for strength.6. ConclusionsThe effects of shrinkage on the behaviour of reinforced and prestressed concrete members under sustained service loads has been discussed. In particular, the mechanisms of shrinkage warping in unsymmetrically reinforced elements and shrinkage cracking in restrained direct tension members has been described. Recent amendments to the serviceability provisions of AS3600 have beenoutlined and techniques for the control of deflection and cracking are presented. Reliable procedures for the prediction of long-term deflections and final crack widths in flexural members have also been proposed and illustrated by examples.收缩，开裂和变形–混凝土结构使用的可靠性里吉尔伯特土木及环境工程学校校长兼教授新南威尔士大学，悉尼，新南威尔士州 2052 号电子邮件：******************.au摘要本文讨论收缩对混凝土结构可靠性的影响，它概述了为什么收缩是重要的，它的主要影响，即对结构最终的开裂程度和挠度大小的影响，以及在设计中应该注意什么？有一种模型可以预测在普通混凝土、高强度混凝土、不稳定性普通混凝土和钢筋混凝土中的收缩应变，无论有没有外部约束的情况下，都可以用这种模型来解释。
土木工程专业外语课文翻译
土木工程专业外语课文翻译专业英语课文翻译Lesson 4Phrases and Expressions1.moisture content 含水量，含湿度; water content 2.cement paste 水泥浆 mortar 3.capillary tension 毛细管张力，微张力 4.gradation of aggregate 骨料级配 coarse fine (crushed stone , gravel ) 5.The British Code PC 100 英国混凝土规范PC 100; nowaday BS 8110 6. coefficient of thermal expansion of concrete 混凝土热膨胀系数 7. The B .S Code 英国标准规范8. sustained load 永久荷载，长期荷载9. permanent plastic strain 永久的塑性应变stress 10. crystal lattice 晶格, 晶格11. cement gel 水泥凝胶体12. water -cement ratio 水灰比13. expansion joint 伸缩缝 14. stability of the structure 结构的稳定性structural stability 15. fatigue strength of concrete 混凝土的疲劳强度 Volume Changes of ConcreteConcrete undergoes volume changes during hardening . 混凝土在硬结过程中会经历体积变化。
If it loses moisture by evaporation , it shrinks , but if the concrete hardens in water , it expands . 如果蒸发失去水分，混凝土会收缩；但如果在水中硬结，它便膨胀。
外文翻译---混凝土,钢筋混凝土和预应力混凝土
Concrete, Reinforced Concrete, andPrestressedConcreteConcrete is a stone like material obtained by permitting a carefully proportioned mixture of cement, sand and gravel or other aggregate, and water to harden in forms of the shape and dimensions of the desired structure. The bulk of the material consists of fine and coarse aggregate.Cement and water interact chemically to bind the aggregate particles into a solid mass. Additional water, over and above that needed for this chemical reaction, is necessary to give the mixture workability that enables it to fill the forms and surround the embedded reinforcing steel prior to hardening. Concretes with a wide range of properties can be obtained by appropriates adjustment of the proportions of the constituent materials.Special cements,special aggregates, and special curing methods permit an even wider variety of properties to be obtained.These properties depend to a very substantial degree on the proportions of the mix, on the thoroughness with which the various constituents are intermixed, and on the conditions of humidity and temperature in which the mix is maintained from the moment it is placed in the forms of humidity and hardened. The process of controlling conditions after placement is known as curing.To protect against the unintentional production of substandard concrete, a high degree of skillful control and supervision is necessary throughout the process,from the proportioning by weight of the individual components, trough mixing and placing, until the completion of curing.The factors that make concrete a universal building material are so pronounced that it has been used, in more primitive kinds and ways than at present, for thousands of years, starting with lime mortars from 12,000 to 600 B.C. in Crete, Cyprus, Greece, and the Middle East. The facility with which , while plastic, it can be deposited and made to fill forms or molds of almost any practical shape is one of these factors. Its high fire and weather resistance are evident advantages.Most of the constituent materials,with the exception of cement and additives,are usually available at low cost locally or at small distances from the construction site. Its compressive strength, like that of natural stones,is high,which makes it suitable for members primarily subject to compression, such as columns and arches. On the other hand, again as in natural stones,it is a relatively brittle material whose tensile strength is small compared with its compressive strength. This prevents its economical use in structural members that ate subject to tension either entirely or over part of their cross sections.To offset this limitation,it was found possible,in the second half of thenineteenth century,to use steel with its high tensile strength to reinforce concrete, chiefly in those places where its low tensile strength would limit the carrying capacity of the member. The reinforcement, usually round steel rods with appropriate surface deformations to provide interlocking, is places in the forms in advance of the concrete. When completely surrounded by the hardened concrete mass, it forms an integral part of the member.The resulting combination of two materials,known as reinforced concrete,combines many of the advantages of each:the relatively low cost,good weather and fire resistance, good compressive strength, and excellent formability of concrete and the high tensile strength and much greater ductility and toughness of steel.It is this combination that allows the almost unlimited range of uses and possibilities of reinforced concrete in the construction of buildings,bridges,dams, tanks, reservoirs, and a host of other structures.In more recent times, it has been found possible to produce steels, at relatively low cost, whose yield strength is 3 to 4 times and more that of ordinary reinforcing steels.Likewise,it is possible to produce concrete4to5times as strong in compression as the more ordinary concrete. These high-strength materials offer many advantages, including smaller member cross sections, reduced dead load, and longer spans. However, there are limits to the strengths of the constituent materials beyond which certain problems arise.To be sure,the strength of such a member would increase roughly in proportion to those of the materials. However, the high strains that result from the high stresses that would otherwise be permissible would lead to large deformations and consequently large deflections of such member under ordinary loading conditions.Equally important,the large strains in such high-strength reinforcing steel would induce large cracks in the surrounding low tensile strength concrete, cracks that would not only be unsightly but that could significantly reduce the durability of the structure.This limits the useful yield strength of high-strength reinforcing steel to 80 ksi according to many codes and specifications; 60 ksi steel is most commonly used.A special way has been found, however, to use steels and concrete of very high strength in combination. This type of construction is known as prestressed concrete. The steel,in the form of wires,strands,or bars, is embedded in the concrete under high tension that is held in equilibrium by compressive stresses in the concrete after hardening,Because of this precompression,the concrete in a flexural member will crack on the tension side at a much larger load than when not so precompressed. Prestressing greatly reduces both the deflections and the tensile cracks at ordinaryloads in such structures, and thereby enables these high-strength materials to be used effectively. Prestressed concrete has extended, to a very significant extent, the range of spans of structural concrete and the types of structures for which it is suited.混凝土，钢筋混凝土和预应力混凝土混凝土是一种经过水泥，沙子和砂砾或其他材料聚合得到经过细致配比的混合物，在液体变硬使材料石化后可以得到理想的形状和结构尺寸。
泡沫混凝土的收缩性能--外文文献
Shrinkage Behavior of Foam ConcreteE.K.Kunhanandan Nambiar1and K.Ramamurthy,M.ASCE2Abstract:In the absence of coarse aggregate,the relative influence of factors affecting the shrinkage of foam concrete are likely to be different as compared to normal concrete.This paper presents the shrinkage behavior of preformed foam concrete for the influences of basic parameters,viz,density,moisture content,composition likefiller-cement ratio,levels of replacement of sand withfly ash,and foam volume.Shrinkage of foam concrete is lower than the corresponding base mix.For a foam concrete with50%foam volume,the shrinkage was observed to be about36%lower than that of a base mix.The shrinkage of foam concrete is a function of foam volume and thus indirectly related to the amount and properties of shrinkable paste.Shrinkage increases greatly in the range of low moisture content.Even though removal of water from comparatively bigger artificial air pores will not contribute to shrinkage,artificial air voids may have,to some extent,an effect on volume stability indirectly by allowing some shrinkage;this effect was more at a higher foam volume.DOI:10.1061/͑ASCE͒0899-1561͑2009͒21:11͑631͒CE Database subject headings:Shrinkage;Dewatering;Foam;Fly ash;Cement;Concrete.IntroductionThe volume change resulting from removal of moisture͑drying shrinkage͒of a cement based material is primarily due to the change in volume of unrestrained hydrated cement paste by the removal of adsorbed water from the surface of gel pores͑Neville 1995͒.As far as normal concrete is considered,the major param-eters identified are the paste shrinkage and aggregate content ͑Hansen and Almudaiheem1987͒.Cellular concrete,like aerated concrete and foam concrete possessing high drying shrinkage due to the absence of aggregates,were up to10times greater than those observed on a normal weight concrete͑Valore1954;Jones et al.2003͒.Significant reduction in shrinkage of aerated concrete obtained by autoclaving suggests that drying shrinkage is pre-dominantly a function of the physical structure of the hydration product͑Ramamurthy and Narayanan2000͒while Tada and Na-kano͑1983͒attributed the higher shrinkage in aerated concrete to its larger volume offiner pores,and Ziembicka͑1977͒and Geor-giades and Ftikos͑1991͒have related shrinkage to the volume and specific surface of micropores.Schubert͑1983͒related shrinkage to volume of pores affecting shrinkage,to the pore distribution and moisture content.In a comparative study on the shrinkage behavior with sand andfly ash͑FA͒asfiller,mixes with sand exhibited smaller drying shrinkage as the sand particles have higher shrinkage restraining capacity compared to FA par-ticles͑Jones et al.2003͒.Nmai et al.͑1997͒,in a study on new foaming agent for CLSM applications,indicated a reduction in shrinkage as density decreases.In addition,lightweight aggregate could be used to reduce the shrinkage of foam concrete͑Regan and Arasteh1990͒.Research SignificanceThe method of curing,composition,density,initial andfinal moisture content,duration and climate of storage,and micropore structure and its distribution are reported to affect the drying shrinkage of cellular concrete.Review shows that most of the earlier research on drying shrinkage of cellular concrete has been confined to aerated concrete.Only limited studies with specific parameters and conditions of test are reported on the shrinkage behavior of foam concrete.Hence,this paper discusses the results of experiments conducted to ascertain the influence of basic com-ponents,viz,density,moisture content,and composition like foam volume͑FV͒,filler-cement͑FC͒ratio,and replacement of sand with FA,on the drying shrinkage of moist-cured preformed foam concrete.Materials and MethodologyConstituent MaterialsThe constituent materials used to produce foamed concrete are given in Table1.Different mixes of foam concrete were made by varying͑1͒FC ratio from1to3͑2͒FA replacement for sand from 0to100%by weight,and͑3͒FV from10to50%.The water-solids ratio of these mixes were reached based on͑1͒the stability of the foam concrete mix which is defined as the state of condi-tion at which measured density is equal to or nearly equal to design density and͑2͒the consistency of mix͑for aflow cone spread value of45Ϯ5%͒͑E.K.K.Nambiar and K.Ramamurthy 2006,2007,2008͒.Experimental InvestigationsTests for drying shrinkage were carried out on prisms of size1Assistant Professor,Dept.of Civil Engineering,NSS College of En-gineering,Palakkad-678008,India.E-mail:ekknambiar@2Professor,Building Technology and Construction Management Div., Dept.of Civil Engineering,Indian Institute of Technology Madras, Chennai-600036,India͑corresponding author͒.E-mail:vivek@iitm.ac.in Note.This manuscript was submitted on February5,2007;approved on March31,2009;published online on October15,2009.Discussion period open until April1,2010;separate discussions must be submitted for individual papers.This paper is part of the Journal of Materials in Civil Engineering,V ol.21,No.11,November1,2009.©ASCE,ISSNof RILEM-ACC 5.2͑RILEM 1992͒and IS 6441-part II ͑Bureauof Indian Standards 1972͒for aerated concrete.Spherical gaugeplugs were attached at both the ends of the specimen to facilitatelength change measurements.For each combination of the param-eters,three specimens were tested for shrinkage and the meanvalue is reported.The specimens were immersed in water for 72h after removalfrom the molds.After this period of immersion,the specimenswere kept in a controlled environment ͑humidity chamber ͒at atemperature of 23Ϯ1.7°C and relative humidity of 50Ϯ4%͓ASTM C 157,ASTM ͑1998͔͒.First length measurement ͑l 1͒was made immediately after 72h of immersion in water.The moisturefrom the surface of the specimen was wiped off and the moistureon the gauge plugs also carefully removed to nullify chance offaulty readings.The length measurements were made in a lengthcomparator with a least count of 0.002mm.Length measurementswere taken for 28days.The change in length,ٌl expressed inpercent is calculated as ͓͑l 2−l 1͒/L d ͔ϫ100,where l 1is the firstreading of length,l 2is the final reading after 28days,and L d isthe original length of the specimen.Results and DiscussionInfluence of Filler-Cement Ratio and Filler TypeFig.1shows the effect of FC ratio on the shrinkage of foamconcrete at the end of 28days.As expected,both cement-sandand cement FA sand mixes showed a reduction in shrinkage withan increase in FC ratio,the variation being relatively steeper forthe FC ratio range of 1to 2.This is can be attributed to thecombined effect of reduction in cement content and restrainingeffect of increased fine aggregate content.Also,for a given FC ratio,cement-sand mix showed lower shrinkage than a typical mix with FA replacing sand ͑40%replacement ͒.This is due to the reduced shrinking ability of the sand particles compared to FA ͑Jones et al.2003;Ramamurthy and Narayanan 2000͒.Fig.2indicates that an increase in the FA content of the mix leads to an increase in shrinkage ͑i.e.,shrinkage of mix with 100%FA is 31%higher than that of mix with sand ͒.Similar observations were reported for foam concrete by Jones and Mc-Carthy ͑2005͒and for aerated concrete by Ramamurthy and Narayanan ͑2000͒.The variation of percentage shrinkage and 28-day compressive strength with dry density for foam concrete with cement-sand and cement FA sand mixes are shown in Fig.3.For a given density,mixes with FA replacement ͑say,40%replace-ment ͒showed relatively higher shrinkage ͑about 20%͒than that in cement-sand mix.Apart from the effect of reduced restraining capacity of FA compared to sand,higher water-solids ratio requirement of mixes with FA for achieving a stable and workable mix also will con-tribute to this higher shrinkage.Such an increase in water-solids ratio makes the mix more pervious resulting in higher water ab-sorption during curing.Higher water content leads to thicker layer of adsorbed water ͑Nmai et al.1998͒.The rate at which this water moves toward the surface of the specimen ͑drying ͒is increased as the mix is more pervious,leading to higher shrinkage.Further-more,mixes with FA takes relatively longer time to form a stable structure and until such a time this adsorbed water is allowed to escape from the surface of the unreacted as well as partially re-Table 1.Constituent Materials Used to Produce Foam ConcreteMaterialsRemarks CementOrdinary Portland cement 53grade conforming to IS 12269͑Bureau of Indian Standards 1987͒SandPulverized and finer than 300microns,specific gravity=2.52FAClass F type conforming to ASTM C 618͑ASTM 1989͒,specific gravity=2.09Foam Preformed foam by aerating an organic basedfoaming agent ͑dilution ratio 1:5by weight ͒using anindigenously fabricated foam generatorfoam density—40kg /m 3S h r i n k a g e%Filler-cement ratio Fig.1.Effect of FC ratio on shrinkage of foam concrete S h r i n k a g e %Fly ash replacement %Fig.2.Effect of FA replacement on shrinkage of foam concreteDry density,kg/m3S h r i n k a g e %0246810121416Compressive strength,MPa Fig.3.Variation of shrinkage and strength with density of foam concreteacted particles.Thus the physical structure of the gel formed with FA is also responsible for its increased shrinkage ͑Ramamurthy and Narayanan 2000͒.Adding to this,relatively lower FV require-ment ͑for mixes with FA to achieve a given density ͒resulting in higher volume of shrinkable paste,contributes to this increase in shrinkage.At the same time,for a constant density of foam concrete,mixes with FA resulted in a relatively higher strength ͑two to three times ͒as compared mixes with cement-sand ͑Fig.3͒.This increase in strength is attributed to the reduced FV requirement for FA mixes over and above the filler and pozzolanic effect ͑E.K.K.Nambiar and K.Ramamurthy 2006,2007,2008͒.Though inclusion of FA in the mix causes a small increase in shrinkage,it significantly contributes in enhancing the strength of foam concrete of comparable density.It can also be seen that irrespective of type of mixes,low density products are stable for drying shrinkage in spite of its low strength.Influence of Foam Volume The variations of shrinkage with time for different mixture com-positions in Figs.4͑a and b ͒indicate that the shrinkage reduces with an increase in FV ͑i.e.,with a reduction in density ͒.It is reported that the shrinkage of cellular concrete is a func-tion of volume and specific surface of micropores of radii be-tween 75and 625Å͑Ziembicka 1977͒.Georgiades and Ftikos ͑1991͒reported that the pore radii range is between 20and 200Å.Hence the removal of water from comparatively bigger pores willnot contribute to shrinkage.According to Cebeci ͑1981͒entrainedlarge air voids do not alter the characteristics of fine pore struc-mix,the micropores which affect shrinkage can be proportion-ately related to the paste content in a foam concrete.Thus lower shrinkage value at a higher FV is caused by lower paste content in the mix.In an attempt to characterize the air voids present in foam concrete at different FV ,images of polished and prepared cut surfaces of specimen were captured by an optical microscope and analyzed using an image processing software,after suitable mor-phological operations and shown in Fig.5for mixes with 10and 50%FV .These images were analyzed for pore wall thickness ͑median value of minimum distances between two air voids measured through the paste phase ͒and its variation with FV plotted in Fig.6shows that the pore wall thickness reduces as the air void vol-ume ͑FV ͒increases.This corroborates the observation of Tada and Nakano ͑1983͒who attributed the lower shrinkage at a higher FV to thinner pore wall and relatively reduced volume of micro-capillary pores which is distributed in this wall.Table 2shows that the shrinkage percentage of foam concrete is lower than the corresponding base mix ͑which is basically a normal mortar ͒.As the FV increases,the difference between the shrinkage values increases and this confirms the effect of paste content and thus the amount of pores which affects shrinkage in the mix.The reduction in shrinkage of foam concrete compared to base mix may also be attributed to the reduction in surface tension of pore water in the presence of foaming agents which are basi-cally surfactants.Similar concept is being used in shrinkage re-ducing admixtures which when added in concrete interfere with the surface chemistry of the air/water interface within the capil-lary pore,reducing surface tension and so reducing shrinkage as water evaporates ͑Concrete Society 2002͒.Similar observation of reduction in shrinkage with reduction in density ͑increase in FV ͒was reported by Nmai et al.͑1997͒for foam concrete and Schubert ͑1983͒for aerated concrete.How-ever,a study by Giannakou and Jones ͑2002͒on shrinkage ofS h r i n k a g e %Time,days (a)S h r i n k a g e %Time,days (b)Fig.4.͑a ͒Variation of drying shrinkage with time ͑foam concretewith cement-sand mix ͒;͑b ͒variation of drying shrinkage with time͑foam concrete with cement FA sand mix ͒(a)10%Foam Volume (b)50%Foam volume (c)Scale mm Fig.5.Typical binary images using an optical microscope showing air-void distribution P o r e w a l l t h i c k n e s s (m e d i a n v a l u e s ),m i c r o n s Foam volume %Fig.6.Variation of pore wall thickness with FVfoam concrete at different densities reported a slight increase inshrinkage at lower plastic densities.Such a behavior is attributedto mixture design procedure adopted by Giannakou and Jones͑2002͒,wherein the cement content and water-cement ratio were kept constant at all densities and the density was varied by replac-ing fine aggregate with air.Hence the sand content becomes lessfor lower densities,resulting in higher shrinkage.In the presentand Nmai et al.͑1997͒studies,the mixture design was done keep-ing the FC ratio constant at all FV dosage and so the reduction involume of paste with increase in FV causes lower shrinkage atlower densities.In order to investigate further the effect of paste content on theshrinkage of foam concrete,the variation of paste ratio ͑PR ͒withshrinkage ratio ͑SR ͒was plotted for both the mixes ͓Figs.7͑a andb ͔͒.The SR is defined as the ratio of shrinkage of foam concreteto corresponding base mix ͑without foam ͒and PR is the ratio ofthe total paste content in foam concrete to base mix.It is seen from the plot that SR reduces with paste content.Dotted line is marked in the plots to check whether the variation is linearly proportional to the paste content.But at any given paste content,the shrinkage was higher than the proportionality line and the difference is higher at high FV .A possible explana-tion for this is that the artificial air voids influence the volume stability by allowing some shrinkage and this effect was relatively more at a higher FV .The following relations for shrinkage of foam concrete fit well with R 2values of 0.974and 0.966for cement-sand mix and cement-sand FA mix,respectively for cement sand mix:s fc =0.9814s c ͑PR ͒0.693for cement-fly ash-sand mix:s fc =0.9993s c ͑PR ͒0.7721where s fc and s c =shrinkage of foam concrete and base mix,re-spectively.Effect of DryingFigs.8͑a and b ͒show the variation of shrinkage with moisture content in foam concrete with different FV .Moisture content was Table parison of Shrinkage of Base Mix with Foam Concrete Mix ͑1:2͒Foam concreteBase mix corresponding to each FV FV ͑%͒Cement-sand Cement-sand FA ͑FA 40%͒Cement-sand Cement-sand FA ͑FA 40%͒100.09890.11170.10780.1190300.08790.09460.11630.1240500.06960.08170.11280.1310S h r i n k a g e r a t i o (S R )Paste ratio (PR)(a)S h r i n k a g e r a t i o (S R )Paste ratio (PR)(b)Fig.7.͑a ͒Influence of paste content on shrinkage for cement-sandmixes;͑b ͒influence of paste content on shrinkage for cement FA sandmixesS h r i n k a g e %Moisture content (%by volume)(a)S h r i n k a g e %Moisture content (%by volume)(b)Fig.8.͑a ͒Relationship of shrinkage with moisture content for cement-sand mix;͑b ͒relationship of shrinkage with moisture content for cement-sand FA mixexpressed in percent by volume,as expressing it in percent byweight will give misleading results due to significant variations infoam concrete density͑E.K.K.Nambiar and K.Ramamurthy2006,2007,2008͒.The initial moisture content͑after storage inwater for72h͒is higher for foam concrete with lower FV.As theartificial air voids are not interconnected as well as air beingtrapped in these air voids,they are not taking part in water ab-sorption.Hence the contribution to water absorption is only bypores other than artificial air voids present in the sorbing paste.Thus the above observed increase in water absorption of foamconcrete containing lower FV͑artificial air voids͒is caused by thehigher volume of sorbing paste͑E.K.K.Nambiar and K.Rama-murthy2006,2007,2008͒.It can be seen that mixes with higherFV dried faster as they contain less absorbed water.Both cement-sand and cement-sand FA mixes showed similarbehavior with marginally higher shrinkage values for FA mixes atall FV contents.At any moisture content,the shrinkage reduceswith an increase in FV which,as mentioned earlier,is due to thelower content of micropores affecting shrinkage in foam concretewith higher FV.In the range of higher moisture content,a rela-tively small shrinkage occurs with loss of moisture as this loss ofmoisture is from relatively larger pores and the loss of free waterfrom such pores do not cause significant shrinkage.As dryingcontinues,the shrinkage rate is increased due to the removal ofwater from very small pores and the adsorbed water from gelsurface.At very low moisture content͑about3%or less͒all mixesexhibited a steep increase in shrinkage without any appreciablechange in moisture content.Similar relationship of shrinkage withmoisture content for aerated concrete was reported by Schubert ͑1983͒.Shrinkage in a conservative system,when no moisture movement to or from the paste is permitted,is known as autog-enous shrinkage͑Neville1995͒and thus at a lower moisture con-tent range autogenous shrinkage may also contribute to this totalshrinkage.Further experimental studies are necessary to explainthe above behavior.ConclusionsAs the FC ratio increases,shrinkage reduces due to the restrainingeffect of increased aggregate content.Shrinkage of foam concreteis lower than the corresponding base mix.For a foam concretewith50%FV,the shrinkage was observed to be about36%lowerthan that of a base mix.Shrinkage decreases with an increase infoam content.The lower shrinkage value at higher FV content iscaused by lower content of paste in the mix and thus the lowercontent of pores affecting shrinkage.The relationships developedconnecting shrinkage of foam concrete to that of base mixthrough PRfit well with R2values of0.974and0.966for cement-sand mix and cement-sand FA mix,respectively.For a typical PRof0.65,the reduction observed in the shrinkage compared to thatof base mix was about30%.The higher the FA content in thefoam concrete mix replacing sand,the higher the shrinkage.Thisis attributed to͑1͒low shrinkage resisting capacity offine FA thansand͑2͒greater volume water-solids ratio requirement with FAfor a stable and workable mix,and͑3͒greater volume of shrink-able paste with FA replacement due to reduced FV requirement ata given density.Even though addition of FA causes a small in-crease in shrinkage,it has a major contribution toward increasingthe strength of foam concrete of comparable density.It can alsobe seen that,irrespective of type of mixes,low density productsare stable for drying shrinkage in spite of its low strength.Artifi-some shrinkage;this effect increases with increase in FV.NotationThe following symbols are used in this paper:L dϭoriginal length of the specimen;l1ϭlength measured after72h immersion in water;l2ϭfinal reading after28days;s cϭshrinkage base mix;s fcϭshrinkage of foam concrete;andٌlϭchange in length expressed in%.ReferencesASTM.͑1989͒.“Standard specification forfly ash and raw or calcined natural pozzolana for use as a mineral admixture in Portland cement concrete.”C618,West Conshohocken,Pa.ASTM.͑1998͒.“Standard test method for length change of hardened hydraulic-cement mortar and concrete.”C157,West Conshohocken, Pa.Bureau of Indian Standards.͑1972͒.“Methods of tests for autoclaved cellular concrete—Determination of drying shrinkage.”IS6441-part II,New Delhi,India.Bureau of Indian Standards.͑1987͒.“Specifications for53grade ordinary Portland cement.”I S12269,New Delhi,India.Cebeci,O.Z.͑1981͒.“Pore structure of air-entrained hardened cement paste.”Cem.Concr.Res.,11,257–265.Concrete Society.͑2002͒.“A guide to the selection of admixtures for concrete.”Technical Rep.No.18,The Concrete Society,Berkshire, U.K.Georgiades,A.,and Ftikos,Ch.͑1991͒.“Effect of micropore structure on autoclaved aerated concrete shrinkage.”Cem.Concr.Res.,21,655–662.Giannakou,A.,and Jones,M.R.͑2002͒.“Potentials of foamed concrete to enhance the thermal performance of low rise dwellings.”Proc., Innovations and Development in Concrete Materials and Construc-tion,R.K.Dhir,P.C.Hewelett,and L.J.Csetenyi,eds.,Thomas Telford,London,533–544.Hansen,W.,and Almudaiheem,J.A.͑1987͒.“Ultimate drying shrinkage of concrete-Influence of major parameters.”ACI Mater.J.,84,217–223.Jones,M.R.,and McCarthy,A.͑2005͒.“Preliminary views on the po-tential of foamed concrete as a structural material.”Mag.Concrete Res.,57,21–31.Jones,M.R.,McCarthy,M.J.,and McCarthy,A.͑2003͒.“Movingfly ash utilization in concrete forward:A U K perspective.”Proc.,2003 Int.Ash Utilisation Symp.,Center for Applied Energy Research,Uni-versity of Kentucky,Lexington,Kent.,20–22.Nambiar,E.K.K.,and Ramamurthy,K.͑2006͒.“Influence offiller type on the properties of foam concrete.”pos.,28,475–480.Nambiar,E.K.K.,and Ramamurthy,K.͑2007͒.“Sorption characteristics of foam concrete.”Cem.Concr.Res.,37,1341–1347.Nambiar,E.K.K.,and Ramamurthy,K.͑2008͒.“Fresh state character-istics of foam concrete.”J.Mater.Civ.Eng.,20͑2͒,111–117. Neville,A.M.͑1995͒.Properties of concrete,Longman’s,London. Nmai,C.K.,McNeal,F.,and Martin,D.͑1997͒.“New foaming agent for CLSM applications.”Concr.Int.,4,44–47.Nmai, C.K.,Tomita,R.,Hondo, F.,and Buffenbarger,J.͑1998͒.“Shrinkage-reducing admixtures.”Concr.Int.,4,31–37. Ramamurthy,K.,and Narayanan,N.͑2000͒.“Influence of composition and curing on the drying shrinkage of aerated concrete.”Mater.Struct.,33,243–250.Regan,P.E.,and Arasteh,A.R.͑1990͒.“Lightweight aggregate foamedRILEM.͑1992͒.“Determination of drying shrinkage of AAC.”RILEM-AAC5.2technical recommendations for the testing and use of con-struction materials,E&FN Spon,London.Schubert,P.͑1983͒.“Shrinkage behaviour of aerated concrete.”Proc., Autoclaved Aerated Concrete,Moisture and Properties,F.H.Witt-mann,ed.,Elsevier Science,Amsterdam,207–217.Tada,S.,and Nakano,S.͑1983͒.“Microstructural approach to propertiesof moist cellular concrete.”Proc.,Autoclaved Aerated Concrete, Moisture and Properties,F.H.Wittmann,ed.,Elsevier Science,Am-sterdam,71–88.Valore,R.C.͑1954͒.“Cellular concrete part2.Physical properties.”ACI J.,50,817–836.Ziembicka,H.͑1977͒.“Effect of micropore structure on cellular concrete shrinkage.”Cem.Concr.Res.,7,323–332.。
混凝土相关词语中英文对照
混凝土相关词语中英文对照Al AbramsAbrams cone—Abrams圆筒(坍落度筒)Abrams law—Abrams定则l Admixture—外加剂→化学外加剂l Aggregate—骨料Absorption of water—吸水率Alkali-carbonate reaction—碱-碳酸盐反应Chloride—氯化物Clay—黏土combination of—结合criteria of acceptance—接受准则frost resistance—抗冻性grading—级配Los Angeles test—洛杉矶实验Maximum size and water requirement—最大粒径和需水量Mechanical properties—力学性能Moisture—含水率organic substance—有机杂质porosity—孔隙率sieve analysis—筛分分析S.S.D.—饱和面干sulphate—硫酸盐water requirement—需水量l Aggressive CO2—侵蚀介质CO2l Alite—阿利特l Ammonium salts—铵盐l Amorphous silica—无定形二氧化硅l ASR Alkali-silica-reaction in aggregate—骨料中的碱-硅反应: Bl Belite—贝利特l Blast furnace cement—矿渣水泥l Bleeding—泌水concrete in floor—地板混凝土grout—水泥浆influence of steel bond—钢筋粘结的影响influence of transition zone—过渡区的影响mortar—砂浆l BolomeyCl Capillary porosity—毛细管孔隙率l Capillary pressure—毛细管压力l Carbonation—碳化l Characteristic strength—特征强度l Chemical admixtures一化学外加剂Air entraining agents(AEA)—引气剂use in shotcrete—在喷射混凝土中的应用ASR inhibitor—碱-硅反应抑制剂Corrosion inhibitors—防腐剂Classification—分类Hardening accelerators—促硬剂Hydrophobic admixtures—防水剂High-range water reducers superplasticizers—高效减水剂(超塑化剂)Retarders—缓凝剂Setting accelerators—促凝剂Use in shotcrete—用于喷射混凝土中Silanes—硅烷Shrinkage-reducing admixtures—减缩剂SRA→Shrinkage-reducing admixturesSuperplasticizers—高效减水剂（超塑化剂）Mechanism of action of—作用机理Slump loss/retention—坍落度损失/保持Multifunctional—多功能的Use in shotcrete—用于喷射混凝土中Use to increase strength/durability—用于提高强度/耐久性Use to reduce cement—用于减少水泥Use to increase workability—用于提高工作性Viscosity modifying agents—黏度调节剂VMA→Viscosity modifying agentsWater-reducers—减水剂l Cement—水泥Norms—标准Set regulator—调凝剂Setting—凝结Strength—强度l Chloride—氯化物Diffusion—扩散l Compactability—密实性l Compacting factor—密实系数l Composite cement—复合水泥l Composite Portland cement—复合硅酸盐水泥l Concrete—混凝土Deterioration—劣化Manufacture—生产Placing—浇筑Prestressed—预应力Reinforced—增强l Corrosion of reinforcement—钢筋的腐蚀Promoted by carbonation—碳化引起Promoted by chloride—氯化物引起l Cracking—开裂l Creep—徐变Basic—基本Drying—干燥Influence of creep on drying shrinkage—徐变对干缩的影响Prediction of creep in concrete structures—混凝土结构的徐变预测l Cored concrete—混凝土芯样l Curing—养护Influence of curing on durability—养护对耐久性的影响Influence of curing on concrete strength—养护对混凝土强度的影响Membrane—薄膜Wet curing—湿养l C3A—铝酸三钙l C4AF—铁铝酸四钙l C3S—硅酸三钙l C2S—硅酸二钙l C-S-H—水化硅酸钙Dl Damage→deterioration—损伤→劣化l DEF—延迟钙矾石形成l Degree of compaction—密实度In shotcrete—喷射混凝土l Degree of consolidation—密实度l Degree of hydration—水化程度l Depassivation—去钝化l Deterioration—劣化l Drying shrinkage→shrinkage—干缩→收缩l DSP一致密小颗粒混凝土l Durability—耐久性Capillary porosity—毛细管孔隙率Concrete cover—混凝土保护层Exposure classes—暴露等级Long term durability—长期耐久性El Entrained air一引气Influence on freezing—对抗冻性的影响Influence on strength—对强度的影响l Entrapped air—夹杂气体l Ettringite—钙矾石Primary—一次Secondary—二次l Expansive agents→Shrinkage compensating concrete—膨胀剂→收缩补偿混凝土Fl Fibre-inforced concrete ( FRC )—纤维增强混凝土Application of FRC一纤维增强混凝土的应用Crack-free concrete一无裂缝混凝土Toughness of concrete—混凝土的韧性Impact strength—冲击强度In shotcrete—喷射混凝土Metallic fibre—金属纤维Polymer mini-fibre—聚合物微纤维Polymer macro-fibre—聚合物大纤维Polymer structure PVA fibres—聚合物结构聚乙烯醇纤维l Fictitious thickness一虚拟厚度l Fire endurance of concrete一混凝土的耐火性Behavior of concrete during fire一混凝土在火中的行为Behavior of high-strength concrete during fire—高强混凝土在火中的行为Influence of the aggregate—骨料的影响Influence of the concrete cover—混凝土保护层的影响Influence of the metallic fibres一金属纤维的影响Influence of the loading in service一服役荷载的影响Influence of the polymeric fibres—聚合物纤维的影响l Fly ash—粉煤灰Beneficiation—选矿l Freezing and thawing一冻融l Füllerl Füller&Thompson→FüllerGl GGBFS→slag—磨细粒化高炉矿渣→矿渣l Gluconate—葡萄糖酸盐l Glucose—葡萄糖l Grout—浆体l Gypsum—石膏Hl Heat—热Cracking due to thermal gradients—温度梯度诱发开裂Of hydration—水化热l Hydration—水化Of aluminates—铝酸盐的水化Of silicates—硅酸盐的水化l High-Performance Concrete—高性能混凝土l High Strength Concrete—高强混凝土l Hooke law—Hooke定律Kl Kiln一烧窑Ll Leaching—析浆l Lightweight concrete—轻混凝土Glassification—分类Expanded clay—陶粒Lightweight aggregate—轻骨料In the Rome Pantheon—罗马万神殿Natural lightweight aggregate(pumice)—天然轻骨料(浮石) Shrinkage—收缩Structural—结构的Precast L. C—预制轻混凝土SCC L. C—自密实轻混凝土Structural L. C for ready-mixed concrete—预拌结构轻混凝土l Lignosulphonate—木素磺酸盐l Lime—石灰l Limestone—石灰石Blended cement一混合水泥l Lyse rule—Lyse准则Ml Magnesium salts—镁盐l Mass concrete—大体积混凝土l Mix design—配合比设计l Modulus—模数Of elasticity—弹性模量Of fineness一细度模数l Mill一磨机l Municipal Solid Waste Incinerator一市政固体废物焚烧炉Pl Passivation—钝化l Permeability—渗透性l Pop-out一凸起l Porosity—孔隙率Capillary—毛细管孔隙Capillary porosity and strength—毛细管孔隙率与强度Capillary porosity and elastic modulus—毛细管孔隙率与弹性模量Capillary porosity and permeability—毛细管孔隙率与渗透性Capillary porosity and durability—毛细管孔隙率与耐久性Gel—凝胶Macroporosity—大孔孔隙率l Portland cement—硅酸盐水泥Blended cements一混合水泥European norm—欧洲标准Ferric一铁相Manufacture—生产White—白色l Powers—能源l Pozzolan一火山灰Activity—活性Industrial—工业的l Pozzolanic cement一火山灰水泥l Precast concrete—预制混凝土Steam curing—蒸养l Prescriptions on concrete structures—混凝土结构的质量要求Concrete composition prescriptions—混凝土组成的质量要求Concrete performance prescriptions—混凝土性能的质量要求Contractor prescriptions一对承包商的要求Rl Reactive Powder Concrete一活性粉末混凝土l Recycled concrete一再生混凝土Process of manufacturing recycled aggregate (RA)一再生骨料的加工工艺Properties of RA一再生骨料的性能Contaminant products—污染物Density of RA一再生骨料的密度Water absorption—吸水率Properties of concrete with RA—含有再生骨料混凝土的性能l Relaxation—松弛l Retempering—重拌合Sl Segregation—离析l SCC→Self-Compacting Concrete—自密实混凝土l Self-Compacting Concrete—自密实混凝土Architectural一装饰High strength—高强Mass concrete—大体积混凝土Lightweight concrete—轻混凝土Shrinkage-compensating—收缩补偿l Setting—凝结l Shrinkage—收缩Drying shrinkage—干缩Influence of aggregate on drying shrinkage一骨料对干缩的影响Influence of high range water reducers on drying shrinkage—高效减水剂对干缩的影响Influence of workability on drying shrinkage一工作性对干缩的影响Prediction of drying shrinkage in concrete structures—混凝土结构干缩的预测Plastic shrinkage—塑性收缩Standard shrinkage—标准收缩l Shrinkage-compensating concrete—收缩补偿混凝土Expansive agents—膨胀剂Combined use of SRA and expansive agents—减缩剂和膨胀剂的结合应用Lime-based expansive agents—石灰基膨胀剂Sulphoaluminate-based expansive agents—硫铝酸盐基膨胀剂Application of shrinkage compensating concrete—补偿收缩混凝土的应用Joint-free architectural buildings—无缝装饰建筑Joint-free industrial floor一无缝工业地板Repair of damaged concrete structures—损坏混凝土结构的修补Expansion of specimen vs. that of structure—试件的膨胀与结构的膨胀Restrained expansion—约束膨胀SCC shrinkage-compensating concrete—自密实收缩补偿混凝土l Shotcrete—喷射混凝土ACI recommendations—ACI建议Bond of shotcrete. to substrate—喷射混凝土与基层的粘结Chemical admixtures in—喷射混凝土的化学外加剂Alkali-free accelerators—无碱促进剂Sodium silicate accelerators—硅酸钠促进剂Composition of一喷射混凝土组成Fibres in—喷射混凝土的纤维High performance—高性能喷射混凝土Influence of steel bars on—配筋的影响Mineral additions in—矿物掺合料Nozzelman喷枪操作工Rebound—回弹l Sieve analysis—筛分l Silica fume—硅灰Silica fume in high strength concrete—高强混凝土中的硅灰l Slag—矿渣Cement—矿渣水泥l Slump—坍落度Slump loss—坍落度损失l SRA→Shrinkage Reducing Admixture in Chemical Admixtures-一化学外加剂中的减缩剂l Standard deviation一标准差l Steam curing—蒸养l Steel-concrete bond—钢筋-混凝土的粘结l Strength—强度Characteristic一特征强度Class of cement—水泥的强度等级Class of concrete一混凝土的强度等级Compressive—抗压强度DSP concrete—细颗粒密实混凝土Flexural—抗折强度High-strength concrete—高强混凝土Influence of compaction on一密实性对强度的影响Influence of cement on concrete一水泥对混凝土强度的影响Influence of temperature on concrete—温度对混凝土强度的影响Influence of transition zone on—过渡区对强度的影响Of cement paste—水泥浆的强度Of cored samples一芯样的强度Of specimens—试件的强度Standard deviation—标准差Tensile—抗拉强度l Stress—应力Compressive—压应力Flexural—弯曲应力Tensile一拉应力l Sulphate attack—硫酸盐侵蚀l Superplsticizer→Chemical. admixtures—超塑化剂(高效减水剂)→化学外加剂Tl Temperature—温度Influence of temperature on concrete strength—温度对强度的影响Influence of temperature on site organization—温度对现场浇筑的影响Placing in summer time一夏季浇筑Placing in winter time一冬季浇筑l Thaumasite—硅灰石膏l Thermal gradients—温度梯度l Transition zone—过渡区Vl Vebe—维勃l Vibration—振动Wl Water—水And workability—水与工作性And strength.一水与强度Addition on job site一水的现场添加l Water-cement ratio—水灰比l Workability—工作性And consolidation—工作性与密实性。
混凝土基本原理词汇
------1-------Concrete structure 混凝土结构Reinforced Concrete structure 钢筋混凝土结构Plain Concrete structure 素混凝土结构Prestressed Concrete structure 预应力混凝土结构Fibre reinforced Concrete structure 纤维增强混凝土结构Rebar (reinforcement) 钢筋Compressive strength 抗压强度Tensile strength 抗拉强度Section 截面Crack 裂缝Stress 应力Strain 应变Beam 梁Bond 粘结Coefficient 系数Rust 生锈Brittle 脆性Ductility 延性Moldability 可焊接性Cast 浇注Strength-cost ratio 强价比Fire-resistance 抗火Wood structure 木结构Masonry structure 砌体结构Steel structure 刚结构Monolithic 整体性Self-weight 自重Span 跨度Light-weight 轻质的High-strength 高强的High-performance concrete 高性能混凝土Prefabrication 预制Plastic 塑性的Load-carrying capacity 承载能力Elastic 弹性的Multiaxial 多轴的scale effect 尺寸效应size effect尺寸效应bond 粘结slip 滑移deformation 变形code 规范adherence 粘结bond 粘结friction 摩擦shrinkage 收缩harden 硬化grip 握裹effect 效应expansion 膨胀water-cement ratio 水灰比matching 匹配impact/collision 冲击static 静力的dynamic 动力的linear 线性的nonlinear 非线性的dissipation 耗散isolation 孤立active control 主动控制torsional 扭的local damage 局部损坏collapse 失效，倒塌road curb walls 道路护栏bridge piers 桥墩dike 岸堤vibration 振动steel-encased concrete structure 钢骨混凝土结构concrete-infilled steel tube structures 钢管混凝土结构steel-concrete composite structuresflow property 流动性permeability 渗透性spray 喷射shear strength 抗剪强度rupture strength 抗弯强度fatigue 疲劳matrix 基体aseismic 抗震的frame 框架hydraulic 水力的synthetic fiber 人造纤维toughness 韧性alkaline 碱性的carbon fiber 碳纤维strengthening 加固member 构件solid web 实腹式open web 空腹式buckle 屈曲-------- 2---------Mechanical 力学的Physical 物理的Hardened cement 水泥石Cement mortar 水泥砂浆Coarse aggregates 粗骨料Base phase 基相Dispersed phase 分散相Dissociative water 游离水Capillary 毛细管Gel 凝胶Skeleton 骨架Unhydrated 未水化的Plastic rheological bodies 塑性流变体Cavity 洞、孔隙Microcrack 微裂缝Microstructure 微观结构Mesostructure 亚微观结构Macrostructure 宏观结构Uniaxial 单轴的Specimen 试件Reliability 可靠性size effect 尺寸效应The conversion coefficient 转换系数Prism棱柱Regression 回归分析Lateral 侧向的Additional eccentricity 附加偏心距Cylinder 圆柱体Instability 失稳Mechanism 机制Quasi-elastic 准弹性Stress concentration 应力集中Non-recoverable 不可恢复的Curve 曲线Critical stress临界应力Coalesce 结合Parallel 平行的Dilation 膨胀Disintegration 瓦解Splitting test 劈裂试验Local bearing strength 局部承载强度Triaxial 三向轴的Empirical 经验的Monotonic 单调的Inflection point 反弯点Convergence point 收敛点Elastic strain 弹性应变Plastic strain 塑性应变Viscous 粘性的The proportional limit 比例极限Helical stirrups 螺旋箍筋Square stirrups 方形箍筋Longitudinal rebars 纵向钢筋Pitch 螺旋的间距螺旋线上两个相应的点之间的距离Gauge length （仪器的）测量长度Slope 斜率Modulus 模数，模量Shear modulus 剪切模量, 剪切弹性模数[系数] Moduli 模数，模量（复数）Tangential modulus 切线模量Secant modulus/deformation modulus 割线模量After-effect 后效Instantaneous strain 瞬时应变Residual strain 残余应变Creep 徐变Long-term loading 长期作用V olume-surface ratio 体表比Yield point 屈服点Flexible reinforcement 柔性钢筋Stiff reinforcement 刚性钢筋Steel shape 型钢Smooth bar，plain bar 光面钢筋Helical ribs 螺旋肋Herringbone ribs 人字肋Crescent ribs 月牙肋Weldability可焊性Hot-rolled bars 热轧钢筋Tendon预应力筋Steel strand钢绞线Yield plateau 屈服平台Indices 指标（index的复数）Elongation ratio 伸长比Fracture 破裂，断裂Cold working 冷加工Cold drawing 冷拉Cold pulling 冷拔Extrusion 挤压Elasto-plastic 弹塑性Bauschinger effect 包兴格效应Spatial loading 空间荷载Additional slanted bar 附加斜筋Stirrups 箍筋Erection bar 架立钢筋Main bar 主筋Bent-up bar 弯起钢筋Hook 弯钩In-situ 现场Anchorage 锚固Ultimate limit state 极限状态Serviceability limit state 使用性能极限状态Action 作用Effect 效应Direct action 直接作用Load effect 荷载效应Permanent load 恒载Variable load 可变荷载Accidental load 偶然荷载Function 函数Reliability 可靠性probability概率Possibility 可能性The design reference period 设计基准期Variable 变量Normal distribution 正态分布Mean value平均值Standard deviation标准偏差Partial safety factor 分项系数Optimization 优化Index 指数--------3-------Truss 桁架Frame 框架Upper chord 上弦杆Failure load 破坏荷载Superposition 叠加Constitutive relation 本构关系Qualitative 定性的Quantitative 定量的Confinement 约束Web member 腹杆Bottom chord，lower chord 下弦杆Vertical 垂直的Linear 线性的Ultimate tensile strain 极限拉应变Geometric 几何的Non-uniformity 不均匀性Tension-load-carrying-capacity受拉承载力Normal section 正截面Perpendicular 垂直的Redistribution 重分布Nonlinearity 非线性Stiffness 刚度Secant stiffness 割线刚度Tension-stiffening effect 拉伸刚化效应Compatibility 兼容性transformed section 换算截面reinforcement ratio 配筋率Ultimate load 极限荷载Short column 短柱Lateral deflection 侧向挠度Additional moment 附加弯矩Long column 长柱Subdividing 再分，细分Deduction 推论Peak strain of concrete 混凝土应变峰值Peak stress 应力峰值Static problems 静力问题Dynamic problems 动力问题Definition 定义Creep coefficient 徐变系数Instantaneous 瞬时的Figure 图形Unloading 卸载Reloading 重加载Creep strain 徐变应变Long-term loading 长期荷载Eccentricity 偏心Second-order effect 二阶效应Slenderness ratio 长细比Stability coefficient 稳定系数Welded circular stirrups 焊接环箍筋Symmetric polygon section 正多边形截面Cover concrete 保护层混凝土Spalling 剥落Passive constraint 被动约束Optimum 最佳的-------------------------moment of inertia惯性矩diagonal compression failure斜压破坏diagonal tension failure斜拉破坏shear compression failure剪压破坏internal force内力crack裂缝ultimate strain极限应变plastic塑性的rebar钢筋yield屈服moment弯矩stiffness刚度plane section assumption平截面假定under-reinforced beam适筋梁over-reinforced beam超筋梁eccentric偏心的section截面stirrups箍筋curvature曲率design设计analysis分析shear剪切，剪力flexure弯曲bending弯曲principal stress主应力anchorage锚固diagonal crack斜裂缝equilibrium平衡compatibility协调mechanism机理aggregate interlock骨料咬合dowel action销栓作用web reinforcement腹筋arch action拱作用truss桁架cantilever悬臂梁torsion扭转specimen试件torque扭矩elasticity弹性，弹性力学slope斜率section modulus截面模量box section箱形截面shear flow剪力流punching冲切local局部的punching shear冲剪，冲切column柱foundation基础slab板variable变量bent-up bar弯起筋bond粘结hook弯钩deformed bar变形钢筋splice搭接simply supported beam简支梁detailing构造support支座joint节点prestress预应力pre-tension先张post-tension后张camber反拱jack千斤顶tendon预应力筋construction施工duct孔道jacking张拉abutment支墩grout灌浆prestress loss预应力损失unbonded无粘结的steel wire钢丝steel strand钢绞线temper回火quench淬火heat treated热处理的relaxation松驰corrugated tube波纹管anchorage锚具control stress控制应力serviceability使用性能deflection挠度。
建筑专业土木工程词汇及术语 中英文对照
工程英语结构工程常用词汇土木工程常用英语术语目录结构工程常用词汇 (1)土木工程常用英语术语 (2)第一节一般术语 (2)第二节房屋建筑结构术语 (5)第三节公路路线和铁路线路术语 (6)第四节桥、涵洞和隧道术语 (7)第五节水工期建筑物术语 (9)第六节结构构件和部件术语 (11)第七节地基和基础术语 (15)第八节结构可靠性和设计方法术语 (15)第九节结构上的作用、作用代表值和作用效应术语 (17)第十节材料性能、构件承载能力和材料性能代表值术语 (21)第十一节几何参数和常用量程术语 (23)第十二节工程结构设计常用的物理学、数理统计、 (25)结构工程常用词汇混凝土：concrete钢筋：reinforcing steel bar钢筋混凝土:reinforced concrete(RC）钢筋混凝土结构:reinforced concrete structure板式楼梯:cranked slab stairs刚度：rigidity徐变：creep水泥：cement钢筋保护层：cover to reinforcement 梁：beam柱：column板:slab剪力墙：shear wall基础:foundation剪力：shear剪切变形:shear deformation剪切模量:shear modulus拉力：tension压力：pressure延伸率：percentage of elongation位移：displacement应力：stress应变：strain应力集中：concentration of stresses 应力松弛：stress relaxation应力图:stress diagram应力应变曲线：stress-strain curve应力状态：state of stress钢丝:steel wire箍筋：hoop reinforcement箍筋间距：stirrup spacing加载：loading抗压强度:compressive strength抗弯强度：bending strength抗扭强度：torsional strength抗拉强度：tensile strength裂缝:crack屈服：yield屈服点：yield point屈服荷载：yield load 屈服极限：limit of yielding屈服强度：yield strength屈服强度下限：lower limit of yield荷载:load横截面:cross section承载力：bearing capacity承重结构:bearing structure弹性模量:elastic modulus预应力钢筋混凝土:prestressed reinforced concrete预应力钢筋:prestressed reinforcement预应力损失:loss of prestress预制板：precast slab现浇钢筋混凝土结构：cast—in—place reinforced concrete双向配筋：two—way reinforcement主梁：main beam次梁：secondary beam弯矩：moment悬臂梁：cantilever beam延性：ductileity受弯构件：member in bending受拉区：tensile region受压区：compressive region塑性:plasticity轴向压力：axial pressure轴向拉力：axial tension吊车梁：crane beam可靠性：reliability粘结力:cohesive force外力：external force弯起钢筋:bent-up bar弯曲破坏：bending failure屋架：roof truss素混凝土：non-reinforced concrete无梁楼盖：flat slab配筋率：reinforcement ratio配箍率：stirrup ratio泊松比:Poisson’s ratio偏心受拉：eccentric tension偏心受压：eccentric compression偏心距：eccentric distance 疲劳强度：fatigue strength 偏心荷载：eccentric load跨度:span跨高比：span-to-depth ratio 跨中荷载:midspan load框架结构：frame structure集中荷载：concentrated load 分布荷载：distribution load 分布钢筋：distribution steel 挠度：deflection 设计荷载：design load设计强度：design strength 构造:construction简支梁:simple beam截面面积：area of section 浇注：pouring浇注混凝土：concreting钢筋搭接:bar splicing刚架：rigid frame脆性：brittleness脆性破坏：brittle failure土木工程常用英语术语第一节一般术语1。
混凝土结构中英文词汇（上）
混凝土结构中英文词汇（上）上册：立方体抗压强度cube s trength 极限状态limit s t at e ultim ate st ate预制混凝土pr efabricat ed concret e 现浇混凝土Cast-in-s itu concr ete预应力混凝土pr es tressed concr ete 设计基准期design refer ence per iod设计使用年限design wo rking life 收缩shrinkage双筋梁doubly r einfo r ced section 轴心受压柱axially loaded column偏心受压柱eccentrically loaded column 偏心距eccentricity 恒荷载permanent load o r dead l oad 活荷载variable load o r live load组合系数co mbinatio n r educt io n fact o r准永久值系数quasi-pe rm anent reducing coefficient结构重要性系数coefficient of s tructural impo rtance 界限配筋balanced r einfo r cement超筋over-reinfo r ced 适筋under-reinfo r ced等效应力矩形equivalent s tress block 最小配筋率minimu m st eel r atio 最大配筋率balanced s t eel r atio 截面有效高度effect ive dept h双筋梁doubly r einfo r ced sect ion T形截面翼缘flangeT形截面腹板web 有效翼缘宽度effective flange width主压应力迹线tr aject o ries of the pr incipal co m pressive s tress 斜裂缝diagonal cr ack腹筋transver se r einfo r cem e nt; web r einfo r cem ent 箍筋ties o r stirrups弯起钢筋inclined bar s bent-up bar s 斜拉破坏diagonalsplitting剪压破坏shear co mpr ession 斜压破坏diagonal co m pression 剪跨比shear span r atio 名义剪跨比gener alized shear span配箍率transver se tie r atio 材料弯矩抵抗图diagr am of bending resis t ance不需要面cut-o ff sect io n 充分利用面fully-developed section 充分利用点fully usable point of bar理论截断点t heo r etical cutting point of bar实际截断点r eal cutting point of bar锚固长度ancho r age length 绑扎搭接binding lapped splice 钢筋表bar schedule 连接区段connection sect o r肋梁楼板结构girder-beam-s lab structural sys t em现浇楼板cas t-in-place slab 预应力楼板pr e-cast slab刚度r igidity 弯矩包络图m o m ent envelope diagr am;ultimat e m o m ent diagram剪力包络图shear envelope diagr am塑性铰plas t ic hinge无梁楼盖flat slab塑性内力重分布法plas t ic r edis tribution of s tresses analysis m et hod弯矩调幅法t he m ethod of amplitude m odulation fo r bending m o m ent CHAPTER 1Plain Concr ete 素混凝土，Reinfo r ced Concr ete 钢筋混凝土，Pr estr essed Concr ete 预应力混凝土，r einfo r cement s t eel bar钢筋（也有人直接用bar,fiber），Po rtland cem ent波特兰水泥Light-weight concr ete 轻质混凝土，high-s trength concret e 高强混凝土，Fiber r einfo r cedconcr ete（FRC）纤维混凝土load 荷载，span 跨径，s tr ain 应变，str ess 应力，co m pression 压力，t ension 拉力，m o m ent弯矩，t o r sion 扭矩，扭转thermal expansion coefficient s 热膨胀系数，co rrosion pr o t ection 防腐蚀，Fir e r esis t ance耐火，hollow floo r空心楼板，wall 墙面，girder主梁，beam横梁，column 柱，foo ting 基础allowable s tress design m et hod 允许应力法，ultimat e s trength design method 极限强度设计法，limit s t at e design m et hod 极限状态设计法，co m posit e s truct ure 混合结构CHAPTER 2sm oo t h bar光圆钢筋，defo rm ed bar螺纹钢筋，ho t r olled bar热轧钢筋，cold dr awn bar冷拉钢筋，st eel wires 钢绞线，heat tr eat ed s t eel bar热处理钢筋stress-s train curve 应力应变曲线，yield plat eau 屈服平台defo rmation 变形，deflection 挠度，yield s tr ength 屈服强度，ultimat e strength 极限强度，ductility 韧性，har dening 强化，cold dr awn 冷拉，t empering treatm ent 回火，quenching tr eatment淬火fatigue 疲劳，shrinkage 收缩，cr eep 徐变，cr ack 开裂,cr ush 压溃wat er-cem ent ratio 水灰比cubic co mpr essive s tr ength 立方体抗压强度，pris m atic co m pressive strength 棱柱体抗压强度elas ticity m odulus 弹性模量（杨氏模量），secant m odulus 割线模量，t angent m odulus 切线模量，shear m odulus 剪切模量，poisso n’s r atio 泊松比uniaxial t ension 单轴拉伸，biaxial loading 双轴加载，triaxial loading 三轴加载CHAPTER 3bond 粘结，ancho r age 锚固，bar splicing 钢筋搭接，splitting 撕裂，cr ush 压溃，pull-o ut failure 刮出式破坏splice length 搭接长度，em bedded length 埋置长度，developm ent length 锚固长度shape coefficient外形系数ribs 钢筋肋CHAPTER 4axial load 轴向加载，axial t ension 轴向拉伸，axial co mpr ession 轴向压力elas ticity 弹性，plas t icity 塑性longitudinal bar s 主筋（纵向钢筋），s t irrup 箍筋，hanger bar架立筋，bent bar弯起钢筋brittle failure 脆性破坏，load carrying capacity 承载能力sho rt column 短柱，slender colu mn 长柱，s t ability coefficient稳定系数cr oss section 截面，cr oss-sectional dimension 截面尺寸spiral stirrup 螺旋箍筋CHAPTER 5box sect ion 箱形截面，hollow slab 空心板，T-sect io n T 形截面over-reinfo r ced beam超筋梁，under-reinfo r ced beam少筋梁，balanced-reinfo r ced beam适筋梁brittle failure 脆性破坏concr ete cover混凝土保护层minimum r einfo r cem ent ratio 最小配筋率flexure theo ry 弯曲理论，plane sect io n assumption 平截面假定neutr al axis 中性轴，coefficient系数，par amet er参数，cons t ant常数stress dis tributio n 应力分布，shear span r atio 剪跨比stress block dept h 应力区高度（受压区高度），r elative s tr ess block dept h 相对应力区高度（相对受压区高度），n o minal str ess block dept h 名义应力区高度（名义受压区高度），flexural capacity 抗弯承载能力symm etry reinfo r cement对称配筋effect ive flange width 有效翼缘宽度，flange 翼缘，web 腹板shear-lag effect剪力滞效应sim ple-suppo rted beam简支梁，continuous beam连续梁deep-bending m ember深受弯构件，deep beam深梁，tr ansfer girder转换梁，tie-reinfo r cem ent拉结筋，ho rizontal dis tributing r einfo r cem ent水平分布钢筋spacing 间距CHAPTER 6eccentricity 偏心率，second-o r der effect二阶效应ultim ate limit st at e 使用极限状态additio nal eccentricity 附加偏心距eccentricity magnifying coefficient偏心距放大系数t ensile failur e 受拉破坏，co mpr essive failur e 受压破坏larger eccentricity 大偏心，s m all eccentricity 小偏心out-plane s trength 片面外强度geo m etric centr al axis 几何中心轴CHAPTER 7shear failu r e 剪切破坏diagonal t ension 斜向拉应力shear flow 剪力流diagonal cr acks 斜裂缝，flexural cr ack 弯曲裂缝，co m pression s trut受压杆web r einfo r cem ent腹筋（抗剪钢筋）truss m odel 桁架模型sl ope angle 倾角upper end of t he cr ack 裂缝上端maximu m spacing of s tirrup 箍筋最大间距concentrat ed load 集中荷载，unifo rm load 均布荷载det ailing r equirement构造要求m o m ent envelope 弯矩包络图，m o m ent diagram弯矩图em bedded length 锚固长度point s of bend 弯起点CHAPTER 8equilibrium t o r s ion 均衡扭转，co m patibility t o r s ion 协调扭转st atic equilibrium静力平衡principal s tr ess 主应力cr acking t o rque 开裂弯曲transver se r einfo r cement横向钢筋elas t o-plas t ic m ode 弹塑性模型Plas t ic space truss design m ethod 塑性空间桁架设计方法，Skew bending design m ethod斜弯设计方法hollow sect io n 空心截面per im eter周长hook 弯钩minimum s t irrup r atio 最小配箍率dis tributio n of r einfo r cem ent钢筋分布CHAPTER 9punching shear冲切，local co m pression 局部受压two way shear双向剪切slab-column joint板柱交接点column cap 柱帽，dr op panel 托板linear interpolatio n 线形内插effect ive dept h 有效高度cr itical width 临界宽度punching shear cone 冲压椎体polar m o m ent of inertia 极惯性矩net ar ea 净面积spiral stirrup 螺旋箍筋，m at r einfo r cement钢筋网splitting 劈裂，chipping 崩裂CHAPTER 10pr es tressed concr ete 预应力混凝土pr et ensioning sys t em先张法，pos t-tensioning sys t em后张法wire 钢丝，s trand 钢绞线，t endon 钢束bo tt o m台座，cas t ing-yard 预制场duct孔道，jack 张拉，gr out灌浆，bond 粘结，unbond 无粘结frictio n 摩擦full pr es tr essing 全预应力，partial pr es tressing 部分预应力cr eep 徐变，shrinkage 收缩stress loss 应力损失gripper s 夹具，ancho r age 锚具permissible s tress 容许应力，s tret ching s tr ess 拉伸应力，effectivepr es tress 有效预应力loss of pr es tress 预应力损失，loss due t o friction 摩擦损失，ancho r age-sect io ns 锚具滑移，elas t ic sho rt ening of concret e 混凝土塑性回缩，s t eel s tress r elaxation 钢筋应力松弛，cr eep loss 徐变损失，shrinkageloss 收缩损失t endo n pr o file 钢束形状，deviation fo r ce 偏向力，curvature effect曲率效应，wobbleeffect抖动效应fixed end 固定端，t ension end 张拉端over s tret ching 超张拉curvat u r e frictio n coefficient曲率摩擦系数transfer length 传递长度，bond s tr ess 粘结应力concr ete depositing 混凝土浇注service st age 使用阶段，cons truction s t age 施工阶段Transfo rm ed ar ea 换算面积，m o m ent of inertia 惯性矩hois ting 吊装，tr anspo rting 运输dynamic fact o r动力系数or dinary r einfo r ced s t eel 普通钢筋no rm al section 正截面，oblique section 斜截面CHAPTER 11serviceability 使用性能reliability 可靠性：safety 安全，applicability 实用，dur ability 耐久deflection 挠度，cr ack width 裂缝宽度transver se cr ack 横向裂缝，plas t ic cr ack 塑性裂缝，t emper ature cr ack 温度裂缝，shrinkage cr ack 收缩裂缝，cr acks due t o r us t锈蚀引起的裂缝，cr acks due t o differ ential settle m ent 不均匀沉降引起的裂缝，l oad-induced cr ack 荷载引起的裂缝freezing-thawing 冻容，alkali-aggr egat e r eact io n 碱骨料反应st andar d value 标准值，frequent value 频遇值，quasi-permanent value 准永久值maximu m cr ack width 最大裂缝宽度cr ack co ntr o l 开裂控制bond-s lip t heo ry 粘结滑移理论，no n-s lipping t heo ry 无滑移理论flexural s t iffness 弯曲刚度__。
混凝土名词解释
混凝土名词解释1．混凝土的收缩：混凝土水化后会将其中的水分都吸收，造成本身体积变小的现象叫做混凝土收缩。
2．线性徐变：混凝土在长期荷载作用下沿着作用力方向随时间不断增长荷载不变而变形随时间增大，这种在长时间荷载作用下产生的变形叫做徐变，线性徐变就是时间和变量成正比，比例为常数。
3．相对受压区高度：受拉钢筋和受压区混凝土同时达到其设计值时的混凝土受压区高度与截面有效高度的比值。
4．大偏心受拉构件：当偏心受拉构件轴向力N 作用在s A 和s A ⋅合理点范围之外时，为大偏心受拉构件。
5．折算荷载：板梁系整体连接，计算时视为铰接，二者存在着差异，为了考虑支座抵抗转动的有利影响，采用增大恒荷载和相应减小活荷载的办法来处理，调整后的荷载称为这算荷载。
6．荷载效应：建筑结构设计中，由荷载引起结构或结构构件的变形，裂缝等现象就是荷载效应。
7．非线性徐变：当混凝土应力较大（c σ>0.50c f ）时，徐变变形与应力不成正比，徐变比应力增长更快，称非线性徐变。
8．界限相对受压区高度：界限受压区计算高度与截面有效高度的比值叫做界限相对受压区高度。
9．T 形截面梁：、把矩形截面受弯构件受拉区的混凝土挖去一部分，并把纵向受拉钢筋集中放在腹板内，由腹板和翼缘两部分组成。
它的正截面受弯承载力与原矩形截面是相同的，但可节省混凝土，也减轻了构件自重。
10．活荷载最不利布置：（1）求某跨跨中截面最大正弯矩时，应在本跨内布置活荷载，然后隔跨布置，（2）求某跨中截面最小正弯矩（或最大正弯矩）时，本跨不布置活荷载，而在相邻跨布置活荷载，然后隔跨布置。
（3）求某一支座截面最大负弯矩时，应在该支座，左右两跨布置活荷载，然后隔跨布置。
（4）求某支座左右的最大剪力时，活荷载布置与求该支座截面最大负弯矩时的布置相同。
11．结构抗力：结构抗力是指整个结构或结构构件承受荷载效应的能力。
12．混凝土的弹性模量：在混凝土的应力-应变曲线的原点引切线，此切线的斜率定义为混凝土的弹性模量。
混凝土收缩
混凝土表面 泌水速率 < 蒸发速率 开裂
荷载导致的变形——徐变
• 荷载作用下超过弹性应变和自由干燥收 缩应变总和的变形。
• 徐变的原因是在荷载作用下，C-S-H凝胶 失去物理吸附水。
• 徐变有可逆与非可逆的区分。
干燥与徐变的可逆性
影响干缩与徐变的因素
• 材料与配合比
Powers认为混凝土收缩（SC）和水泥浆收缩 （SP）之比与混凝土中骨料的体积分数（g） 有指数关系：
• 水泥的细度和组分影响水化速率，但不影响水 化产物的体积和特性。水泥的细度和组分变化 可影响砂浆或净浆试件的干缩，但对混凝土无 甚影响。如果水泥品种对混凝土强度有影响时， 则也将影响混凝土的徐变。
• 水泥用量和用水量不直接影响混凝土的干缩和 徐变。
• 时间与湿度：混凝土中水分扩散是缓慢的过程。 两周仅完成20年干缩的20~25%；3个月完成 50~60%；1年完成75~80%。
开裂的影响因素
• 材料因素：胶凝材料的细度、水化速率、 水化热、强度发展速率。
• 配合比因素：水胶比、浆体含量、骨料 弹性模量。
• 约束因素：体积、配筋率 • 环境因素：气温、风速、湿度。
圆环试验结果
1
Yj普通 - 7d 0.9
Yc 高强 - 2.5d 0.8
Yk 矿渣 - 30% - 2d
0.7
[Lmax ] 2
EH arcch T
Cx
T p
式中：E：混凝土的弹性模量 H：结构物高（厚）度 Cx：地基水平阻力系数 α：温度变形系数 εp：极限应变，应考虑配筋和徐变的影响 T：温度差，包括水化温差、气温差、收缩当量温差
• 底板与垫层间的摩擦情况影响开裂间距。 • 通常│αT│大于│εp│，两者差越大，开裂间距
高强与高性能混凝土06收缩综述
高强与高性能混凝土06收缩综述P. C. Aïtcin, A. M. Neville, and P. Acker“收缩”看起来似乎就是混凝土失水造成体积缩小的简单现象。
严格地说，它是三维变形，但通常以线性变形表示，因为大多数情况下，混凝土构件一个或两个方向的尺寸往往要比第三个方向小很多，尺寸最大的方向上收缩也最大。
通常所谓收缩，是混凝土暴露在相对湿度小于100%的空气中产生“干燥收缩”的简称。
然而由于环境的作用，混凝土还会产生许多其它种类的收缩变形，它们彼此独立地发生或者同时出现。
文章提出了一些建议，以便尽量减小混凝土，尤其是高性能混凝土，由于收缩带来非常有害的结果。
硬化混凝土发生的干燥收缩是大家所最熟悉的。
按照时间顺序来划分，干燥收缩发生之前，即混凝土尚处于塑性状态时产生的收缩是塑性收缩。
通常，水分是往大气蒸发的，但也有可能被结构物下面干燥的混凝土或土壤所汲取。
其次，硬化混凝土的收缩变形，还由于水泥水化的进行所导致。
因为这种收缩发生在混凝土体内，与周围介质不相干，常称之为“自干燥收缩”(self-desiccation shrinkage)。
表示该收缩现象的另一个术语是“自身收缩”(autogenous shrinkage)，在这里用该术语是为了与所有有关收缩的称呼相对应，偶尔也称其为“化学收缩”。
收缩变形还会自混凝土凝固，即构件体积与重量不再变化时，因温度下降而产生，这里称其为热收缩。
此外，水化水泥浆，在有水分存在时，与大气里的二氧化碳反应，要产生碳化收缩。
上述各种收缩，或某几种收缩同时产生时，它们的和称为总收缩。
为了充分地认识各种收缩的机理，首先要了解水泥的水化及其物理、力学与热力学作用，在此基础上才可能采取适当的方法，以减小各种收缩或者减轻它们造成的后果。
所谓水泥的水化，是硅酸盐水泥与水发生化学反应时出现几种现象的总称。
该反应生成有粘结力与粘附性的固相——水化水泥浆——混凝土产生强度的基图1—水化“永恒的三角”：强度、热和水化本成分。
混凝土行业中英文单词对照表
混凝土行业中英文单词对照表1. 混凝土 Concrete2. 水泥 Cement3. 砂子 Sand4. 石子 Aggregate5. 混凝土搅拌车 Concrete Mixer Truck6. 混凝土泵车 Concrete Pump Truck7. 模板 Formwork8. 钢筋 Reinforcement9. 混凝土浇筑 Concrete Pouring10. 混凝土养护 Concrete Curing11. 混凝土强度 Concrete Strength12. 混凝土抗渗性 Concrete Impermeability13. 混凝土抗冻性 Concrete Frost Resistance14. 混凝土耐久性 Concrete Durability15. 混凝土裂缝 Concrete Crack17. 混凝土施工工艺 Concrete Construction Technology18. 预制混凝土构件 Precast Concrete Component19. 现浇混凝土 Castinsitu Concrete20. 混凝土外加剂 Concrete Admixture21. 混凝土试验 Concrete Test22. 混凝土检测 Concrete Inspection23. 混凝土修复 Concrete Repair24. 混凝土结构设计 Concrete Structure Design25. 混凝土建筑 Concrete Construction26. 混凝土框架 Concrete Frame27. 混凝土梁 Concrete Beam28. 混凝土柱 Concrete Column29. 混凝土板 Concrete Slab30. 混凝土基础 Concrete Foundation31. 混凝土路面 Concrete Pavement32. 混凝土桥梁 Concrete Bridge33. 混凝土隧道 Concrete Tunnel34. 混凝土预制件 Concrete Precast35. 混凝土配合比 Concrete Mix Design36. 混凝土坍落度 Concrete Slump37. 混凝土搅拌站 Concrete Batching Plant38. 混凝土输送带 Concrete Conveyor Belt39. 混凝土喷射 Concrete Spraying40. 混凝土装饰 Concrete Decoration41. 混凝土着色 Concrete Staining42. 混凝土雕刻 Concrete Sculpting43. 混凝土保护剂 Concrete Sealant44. 混凝土修补材料 Concrete Repair Mortar45. 混凝土表面处理 Concrete Surface Treatment46. 混凝土防滑 Concrete Antislip47. 混凝土隔声 Concrete Soundproofing48. 混凝土防火 Concrete Fireproofing49. 混凝土轻质 Lightweight Concrete50. 混凝土透水 Permeable Concrete这份对照表旨在帮助行业内的人员更好地理解和沟通混凝土相关的术语。
外文资料翻译——混凝土结构的耐久性
中文2915字毕业设计外文资料翻译（一）外文出处：Jules Houde 《Sustainable development slowed downby bad construction practices and natural and technological disasters》1、外文原文（复印件）毕业设计外文资料翻译（二）外文出处：Jules Houde 《Sustainable development slowed down by bad construction practices and natural and technological disasters》2、外文资料翻译译文混凝土结构的耐久性即使是工程师认为的最耐久和最合理的混凝土材料，在一定的条件下，混凝土也会由于开裂、钢筋锈蚀、化学侵蚀等一系列不利因素的影响而易受伤害。
近年来报道了各种关于混凝土结构耐久性不合格的例子。
尤其令人震惊的是混凝土的结构过早恶化的迹象越来越多。
每年为了维护混凝土的耐久性，其成本不断增加。
根据最近在国内和国际中的调查揭示，这些成本在八十年代间翻了一番，并将会在九十年代变成三倍。
越来越多的混凝土结构耐久性不合格的案例使从事混凝土行业的商家措手不及。
混凝土结构不仅代表了社会的巨大投资，也代表了如果耐久性问题不及时解决可能遇到的成本，更代表着，混凝土作为主要建筑材料，其耐久性问题可能导致的全球不公平竞争以及行业信誉等等问题。
因此，国际混凝土行业受到了强烈要求制定和实施合理的措施以解决当前耐久性问题的双重的挑战，即：找到有效措施来解决现有结构剩余寿命过早恶化的威胁。
纳入新的结构知识、经验和新的研究结果，以便监测结构耐久性，从而确保未来混凝土结构所需的服务性能。
所有参与规划、设计和施工过程的人，应该具有获得对可能恶化的过程和决定性影响参数的最低理解的可能性。
这种基本知识能力是要在正确的时间做出正确的决定，以确保混凝土结构耐久性要求的前提。
混凝土专业英语
Concrete curing
欢迎您的下载，
资料仅供参考！
致力为企业和个人提供合同协议，策划案计划书，学习课件等等
打造全网一站式需求
混凝土
Concrete
混凝土强度
Concrete strength
塌落度
Slump test
富混凝土
Rich concrete
预拌混凝土
Ready-mixed concrete
无筋混凝土
Plain concrete
细骨料混凝土
Fine concrete
细石混凝土
Pea gravel concrete
钢筋混凝土中英文资料外文翻译文献
钢筋混凝土中英文资料翻译1 外文翻译1.1 Reinforced ConcretePlain concrete is formed from a hardened mixture of cement ,water ,fine aggregate, coarse aggregate (crushed stone or gravel),air, and often other admixtures. The plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction lf the cement/water mix, resulting in hardened concrete. The finished product has high compressive strength, and low resistance to tension, such that its tensile strength is approximately one tenth lf its compressive strength. Consequently, tensile and shear reinforcement in the tensile regions of sections has to be provided to compensate for the weak tension regions in the reinforced concrete element.It is this deviation in the composition of a reinforces concrete section from the homogeneity of standard wood or steel sections that requires a modified approach to the basic principles of structural design. The two components of the heterogeneous reinforced concrete section are to be so arranged and proportioned that optimal use is made of the materials involved. This is possible because concrete can easily be given any desired shape by placing and compacting the wet mixture of the constituent ingredients are properly proportioned, the finished product becomes strong, durable, and, in combination with the reinforcing bars, adaptable for use as main members of anystructural system.The techniques necessary for placing concrete depend on the type of member to be cast: that is, whether it is a column, a bean, a wall, a slab, a foundation. a mass columns, or an extension of previously placed and hardened concrete. For beams, columns, and walls, the forms should be well oiled after cleaning them, and the reinforcement should be cleared of rust and other harmful materials. In foundations, the earth should be compacted and thoroughly moistened to about 6 in. in depth to avoid absorption of the moisture present in the wet concrete. Concrete should always be placed in horizontal layers which are compacted by means of high frequency power-driven vibrators of either the immersion or external type, as the case requires, unless it is placed by pumping. It must be kept in mind, however, that over vibration can be harmful since it could cause segregation of the aggregate and bleeding of the concrete.Hydration of the cement takes place in the presence of moisture at temperatures above 50°F. It is necessary to maintain such a condition in order that the chemical hydration reaction can take place. If drying is too rapid, surface cracking takes place. This would result in reduction of concrete strength due to cracking as well as the failure to attain full chemical hydration.It is clear that a large number of parameters have to be dealt with in proportioning a reinforced concrete element, such as geometrical width, depth, area of reinforcement, steel strain, concrete strain, steel stress, and so on. Consequently, trial and adjustment is necessary in the choice of concrete sections, with assumptions based on conditions at site, availability of the constituent materials, particular demands of the owners, architectural and headroom requirements, the applicable codes, and environmental reinforced concrete is often a site-constructed composite, in contrast to the standard mill-fabricated beam and column sections in steel structures.A trial section has to be chosen for each critical location in a structural system. The trial section has to be analyzed to determine if its nominal resisting strength is adequate to carry the applied factored load. Since more than one trial is often necessary to arrive at the required section, the first design input step generates into a series of trial-and-adjustment analyses.The trial-and –adjustment procedures for the choice of a concrete section lead to the convergence of analysis and design. Hence every design is an analysis once a trial section is chosen. The availability of handbooks, charts, and personal computers and programs supports this approach as a more efficient, compact, and speedy instructionalmethod compared with the traditional approach of treating the analysis of reinforced concrete separately from pure design.1.2 EarthworkBecause earthmoving methods and costs change more quickly than those in any other branch of civil engineering, this is a field where there are real opportunities for the enthusiast. In 1935 most of the methods now in use for carrying and excavating earth with rubber-tyred equipment did not exist. Most earth was moved by narrow rail track, now relatively rare, and the main methods of excavation, with face shovel, backacter, or dragline or grab, though they are still widely used are only a few of the many current methods. To keep his knowledge of earthmoving equipment up to date an engineer must therefore spend tine studying modern machines. Generally the only reliable up-to-date information on excavators, loaders and transport is obtainable from the makers.Earthworks or earthmoving means cutting into ground where its surface is too high ( cuts ), and dumping the earth in other places where the surface is too low ( fills). Toreduce earthwork costs, the volume of the fills should be equal to the volume of the cuts and wherever possible the cuts should be placednear to fills of equal volume so as to reduce transport and double handlingof the fill. This work of earthwork design falls on the engineer who lays out the road since it is the layout of the earthwork more than anything else which decides its cheapness. From the available maps ahd levels, the engineering must try to reach as many decisions as possible in the drawing office by drawing cross sections of the earthwork. On the site when further information becomes available he can make changes in jis sections and layout,but the drawing lffice work will not have been lost. It will have helped him to reach the best solution in the shortest time.The cheapest way of moving earth is to take it directly out of the cut and drop it as fill with the same machine. This is not always possible, but when it canbe done it is ideal, being both quick and cheap. Draglines, bulldozers and face shovels an do this. The largest radius is obtained with the dragline,and the largest tonnage of earth is moved by the bulldozer, though only over short distances.The disadvantages of the dragline are that it must dig below itself, it cannot dig with force into compacted material, it cannot dig on steep slopws, and its dumping and digging are not accurate.Face shovels are between bulldozers and draglines, having a larger radius of action than bulldozers but less than draglines. They are anle to dig into a vertical cliff face in a way which would be dangerous tor a bulldozer operator and impossible for a dragline.Each piece of equipment should be level of their tracks and for deep digs in compact material a backacter is most useful, but its dumping radius is considerably less than that of the same escavator fitted with a face shovel.Rubber-tyred bowl scrapers are indispensable for fairly level digging where the distance of transport is too much tor a dragline or face shovel. They can dig the material deeply ( but only below themselves ) to a fairly flat surface, carry it hundreds of meters if need be, then drop it and level it roughly during the dumping. For hard digging it is often found economical to keep a pusher tractor ( wheeled or tracked ) on the digging site, to push each scraper as it returns to dig. As soon as the scraper is full,the pusher tractor returns to the beginning of the dig to heop to help the nest scraper.Bowl scrapers are often extremely powerful machines;many makers build scrapers of 8 cubic meters struck capacity, which carry 10 m ³ heaped. The largest self-propelled scrapers are of 19 m ³ struck capacity ( 25 m ³ heaped )and they are driven by a tractor engine of 430 horse-powers.Dumpers are probably the commonest rubber-tyred transport since they can also conveniently be used for carrying concrete or other building materials. Dumpers have the earth container over the front axle on large rubber-tyred wheels, and the container tips forwards on most types, though in articulated dumpers the direction of tip can be widely varied. The smallest dumpers have a capacity of about 0.5 m ³, and the largest standard types are of about 4.5 m ³. Special types include the self-loading dumper of up to 4 m ³and the articulated type of about 0.5 m ³. The distinction between dumpers and dump trucks must be remembered .dumpers tip forwards and the driver sits behind the load. Dump trucks are heavy, strengthened tipping lorries, the driver travels in front lf the load and the load is dumped behind him, so they are sometimes called rear-dump trucks.1.3 Safety of StructuresThe principal scope of specifications is to provide general principles and computational methods in order to verify safety of structures. The “ safety factor ”, which according to modern trends is independent of the nature and combination of the materials used, can usually be defined as the ratio between the conditions. This ratio is also proportional to the inverse of the probability ( risk ) of failure of the structure.Failure has to be considered not only as overall collapse of the structure but also as unserviceability or, according to a more precise. Common definition. As the reaching of a “limit state ” which causes the construction not to accomplish the task it was designedfor. There are two categories of limit state :(1)Ultimate limit sate, which corresponds to the highest value of the load-bearing capacity. Examples include local buckling or global instability of the structure; failure of some sections and subsequent transformation of the structure into a mechanism; failure by fatigue; elastic or plastic deformation or creep that cause a substantial change of the geometry of the structure; and sensitivity of the structure to alternating loads, to fire and to explosions.(2)Service limit states, which are functions of the use and durability of the structure. Examples include excessive deformations and displacements without instability; early or excessive cracks; large vibrations; and corrosion.Computational methods used to verify structures with respect to the different safety conditions can be separated into:(1)Deterministic methods, in which the main parameters are considered as nonrandom parameters.(2)Probabilistic methods, in which the main parameters are considered as random parameters.Alternatively, with respect to the different use of factors of safety, computational methods can be separated into:(1)Allowable stress method, in which the stresses computed under maximum loads are compared with the strength of the material reduced by given safety factors.(2)Limit states method, in which the structure may be proportioned on the basis of its maximum strength. This strength, as determined by rational analysis, shall not be less than that required to support a factored load equal to the sum of the factored live load and dead load ( ultimate state ).The stresses corresponding to working ( service ) conditions with unfactored live and dead loads are compared with prescribed values ( service limit state ) . From the four possible combinations of the first two and second two methods, we can obtain some useful computational methods. Generally, two combinations prevail:(1)deterministic methods, which make use of allowable stresses.(2)Probabilistic methods, which make use of limit states.The main advantage of probabilistic approaches is that, at least in theory, it is possible to scientifically take into account all random factors of safety, which are then combined to define the safety factor. probabilistic approaches depend upon :(1) Random distribution of strength of materials with respect to the conditions offabrication and erection ( scatter of the values of mechanical properties through out the structure );(2) Uncertainty of the geometry of the cross-section sand of the structure ( faults and imperfections due to fabrication and erection of the structure );(3) Uncertainty of the predicted live loads and dead loads acting on the structure;(4)Uncertainty related to the approximation of the computational method used ( deviation of the actual stresses from computed stresses ).Furthermore, probabilistic theories mean that the allowable risk can be based on several factors, such as :(1) Importance of the construction and gravity of the damage by its failure;(2)Number of human lives which can be threatened by this failure;(3)Possibility and/or likelihood of repairing the structure;(4) Predicted life of the structure.All these factors are related to economic and social considerations such as：(1) Initial cost of the construction;(2) Amortization funds for the duration of the construction;(3) Cost of physical and material damage due to the failure of the construction;(4) Adverse impact on society;(5) Moral and psychological views.The definition of all these parameters, for a given safety factor, allows construction at the optimum cost. However, the difficulty of carrying out a complete probabilistic analysis has to be taken into account. For such an analysis the laws of the distribution of the live load and its induced stresses, of the scatter of mechanical properties of materials, and of the geometry of the cross-sections and the structure have to be known. Furthermore, it is difficult to interpret the interaction between the law of distribution of strength and that of stresses because both depend upon the nature of the material, on the cross-sections and upon the load acting on the structure. These practical difficulties can be overcome in two ways. The first is to apply different safety factors to the material and to the loads, without necessarily adopting the probabilistic criterion. The second is an approximate probabilistic method which introduces some simplifying assumptions ( semi-probabilistic methods ) 。
混凝土收缩对结构的影响
收缩产生的机理以及对结构的影响[摘要] 干缩是混凝土浇捣3d 以后的最主要收缩组成部分，在后期，干缩的发展往往与荷载因素共同作用，从而加速裂缝的产生。
混凝土的干燥收缩机理通常用毛细孔失水，形成弯月面，在毛细孔张力的作用下产生收缩。
本文采用物理图解和数学推导，形象地描述了混凝土干燥收缩的物理力学机制。
[关键词] 干燥收缩；凝胶颗粒；气液弯月面；毛细孔张力；孔径分布干燥收缩（drying shrinkage）通常是混凝土停止养护后，在不饱和的空气中失去内部毛细孔和凝胶孔的吸附水而发生的不可逆收缩，随着相对湿度的降低，水泥浆体的干缩增大。
干缩主要发生在浇筑后3～90d 龄期内，事实上，文献[ 1 ]的研究表明，若养护不好，早期（龄期前3d）的干缩相当大，不可忽视。
干缩是混凝土浇捣3d 以后的最主要收缩组成部分，在后期，干缩的发展往往与荷载因素共同作用，从而加速裂缝的产生。
一直以来它都是混凝土收缩研究的重点，其形成机理通常基于毛细孔理论展开的。
对此，本文将结合作者的一点认识重新加以阐述，希望寄此能对干缩有更清晰深入的认识。
1 干缩机理描述干缩机理与水泥浆体内部孔隙有关。
水泥水化的结果是生成水化硅酸钙（C-S-H）等水化产物及在内部形成大量并被水填充的微细孔（ > 5nm 的毛细孔与0.5～2.5nm 的凝胶孔），这些微细孔中储存有水化未消耗的多余水分。
混凝土干燥的时候，水的蒸发速度可能超过混凝土向外泌水迁移的速度，因此，表层毛细孔中的水面降低，并随着蒸发的继续，水分的失去从表层逐渐向混凝土内部不断发展，毛细孔与凝胶孔中的吸附水相继失去。
这些微细孔内水分的失去将在孔中产生毛细管负压，并促使气液弯月面（meniscus）的形成，从而对孔壁产生拉应力，造成水泥浆体收缩。
这一过程可通过图1 加以比较清晰的描述。
从图1a 中可以看到，混凝土处于干燥环境下时，泌出的水分在混凝土表面被蒸发，当表层水分的蒸发较快，内部水分迁移来不及补充时，在气液界面的外表面（气相）形成毛细孔负压，即毛细孔内溶液表面蒸汽压与液压（水压）的压力差ΔP（图1c），由于这一压力差的存在，促使凝胶颗粒间产生一个气液弯月面。
混凝土的自缩及其控制措施
混凝土的自缩及其控制措施近年来，随着混凝土科学的发展，尤其是高效减水剂和矿物掺合料在混凝土中的广泛应用，混凝土的水灰比（或水胶比）大大降低。
这种低水灰比的混凝土（水灰比不大于0.40）有很高的强度和很低的渗透性，在不发生裂缝的前提下是十分耐久的。
但在低水灰比的情况下，强烈的水化会促使混凝土中毛细管弯月面快速向内推进和相对湿度的很快下降，在混凝土中出现自干燥现象（self-desiccation）。
混凝土的自干燥必将引起混凝土宏观体积的减小，这种现象被称为混凝土的自缩（self-desiccation shrinkage or autogenous shrinkage）。
在低水灰比的情况下，混凝土在硬化的早期就会产生很大的自缩。
在实际的混凝土工程中，混凝土又不可避免地受到约束的作用。
在约束存在的情况下，这种高自缩的混凝土发生开裂的可能性大大增加。
由于混凝土的自缩与混凝土的早期开裂现象关系紧密，因此有必要对混凝土的自缩性能加以研究。
1混凝土的自缩及产生机理混凝土的自缩是指混凝土硬化阶段（终凝以后），在恒温、与外界无水分交换的条件下混凝土宏观体积的减小。
自缩和干缩不同，它在混凝土体内相当均匀地发生，而不仅仅在混凝土表面发生。
一般认为，混凝土自缩是混凝土中水泥水化形成的混凝土内部空隙产生的毛细管张力造成的。
其具体过程如下:水泥和水发生水化作用时，所形成的水化产物的体积小于水泥和水的总体积，在混凝土具有较大流动性时，混凝土通过宏观体积的减小来补偿水泥水化产生的体积变化，随着水泥水化的进行，混凝土的流动性逐渐降低，混凝土不能完全靠宏观体积的减小来补偿水泥水化产生的体积变化，这时混凝土通过形成内部空隙和宏观体积减小两种形式补偿水泥水化产生的体积变化。
随着水泥水化的进一步发展，混凝土产生一定的强度，这时混凝土主要通过形成内部空隙来补偿水泥水化产生的体积变化。
在混凝土终凝以后，虽然水泥水化产生的体积变化主要通过形成内部空隙来补偿，但由于内部空隙的形成而产生的毛细管张力将使混凝土的宏观体积收缩。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
科技资料原文Shrinkage of ConcreteWhen concrete loses moisture by evaporation it shrinks. Shrinkage strains are mdependent of the stress conditions in the concrete. If restrained, shrinkage strains can cause cracking of concrete and will generally cause the deflection of structural members to increase with time. The calculation of stress and deformations due to shrinkage is deferred until Chapter 10.A curve showing the increase in shrinkage strain with time appears inFig.2.21. The shrinkage occurs at a decreasing rate with time appeard in shrinkage strains vary greatly, being generally in the range 0.0002 to 0.0006 but sometime as much as 0.0010.Fig.2.21. Typical shrinkage curve for concreteShrinkage is to a large extent a reversible phenomenon. If the concrete is saturated with water after it has shrunk, it will expand to almost its original volume. Thus alternating dry and wet conditions will cause alternating volume changes of concrete. This phenomenon is partly responsible for the fluctuating deflections of structures (e.g. concrete bridges) exposed to seasonal changes each year.As a rule, concrete that exhibits a high creep also displays high shrinkage. Thus the magnitude of the shrinkage strain depends on the composition of the concrete and on the environment in much the same way as discussed previously for creep.Both the ACI Committee 2092.26 and the CEB-FIP 2.27 have proposed empirical methods for the estimation of shrinkage strains. The former approach is described blow.According to ACI Committee 2092.26 for normal weight, sand lightweight concrete (using both moist and steam ouring and types I and III cement), the unrestrained shrinkage strain at any time t is given byWhere the coefficients are given below.Ultimate shrinkage strain,The value of can vary widely. In ACI Committee 209 review,was found to be in the range 0.000415 to 0.00107, with mean values of 0.00080 for moist-cured concrete or 0.00073 for steam-cured concrete. These average valuesS h r i n k a g e s t r a i n sh shu t h th s f e c s s s s s s s εε=shu εshu εshu εshould be assumed only in the absence of more exact date for the concrete to be used.Time of shrinkage coefficient, S tAt any time after age 7 days, for moist-cured concrete,(2.17a)Where t = time in days from age 7 days(St=0.46, 0.72, 0.84, 0.91,and 0.98 for t = 1 month, 3 months, 6months, 1 year, and 5 years, respectively)or, at any time after age 1 to 3 days for steam-cured concrete,(2.17b)Where t = time in days from age 3 days(St=0.35, 0.62, 0.77, 0.87,and 0.97 for t = 1 month, 3 months, 6months, 1 year, and 5 years, respectively)For shrinkage considered from greater ages than given above, the difference may be determined use Eq.2.17a or 2.17b for any period after than time. That is shrinkage for moist-cured concrete between, say, 1 month and 1 year would be equal to the 7-day to 1-year procedure assumes that the moist-cured concertehs been cured the shrinkage needs to be multiplied by 1.2; a linear interpolation between 1.2 at 1day and 1.0 abd 1.0 at 7 days may be used.Relative humidity coefficient, S hS h =1.4-0.01H for 40<H<80% (2.18a)or,S h =3.0-0.03H for 80<H<100% (2.18b)Where H = relative humidity in percent(S h = 1.00, 0.80, 0.60, 0,for 40, 60, 80, and 100% relative humidity)Minimum thickness of member coefficient, S thSth = 1.00 for 6 in or less and 0.84 for 9 in (1 in = 25.4mm)Slump of concrete coefficient, SsSs = 0.97 for 2 in ,1.00 for 2.7 in, 1.01 for 3in, 1.05 for 4 in, and 1.09 for 5 in (1 in =25.4mm)Fines coefficient, S fS f =0.86 for 40%, 1.00 for 50%, and 1.04 for 70% fines by weightAir content coefficient, S eS e =0.98 for 4%, 1.00 for 6%, and 1.03 for 10% airCement content factor, S c35t tS t =+55t tS t =+≤S c =0.87 for376 1b/yd 3, 0.95 for564 1b/ yd 3 ,1.00 for705 1b/yd 3 and1.09for 940 1b/yd 3(1 1b/yd 3=0.593kg/m 3)Example 2.2Estimate the free shrinkage strain that can be expected to occur in a 9 in (230mm) thick concrete wall from the age of 7 days during a 5-year period at a relative humidity of 60%. The concrete has a slump of 3 in (76mm), a fines content of 34% by weight, a cement content of 600 1b/yd 3 (356kg/m 3), an air content of 5%, and is moist cured for 5days after being placed.SolutionFrom Eq.0.16 we have原文翻译 混凝土的收缩当混凝土由蒸发丢失水分时便产生了收缩现象。
混凝土的收缩是一种自发的变形，并不依靠作用在混凝土上的外力。
因此当收缩变形不能自由进行时，有可能导致混凝土产生裂缝，并且裂缝的数量随着时间的增加而增多。
在后面的第10章具体介绍收缩产生的变形和裂缝的计算。
图2.2.1反应了混凝土的收缩随时间发展的规律，早期混凝土的收缩变形速率随时间的增加变化较快，但是到了后期混凝土的收缩变形和初期相比有很大的不同，收缩的总量一般为（2～5）×10-4，有时达到1×10-3。