Chloride Transport Property Of Engineered Cementitious Composites

Engineered cementitious composite(ECC)shows multiple cracking and strain hardening behaviours in tension.It has been successfully applied on multiple projects throughout the world including bridge decks,building dampers,retaining walls,irrigation channels and so forth.Despite its mechanical properties being well known other properties such as its chloride transport properties have not been thoroughly studied.The purpose of this research is to study the chloride transport properties of ECC.The most important parameter to consider when studying the chloride transport properties is the chloride diffusion coefficient.In this paper the chloride diffusion coefficient of ECC was determined through the use of a model.The ECC prepared in this study used raw materials and mix proportions that optimized material costs and improved its greenness.Untreated PVA fibres were used,and micro silica sand was replaced with river sand.The volume of fly ash(FA)was significantly increased and silica fume(SF)was added in the matrix as well.The result was an ECC that exhibited strain-hardening and multiple cracking behaviour.The compressive strength and uniaxial tensile property of ECC were tested.The chloride diffusion coefficient of ECC was determined by first findings the chloride diffusion coefficients of cement paste and interfacial transition zone(ITZ)this was done through calculating with their porosities,respectively.Porosity of ITZ was obtained with w/b ratio based on a porosity model.The chloride diffusion coefficient of the matrix was then determined according to the general self-consistent scheme,and the influence of PVA fibers was simplified with its volume fraction.The results of the model were compared with that of a bulk diffusion test.Using the critical chloride content,the service life was calculated using the calculated diffusion coefficient.