Effect of cementitious capillary crystalline waterproof material on the various transport properties of cracked cementitious composites

The chemical reaction of CCCW endows it with the promise of improving self-healing behavior of crack of cementitious materials. However, there are few relevant studies about the self-healing behavior of CCCW in the different environments. Thus, the effect of CCCW on the various transport properties of cracked cementitious composites was explored in this paper, to clear the potential of CCCW in enhancing the durability recovery of cracked specimens. Four types of engineered cementitious composites (ECC) with various CCCW content were pre-cracked followed by curing in water, Ca(OH)2 solution and air. Water absorption and rapid chloride pene-tration tests were adopted to evaluate the various transport properties. And the closure behavior of crack was observed by the microscope. The composition and proportion of the self-healing products were analyzed by TG, XRD and FITR. Test results indicated that CCCW can promote the rapid reduction of water absorption of cracked specimens in early healing stage. The reduction range of charge passed of pre-cracked specimen with 4.5 % CCCW content were 8.03 % and 16.27 % higher than those of specimens without CCCW after curing in water and CH solution. CCCW facilitated lowering the various transport properties of cracked specimens, easier to restore to the uncracked state, especially in Ca(OH)2 solution. The healing degree of crack without CCCW with a width of 240.25 mu m is only 36.61 %. However, the maximum crack width completely closed increased to 402.82 mu m in Ca (OH)2 solution by adding 4.5 % CCCW content. After healing for 14 wet-dry cycles, the content of calcium carbonate in the healing products with CCCW was 12.19 % higher than that without CCCW. The formation of calcium carbonate was accelerated by CCCW in the entire healing process, increasing the number of healing products, thus helping to reduce the transport properties of cracked specimens.