Effect Of Mineral Admixtures On Mechanical And Self-healing Performance Of Engineered Cementitious Composite

With the progress of society,the performance and function of cement-based materials have become increasingly demanded by humans.In recent years,continuous research on fiber-reinforced concrete has begun,and ECC(Engineered Cementitious Composites)is the one that should be transported under this trend.ECC is an ultra-high toughness cement-based composite material with excellent tensile properties and excellent multifracture properties based on fracture mechanics and micro-mechanics design.However,the amount of cement used to prepare ECC is high,and this problem will limit the largescale application of ECC in engineering.In response to this problem,this article mainly studied the effect of different mineral admixtures to replace part of the cement on the mechanical properties and healing properties of ECC.By blending single and multiple admixed mineral admixtures with different proportions,several groups of different mix ratio specimens were prepared.The effects of mineral admixtures on the mechanics and healing properties of ECC were studied through tensile tests,compression and flexural resistance tests,fluidity tests,and capillary water absorption tests.The main research contents are as follows:Effects of mineral admixtures on mechanical properties of ECC.Firstly,fly ash,silica fume,limestone powder and coal gangue were used to study the effect of PE-ECC on the mechanical properties and crack width of single-doped and multi-doped concrete.It was found that the ratio of compound mineral admixtures had a certain degree of influence on the mechanical properties of the specimens.On this basis,To systematically study the influence of mixed mineral admixtures with different proportions on the mechanical properties and crack width of PVA-ECC.At the same time,there were obvious differences in the mechanical properties and crack widths of the ECC with different fiber types.It was found that there was an optimal compounding ratio when the fly ash was mixed with other mineral admixtures,leading to the specimens obtained good mechanical propertiesAccording to effects of mineral admixtures on mechanical properties of ECC,studying effects of mineral admixtures on the self-healing properties of ECC.Three types of curing environment were selected: Ca(OH)2 solution,Na2SO4 solution and H2 O.The pre-cracked 1% test specimens were self-healed and cured under three kinds of curing conditions.The cured specimens were subjected to tensile test and capillary water absorption test to evaluate the self-healing properties of the specimens.Experiments show that all pre-cracked specimens have the highest degree of self-healing in Ca(OH)2 solution;the incorporation of sodium hexametaphosphate as the active material in the penetrating crystalline material is most beneficial to improve the self-healing properties of ECC.