低收缩延性纤维增强水泥基复合材料抗氯离子渗透性能

Chloride Ion Permeability of Low Shrinkage Engineered Cementitious Composite

为研究低收缩延性纤维增强水泥基复合材料(LSECC)抗氯离子渗透性能,首先研究了水胶比、成型方法以及养护龄期对未开裂LSECC抗氯离子渗透性的影响;然后基于LSECC抗弯力学性能特点,通过四点抗弯方法,并同时控制试件底部受拉区变形值,对不同水胶比LSECC进行预开裂损伤;最后分别采用ASTM C1202电通量法和NEL扩散系数法来评价开裂LSECC的抗氯离子渗透性.结果表明:采用挤压成型且水胶比较低、养护龄期较长的未开裂LSECC抗氯离子渗透性较好;开裂LSECC抗氯离子渗透性可分为基材开裂前和基材开裂后2个阶段;随着水胶比的降低,基材开裂后的裂缝数量和宽度均有所减小,抗氯离子渗透性衰减速度减弱;NEL扩散系数法测试结果对开裂LSECC抗氯离子渗透性变化不敏感.

Chloride ion permeability of low shrinkage engineered cementitious composites（LSECC）was studied.Specimens of non-cracking LSECC with different water-binder ratios,molding methods and curing ages and cracking LSECC induced by 4-point bending test controlled by deformation in tensile zone were prepared.Chloride ion permeability was evaluated by both ASTM C1202 and NEL methods.Results show that chloride ion permeability of non-cracking LSECC is decreased by utilizing lower water-binder ratio,extrusion method and longer curing age.Chloride ion permeability of cracking LSECC can be divided into two stages：before and after matrix cracking.Number and width of cracks are decreased by lowering waterbinder ratio,and similar conclusion can be drawn with the reduction rate of chloride ion penetration.ASTM C1202 method is more sensitive to chloride ion permeability of cracking LSECC than NEL method.