Durability of Concrete
concrete 单词
ConcreteIntroductionConcrete is a versatile building material that has been used for centuries. It is composed of cement, water, and aggregates such as sand and gravel. The mixture is poured into molds or forms and left to harden, resulting in a solid and durable structure. Concrete is widely used in construction due to its strength, durability, and affordability. In this article, we will explore the various applications, advantages, and disadvantages of using concrete.Applications of ConcreteConcrete has a wide range of applications in the construction industry. Some of its common uses include:1.Buildings: Concrete is commonly used in the construction ofbuildings, both residential and commercial. It provides structural stability and can withstand various weather conditions.2.Roads and Bridges: Concrete is widely used for constructing roadsand bridges. The durability of concrete makes it an ideal choicefor withstanding heavy traffic and harsh weather conditions.3.Dams and Reservoirs: Concrete is used to build dams andreservoirs due to its ability to withstand the pressure of largevolumes of water. It is also resistant to corrosion, making itsuitable for water-related structures.4.Foundations: Concrete is often used to create strong and stablefoundations for buildings. Its strength and ability to resistcompressive forces make it an ideal choice for this application. 5.Sidewalks and Driveways: Concrete is commonly used for sidewalksand driveways due to its durability and low maintenancerequirements.Advantages of ConcreteThere are several advantages to using concrete in construction:1. Strength and DurabilityConcrete is known for its strength and durability. It can withstand heavy loads and is resistant to fire, water, and weathering. This makes it a reliable choice for long-lasting structures.2. VersatilityConcrete can be molded into various shapes and sizes, allowing for flexible and creative designs. It can also be colored, stained, or stamped to achieve the desired aesthetic appeal.3. Low MaintenanceOnce concrete has hardened, it requires minimal maintenance. It does not rot or warp like wood and does not require periodic painting or sealing.4. Environmentally FriendlyConcrete is an eco-friendly material as it can be produced from locally available resources. It also has a long lifespan, reducing the need for frequent replacements and minimizing waste.Disadvantages of ConcreteWhile concrete has many advantages, there are also some disadvantages to consider:1. Initial CostThe initial cost of using concrete can be higher compared to other building materials. The cost of materials, labor, and equipment required for concrete construction can add up, especially for large-scale projects.2. WeightConcrete is a heavy material, which can pose challenges during transportation and construction. Special equipment may be required to handle and transport large quantities of concrete.3. CrackingAlthough concrete is strong and durable, it is prone to cracking over time. Changes in temperature, moisture, and settlement can cause cracks to form, requiring repair and maintenance.4. Environmental ImpactThe production of cement, a key component of concrete, releases a significant amount of carbon dioxide, contributing to greenhouse gas emissions. Steps are being taken to reduce the carbon footprint of concrete production through the use of alternative materials and technology.ConclusionConcrete is a widely used building material due to its strength, durability, and versatility. It has numerous applications in construction, ranging from buildings and roads to dams and foundations. While there are advantages to using concrete, such as its strength and low maintenance requirements, there are also disadvantages to consider, including the initial cost and environmental impact. As technology advances, efforts are being made to further improve the sustainability and performance of concrete in construction.。
建筑工程英标规范(混凝土)中英文
SECTION: 2 第2章混凝土PART 1 GENERAL 第1节总则1 DESCRIPTION 说明All concrete work is governed by this Section.所有混凝土工程受本章的管理。
Work Included: Provide all cast—in-place concrete，complete and in place，as required by the Work，specified hereinon the drawings and specifications. 包括的工作：按照图纸上规定的工作和相关标准要求，完整而到位地提供所有现浇混凝。
RELATED WORK：有关工作1 General Requirements一般要求2 Material 材料3 Concrete Mix 混凝土配合比4 Construction Requests 施工要求1.1. GENERAL REQUIREMENTS：一般要求1.1.1. Concrete shall be batched only with approved materials, approved mix designs，and atapproved facilities。
只能使用批准的材料、批准的配合比设计和在批准的设施内对混凝土进行配料.1.1.2. The Contractor shall define the method of design of the mix，by reference to arecognised published design method. 承包商应通过参考认可的设计方法确定配合比设计.1.1.3. Plant trials shall be carried out for each grade and type of concrete in the contract, 你unless approved otherwise by the Engineer. 除非监理工程师另有批准，应对每种标号和种类的混凝土进行工厂试验。
含气量与混凝土性能的关系
含气量与混凝土的关系5079 引气混凝土Air-entrainment Concrete摘要：系统地研究了引气对混凝土力学性能、早期抗裂性能以及耐久性能的影响，这些耐久性包括抗冻性、Cl —侵入、盐结晶破坏、碳化等。
研究结果表明：混凝土中适当引气可以改善混凝土的综合耐久性能。
引气除了可以大幅度提高混凝土的抗冻性、改善混凝土的工作性外，在同等强度下，引气还可显著改善混凝土的抗渗性、抗Cl —渗透和抗碳化性能；通过引气还可显著改善混凝土的盐结晶、碱—集料反应引起的破坏；混凝土引气后韧性提高，早期抗裂性能也得到改善。
关键词：引气；混凝土；耐久性；抗冻性；抗渗性Abstract: The effects of air-entraining agents on mechanical properties, early cracking and durability of concrete were systematically studied; The durability includes freeze-thawing cycles, chlorine ion intrusion, sulfate erosion, carbonation, et al. Besides a dramatically improved freeze resistance and workability, the permeability of both water and C l －of air-entrained concrete were decreased distinctly, and carbonation resistance, sulfate erosion resistance and AAP resistance of air-entrained concrete were improved remarkably in comparison with those of ordinary concrete at equal 28d compressive strength. The comprehensive durability can be improved by air entrainment in comparison with the ordinary concrete.Key words: air-entrainment; concrete; durability; freeze resistance; permeability1 引气混凝土的应用情况引气技术在混凝土工程中应用已有半个多世纪的历史，从1938 年开始，引气剂就在美国公路中推广应用，1942 年美国首先制定了引气混凝土的施工规范，美国材料试验学会(ASTM) 也制定了相应的标准，1948 年以后，引气剂和引气减水剂在美国公路、港口、桥梁等工程中广泛应用。
The durability of concrete 英文版混凝土论文
The durability of concreteIn civil engineering, concrete is the most widely used and the amount of one of the largest building materials. Over the past century, the concrete strength to continuously improve its main development trends. China's large population, the urgent need for housing.Structural Design not only to meet the requirements of safe and reliable indicators, but also consider the durability requirements.The durability of concrete issues, refers to the structure in the environment and cause long-term evolution of the structure due to internal or external reasons, the concrete has to lose the ability to use. That for durability failure, the durability of many reasons, have antifreeze failure, failure of alkali - aggregate reaction, chemical corrosion failure. Part of the concrete structure in the environment below freezing, water in the pores will freeze, resulting in volume expansion of cold water migration, the formation of various pressures, when the pressure reaches a certain level, resulting in the destruction of the concrete.Alkali - aggregate reaction of concrete chemical reactions that occur by the active component of the alkali in the concrete aggregates, causing the expansion of the concrete, cracking, or even destroy. Response factors in the concrete, and its harmful effects are often not the root of the rule is a big hidden in the concrete works. Concrete structures in aggressive media environment, will cause the cement paste to a series of chemical, physical, and materialized change gradually been eroded, cement strength to reduce serious, as well as destruction. In concrete engineering in order to meet the requirements of concrete construction work, that is, water consumption, water-cement ratio is high, resulting in high porosity of the concrete, durability reduce. Also, the lack of hydrate stability in the cement paste will have an impact on the durability.Therefore, to improve the durability of concrete, must reduce the porosity of the concrete, especially the capillary porosity, the most important method is to reduce the concrete mixing water. But if we simply reduce the amount of water, the concrete decreases, will lead to tamping forming a total of difficulties, the same result in the concrete structure is not dense, and even cellular and macroscopic defects such as, not only reduce the strength of concrete, and the durability of concrete also reduced. To improve the durability of concrete basic There are several ways: First, the strength of the material and engineering properties of cement cement is hardening formed by the condensation of the cement mortar, cement paste, once damaged, the durability of concrete is damaged, the choice of cement should pay attention to the specific performance of the varieties of cement, select alkali content, low heat of hydration, shrinkage of a small, heat resistance, water resistance, corrosion resistance, good frost resistance of cement and in the circumstances to choose . The strength of cement is not the sole criterion to determine the concrete strength and performance, such as lower grade cement can also be the preparation of high-grade concrete. Therefore, the project select the strength of cement at the same time, the need to consider the engineering performance, and sometimes, its engineering performance is more important than the strength. Aggregates and admixtures choice of the aggregate consideration should be given its alkali activity to prevent the harm caused by alkali-aggregate reaction, corrosion resistance and water absorption of the aggregate, reasonable choice of gradation, to improve the workability of the concrete mixture to increase concrete density; a large number of studies have shown that the doped fly ash, slag, silica fume, etc. the mixed caineng effectively improve the performance of the concrete, to improve the pore structure of concrete, filling the internal voids, and to increase the density, high-ash concrete can inhibition of alkali-aggregate reaction, and thus doped hybrid materials of concrete, is to improve the durability of concrete and effective measures. Development in recent years, high-performance concrete. Second, the rational design of concrete mix mix design meet the concrete strength, work should be considered to minimize the amount of cement and water consumption, lower heat of hydration, reduce shrinkage cracks, and to increase the density, and reasonable water reducer and air entraining agent, to improve the internal structure of concrete, mixed with a sufficient amount of mixture to improve concrete durability. Structural members shall use the environmental design of the concrete cover thickness, to prevent the outside media to penetrate the internal corrosion of reinforced. Node structural design of the structure should also be considered a component to the overallendurance capacity after partial damage. The structural design shall also control the crack width of concrete cracks. Third, the incorporation of an appropriate amount of admixtures, water-reducing agent such as: liquidity needed to ensure that concrete mixture at the same time, minimizing water consumption, reduce water-cement ratio, so that the total porosity of the concrete, in particular, the capillary porosity substantially reduced. 4, the incorporation of the hydrate stability, lack of efficient activity of mineral admixtures: ordinary Portland cement concrete, cement paste is another major factor in the concrete can not be super durable.To eliminate the structure of the concrete itself disruptive factor: In addition to concrete structural damage caused by environmental factors, some of the concrete itself, physical and chemical factors may also cause serious damage of the concrete structure, resulting in concrete failure. To ensure the strength of concrete: strength and durability is a different concept, but is closely related to the nature of links between them is based on the internal structure of the concrete with water-cement ratio, this factor is directly related.Concrete construction should also consider the durability of concrete mixing and maximize the use of the second mixing method, wrap the sand method, wrapped in the process of gravel law, improve the workability of the concrete mixing materials, water retention and improve the concrete strength, reduce water consumption; pouring mass concrete vibrators shall control the temperature of concrete cracks, shrinkage cracks, construction cracks, concrete pouring and vibrating system, to improve concrete density and impermeability, attention to the process of the surface after the concrete vibratorsand enhance the conservation, in order to reduce the concrete cracks. Concrete construction process control component appearance of cracks, construction cracks is essential and should strengthen the construction quality management, the special season of construction of concrete structures, there should be to take special measures.So, we want to develop the new concrete, such as high performance concrete.Therefore, to improve the durability of concrete is the inevitable trend of development of the concrete.。
混凝土词汇
混凝土词汇混凝土concrete新拌混凝土green concrete机敏混凝土smart concrete高技术混凝土high technique concrete生态混凝土ecological concrete智能混凝土intelligent concrete泡沫混凝土foam concrete水下混凝土underwater concrete混凝土的裂缝分析analysis of concrete crack混凝土收缩裂缝分析analysis on shrinkage cracks of concrete富浆碾压混凝土GEROC碾压混凝土RCC混凝土预制件prefabricated concrete component节段梁segmental beam混凝土布料机现状developing situation of concrete distributor混凝土的耐久性durability of concrete谈混凝土缺陷discussion about blemish of concrete混凝土技术研究Study on the Technical of Concrete混凝土气密性研究Study on Gas-tightness of Concrete改性混凝土综述SUMMARY OF MODIFIED CONCRETE混凝土裂缝的探讨Discussion on concrete crack导电混凝土技术The Techniques of Conductive ConcreteKNAUER400-5水泥混凝土预制件制作机液压系统分析Hydraulic System Analysis of KNAUER 400-5 Concrete Prefabricate Machine高聚物浸渍混凝土Polymer Impregnated Concrete粉煤灰混凝土Study on the Fly Ash Concrete浅谈耐酸混凝土Researching on the acid-resisting concrete浅谈混凝土外加剂The additive of concrete再生混凝土骨料aggregate of recycled concrete绿化混凝土概论Outline for Green Concrete混凝土抗压强度预测concrete compressive strength prediction废混凝土利用utilization of waste concrete混凝土与环境concrete and surroundings混凝土微细裂缝灌浆grouting for micro-cracks in concrete薄层混凝土路面Thin-lift Concrete Pavement高性能混凝土high performance concrete混凝土损伤研究Study on Damage of Concrete自保温混凝土Self-conserving Heat Concrete浅谈混凝土裂缝 A Brief Talk On Concrete Crack混凝土与可持续发展Concrete and Sustainable Development混凝土速凝剂concrete accelerator混凝土压舱块concrete ballast混凝土浇注吊桶concrete bucket混凝土饰面concrete casing混凝土覆盖层concrete coating混凝土防御工事concrete fortifications混凝土基础concrete foundation混凝土构架concrete frame混凝土重力式平台concrete gravity platform 混凝土重力式岸壁concrete gravity quaywall 混凝土外壳concrete haunching混凝土衬砌concrete lining混凝土搅拌车concrete mixer truck混凝土搅拌船concrete mixer vessel混凝土搅拌机concrete mixer名数concrete number混凝土基墩concrete piers混凝土管concrete pipe混凝土浇注机concrete placer混凝土护岸concrete revetment混凝土涂层concrete sheath coat劲性钢筋concrete steel混凝土建筑物concrete structure混凝土池concrete sump混凝土罐concrete tank混凝土加重层concrete weight-coating 水泥喷枪concrete-gun混凝土强度concrete strength混凝土低塌落度low slump。
混凝土外国参考文献
混凝土外国参考文献混凝土外国参考文献---为了更好地理解和研究混凝土材料，许多研究人员和学者在世界各地进行了大量的研究工作，并发表了许多有价值的外国参考文献。
本文将对混凝土领域的一些重要外国参考文献进行综述和分析，以帮助读者更深入地了解混凝土的发展和应用。
1. ACI 318-14 "Building Code Requirements for Structural Concrete"这是美国混凝土协会（American Concrete Institute）发行的一份重要标准，规定了混凝土结构的设计和施工要求。
该标准详细说明了混凝土的材料性能、设计原则、施工方法和质量控制等方面内容。
它为混凝土结构的安全性、可靠性和持久性提供了指导，是混凝土工程设计师必不可少的参考文献。
2. “Concrete Technology” by A.M. Neville这本书是混凝土技术领域的经典之作，由著名学者A.M. Neville撰写。
该书系统地介绍了混凝土材料的性质、制备方法、试验方法以及各种混凝土结构的设计和施工技术。
通过对混凝土技术的全面概述，读者可以深入了解混凝土的特性、应用和发展趋势。
3. "Concrete: Microstructure, Properties, and Materials" by P. Kumar Mehta and Paulo J.M. Monteiro这本书详细介绍了混凝土的微观结构、物性和材料特性。
它提供了混凝土材料学的深入分析，涵盖了混凝土组成材料的特点、胶凝材料的反应机理以及微观结构对混凝土性能的影响等内容。
通过对混凝土材料学的系统研究和解释，读者可以更好地理解混凝土的性能和行为。
4. "Durability of Concrete Structures: Investigation, Repair, Protection" by Carmen Andrade and Jorge M.Ferreira这本书重点介绍了混凝土结构的耐久性问题，涉及到检测、修复和保护混凝土结构的方法和技术。
Durability of concrete 混凝土的耐久性
cavitation effects of fast-moving water,abrasive material in water,wind blasting and attrition and impact of traffic. Attrition：摩擦 impact 碰撞，冲击力 混凝土磨损的主要原因有高速水流所产生的气 蚀效应，水中有磨蚀作用的物质，疾风，交通 的摩擦和碰撞。
Chemical agents essentially react with certain
compounds of the hardened cement paste and the resistance of concrete to chemical attack therefore can be affected by the type of cement used. the hardened cement paste:水泥石 化学物质本质上是与某些水泥石化合物发生反 应。因此，混凝土的抗化学侵蚀能力与所使用 的水泥种类有关。
Durability of concrete 混凝土的耐久性
08工程管理（1）班 李海姣、纪飞、刘涛、林新、王腾
Besides its ability to sustain loads, concrete is
also required to be durable.
durable ['djuərəbl] 耐久的 混凝土除了承受荷载之外，还需要有一定的耐
In general,the resistance of concrete to
erosion and abrasion increases with increase in strength.
Durability of concrete made with EAF slag as aggregate
Durability of concrete made with EAF slag as aggregateJuan M.Mansoa,*,Juan A.Polanco b ,Milagros Losan ˜ez c ,Javier J.Gonza´lez daCivil Engineering Department,Escuela Polite´cnica Superior,University of Burgos,Calle Villadiego s/n,09001Burgos,Spain bMaterials Science and Engineering Department,ETSICCP,University of Cantabria,Avda.de los Castros s/n,39005Santander,SpaincFundacio´n Eraiker,Casa Nao No 3.Barrio Alza.Apartado (Postal Box)4022,20080San Sebastia ´n,Spain dMining and Metallurgical Engineering Department,ETSIB,University of Basque Country,Alameda de Urquijo s/n,48013Bilbao,SpainReceived 4February 2005;accepted 8February 2006Available online 30March 2006AbstractElectric arc furnace (EAF)slag,a by-product of steelmaking recovered after the oxidizing process,is useful when employed as aggre-gate in hydraulic concrete and bituminous mixtures.Concrete made with EAF oxidizing slag as an aggregate shows good physical and mechanical properties and further study of its durability will ensure greater reliability in its usage.This paper details a systematic study of slag concrete behaviour under severe test conditions.The tests were designed to evaluate the internal expansivity of the slag,its chemical reactivity with some components of the cement and its resistance to environmental agents,ice and moisture.The results indicate that the durability of slag concrete is acceptable,though slightly lower than that of conventional concrete.When the mix proportions are ade-quate,both the mechanical strength and the durability of slag concrete are satisfactory,although in less care mixes durability is likely to be impaired.Finally,leaching tests were performed to determine the environmental impact of the concrete,which,in comparison to results obtained directly from the slag,confirmed an important cloistering effect of the cementitious matrix on contaminant elements.Ó2006Elsevier Ltd.All rights reserved.Keywords:Steelmaking slag;Concrete;Durability;Weathering;Mechanical testing1.IntroductionIron and steelmaking slag has been employed in the European Union (EU)as a component of both cement and concrete.The use of ground granulated blast furnace slag in the manufacture of cement as a partial substitute for Portland cement clinker is a well-known practice –see EN 197-1standard [1]–as is the use of other kinds of slag as aggregates in concrete,especially in the field of civil engineering [2,3].Over recent decades,the steelmaking industry in Spain has been transformed,as electric arc furnaces have largely replaced blast furnaces and LD (Linz-Donawitz)convert-ers,leading to the appearance of a new by-product:electric arc furnace (EAF)oxidizing slag or black slag.Its charac-teristics differ from those of other slags and 1.5M tons of this type of slag are produced annually in Spain.Similar changes have also taken place in other EU countries,and electric arc furnaces currently account for more than 40%of global steel production (41.1M tons in 2002)[4].In the interests of sustainable development efforts must be made to reuse this product in various ways so as to contri-bute to a recycling-orientated society and to avoid exces-sive amounts being dumped in the environment.Several studies have been made of the characteristics of EAF oxidizing slag with respect to its application in the con-struction industry,in particular of its attributes as a material [5–7],its potential expansivity [8]and its chemical reactivity [9].The possibility of EAF slag being used satisfactorily in concrete has been demonstrated [10–12].The principal problems in this field remain the durability of this type of concrete [13,14]and its environmental tolerance [15].Correctly manufactured EAF slag concrete has good0958-9465/$-see front matter Ó2006Elsevier Ltd.All rights reserved.doi:10.1016/j.cemconcomp.2006.02.008*Corresponding author.Tel.:+34947259076;fax:+34947258910.E-mail address:jmmanso@ubu.es (J.M.Manso)./locate/cemconcompCement &Concrete Composites 28(2006)528–534mechanical properties,and its high density is an advanta-geous property where weight is a key factor,in such con-structions as breakwater blocks,foundations,shoring walls, noise barriers,and radiation insulators,among others.A detailed study has been reported to define and analyse the properties of EAF oxidizing slag,its performance as an aggregate,and the attributes of the concrete in which it is a component[16].The manufacturing process and results related to the physical and mechanical properties of this type of concrete have also been presented in a previous paper[17].In the present paper,a further aspect is exam-ined to evaluate its reliability as a concrete aggregate:the effect of detrimental processes,or in other words,the dura-bility of concrete produced with EAF slag aggregate.2.Materials2.1.Cement,water and limestone aggregatePortland cement type I/42,5R,the chemical composi-tion of which is given in Table1,and tap water were usedfor the production of the concrete,as was crushed lime-stone.This was extracted from local quarries,in the form offine and coarse aggregate,widely used in the manufac-ture of structural concrete.2.2.Electric arc furnace slagOxidizing slag taken from the EAF has to undergo the following conditioning process prior to its use as an aggregate:•Reduction to standard aggregate sizes following appro-priate crushing.•Stabilisation by exposure to weathering over several weeks.Appropriate crushing produces a maximum-sized aggre-gate of between20and30mm,and its grading presents a low proportion offine fractions.Crushing performed to obtain maximum sizes of up to30mm is inadvisable–the results of the Los Angeles test show higher than permit-ted losses[16].Crushing the slag more severely to obtain a larger proportion offine sizes has also been found to be disadvantageous[16].Such production methods are made all the more expensive by the need for several controlled stages in the milling process.In addition,a decrease is predictable in the cloistering effect on the heavy metals contained in the slag.In view of these factors,the most advantageous solution is,firstly,to subject the slag to a primary crushing process and then to complete its grading by the addition of a suit-able proportion of mineralfiller.The same solution has been employed in several other studies[10,11,18].In this study,limestonefiller,a very cheap by-product from local quarries,has been used but many other possibilities also exist.This solution also achieves a further important goal, insofar as all the available EAF slag is recycled.Following the crushing process,it has been shown [16,19]that when the stabilization treatment is correctly performed[3](permanent wetting,homogenization through periodic turning of the heaps and a minimum weathering period of90days),significant improvements are noted in the expansive behaviour of the slag.The origi-nal expansion values of between0.5%and2.5%,obtained immediately after crushing,are reduced to values of between0.15%and0.4%in tests using ASTM D4792 standard[20].Several alternative methods have been formulated to perform this operation[21,22]that are,in general,more expensive than the option presented in this paper.Table1shows the main physical properties and chemical composition of EAF slag ready to be used as concrete aggregate.Figs.1a and1b contain the grading curves of coarse andfine slag aggregate obtained after crushing.Table1Physical properties and chemical composition of EAF slag and cement Property Coarse slag Fine slagSize(mm)4–200–4Proportion after primary crushing%7624Apparent specific gravity(Mg/m3) 3.35 3.70Water absorption(%)10.5–Los Angeles loss(%)<20–Expansion average(ASTM D-4792)0.25%0.25% Chemical composition Percentage weightEAF Slag P.cementR Iron oxides42.5 3.7SiO215.321.9CaO23.964.2Al2O37.4 5.1MgO 5.10.9MnO 4.50.01SO30.1 3.3Others(P2O5+TiO2+Na2O+K2O)1.00.9Free CaO0.45Not measured Free MgO$1.0Not measured Glassy phase<5.0Not measuredJ.M.Manso et al./Cement&Concrete Composites28(2006)528–534529Free lime content was determined according to EN 1744-1standard[1].Periclase content was estimated by X-ray diffraction analysis using the peak at2.11A˚.Estima-tion based on X-ray diffraction diagrams[23]found that the presence of glassy phase was under5%.3.Concrete mixturesSix experimental concrete mixtures were designed,all subject to the following initial conditions:•cement content:310kg/m3,•ratio w/c:60.6,•workability:60–90mm(slump test),•no admixtures.In each case,15–150mm cubes were used in various experiments to analyse their properties and durability.As shown in Table2,the M-1mixture is a standard structural concrete made with crushed limestone aggre-gates,and serves as a reference.M-2is a concrete prepared with only crushed slag as aggregate.The M-3,M-4,M-5 and M-6mixtures are variants in the search for the optimal solution.M-3has the samefine aggregate(<4mm)as M-1. In M-4,M-5,and M-6thefine aggregate was prepared as detailed above.The results obtained from an exhaustive analysis of the features of each concrete are summarized in Table3,in which tests to determine apparent specific gravity,water absorption and porosity were performed on different mixes stored in a moist room for28days.The values,in general,show satisfactory compressive strength,being in all cases above30MPa at28days,except for mixture M-2.Mixture M-1is the strongest concrete at7 and28days,and those mixtures containing EAF slag pres-ent a slightly lower strength.However,after90days or1 year in a moist room,the strength of the best EAF slag concrete reaches values comparable to that of the reference concrete.Mix proportions,as set out in Table2,are an extremely important factor,whenever EAF slag is used as aggregate.In the water penetration test,the M-4and M-5mixtures, both of which are made with afine aggregate compound of 50%EAF slag and50%filler limestone,show greater impermeability.M-6has the highest total porosity from among the correct mixtures(excluding M-2),giving a valueTable2Composition of concrete mixturesMixture Water(kg)Cement(kg)Aggregate0/4(kg)Aggregate4/20(kg)Slump test(mm) Limestone Slag Limestone SlagM-1186310930–935–70M-2186310–950–945Collapse M-3186310960––89550M-4186310480a480–89570M-5186310480a480–620120M-6186310330a630–62070a Indicates limestone aggregate of low size(less than1mm)employed as limestonefiller mixed with slagfine aggregate.Table3Properties of EAF slag concretesMixture Apparent specificgravity(Mg/m3)a Water absorption(%)aPorosity(%)aCompressive strength(MPa)b Water penetration(mm)c7days28days90days1year Maximum AverageM-1 2.34 5.513.031.638.541.942.75032M-2 2.3912.730.412.820.622.4–Total Total M-3 2.38 6.816.227.433.739.241.17045M-4 2.50 6.516.028.135.343.845.6115M-5 2.56 6.917.623.830.238.340.575M-6 2.597.619.625.130.738.140.23525 Test performed according a EN12390-7Standard,b EN12390-3Standard,c EN12390-8Standard.530J.M.Manso et al./Cement&Concrete Composites28(2006)528–534for water penetration slightly lower than reference concrete M1.4.Durability of concrete4.1.Accelerated ageing test.(Batch test related to possible internal damage of concrete due own composition)4.1.1.Autoclave testTwo cube specimens of each mixture cured in a moist room over28days were subjected to an autoclave test, using the following parameters:•initial warming-up,for1h reaching2MPa,•maintaining2MPa for3h,•secondary warming-up reaching4MPa,•maintaining4MPa for2h,•slow cooling and immersion in water at90°C,•cooling at room temperature,•weathering for90days,protected from direct sunlight and rain.This test is based on the autoclave test to detect the pres-ence of expansive compounds,free lime or free magnesia in Portland cement according to ASTM C-151[20].In this case,the parameters applied for pressure and time differ from those originally proposed in the standard,although the intention remains the same.The test,as performed here,is a very severe one,not only during the maintenance of specimens in the autoclave but also throughout the subsequent period of weathering. During this period,expansive chemical reactions of com-pounds present in the concrete during the exposure period in the autoclave and the environment can occur.The results are summarized in Table4for mixtures M-1, M-3and M-4.Immediately after the autoclave test,the superficial appearance was normal in all cases and the results show lack of expansivity in the specimens,the behaviour of the reference concrete being similar to the EAF slag concrete.After90days of weathering,the mixtures showed slight (M-3and M-4)or medium(M-1)superficial cracking.The reference concrete M-1made with limestone coarse aggre-gate was more susceptible to loss of mechanical strength. The cementitious matrix is weakened and,in all probabil-ity,the greater compressive strength of the EAF slag con-cretes may be explained in terms of the convex geometric form of limestone aggregate particles set against the conc-oidal,cavernous and vesicular geometrical form of the slag. In fact,the compressive rupture of M-1showed a non-cohesive separation between the matrix and aggregate,a situation that was not so clearly observed in mixtures M-3and M-4.In the case of M-3,in which thefine aggregate is made up only of crushed limestone,its performance is slightly worse than that of M-4,in which thefine aggregate is composed of equal proportions(50–50%)of EAF slag and limestone.4.1.2.Accelerated ageingAs a complement to the autoclave test,a further durabil-ity test was performed,based on the methodology proposed in the ASTM D-4792standard[20],allowing a final evaluation of concrete strength[16]instead of measur-ing the vertical expansion of the specimen(less significant than the vertical expansion of a properly compacted gran-ular material).In this case,cube specimens,having been stored for28 days in a moist room,were kept under water at a temper-ature of70°C for32days.Following this,they were exposed to the weather for90days under moist atmo-spheric conditions,avoiding any direct exposure to sun-light and rain.The objective of this test is to provoke the hydration of free lime and periclase within the slag aggre-gate through expansion in hot water.Subsequently,the specimens were left for90days to allow the effects to be fully extended into the concrete.Table5shows the results for compressive strength and highlights improvements after testing.Improvements in the strength of these concretes,after being held for90days in a moist room(see Table3),are greater than those obtained after this test from150-day-old specimens.How-ever,it should be observed that the behaviour of the refer-ence concrete is in general similar to concretes made with EAF slag,and it can therefore be concluded that the use of the slag aggregate is not significant in this test.Other authors[24]have proposed alternative methodol-ogies to evaluate the effects on this kind of concrete underTable4Properties of slag concretes after autoclave test and90days weathering periodMixture Variationin weight(%)Compressivestrength(MPa)Loss ofstrength(%)Appearance Before AfterM-1À0.4838.518.452SuperficialcrackingM-3À0.1533.720.938Slight superficialcrackingM-4À0.2835.323.833Slight superficialcracking Table5Properties of slag concretes after accelerated ageingMixture Change inweight(%)Compressivestrength(MPa)SuperficialappearanceBefore AfterM-1À0.2638.539.6GoodM-3À0.7033.735.9FlakesM-4À0.9035.339.4FlakesM-5À0.6030.233.5GoodM-6À0.8030.734.1GoodJ.M.Manso et al./Cement&Concrete Composites28(2006)528–534531accelerated ageing,measuring dimensional transformations after leaving specimens in a climatic chamber for several weeks at a controlled temperature and humidity.This is an interesting avenue of research that should be further explored.4.2.Chemical reactivity test(a batch test related to possible reactions between the slag aggregate andother components of the concrete)4.2.1.Alkali-aggregate reactionThis test evaluates the potential damage in the concretemass due to the possibility of a chemical reaction between alkaline hydroxides and certain EAF slag components.In general,the silicates present in the slag(larnite,meli-lite,merwinite,diopside...)are quite stable when in con-tact with alkalis.However,the slag has an appreciable proportion of glassy phase,which is usually capable of producing a reaction with the alkalis in cement.Moreover, because of the variable nature of the chemical and micro-structural components of EAF oxidizing slag,any possible reactivity with alkalis must be taken into account.It is therefore advisable to perform this test on each different batch of EAF slag.The tests were performed according to ASTM C-1260 standard[20],and were evaluated as per ASTM C-227 standard[20].The average value of expansion after16days was0.14%. After28days,the value of0.15%was below the critical value of0.2%,set as the ASTM C-227limit,which suggests low alkali-slag aggregate reactivity.However,the result is significant,and points to some sort of activity within the concrete.The comments written in ASTM C-227standard, Section3.3,indicate that the effect of free lime,periclase and sulphates,if they are presents in the aggregate,overlap the alkali-aggregate expansive reaction and contribute to total expansion at the end of the test.Despite the low proportions of free lime and periclase in the slag,their presence probably explains the expansion of0.15%.4.3.Environmental test(batch test related to possible environmental degradation of concrete)4.3.1.Freezing and thawing cyclesIn this test,three specimens of each mixture stored in a moist room for28days,were subjected to25cycles of freezing and thawing:•immersed in water at4°C for6h,•maintained in frost storage atÀ17°C for18h.These conditions,guided by past experience,are suffi-ciently severe to highlight differences among concretes, for which compressive strength at28days is in the range of30–40MPa.At the end of the test,the superficial appearance,variation in weight and compressive strength were all recorded.The results are summarized in Table6.The internal pressure of ice in the accessible pores of the concrete(matrix and aggregates)accompanied by the ther-mal changes produce superficial spalling in the samples and leads to a dramatic decrease in their compressive strength (see also Figs.2a and2b).The test severity level,as was desired,is very high.Table6Properties of slag concretes after freezing and thawing cyclesMixture Variationin weight(%)Compressivestrength(MPa)Loss ofstrength(%)SuperficialappearanceBefore AfterM-1À0.1438.532.715GoodM-3À1.0233.720.639Noteworthy damageM-4À0.2735.327.223Slight damageM-5À0.9430.216.944One sample crackedM-6À1.1830.716.048Noteworthydamage Fig.2a.Mixture M-3.Noteworthy damage after freezing and thawingcycles.Fig.2b.Mixture M-5.Cracked sample after freezing and thawing cycles.532J.M.Manso et al./Cement&Concrete Composites28(2006)528–534The most resistant concrete is M-1,which has the best initial strength.The concretes made with EAF slag show variable degrees of damage.Mixture M-4is the best of the EAF slag concretes,probably due to its greater strength and lower water penetration.The results show the influence of greater porosity and the slightly lower strength of mixtures M-3,M-5and M-6.The use of air-entraining admixtures should increase their resistance to freezing. 4.3.2.Wetting and drying testThree specimens of each mixture,cured in a moist room for28days,were subjected to30cycles of wetting and drying as follows:•immersion in potable water for16h,•oven drying at110°C for8h.The severity level of this test is also intended to be high. Following the test,the main parameters were monitored and the results are summarized in Table7.In this case, damage is produced by two combined effects:thermal dila-tion and contraction,and shrinkage due to variations in humidity.Loss of particular characteristics is evident in all of the mixtures,though M-1and M-4are less susceptible to loss of strength.The superficial damage is low in almost all cases.Strength is also considered to be a critical factor,and similar results for percentage strength loss between M-1 and M-4suggest that the deleterious effects on the cemen-titious matrix are comparable and noteworthy in both cases,but occur less so than in other mixtures.4.4.Environmental test(test related to possible attackof concrete to environment.Leaching test)Nowadays,industrial by-products require a study of their potential toxicity.In the case of steelmaking slag, there are several dangerous heavy metals and salts which can be present after a manufacturing process that involves scrap steel.A leaching test is required prior to EAF slag being used directly as afilling material.Table8shows the results of the analysis of leached water from crushed slag–coarse andfine aggregates–used in the M-1and M-4mixtures,to detect sulphate,fluoride and total chromium.The leached water was obtained according to EN12457standard[1].It can be observed that the smaller sizes of crushed slag produce higher concentrations of dangerous substances in the leached water than the larger sizes,in which the clois-tering effect is greater.It can be expected that the use of EAF slag as an aggregate in concrete will allow its poten-tial toxicity to be reduced.A beneficial cloistering role of concrete onfluorides and chromium can be appreciated in the results of Table8.In the case of sulphates,the results correspond to the mass dilution of slag in the total con-crete.All values are under the maximum limits stipulated by local legislation.5.Concluding commentsElectric arc furnace oxidizing slag,obtained from the manufacture of plain and low-alloy carbon steels,can be used as aggregate in concrete following appropriate condi-tioning.Special attention must be paid to the crushing process to produce a suitable grading to obtain the best results in Los Angeles test.In this study,an adequate grad-ing has been achieved by adding mineralfillers to complete thefine fraction.When using EAF slag concrete,it is important to produce appropriate mixtures to guarantee the correct level of durability.High compressive strength and low water penetration should be the main characteristics.Systematic testing to verify the efficiency of slag stabilization treatmentTable7Properties of slag concretes after wetting and drying cyclesMixture Variationin weight(%)Compressivestrength(MPa)Loss ofstrength(%)Superficialappearance Before AfterM-1À0.0838.527.329GoodM-3À0.1233.719.941Slight damageM-4À0.1535.324.730GoodM-5À0.1630.216.645Slight damageM-6À0.2830.715.649One samplecrackedTable8Leaching test on concrete and crushed slagMixture Sulphates(mg/kg)Fluorides(mg/kg)Cr total(mg/kg)A2a A2–10b Maximum limit A2a A2–10b Maximumlimit A2a A2–10b MaximumlimitM-114.158.53770.110.81180.030.12 2.6M-4 6.238.63770.120.36180.020.10 2.6CS c(0/4mm)93.7115.4377 6.6012.40180.20 1.02 2.6CS c(>4mm)76.495.1377 5.3010.10180.160.80 2.6a Ratio liquid/solid=2.b Ratio liquid/solid=2,in addition with ratio liquid/solid=10.c CS=crushed slag.J.M.Manso et al./Cement&Concrete Composites28(2006)528–534533is strongly suggested as such measures allow any possible expansivity to be carefully monitored.The results show that the performance of EAF slag con-cretes is similar to that of a more traditional concrete in terms of its strength and slightly less so in terms of its durability.The high porosity of EAF slag is an obstacle to making a concrete resistant to freezing.Eventual improvements in thisfield could be further analysed by adding specific admixtures.Finally,the leaching test is seen as compulsory and this study shows a substantial cloistering effect of concrete on the toxic products present in EAF slag.AcknowledgementsThanks are due to the Diputacion Foral de Guipuzcoa forfinancial support in the Research Project Valorizacio´n 98/99.Also,to the Basque Country Government forfinan-cial support in the Research Projects UE97-19and UE98-15.References[1]CEN.European Committee for Standardization.Rue de Stassart,36.Brussels B-1050.[2]Motz H,Geiseler J.Products of steel slags:an opportunity to savenatural resources.Waste Manage.2001;21:285–93.[3]Dunster AM.The use of blast furnace slag and steel slag asaggregates.In:Zoorab,Collop,Brown,editors.Performance of bituminous and hydraulic materials in pavements.Lisse:Swets and Zeitlinger;2002,ISBN9058093751.p.257–60.[4]/media/ssy.Steel Statistical Yearbook2003.International Iron and Steel Institute,Brussels.[5]Lo´pez FA,Lo´pez-Delgado A,Balca´zar N.Physico-chemical andmineralogical properties of EAF and AOD slags.Afinidad LIII1996;461:39–46.[6]Luxa´n MP,Sotolongo R,Dorrego F,Herrero E.Characteristics ofthe slags produced in the fusion of scrap steel by EAF.Cem Concr Res2000;30(4):517–9.[7]San Jose´JT.Reutilizacio´n y valoracio´n en obra civil de escorias dehorno ele´ctrico de arco producidas en la CAPV.Arte y Cemento 2000:124–6.[8]Frias Rojas M,Sa´nchez de Rojas MI,Uria A.Study of the instabilityof black slags from EAF steel industry.Mater Construcc2002;52(267):79–83.[9]Va´zquez-Ramonich E,Barra M.Reactivity and expansion of electricarc furnace slag in their application in construction.Mater Construcc 2001;51(263–264):137–48.[10]Maslehuddin M,Sharif AM,Shameem M,Ibrahim M,Barry MS.Comparison of properties of steel slag and crushed limestone aggregate concretes.Constr Build Mater2003;17:105–12.[11]Moon Han Young,Yoo Jung Hoon,Kim Seong Soo.A fundamentalstudy on the steel slag aggregate concrete.Geosyst Eng2002;5(2): 38–45.[12]Beshr H,Almusallam AA,Maslehuddin M.Effect of coarse aggregatequality on the mechanical properties of high strength concrete.Constr Build Mater2003;17:97–103.[13]Morino K,Iwatsuki E.Durability of concrete using electric arcfurnace oxidizing slag aggregates.In:Swamy N,editor.Proceedings international conference,Sheffield1999:213–22.[14]Geyer RT,Dal Molin D,Vilella A.Availac¸ao da durabilidade doconcreto armado com adicao de escoria d’aciaria eletrica56°Congreso ABM,Belo Horizonte,July2001.p.127–36.[15]Hino M,Miki T.New role of steelmaking slags for the environmentalprotection of ocean.Shiraishi Memorial Lecture of the Iron Institute of Japan,Tokyo2001;44–45:99.[16]Manso JM.Fabricacio´n de hormigo´n hidra´ulico con escorias dehorno ele´ctrico de arco.Ph.D.Engineering Thesis.University of Burgos,Spain,2001.[17]Manso JM,Gonza´lez JJ,Polanco JA.EAF slag in concrete.J MaterCivil Eng2004;16(6):639–45.[18]Papayianni I,Anastasiou E.Concrete incorporating high volumes ofindustrial by-products.Aristotle University Greece.In:Dhir RK, Newlands MD,Payne KA,editors.Role of concrete in sustainable development,Proceedings of international symposium dedicated to Professor Surendra Shah.Dundee,United Kingdom,September 2003,Thomas Telford Publ.p.595–604.[19]Oliveira da Silveira N,Almeida Melo e Silva MV,Agrizzi EJ,Fernandes de Lana M,Antonio da Silva E,Lacourt de Mendoca R.Acerita–steel slag with reduced expansion Revue de Metallurgie–CIT.October2004.p.779–85.[20]Annual Book of ASTM Standards.West Conshohocken,PA,19428-2959USA.[21]Cen Y,Chen Q.Experiment on crushing EAF slag.SEAISI Quart1993;22(4):81–5.[22]Watanabe T,Okamoto T,Takahashi H.Development of a new dustand slag treatment technology.In:SEAISI2000Australia Confer-ence.Perth,May2000,Proceedings vol1,S3,P6.[23]Bish DL,Howard SA.Quantitative phase analysis using the Rietveldmethod.J Appl Crystallogr1988(21):86–91.[24]Vazquez-Ramonich E,Barra M.Durability of concretes with steelslag as aggregates.Workshop on R+D+I in Technology of concrete structures–a tribute to Dr.Ravindra Gettu.Barcelona.October2004.p.23–30.534J.M.Manso et al./Cement&Concrete Composites28(2006)528–534。
Durability of Concrete
Durability of ConcreteBesides its ability to sustain loads, concrete is also required to be durable. The durability of concrete can be defined as its resistance to deterioration resulting from external and internal causes. The external causes include the effects of environmental and service conditions to which concrete is subjected, such as weathering, chemical actions and wear. The internal causes are the effects of salts, particularly chlorides andsulphates, in the constituent materials, interaction between the constituent materials, such as alkali aggregate reaction, volume changes, absorption and permeability.In order to produce a durable concrete care should be taken to select suitable constituent materials. It is also important that the mix contains adequate quantities of materials in proportions suitable for producing a homogeneous and fully compacted concrete mass.Deterioration of concrete by weathering is usually brought about by the disruptive action of alternate freezing and thawing of free water within the concrete and expansion and contraction of the concrete, under restraint, resulting from variations in temperature and alternate wetting and dryingDamage to concrete from freezing and thawing arises from the expansion of pore water during freezing; in a condition of restraint, if repeated a sufficient number of times, this results in the development of hydraulic pressure capable of disrupting concrete. Road kerbs and slabs, dams and reservoirs are very susceptible to frost action.The resistance of concrete to freezing and thawing can be improved by increasing its impermeability. This can be achieved by using a mix with the lowest possible water cement ratio compatible with sufficient workability for placing and compacting into a homogeneous mass. Durability can be further improved by using air entrainment, an air content of 3 to 6 percent of the volume of concrete normally being adequate for most applications. The use of air-entrained concrete is particularly useful for roads where salts are used for deicing.In general, concrete has a low resistance to chemical attack. There are several chemical agents, which react with concrete, but the most common forms of attack are those associated with leaching, carbonation, chlorides and sulphates. Chemical agents essentially react with certain compounds of the hardened cement paste and the resistance of concrete to chemical attack, therefore, can be affected by the type of cement used. The resistance to chemical attack improves with increased impermeability.The main causes of wear of concrete are the cavitation effects of fast-moving water, abrasive material in water, wind blasting and attrition and impact of traffic. Certain conditions of hydraulic flow result in the formation of cavities between the flowing water and the concrete surface. These cavities are usually filled with water vapor charged with extraordinarily high energy and repeated contact with the concrete surface results in the formation of pits and holes, known as cavitation erosion. Since even a good-quality concrete will not be able to resist this kind of deterioration, thebest remedy is therefore the elimination of cavitation by producing smooth hydraulic flow. Where necessary, the critical areas may be lined with materials having greater resistance to cavitation erosion.In general, the resistance of concrete to erosion and abrasion increases with increase in strength. The use of a hard and tough aggregate tends to improve concrete resistance to wear.Certain natural aggregates react chemically with the alkalis present in Portland cement. When this happens these aggregates expand or swell resulting in cracking and disintegration of concrete.Principal factors responsible for volume changes are the chemical combination of water and cement and the subsequent drying of concrete, variations in temperature and alternate wetting and drying. When change in volume is resisted by internal or external forces, this can produce cracking, the greater the imposed restraint, the more severe the cracking. The presence of cracks in concrete reduces its resistance to the action of leaching, corrosion of reinforcement, attack by sulphates and other chemicals, alkali-aggregate reaction and freezing and thawing, all of which may lead to disruption of concrete. Severe cracking can lead to complete disintegration of the concrete surface particularly when this is accompanied by alternate expansion and contraction.V olume changes can be minimized by using suitable constituent materials and mix proportions having due regard to the size of structure. Adequate moist curing is also essential to minimize the effects of any volume changes.Permeability refers to the ease with which water can pass through the concrete. This should not be confused with the absorption property of concrete and the two are not necessarily related. Absorption may be defined as the ability of concrete to draw water into its voids. Low permeability is an important requirement for hydraulic structures and in some cases water tightness of concrete may be considered tobe more significant than strength although, other conditions being equal, concrete of low permeability will also be strong and durable. A concretewhich readily absorbs water is susceptible to deterioration.Concrete is inherently a porous material. This arises from the use of water in excess of that required for the purpose of hydration in order to make the mix sufficiently workable and the difficulty of completely removing all the air from the concrete during compaction. If the voids are interconnected concrete becomes pervious although with normal care concrete is sufficiently impermeable for most purposes. Concrete of low permeability can be obtained by suitable selection of its constituent materials and their proportions followed by careful placing, compacting and curing. In general, for a fully compacted concrete, the permeability decreases with decreasing water-cement ratio. Permeability is affected by both the fineness and the chemical composition of cement. Aggregates of low porosity are preferable when concrete with a low permeability is required. Segregation of the constituent materials during placing can adversely affect the impermeability of concrete.。
alex-Durability of Concrete Materials
当侵蚀溶液中SO42-浓度>1000 mg/L 时，侵蚀性介质中硫
酸盐与水泥浆体中的Ca(OH)2发生化学反应，生成钙矾石和二 水石膏。
2.混凝土硫酸盐侵蚀机理与分类
2.3. 石膏结晶型
SO42-浓度小于1000mg/L SO42-浓度大于1000mg/L
水泥 水化产物
钙钒石
二水 石膏
Ca(OH)2
产生较大的破坏性内应力。达到一定程度后，会破坏混凝土结构。
2.混凝土硫酸盐侵蚀机理与分类
2.3. 石膏结晶型
结构不发生破坏
浆体中的C-S-H 和C-A-H会发生 水解。结构发生 破坏
2.混凝土硫酸盐侵蚀机理与分类
2.3. 石膏结晶型
前苏联的B.B Kind等人认为：
SO42-浓度的高低决定了所形成的晶体种类。 当侵蚀溶液中SO42-浓度<1 000 mg/L 时，只有钙矾石结晶 形成。
1892年，Michalis 通过实验发现硫酸盐对混凝土有侵蚀作用，
并发现一种当时称作“ 水泥杆菌”的物质。（首次人工合成） 水泥杆菌 =水化硫铝酸钙（钙矾石）图片 1923年，美国学者米勒开始在含硫骏盐土壤中进行混凝土的腐蚀试验.
我国的混凝土硫酸盐侵蚀的研究起步于20世纪50年代。在1959到
2.混凝土硫酸盐侵蚀机理与分类
2.2. 钙矾石结晶型
(a) Diagrammatic representation of the expansion of a mortar or concrete caused by delayed ettringite formation (DEF). (b) Scanning electron micrograph of a mortar affected by delayed ettringite formation（DEF）
聚羧酸减水剂 竣工验收
聚羧酸减水剂竣工验收英文回答：Polycarboxylate superplasticizers (PCEs) are widely used in modern concrete construction due to their remarkable water-reducing and workability-enhancing abilities. They meet various performance requirements specified in construction codes and standards worldwide. At the acceptance stage of a concrete project, the performance of PCEs is rigorously evaluated to ensure compliance with the project specifications.Acceptance criteria for PCEs typically include:Water reduction: The ability of the PCE to reduce the water content of concrete without compromising its workability is a crucial factor. It is usually expressed as a percentage reduction in water demand compared to acontrol mix.Slump retention: PCEs should maintain the concrete's workability and consistency over a defined period, allowing ample time for placement and finishing. This is typically measured by slump loss or slump retention at specified time intervals.Air content: PCEs can affect the air content of concrete, which influences its properties. The acceptance criteria specify the allowable range of air content to ensure optimal performance.Setting time: The influence of PCEs on the setting time of concrete is evaluated to ensure proper setting and hardening characteristics.Strength development: PCEs may impact the strength development of concrete, which is a critical aspect of structural performance. The acceptance criteria specify the minimum compressive strength at specified ages.Durability: The durability of concrete is crucial for long-term performance. Acceptance criteria may includeresistance to freezing and thawing, chloride penetration, and sulfate attack.Acceptance testing of PCEs involves a series of laboratory tests conducted on concrete samplesincorporating the PCE. These tests adhere to standardized procedures and are performed by qualified laboratories. The test results are analyzed to assess the PCE's performance against the specified criteria.In addition to the standard acceptance criteria,project-specific requirements may also be imposed. These requirements could relate to specific performanceattributes, such as high-early strength, self-compacting properties, or compatibility with other concrete admixtures.Meeting the acceptance criteria for PCEs is essentialfor ensuring the quality and performance of concrete structures. Rigorous testing and evaluation at the acceptance stage provide confidence that the PCE meets the project specifications and contributes to the durabilityand longevity of the concrete structure.中文回答：聚羧酸减水剂竣工验收。
耐久性设计规范简介
9 引气 (air entrainment) 混凝土拌和时用表面活性剂在混凝土中形成均匀、稳 定球形微气泡的工艺措施。 10 含气量 (concrete air content) 混凝土中气泡体积与混凝土总体积的比值。对于采用 引气工艺的混凝土，气泡体积包括掺入引气剂后形成 的气泡体积和混凝土拌和过程中挟带的空气体积。 11 气泡间隔系数 (air bubble spacing) 硬化混凝土或水泥浆体中相邻气泡边缘之间的平均距 离。 12 维修 (maintenance) 为维持结构在使用年限内所需性能而采取的各种技术 和管理活动。
Introduce to Code for Design Durability of Concrete Structure
扬州科技学院土木工程系朱平华
规范的主要内容
编制说明 1.总则 2. 术语和符号 3. 基本规定 4. 各种环境下混凝土结构耐久性设计: 一般环境、冻融环境、氯化物环境、 化学腐蚀环境 5.后张预应力混凝土结构
3.1 设计原则
混凝土结构的耐久性设计原则： 结构的设计使用年限、 结构所处的环境类别、 结构所处的环境作用等级。 对于氯化物环境下的重要混凝土结构， 尚应按本规范附录A的规定采用定量方 法进行辅助性校核。 相关原则见附录A
混凝土结构的耐久性设计包括如下内容：
1 结构的设计使用年限、环境类别及其作用等级； 2 有利于减轻环境作用的结构类型、布置和构造； 3 混凝土材料与钢筋的耐久性质量要求； 4 钢筋混凝土保护层厚度； 5 混凝土裂缝控制要求； 6 防水、排水等构造措施； 7 严重环境作用下合理采取防腐蚀附加措施或多重防护策 略； 8 耐久性需要的施工养护与保护层厚度的施工质量验收要 求； 9 提出结构使用阶段的维护与检测要求。
durability
CE 60 Instructor: Paulo Monteiro
Water in the capillary
CE 60 Instructor: Paulo Monteiro
Definition
• Permeability is defined as the property that governs the rate of flow of a fluid into a porous solid.
CE 60 Instructor: Paulo Monteiro
Permeability of Aggregate
• However, the coefficient of permeability of aggregates are as variable as those of hydrated cement pastes of water/cement ratios in the range 0.38 to 0.71
CE 60 Instructor: Paulo Monteiro
Darcy’s law
• For steady-state flow, the coefficient of permeability K is determined from Darcy's expression:
Dq/dt = K (∆ H A)/(Lν)
CE 60 Instructor: Paulo Monteiro
Reason
• The reason some aggregates give much higher permeability than the cement paste is that the size of capillary pores in aggregate is usually much larger. • Most of the capillary porosity in a mature cement paste lies in the range 10 to 100 nm, while pore size in aggregates are, on the average, larger than 10 microns.
Durability of concrete 混凝土的耐久性
Chemical agents essentially react with certain
compounds of the hardened cement paste and the resistance of concrete to chemical attack therefore can be affected by the type of cement used. the hardened cement paste:水泥石 化学物质本质上是与某些水泥石化合物发生反 应。因此，混凝土的抗化学侵蚀能力与所使用 的水泥种类有关。
In general,the resistance of concrete to
erosion and abrasion increases with increase in strength.
一般来说，混凝土的抗腐蚀和抗磨损能力随它
的强度的增大而增大。
The use of a hard and tough aggregate tends
to improve concrete resistance to wear.
使用强硬的骨料有助于提高混凝土抗磨强度。
水工建筑物?低渗透性是水工建筑物中的一个重要要求在某些情况下会认为混凝土的水密性比强度更重要即使其他条件相同混凝土的低渗透性也要很强很耐久
Durability of concrete 混凝土的耐久性
08工程管理（1）班 李海姣、纪飞、刘涛、林新、王腾
Besides its ability to sustain loads, concrete is
耐久性可以通过使用引气剂而进一步提高，通
常空气含量占混凝土体积的3%~6%即可胜任 大部分应用。
混凝土技术服务和质保期服务计划
混凝土技术服务和质保期服务计划英文回答：Concrete Technology Services and Warranty Service Plan.Concrete technology services are essential for ensuring the quality and durability of concrete structures. These services encompass a wide range of activities, including mix design, testing, quality control, and troubleshooting. By providing expert guidance and support, concrete technology services help to ensure that concrete structures meet the required standards and specifications.One important aspect of concrete technology services is the development of a comprehensive mix design. This involves determining the optimal proportions of cement, aggregates, water, and admixtures to achieve the desired strength, workability, and durability of the concrete. The mix design is tailored to the specific requirements of the project, taking into account factors such as the type ofstructure, environmental conditions, and construction methods.In addition to mix design, concrete technology services also involve testing and quality control. This includes conducting laboratory tests to assess the properties of the concrete, such as compressive strength, slump, and air content. Quality control measures are implemented throughout the construction process to ensure that the concrete meets the specified requirements. This may involve on-site inspections, sampling and testing of fresh and hardened concrete, and monitoring of curing conditions.Troubleshooting is another important aspect of concrete technology services. Sometimes, issues may arise during the construction process or after the completion of the structure. These issues can include problems with concrete placement, curing, or durability. Concrete technology services can help to identify the root causes of these issues and provide recommendations for corrective actions. This may involve conducting investigations, performing additional tests, and proposing remedial measures.In addition to concrete technology services, a warranty service plan is often provided to ensure the long-term performance of concrete structures. This plan typically covers a specific period, such as 5 or 10 years, and includes provisions for addressing any defects or issues that may arise during this period. The warranty service plan provides peace of mind to clients and helps to establish trust and confidence in the quality of the concrete work.Concrete technology services and warranty service plans are important for both the clients and the concrete contractors. For clients, these services ensure that their structures are built to last and meet the required standards. They provide assurance that the concrete work is of high quality and will perform as expected. For concrete contractors, these services help to differentiate their services from competitors and build a reputation for excellence. By offering comprehensive concrete technology services and warranty service plans, contractors canattract more clients and secure repeat business.中文回答：混凝土技术服务和质保期服务计划。
四、混凝土的耐久性
DURABILITY of CONCRETE
概 念
混凝土耐久性
混凝土材料在长期使用过程中，抵抗因服役环境 外部因素和材料内部原因造成的侵蚀和破坏，而保 持其原有性能不变的能力。
混凝土构筑物的服役寿命
混凝土构筑物受到其服役环境因素的侵蚀和破坏， 导致其使用性能下降到最低设计值时，所经历的时 间( 年 ) 。
一、混凝土的抗渗性 Permeability of Concrete
定义：混凝土抵抗压力水(油、液体)渗透的能 力，称为抗渗性。
• 水是混凝土生产过程，同时也是破坏过程 的主要介质。不仅物理劣化过程与水有关，同时 作为传输侵蚀性离子的介质，水又是化学劣化过 程的一个根源。
所以水是大多数混凝土耐久性问题的核心！！！
什么是碱骨料反应？
最常见、最重要的反应是碱 — 硅反应 (简称ASR)，它是骨料中所含的无定形硅与 孔隙里含碱(钠、钾、钙的氢氧化物)的溶液 反应，生成易于吸水膨胀的碱 -硅凝胶，当 结构物暴露在潮湿环境中，混凝土体内相 对湿度超过85%时，就会出现膨胀，直到引 起混凝土开裂与破坏。
常见的碱—骨料反应破坏形式
条件：氯离子扩散、氧与水分；与保护层厚度、 水灰比、水泥用量等有关。
钢筋锈蚀导致混凝土构件破坏的几种形式
混凝土中钢材锈蚀的防护措施
下列几种新措施，可以在原材料选择、配合比设计、 保护层厚度与施工过程的基础上，进一步改善对钢材腐 蚀的防护作用： 1)在新拌混凝土里掺用阻锈剂，如亚硝酸钙；
2)用不锈钢作为配筋，或环氧涂层钢筋； 3)混凝土采用涂层保护，减少氯盐与氧的侵入； 4)对钢筋进行阴极保护，即外加电压以保持钢筋处于 阴极区。
综合
钢筋混凝土桥梁的侵蚀损毁
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Durability of Concrete
一个最重要的要求是，它应该是一定暴露条件下的混凝土耐久。
为了实现这个耐久性，正确的选择材料，良好的设计和在混合，浇筑和养护混凝土时严格的质量控制，是必不可少的。
恶化，可以出现在各种形式，如碱-骨料反应，冻融膨胀，盐除冰，由于碳化，被地面水域含有硫酸根离子硫酸盐侵蚀，海水腐蚀和盐引起的腐蚀的盐造成收缩和放大会腐蚀加固钢筋。
添加外加剂可以控制这些有害影。
空气夹带的结果增加了防止冻融作用，抑制腐蚀外加剂提高耐腐蚀，加入硅粉的混凝土渗透性降低，结果是盐进入率增加，并增加渣混凝土的抗硫酸盐侵蚀性能的提高。
综合设计耐久性好的、高品质的混凝土
术语“高品质”用来形容具有良好的和易性和硬化后具有高致密性的混凝土
在设计混凝土配合物应考虑到的因素包括使用水泥的标号，水泥与骨料比率，集料种类，骨料粒度分布和水灰比。
混凝土所反映出来的物理和化学反应的条件都依赖于上述的因素。
设计混凝土本应该主要目的是减少相互关联的孔隙，但是使用的水灰比太高了。
消除混凝土微缝也应考虑。
这些裂缝可能是来自骨料和加固钢筋处水流动产生的，干燥收缩的水泥浆体和不同的热膨胀系数的骨料黏贴产生的。
这些裂缝存在可能降低混凝土抗疲劳，磨损和腐蚀。
以及设计的组合，安置的混凝土应认真监督。
混凝土的厚度覆盖了加固是控制二氧化碳或氯化物渗透到混凝土非常重要的。
这是因为渗透深度约为一个曝光时间的平方根的函数。
这意味着一半的混凝土厚度，它要用100年时间碳化达达到加固将会导致碳化达到加固只需
25年就够了。
压实，养护也至关重要。
压实度不足可导致超过10倍增加通透性。
养护不好，其中造成混凝土干过早，可能导致五至十倍增加混凝土的渗透性。
高品质的混凝土要求水泥含量充足，良好的压实，伴随养护和Cs反应。
相对于这些重要性，在混凝土重要性为1:3:5。
需要生产耐久性的混凝土的一般因素具体概括为：
使用优质混凝土，水泥含量充足，良好的压实和养护。
混凝土的混合必须保持统一和一致性，易于浇筑并且不易分离
预防钢筋锈蚀。
它必须有足够的厚度，质量好的混凝土覆盖。
钢筋必须在浇筑是不移动，而且不阻碍一混凝土流动。
维修考虑。
在设计阶段时候这个必须考虑，提前预定。
例如预定疏通排水通道，防止饱和水对混凝土的侵蚀。
养护剂的使用
确保有混凝土的充分的养护，使用养护剂可以限制的混凝土表面水蒸发损失率。
这些化合物形成连续的膜覆盖在混凝土的表面，当混凝土充分硬化是，足以使表面无破坏。
喷涂，刷涂或滚应用程序通常被采用。
以及保证混凝土养护剂限制蒸发作用，反射颜料，如二氧化钛或铝片可混合城的养护剂减少通过太阳辐射对混凝土的加热。
火山灰的使用
在混凝土中加入火山灰与氢氧化钙形成CSH凝胶导致减孔隙率减少。
然而，这些添加剂也导致混凝土早期硬化强度降低，尽管这样，其后期强度往往高于没有添加火山灰的混凝土强度。
这意味着，添加火山灰材料混凝土养护比普通混凝土养护条件更加苛刻。
.
添加粉煤灰或其他火山灰材料来改善混凝土是为了减少混凝土的孔隙率，但是也降低其抗渗性。
抗硫酸盐侵蚀性能的改善是由于减少氢氧化钙与硫酸反应，但是，反过来导致生成钙矾石的数量减少。
以粉煤灰为例，抗硫酸盐侵蚀性能进一步提高，因为在表面灰分存在的三氧化硫与C3A充分反应形成一层钙矾石保护膜，从而硫酸盐不能进一步侵蚀混凝土。
尽管事实上火山灰与混凝土中的氢氧化钙反应，很少有证据表明，混凝土的PH因为他们的存在大大改变了。
这是说，即使非常高浓度粉煤灰没有降低混凝土的PH值以至于道道到极低值可能导致钢没有钝化。
硅粉添加剂
在混凝土中加入硅粉将延缓氯盐腐蚀。
硅微粉的可能，然而，缩短碳酸盐腐蚀时间，但只有在低标号混凝土中。
在混凝土抗压强度大于40兆帕时碳化通常不被当成是一个问题。
它还指出，在实践中的情况更为复杂，因为它是这些可控制腐蚀的危险因素结合，而这些不同的结合是难以预测。
但是证据表明，硅粉，提高混凝土的耐久性，也要改善嵌入式钢材腐蚀性能。
在含硅微粉的混凝土中加入亚硝酸钙保护混凝土内钢筋免受腐蚀。
在这种情况下，硅粉添加剂降低混凝土的渗透性与亚硝酸钙一点腐蚀抑制剂，表现为钢筋的稳定钝化层。