混凝土气孔结构对其强度及界面过渡区的影响

Effect of Air Void Structure on Strength and Interfacial Transition Zone of Concrete

摘要:

为便于高性能混凝土引气剂的开发和应用，采用定量体视学图像分析法，测定掺有9种引气剂的混凝土28 d气孔结构参数，运用灰色关联分析方法，研究不同范围孔径对混凝土抗压强度的影响，并采用显微硬度仪对混凝土界面过渡区进行了测试分析.结果表明：各范围孔径与抗压强度的关联性均为负；但不同的范围孔径对混凝土28 d抗压强度的影响有所不同，混凝土总孔隙率相近条件下，增加10~200 μm范围孔径的气孔孔隙率，减少200~1 600 μm范围孔径的气孔孔隙率，使气孔的平均孔径及平均间距系数减小，混凝土的界面过渡区宽度缩短，显微硬度提高，有利于减小因引气而造成的抗压强度损失.

Abstract:

In order to facilitate the development and application of air entraining agents (AEA) in the high performance concrete, entrained air void structure parameters of 28 d concrete were measured by image analysis method. The relationship between the air void size distribution and strength of concrete was studied with the method of grey connection analysis. In addition, the effect of air voids on the paste aggregate interfacial transition zone (ITZ) was analyzed by Microhardness. The results show that the correlation between different pore size range and the compressive strength is negative. The effect of air void size distribution on 28 days compressive strength is different: under the condition of similar total porosity, with the increase of the porosity of the air void size, ranging from 10 μm to 200 μm, and the decrease of the porosity, ranging from 200 μm to 1 600 μm, the average air void diameter and mean free spacing are decreased; as well as the width of ITZ. On the contrary, the microhardness of the ITZ is increased while the compressive strength loss is decreased.