孔结构
孔隙结构的研究方法
碳酸盐岩的铸体薄片镜下孔隙特征（陶艳忠）
(a）残余颗粒云岩，残余鲕粒铸模孔a、生屑铸模孔b、蓝色铸 体，单偏光，四川盆地，三叠系，下三叠统，飞仙关组, WL1 井, 4352. 5m; (b) 粉晶藻灰岩，溶蚀孔，蓝色铸体，单江偏光 ，四川盆地，三叠系，飞仙关组，北碚剖面
a）岩石结构构造、主要粒径范围、颗粒 分选磨圆、岩石胶结类型等岩石基础信息
b）粒间填隙物类型及含量
c）孔隙类型、相对含量、孔隙发育程度
d) 岩石定名
二、扫描电子显微镜（SEM）法
二、扫描电子显微镜（SEM）法
• 扫描电镜法的机理与电视摄像存在一定近似度，在于通过电子枪发射出 电子束，在加速作用下实现偏转，电子束对样品表层展开扫描，样品与电 子间形成作用，激发出一系列信号，此信号经处理后于荧光屏上成像。
接收样品——样品制备——配置液态浸染剂—— 真空灌注——加压灌注——加温固——分样— —磨铸体薄片、铸体样品酸蚀
铸体技术
• 铸体骨架：若将注入了浸染剂的岩石用酸 处理，溶蚀掉组成岩石的碎屑矿物、岩块 和胶结物，即成为岩石孔隙的空间结构。
• 铸体薄片：将注入浸染剂的岩石进一步加 工成岩石薄片。
一、薄片法--铸体薄片法
（焦淑静，2012）
三、毛管压力曲线法--压汞法
三、毛管压力曲线法--压汞法
基本原理： 对于岩石而言，汞是非润湿相流体，若将汞注入被抽空的岩样孔隙系统内，
则必须克服岩石孔隙喉道所产生的的毛细管阻力。因此，当某一注汞压力与岩样 孔隙吼道的毛细管阻力达到平衡时，便可测得该注汞压力及其该压力条件下进入 岩样内的汞体积。
四、数字岩心法--CT技术
四、数字岩心法--CT技术
孔隙结构分类
孔隙结构分类
孔隙结构的分类主要有以下几种：
1. 按孔隙成因分类：孔隙可分为原生孔隙和次生孔隙。
原生孔隙是在沉积成岩过程中形成的，不受后期成岩作用的影响；次生孔隙则是受沉积后压实作用和成岩作用的影响形成的。
2. 按孔隙产状分类：根据孔隙的产状，孔隙可分为粒间孔隙、粒内孔隙、微孔隙及裂缝孔隙等四种类型。
3. 按孔隙大小分类：孔隙可分为超毛细管孔隙、毛细管孔隙和微毛细管孔隙等。
4. 按孔隙空间构造分类：孔隙可分为孔隙缩小型、孔隙展大型、孔隙裂缝型等。
5. 按流体渗滤及几何特征的裂缝性碳酸盐岩孔隙结构分类：孔隙可分为裂缝型、缝洞型、裂缝-孔洞型和无规则型等。
总的来说，不同的分类标准使孔隙结构变得多种多样，具体使用哪一种分类方法应根据具体研究或工程实践的目的和要求来确定。
水泥石的孔结构
（3）水泥矿物组成对水泥石孔 水泥矿物组成对水泥石孔 分布的影响
水泥单矿物硬化体(标准条件下硬化28天)的孔分布试验结果见表2—2— 7—7所示。
- Click to add Text - Click to add Text - Click to add Text
6.影响水泥石孔分布的因素
(1)水化龄期对孔分布的影响
(2)水灰比对水泥石孔分布的影响
Content Title
（3）水泥矿物组成对水泥石孔分布的影响
（4）掺外加剂对水泥石孔分布的影响
Content Title
（5）养护条件对水泥石孔分布的影响
Content Title
(1)水化龄期对孔分布的影响
该图说明，随龄期的增长大孔减少，小孔增多。而掺入火山灰后， ThemeGallery is a Design Digital Content & 随龄期的增长，新生水化物填充孔隙，不仅使总孔隙率降低，而且 Description of Contents mall developed 大孔也减少。 the contents
2.水泥石孔的分类及作用
水泥石中孔的分布范围很广，孔径可从10um，一直小到0．005um。孔 隙不仅存在于水泥水化物占有的空间中，而且也存在于C-S-H凝胶粒子 的内部。如下图：
•分类及作用：关于水泥人中孔的分类方法很多，并有许多观点也不一致。 分类及作用： 分类及作用 Jawed等人通过对水泥石中孔结构研究后，给出了水泥石中不同类型的孔尺 寸及来源、相应的测试方法、对水泥石性质的主要影响(见表2—2-7—2)c
孔结构测定的原理和方法
D类吸附回线
E类吸附回线
p/p0 四面都开放的尖劈形毛细孔
131
p/p0
特征：吸附支缓慢上升到高压区，吸 附量增加趋近恒定，脱附支非常缓慢 地移动到中等p/p0区，陡然下降。
具有细颈和广体的管子或墨水瓶形状的孔 132
开始凝聚 的情况
开始蒸发 的情况
p/p0
吸附：曲率半径增大， 脱附：孔口曲率半径远 瓶体充满直至孔口 小于瓶体，限制了瓶体
ln(
p/p0
)
=
-
2γVM cosθ RTrk
rk
¾ p/p0≤1，rk越小 Î 发生毛细凝聚时的p/p0也越小
¾ 吸附时p逐渐增大，凝聚作用由 小孔Î大孔 ¾ 脱附时p逐渐减小，解凝蒸发由 大孔Î小孔
121
例：设吸附剂的孔为一端开口半径为R的圆筒，R的大小属于
中孔范围，可以应用Kelvin公式。设液体能完全润湿孔壁， 这样所得的吸附等温线如图(a)所示。
r = - 2γcos θ p
Washburn公式
141
对于汞来说，取θ=140°， γ = 480°10-5 N/cm 则上式进一步简化为： r = 7500
p
r — 孔的半径，nm； p — 外加压力，kg/cm2 (1kg/cm2 = 98.1kPa)
Î 压汞测孔法所测孔半径的大小仅与外压有关, 到达压力p 时,汞进入并充满所有半径大于r的孔中
¾ r ≤ rk 发生毛细凝聚 ¾ r > rk 不会发生毛细凝聚，而只有孔壁上的多分子层液膜
p1 ⇔ r1 , p2 ⇔ r2 Î 在蒸汽压 p1 和 p2 时测得的吸附量之差，就是孔半径届于 r1 和 r2 之间的孔体积 Î 孔分布
150
分子筛的结构单元和孔结构
谢谢大家！
●孔道的维数：可以是一维、二维的或三维的。 ●孔径大小：分子筛可以分为小、中、大、超大
孔，它们的窗口分别由8、10、12和大于12个 TO4四面体联接而成。 ●孔道的形状：直孔道形，笼状（呈葫芦状）
分子筛的孔道 -------常见沸石的孔道
☞A型沸石(LTA) 互相垂直的三维孔道体系，主孔道为八元环，直径 约0.42nm，笼的最大直径为1.14nm
分子筛的结构单元及孔结构
PPT制作:韩琳琳
目录
1、分子筛简介
1.1定义 1.2分类 1.3特点
2、分子筛的结构
2.1一级结构 2.2二级结构 2.3三级结构
3、分子筛的孔道
3.1描述分子筛空间结构的几个基本概念 3.2常见沸石的孔道
分子筛简介
定义： 广义：具有网状结构的天然或人工合成的化
学物质如交联葡聚糖、沸石等，当作为层 析介质时，可按分子大小对混合物进行分 级分离。
分子筛的结构
二级结构———环
四面体通过特定氧原子相连
分子筛的结构 二级结构-----多元环
分子筛的结构 三级结构 -------笼
二级结构单元通过氧桥进一步互相连接形成三维空
间的多面体，这种多面体叫做晶穴或称空穴空腔、
笼是构成沸石分子筛的主要结构单元 包括六方柱笼、立方体（γ）笼、α笼、β笼，八面
沸石笼等。 Biblioteka 笼进一步排列构成沸石骨架分子筛的结构
三级结构 -------笼
六方柱笼
混凝土孔结构的预测模型
International Journal of Concrete Structures and MaterialsVol.3, No.2, pp. 81~90, December, 2009DOI 10.4334/IJCSM.2009.3.2.081Predicting Model for Pore Structure of Concrete IncludingInterface Transition Zone between Aggregate and Cement PasteGi-Sun g Pan g,1) Sun g-Tae Chae,2) an d Sun g-Pil Chan g3)(Received September 8, 2008, Revised July 30, 2009, Accepted November 20, 2009)Abstract:This paper proposes a semi analytical model to describe the pore structure of concrete by a set of simple equations. The relationship between the porosity and the microstructure of concrete has been considered when constructing the analytical model. The microstructure includes the interface transition zone (ITZ) between aggregates and cement paste. The predicting model of porosity was developed with considering the ITZ for various mixing of mortar and concrete. The proposed model is validated by the rapid experimental programs. Although the proposed model is semi-analytical and relatively simple, this model could be reasonably utilized for the durability design and adapted for predicting the service life of concrete structures. Keywords:porosity, microstructure, interface transition zone, durability, service life.1. IntroductionIt has been established for many years in the research community that the presence of chloride ions is the most significant cause for the corrosion of reinforcing bars in concrete structures. A great deal of work has been done to characterize and prevent the ingress of these chlorides into concrete. It is known from research works that the microstructure of concrete is the key to understand chloride diffusivity of concrete. The modeling of concrete material should be conducted considering the microstructure in order to predict the realistic deterioration of structures. Chloride diffusivity is strongly affected by the pore size distribution and connectivity. There are different types of pores in concrete: the gel pores in the cement gel, the capillary pores between the solids in the cement gel and finally, the pores in the interface between the cement gel and the aggregate. In addition, there can be air voids and cracks.During recent decades, a number of models have been developed for describing concrete, cement paste and the interfacial zone between cement paste and aggregates. The aim of these models has varied ; Earlier models1 aimed principally at the understanding of the physical behavior, geometry and shape of the paste, ranging from nano scale to micro scale. On the contrary, later models2 are frequently of numerical nature aiming at calculating the time-dependent specific properties such as porosity and pore geometry, heat of hydration, strength, transport properties, or aiming at developing numerical models regarding long-term properties, such as durability.This paper proposes a semi analytical model to determine the porosity for the Ordinary Portland Cement. This model has been developed to use the diffusivity analysis of concrete. To this end, the relationship between the porosity and the microstructure of concrete has been established by mathematical equations. The microstructure includes the interface transition zone (ITZ) between aggregate and cement paste. The predicting model of porosity was developed with considering the various mixing of mortar and concrete. The model proposed in the present study has been validated by three types of experimental programs on cement paste, mortar and concrete. The analytical results are discussed and compared to the test results in order to validate the new model.2. Microstructure of concrete2.1 Composition of concreteAt the macroscopic level, concrete is made up of two main phases: aggregate and cement paste. The aggregate is fixed within the cement paste by bond between the particles of the aggregate. Concrete is usually composed of approximately 65%~75% with aggregate and 25%~35% with cement paste.It is obvious at the microscopic level that the two phases, aggregate and paste, are neither homogeneously distributed with respect to each other, nor are themselves homogenous.At the casting of the concrete, air voids are entrapped due to treatment or compression work, or entrained when frost-entraining agents are added. Such air voids are much larger (0.3~1mm) than the other pores in the paste, but are normally assigned to the paste phase. In the presence of aggregate, the structure in the vicinity of large aggregate particles is usually very different from1)KCI Member, Electric & Nuclear Power Division, Korea Insti-tute of Energy Technology Evaluation and Planning, Seoul 135-280, Korea. Email: gspang@ketep.re.kr.2)KCI Member, Korea Institute of Construction Materials, Seoul137-707, Korea.3)KCI Member, Dept. of Civil and Environmental System Engi-neering, University of Incheon, Incheon 402-749, Korea.Copyright ⓒ 2009, Korea Concrete Institute. All rights reserved,includ ing the making of copies without the written permission ofthe copyright proprietors.8182│International Jou rnal of Concrete Stru ctu res and Materials (Vol.3 No.2, December 2009)that of the bulk paste. There is a third phase, the transition zone,which represents the interfacial region between the large aggregate particles and the cement paste. A schematic picture of the composition of concrete is shown in Fig. 1.2.2 Microstructure of cement pasteWhen cement and water are mixed, the cement reacts with the water to form a porous conglomerated mass of fine crystal-like gel particles constituting the cement gel, see Fig. 2. The main volume of the gel consists of calcium-silicate-hydrate (C-S-H) products in which calcium hydroxide (CH) is incorporated, and the gel volume grows as the hydration proceeds. Part of the original volume not occupied by gel consists of capillary pores, which are much coarser than gel pores. Y oung pastes have a inter-connected capillary-pore system but, as hydration proceeds, the hydration products grow into the capillary pores resulting in the reduction of the capillary pore volume.Photographs taken by an SEM microscope, one of the specimen tested in the present work are shown in Fig. 3 obtained from theprevious research.3The physical structure of the cement paste can be discerned to some extent there. The fluffy balls consist of hydrated C-S-H gels that have grown into the capillary pores. The internal porosity of the cement paste is high, as can be seen. The CH grows inside the C-S-H, or between the parts of it. It is limited in size by the space available.The older the cement paste becomes the denser and the more featureless the C-S-H gel appears. T obermorite and Jennit are natural minerals that resemble C-S-H gel. This has an extraordinarily high internal surface area as measured by water adsorption, in the range of 250 ~ 450m 2/g or 100 ~ 700m 2/g.4,52.3 Volume relationship of cement pasteA classification of the porosity of cement paste is given in T able 1.4Table 1 shows there is an enormous range of pore size distribution,from 10µm to less than 0.5nm in diameter. It is known that the pore size distributions are mainly affected by the w/c ratio and the degree of hydration. As can be seen in Table 1, porosity over the whole size range of pores has an influence on paste properties. Y et it is difficult to get an exact assessment of pore-size distributions because no one measurement encompasses the whole size range and because it is difficult to interpret experimental data. Thus,comparisons of porosity should be made with care.4Basic volume relationships between cement, cement gel, gel pores, capillary pores and water in cement paste are shown in Figs. 4 and 5. Figure 4 shows that the volume relationship in cement paste varies with increasing hydration. As shown in Fig. 5,increasing w/c ratio results in increasing capillary pore volume,but maintaining the constant level of gel pores.Fig. 2 Development of the struc ture of c ement paste ac c ording to Powers.1Fig. 3 SEM photograph.3Fig. 1 Sc hematic pic ture of the c omposition of c onc rete.International Jou rnal of Concrete Stru ctu res and Materials (Vol.3 No.2, December 2009)│833. Analytical model of pore structure ofconcrete3.1 Porosity of cement pasteIn this study, the structure of the concrete is based on a structural model described in Fagerlund,6 which is based on the work ofPowers.1The model is described mathematically by a set of simple equations, for calculating the volume fraction of the ordinary Portland cement, hydration products (gel) and pores. Powers proposed certain empirically based equations, derived from experimental data. The equations do not distinguish between the various hydration states and different types of the hydration products, all are regardedas cement gel. Besides, a given increase in degree of hydration is assumed to create the same amount and structure of cement gel irrespectively of at what hydration state this additional hydration occurs.The total pore volume (V p )p of the cement paste is as shown in Fig. 6.(1)where (V p )p =total pore volume of the cement paste (m 3); W =content of water mixed (kg); W n =chemically bound water (kg);ρw =density of water (kg/m 3); and w/c =water to cement ratio.In the above model, it is assumed that the chemically bound water “decreases” in volume to 0.75 of the volume it had prior to hydration, and the water bound chemically in the hydration process is , where α=degree of hydration (−). The typical value of k is 0.23.For the following expression, the maximum possible degree of hydration, αmax equal to (w/c)/(w/c)*, must be substituted for a if w/c ≤w/c *. The typical value of w/c * is 0.38.The compact volume, i.e. the solid volume without any pores,of the cement paste (V 0)p is;(2)where (V 0)p =compact volume of the cement paste (m 3),ρc =density of the cement (kg/m 3)The total volume of the cement paste V p is the sum of the pore volume and the compact volume (3)The total porosity of the cement paste P p is (4)The ratio of the volume of hydration product to that of the cement from which it is formed may be calculated by dividing the former quantity by the volume of cement reacted per unit mass ofcement, which is α/ρc , giving . Therefore, theV p ()p W 0.75W n –ρw ---------------------------W 0.75k αC –ρw ------------------------------Cρw-----w/c 0.75k α–()===k αC ⋅⋅V o ()p C ρ---c 0.75W n ρw -----------------+C ρw -----ρwρc-----0.75k α+⎝⎠⎛⎞==V p V p ()p V 0()p +C ρw -----ρwρc-----w/c +⎝⎠⎛⎞==P p V p ()p V p------------w/c 0.75k α–ρw ρc-----w/c +------------------------------==1w/c ()*ρc /ρw +Table 1 Classific ations of the pore sizes in hydrated c ement.Type Diameter (nm)Description Role of waterPaste properties affectedCapillary pores 50~10,000Large capillariesBehaves as bulk waterStrength, permeability10~50Medium-sized capillaries Moderate surface tension forces generated Strength. permeability; shrinkage at high humidity Gel pores2.5~10Small (gel) capillaries Strong surface tension forces generated Shrinkage to 50% RH 0.5~2.5MicroporesStrongly adsorbed water; no menisci form Shrinkage, creep <~0.5Micropores “interlayer”Structural water involved in bondingShrinkage, creepFig. 4 Volume relationship of hydrated pastes by c hangingdegree of hydration.4Fig. 5 Volume relationship of hydrated pastes by c hanging w/cratios.4Fig. 6 Volume relationships among constituents of the hydratedpaste.84│International Jou rnal of Concrete Stru ctu res and Materials (Vol.3 No.2, December 2009)volume of the cement gel is;(5)It is assumed that the cement gel formed during hydration has aporosity of 28%, therefore the volume of the gel pores (V gel )p is;(6)The gel porosity of the cement paste P gel is (7)The volume of the capillary pores (V cap )p in the cement paste is =(8)The capillary porosity P cap of the paste is(9)3.2 Interfacial zones between cement paste and aggregateThe structure of aggregate depends on the types of minerals in the aggregate and on its geological history which differ markedly from one location to another. In Korea, fractions of crushed granite and gneiss are normally used. Such aggregates are hard, tight and not easily dissolved. Although the porosity is low, only about 0~1%,the pores in these types of aggregate are quite coarse and are often so interconnected that the permeability and the diffusivity of for example, granite, are in parity with that of cement paste of a highw/c ratio.5,7Between the cement paste and the aggregate there is a thin,rather porous inter-facial zone (sometimes called the transition zone, tz), see Fig. 7. It becomes increasingly porous during hydration and normally has a larger content of CH-crystals than the bulk paste located farther from the aggregate does. This zone may also crack due to differences in modulus of elasticity and strength of aggregate and cement paste. Referring to the work of other researchers,Winslow et al.2 noted a region of approximately 50nm thickness which, has quite different properties than the rest of the bulk paste.Bourdette et al.8 estimated from the literature the transition zone (tz) to be 30µm thick. Using their models of hydration around the tz, they obtained results for porosity three times as high in tz as in the bulk paste, although it decreased with hydration age, whereas the porosity of the bulk paste remained relatively constant.3.3 Porosity and density of concreteFor mortar and concrete, additional porosity occurs in pore sizeslarger than the plain paste’s threshold diameter measured by mercury intrusion porosimetry (MIP).2 In Winslow et al., mortars with a w/c of 0.4 were made with aggregate of different ratios.The samples were hydrated in lime-saturated water for 28 days and were then oven dried at 105o C. The pore size distributions of the pastes were obtained by MIP . An average thickness of the paste surrounding each aggregate particle was calculated by dividing the volume of paste in the mixture by the surface area of the sand in the mixture. A computer program for random particle placement, percolation assessment and phase fraction estimation was developed. By executing the program for different number of aggregate particles, the volume fraction of aggregate required for interfacial zone percolation for a given aggregate size distribution and interfacial zone thickness was determined and compared to experimental results. An interfacial zone thickness of 15~20µm was found to be most consistent with results of the experiments.In this study, the volume of tz is calculated from the concept of equivalent radius of aggregate and thickness of tz. It is assumed that maximum thickness of tz is 30mm, which increases by degree of hydration. The equivalent radius of aggregate is calculated from the size distribution of sand and coarse aggregate as follows;(10)where r e =equivalent radius of aggregate, t TZ =thickness of tz,r i =radius of aggregate used and m i =mass ratio of aggregate, r i ,in this study, t TZ =30 (µm).In this study, the pore volume of aggregate is ignored. The volume of aggregate is (11)where β=G/CIt is assumed that the volume of tz is proportion to degree of hydration. The total volume of tz is calculated as follows;(12)V gel C αρc -------1w/c ()*ρc ρw -----+⎝⎠⎛⎞C αρw -------ρw ρc-----w/c ()*+⎝⎠⎛⎞==V gel ()p 0.28V gel 0.28αC ρw -------ρwρc-----w/c ()*+⎝⎠⎛⎞==P gel V gel ()p V p---------------0.28αρw ρc -----w/c ()*+⎝⎠⎛⎞/ρw ρc -----w/c ()+⎝⎠⎛⎞==V cap ()p V p ()p V gel ()p –=Cρw-----w /c 0.75k 0.28ρw ρc -----w/c ()*+⎝⎠⎛⎞+⎝⎠⎛⎞α–P capw /c 0.75k 0.28ρwρc-----w /c ()*+⎝⎠⎛⎞+α–ρwρc-----w /c +-----------------------------------------------------------------------------------=r e t TZ +()3r e ()3–r i t TZ +()3r i ()3–[]m i∑=V a G ρG ------C ρw -----ρw ρG ------β⎝⎠⎛⎞==V TZ 1t TZ r e ------+⎝⎠⎛⎞31–G ρG ------α1t TZ r e ------+⎝⎠⎛⎞31–C ρw -----ρw ρG ------β⎝⎠⎛⎞α==Fig. 7 Sc hematic representation of the transition zone.5International Jou rnal of Concrete Stru ctu res and Materials (Vol.3 No.2, December 2009)│85where G =aggregate content, ρG =density of aggregate.The porosity of tz is three times as high as in the bulk cement paste,8the pore volume of tz can be calculated;(13)The total pore volume of the mortar or concrete is as shown in Fig. 8. The Equation (1) is modified since pore volume of tz and airs are included.(14)The total volume of the mortar or concrete is; (15)The total porosity of mortar or concrete is (16)It is assumed that the volume of gel pore is same as the cement past, so gel porosity of concrete is =(17)The pore volume of tz is included in the volume of the capillary pore in the mortar or concrete because pore size of tz belongs to capillary pore. The volume of capillary pore and porosity are; (18)The porosity of cement paste in mortar and concrete is; (19)V TZ ()p 3w/c 0.75k α–ρw ρc-----w/c +------------------------------1t TZ r e ------+⎝⎠⎛⎞31–C ρw -----ρw ρG ------β⎝⎠⎛⎞α=V c ()p V p ()p V TZ ()p V air ++Cρw-----w/c 0.75k α–()==3+w/c 0.75k α–ρwρc-----w/c +------------------------------1t TZ r e ------+⎝⎠⎛⎞31–C ρw -----ρw ρG ------β⎝⎠⎛⎞αV air +V c V a V p V TZ V air +++C ρw -----ρw ρG ------β⎝⎠⎛⎞C ρw -----ρw ρc -----w/c +⎝⎠⎛⎞+== 1t TZ r e ------+⎝⎠⎛⎞31–C ρw -----ρw ρG ------β⎝⎠⎛⎞αV air ++P c V c ()pV c------------=w/c 0.75k α–()3w/c 0.75k α–ρw ρc-----w/c +-----------------------------1t TZ r e ------+⎝⎠⎛⎞31–ρw ρG-----β⎝⎠⎛⎞αρw C -----V air++ρw ρc -----w/c +⎝⎠⎛⎞11t TZ r e ------+⎝⎠⎛⎞31–α+⎝⎠⎛⎞ρw ρG-----β⎝⎠⎛⎞ρw C -----V air++-------------------------------------------------------------------------------------------------------------------------------------------------P gel c,V gel ()p V c---------------=0.28αρwρc -----w/c ()*+⎝⎠⎛⎞ρw ρc -----w/c +⎝⎠⎛⎞11t TZ r e ------+⎝⎠⎛⎞31–α+⎝⎠⎛⎞ρw ρG ------β⎝⎠⎛⎞ρw C-----V air++----------------------------------------------------------------------------------------------------------------------P cap c ,V p ()p V gel ()p V TZ ()p+–V c------------------------------------------------------=w/c α0.75k 0.28ρwρc -----w/c ()*+⎝⎠⎛⎞+⎝⎠⎛⎞–= 3w/c 0.75k α–ρw ρc-----w/c +------------------------------1t TZ r e ------+⎝⎠⎛⎞31–ρw ρG------β⎝⎠⎛⎞α+ρw ρc -----w/c +⎝⎠⎛⎞11t TZ r e ------+⎝⎠⎛⎞31–α+⎝⎠⎛⎞ρw ρG------β⎝⎠⎛⎞ρwC -----V air++------------------------------------------------------------------------------------------------------------------------P ′gel c ,V gel ()pV c V a–---------------=0.28αρw ρc -----w/c ()*+⎝⎠⎛⎞ρw ρc -----w/c +⎝⎠⎛⎞1t TZ r e ------+⎝⎠⎛⎞31–αρw ρG------β⎝⎠⎛⎞ρw C -----V air++-------------------------------------------------------------------------------------------------------------=Fig. 8 Sc hematic volume frac tions of pores and solid materials.86│International Jou rnal of Concrete Stru ctu res and Materials (Vol.3 No.2, December 2009)(20)4. Experiments4.1 Materials and mixture proportionsThe three types of experiments (cement paste, mortar, and concrete) were conducted for the evaluation of porosity. The materials used and mixture properties are summarized in Table 2,Tables 3 and 4. The Ordinary Portland Cement was used for all experiments and porosities are tested at various times, such as 1, 3,7, 14, 28 and 91days.The water-binder ratios of cement pastes are 0.3, 0.35, 0.4, 0.5,0.6 and 0.7 in cement paste. For evaluating the effects of aggregate,mortar were manufactured. The main variables are w/c (0.4, 0.5,0.55, 0.6 and 0.65) and the mass ratio of sand and cement (S/c =1,1.5 and 2). The maximum sizes of fine and coarse aggregate are 5mm, 13mm respectively and various w/c ratios (0.4, 0.5 and 0.6) are used.4.2 Test methodsMercury Intrusion Porosimetry (MIP) is a technique used tomeasure pore size distribution, and has an advantage in that it is able to span the measurement of pore sizes ranging from a few nanometres, to several hundred micrometers. As concrete has a distribution of pore sizes ranging from sub-nanometer to many millimeters, MIP has formed an important tool in the characterization of pore size distribution and total volume of porosity.The specimens are dried to remove all moisture from the pore structure. They are then placed into sealed “penetrometers” which are weighed both before and after being loaded with the specimen.The penetrometers are placed into the machine where they are evacuated and then filled with mercury. The pressurized testing then commences and the machine calculates and records how much mercury is being forced into the pore structure.The degree of hydration, α, is defined as the fraction of cement that has fully hydrated. For the present experiments, α was determined experimentally by comparing the amount of non-evaporable water in a sample to the amount needed for complete hydration. To determine the non-evaporable water content, four dried specimens from each paste group were subjected to ignitionat 800oC for 2h, cooled in vacuum desiccators at less than 20Pa for 1h, and then weighed. The water in the paste that was not removed by the drying process, W n , (also known as the non-evaporable water) is then estimated as shown in Eq. (21).(21)where, w 1 and w 2 are the weights of the dry specimen before and after ignition, respectively.The degree of hydration can then be calculated as shown in Eq.(22)(22)where (W n /C )* is the non-evaporable water corresponding to a completely hydrated paste. The typical value of it is 0.25.The total porosity of specimen is calculated by Eq. (23).(23)where, W 1, W 2, and W 3 are weight after 105oC oven dry, weight in water and weight in surface dry condition.4.3 MeasurementsThe results obtained from the instrument are;1)pore size distribution(macro/meso range of porosity spectrum)2)hysteresis curve, specific surface, bulk density 3)total porosity (%), particle size distributionThe non-evaporable water contents by degree of hydration, the measured results are summarized in Table 5. The porosities of capillary pore volume were obtained by MIP . The effects of water/cement ratios and sand contents on porosity are estimated by MIP .For various degree of hydration, porosities of specimens are measured and the results are summarized in Table 6.w/c α0.75k 0.28ρwρc -----w/c ()*+⎝⎠⎛⎞+⎝⎠⎛⎞–P ′cap c ,= 3w/c 0.75k α–ρw ρc-----w/c +------------------------------1t TZ r e ------+⎝⎠⎛⎞31–ρw ρG ------β⎝⎠⎛⎞α+ρw ρc -----w/c +⎝⎠⎛⎞1t TZ r e ------+⎝⎠⎛⎞31–αρw ρG------β⎝⎠⎛⎞+------------------------------------------------------------------------------------------------------------------------W n w 1w 2–w 2----------------C =αW nW n /C ()*C -----------------------W n 0.25C--------------==P t W 3W 1–W 3W 2–------------------=Table 2 Mixture proportions for c ement pastes.ID w/c (-)Cement (kg)Type of cementCP 0.3, 0.35, 0.4, 0.5, 0.6, 0.7300OPCTable 3 Mixture proportions for c onc rete spec imens.Specimenw/b (-)Water (kg m -3)Binder (kg m -3)Sand (kg m -3)Gravel (kg m -3)Type of cementC400.41403507421,135OPC C500.51583507241,107OPC C600.61753507071,080OPCTable 4 Mixture proportions for mortar spec imens.Specimen w/c (-)Water (kg)Cement (kg)Sand (kg)Type of cement M1-10.4120300300OPC M1-1.50.4120300450OPC M1-20.4120300600OPC M2-10.5150300300OPC M2-1.50.5150300450OPC M2-20.5150300600OPC M30.55165300600OPC M40.6180300600OPC M50.65195300600OPCInternational Jou rnal of Concrete Stru ctu res and Materials (Vol.3 No.2, December 2009)│875. Validation of analytical model5.1 Model for cement pasteFor validating of the proposed model, the predicted values by Eq. (4) are comprised with data of other researchers as shown in Fig. 9. Figure 9 includes porosities derived from calculated phase compositions, the degree of hydration is assumed to be the valueof maximum and a specific volume of cement is 3.17×10-4 m 3kg -1.As expected, the capillary porosities decreased with the increase of the degree of hydration and the water/cement ratio for all specimens as shown in Fig. 10; capillary pore space is filled with cement hydrates by hydration reaction (pore volume of gel increases by degree of hydration). From the Fig. 10, the predicted values by Eq. (9) are very similar with the measurements.Table 5 Measured properties of c ement paste.TypeTime (days)137142891w/c =0.3W n (kg m -3)23.82 27.91 30.06 30.92 33.02 35.10 α (-)0.345 0.404 0.436 0.448 0.479 0.509 P p (-)0.269 0.225 0.201 0.178 0.170 0.159 w/c =0.35W n (kg m -3)-26.91 29.95 ---α (-)-0.390 0.434 ---P p (-)-0.315 0.285 ---w/c =0.4W n (kg m -3)24.34 31.93 35.45 38.64 42.69 41.78α (-)0.353 0.463 0.514 0.560 0.619 0.605 P p (-)0.376 0.315 0.271 0.257 0.227 0.226 w/c =0.5W n (kg m -3)24.60 30.89 36.68 44.74 46.26 51.97 α (-)0.356 0.448 0.532 0.648 0.670 0.753 P p (-)0.439 0.399 0.355 0.327 0.299 0.287 w/c =0.6W n (kg m -3)24.08 30.18 38.49 45.65 48.79 53.27 α (-)0.349 0.437 0.558 0.662 0.707 0.772 P p (-)0.496 0.475 0.421 0.394 0.382 0.340 w/c =0.7W n (kg m -3)23.82 30.96 38.04 48.18 51.06 56.45 α (-)0.345 0.449 0.551 0.698 0.740 0.818 P p (-)0.548 0.522 0.494 0.455 0.425 0.395Table 6 Measured properties of mortar.Specimen w/c Wn (kg m -3)α (-)P cap (-)Sand/cement M1-10.436.018 0.522 0.213 10.444.505 0.645 0.177 1M1-1.50.435.466 0.514 0.188 1.50.443.470 0.630 0.166 1.5M1-20.425.530 0.370 0.217 20.435.445 0.514 0.169 20.444.712 0.648 0.149 20.452.026 0.754 0.123 2M2-10.540.158 0.582 0.268 10.550.094 0.726 0.227 1M2-1.50.538.364 0.556 0.248 1.50.545.264 0.656 0.220 1.5M2-20.528.911 0.419 0.254 20.537.398 0.542 0.230 20.548.231 0.699 0.196 20.556.580 0.820 0.176 2M2-30.5529.514 0.428 0.276 20.5540.779 0.591 0.255 20.5550.057 0.725 0.214 20.5559.340 0.860 0.195 2M2-40.634.500 0.500 0.280 20.643.539 0.631 0.263 20.656.580 0.820 0.223 20.663.480 0.920 0.208 2M2-50.6534.500 0.500 0.308 20.6544.850 0.650 0.288 20.6558.650 0.850 0.238 20.6564.860 0.940 0.225 2Fig. 9 Relation between total porosity and water/cement ratio.For various degree of hydration, Figs. 11 and 12 show therelation between porosity and water cement ratio by the proposed model. The porosity of gel increases with the increase of the degree of hydration and decreases with water/cement ratio, but reverse tendency occurs to the critical water/cement ratio at full hydration because water is insufficient for full hydration.5.2 Model for mortarFig. 13 shows the experimental results and comparisonsbetween measured and predicted data by Eq. (19). It is thoughtthat predicted values are very close to the measured ones like thecement paste, the capillary porosity of mortar decreases withincreasing hydration. As shown in Fig. 13, high water/cementratio increases the pore volume of mortar.Mortar and concrete can not properly be described as thecomposites of coarse and fine aggregates in a matrix of cementpaste otherwise identical with the aggregate-free material. Themicrostructure of the paste close to the aggregate differs from thatof cement paste in bulk, and much of the paste in concrete ormortar places or lies in this category.Interface transition zone (ITZ) between aggregate and cementpaste has more pore space than bulk cement paste because thesurfaces of aggregates were closely covered with poorly crystallinematerial as CH(Ca(OH2). In this zone, it is up to about 30µmwide; the paste is of increased porosity and presumably low instrength.The porosity of cement paste in mortar and concrete differsfrom the aggregate-free cement paste. Therefore, property ofinterface transition zone on porosity must be considered for moreaccuracy. Figs. 14 and 15 show the relation between sand contentand capillary porosity. The capillary porosity of mortar with Fig. 10 Comparison of the calculated and measured capillaryporosities.Fig. 11 Relation between capillary porosity and water/cement ratio.Fig. 12 Relation between gel porosity and water/c ement ratio.Fig. 13 Relation between water/cement ratio and capillary porosity.Fig. 14 Relation between G/C ratios and capillary porosity (w/c = 0.4).88│International Jou rnal of Concrete Stru ctu res and Materials (Vol.3 No.2, December 2009)。
多孔材料孔结构表征ppt课件
3. 孔结构的表征技术
3. 孔结构的表征技术
总结 显微法是研究100nm以上的大孔较为有 效的手段 ，能直接提供全面的孔结构信息。 对于孔径在30nm以下的纳米材料，常用气体 吸附法来测定其孔径分布；而对于孔径在 100μm以下的多孔体，则常用压汞法来测定 其孔径分布。
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多孔材料孔结构表征
目录
1 引言 2 多孔材料的特性 3 孔结构的表征技术
1.引言
多孔材料普遍存在于我们的周围，在 结构、缓冲、减振、隔热、消音、过滤等 方面发挥着重大的作用。高孔率固体刚性 高而密度低，故天然多孔固体往往作为结 构体来使用，如木材和骨骼；而人类对多 孔材料使用，不但有结构的，而且还开发 了许多功能用途。
①孔径； ②孔径分布； ③孔形态； ④孔通道特性等
3. 孔结构的表征技术
3.1.显微法 显微法就是采用扫描电子显微
镜或透射电子显微镜对多孔陶瓷进 行直接观察的方法。该法是研究 100nm以上的大孔较为有效的手段 ，能直接提供全面的孔结构信息。 但显微法观察的视野小，只能得到 局部信息；而透射电子显微镜制样 较困难，孔的成像清晰度不高；显 微法是属于破坏性试验等，这些特 点使它成为其他方法的辅助手段， 用于提供有关孔形状的信息。
我们以沸石为例，现有制得的两 种沸石NaX和MNaX。
采用扫描电镜、X 射线衍射、氮 气吸附/脱附等对样品的结构表征结果
2. 孔结构的表征技术
图为NaX 和MNaX 的XRD 图谱,与标准 样对比未观察到任 何其它的杂峰, 说 明它们具有沸石固 有的FAU 拓扑结构 。MNaX 的衍射峰表 现出宽化的迹象, 说明它晶粒小。
MNaX体现出Ⅰ和Ⅳ型结合的特征，在较低的相对压力 (p/p0<0.01)下吸附量随压力的增大迅速上升, 即微孔填 充, 而后吸附量随压力的增加继续缓慢增加, 并当相对压 力达到p/p0≈0.4 时吸附量随压力增加迅速增加,吸附和脱 附过程变得不可逆, 即出现毛细凝聚现象，等温线上出 现明显的滞后环, 表现出典型的介孔材料特征。
孔隙结构特征 [自动保存的]
![孔隙结构特征 [自动保存的]](https://img.taocdn.com/s3/m/28dd432ef78a6529647d534e.png)
1 压汞法 1.1 原理
采用压汞法注入水银时，因为水银是非润湿相液体，欲进入孔隙系统，需要克服表面张力所产
生的毛细管阻力。控制水银进入孔隙系统的是喉道大小而不是孔隙大小，所以在测量过程中求得与
小、喉道极细的特点。 强烈的压实作用使颗粒呈镶嵌式接触，不但 孔隙很小、喉道极细，而且呈弯片状。该类 喉道细小、弯曲、粗糙，容易形成堵塞。 多见于杂基支撑、基底式及孔隙式胶结类型 的砂岩。
喉道类型
4.弯片状喉道 5.管束状喉道
（a ）
（b）
（c）
按孔隙直径大 小分类 管形＜0.2um，裂缝＜0.1um。粘土、致密岩中的 一些孔隙属于此类型。因流体与周围介质分子之 间的巨大引力，在通常温压下流体在这种孔隙中 不能流动，增大温度和压力也只能引起流体呈分 子或分子团状态扩散。
3.微毛管孔隙
碎屑岩孔隙结构 对于碎屑岩，可将空隙分为两大类，即狭义的孔隙和裂缝。进一步分为四小类：粒间孔隙、粒内孔隙、 填隙物内孔隙和裂缝。按成因将其分为原生孔隙和次生孔隙两大类，然后按产状和几何形状进一步分类。 粒间孔隙：顾名思义，粒间孔隙就是碎屑颗粒之间的孔隙，这些孔隙可以是原生粒间孔隙、 粒间溶孔、铸模孔或超粒孔等，也可以是次生的溶蚀粒间孔。所谓的溶蚀是指地表水和地下水相结合， 对以碳酸盐为主的可溶性岩石产生化学溶解和侵蚀作用。这种溶孔，形态多种多样，有港湾状、伸长状 等。粒间溶孔往往是在原生粒间孔隙或其他孔隙的基础上发展起来的。 粒内孔隙:颗粒内部的孔隙包括原生粒内孔、矿物解理缝和粒内溶孔。原生粒内孔主要是岩屑内的粒间微 孔或喷出岩屑内的气孔。常沿解理缝发生溶解作用。 填隙物内孔隙:填隙物内孔隙包括杂基内微孔隙、胶结物内溶孔(图2.4)和晶间孔等。杂基内微孔隙通常 是在黏土杂基和碳酸盐泥中所存在的微孔隙。这种孔隙极为细小在所有的碎屑岩储集岩中都或多或少存 在这种微孔隙。这种孔除虽可形成百分之几十的孔隙度，但由于孔隙半径小，渗透率往往很低。胶结物 内溶孔为胶结物内发生溶解作用形成的溶孔。晶间孔为胶结物晶体之间的残留孔隙。 裂缝:裂缝包括沉积成因的层面缝以及成岩和构造作用等形成的裂缝。
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下图反映了孔隙率与渗透性的关系
三、影响混凝土孔结构的因素
水灰比
水化龄期 水泥的矿物组成 养护条件
（一）水灰比
（二）水化龄期
（三）水泥的矿物组成
水泥熟料单矿物水化后，总孔隙率越低，凝胶 孔含量越多的组分，其分形维数越高，分形 维数大小顺序为C3s>C2s>C4AF>C3A，分 行维数越高，材料的凝胶孔越多，有害孔越 少。
（三）压力法 压力法(Pressure method)是在现场和实验室 最常用的新拌混凝土含气量测定方法。该法依据新 拌混凝土在给定压力下的体积变化，这个体积变化 被认为是完全由空气被压缩引起的，Boyle定律被用 来计算混凝土的含气量，在我国测定混凝土含气量 多用此方法，但不能给出气泡大小、气泡间距等参 数。
5 采用特殊工艺以达到“无孔” D．L．Roy教授用热压的方法，使水泥 浆体抗压强度达到600MPa，经热压后，可达 到几乎无孔隙。
五、混凝土孔检测的方法 （一） 压汞法 基于毛细孔中不润湿液体这一原理。它不仅可测 得大孔的比表面积，而且还可测样品的孔隙率及孔 径分布状况，操作简单、迅速，但该方法所得结果 受到诸多因素影响。对同一物质要注意以下几点： 1 实验用汞一定要纯净，加压介质要纯净，排除 气泡的干扰； 2 待分析的样品要经过干燥处理，表面清洗； 3 要保持分析条件的一致，如：用压力扫描法分 析时要用相同的扫描及升压速率。
谢谢 大 家
3 采用聚合物浸渍混凝土 聚合物进入混凝土中，可以填充混凝土的 孔隙，这不仅可以使混凝土的孔隙率降低,混 凝土的孔分布也将得到显著改善。
4 加强养护 加强养护，提高水泥的水化程度。水胶 比的大小决定了混凝土的初始孔隙率，而 水泥水化形成的水化产物可以填充这些孔 隙。显然，水泥的水化程度越高，所形成 的水化产物越多，它的填充作用也就越强。 因此，从改善混凝土的孔结构角度来说,加 强混凝土的养护使水泥有较好的水化条件的方法
1 降低水灰比 通过掺入高效减水剂或者调整混凝土配合 比，使各种固体颗粒具有较好级配的方法来 减少混凝土用水量，以实现降低水灰比。降 低水灰比不仅可以减少总孔隙率。而且可以 使凝胶孔相对含量增多，毛细孔相对含量减 少。
2 掺入适量的细矿粉 掺入细矿粉(如：粉煤灰、硅灰、火山灰等) 有利于初始孔隙“细化”．有些细矿粉(如： 型粉煤灰)还具有减水作用，这些作用都有利 于改善混凝土的孔结构。但掺入细矿粉时应 注意适量，掺入过多的矿粉将导致胶凝材料 的水化速度减慢，反而会导致孔结构的恶化 。
关于混凝土中孔结构的简介
一、孔结构的介绍及分类 二、孔结构对混凝土的影响 三、影响混凝土孔结构的因素 四、改善混凝土孔结构的方法
五、混凝土孔检测的方法
一、孔结构的介绍及分类
介绍
国际混凝土界的著名教授P．K．Mehta指出“混 凝土世界与人类世界一样是非线性的，且在非线性 中还有着不连续性”。 为了描述混凝土水泥浆体内部孔隙的尺寸范围( 包括7个数量级)有多么宽广，Mehta教授列出了相 似的范围：以人的身高(相当于CSH中的层间孔)为 起点，经过类似埃菲尔铁塔、珠穆朗玛峰等6个级 别的变化后，以火星直径(相当于浆体中带入的气孔 )为终点。
（二） 气体吸附法 气体吸附法(BET法)是测量比表面积的经典方 法，具体包括静态法和动态法。常用的吸附质为氮 气或二氧化碳，但由于混凝土是碱性复合系统，若 采用二氧化碳做为吸附质，则容易发生反应导致结 果严重偏大，所以一般采用氮气。而与压汞法相反 ，该法可测中微孔，而对大孔的测定会产生较大的 误差，并且测试时间较长。
（四）x射线小角衍射(SAXS) 优点：不需考虑的介质和表面的相互作用问 题；不需要对样品进行抽空、干燥等预处理；实 验过程不破坏原始的结构状态；实验重复性高； 它可以测出包括闭口孔在内的所有孔，即便可能 存在的封闭孔和细颈孔等均不影响测定效果。 不足：在趋向大角一侧的强度分布往往都很 弱，且起伏较大。
目前在实际工作与研究中，孔隙率(porosity)、 孔型、孔径分布(pore size distribution)、孔 的状态及其测试与评价已成为混凝土材料科 学研究的重要内容．
二、孔结构对混凝土的影响
综述 混凝土的孔结构特征强烈地影响着混凝 土材料的抗渗性、气密性、抗冻性、抗腐蚀 性等物理特性和强度、刚度、韧性等力学行 为． 而普遍认为孔结构对抗渗性的影响，进一 步会加剧其他性能的变化（物理特性和力学 行为等）。
混凝土内部的孔隙通常是不规则的，是无序分布、千奇百怪的 。图1为砂浆孔隙的扫描电镜照片和断面孔隙轮廓的曲线，从 照片中完全可以看出混凝土中孔隙的复杂性．
不同的国家对孔的划分有不同的说法，但基本是 相同的。我国吴中伟先生根据不同孔径对混凝土性 能的影响，将混凝土中的孔划分为四个等级，分别 为<20nm的无害孔级、20nm一50nm的少害孔级、 50nm一200nm的有害孔级和>200nm的多害孔级， 并指出增加50nm以下孔的比例，减少100nm以上的 孔含量，可显著改善混凝土的性能。 而著名学者Powers认为，当孔隙率低于20％时 ，水泥石的渗透系数非常小，而当孔隙率大于25％ 时，水泥石的渗透系数随着孔隙率的增大而急剧增 加。