TRANSPORT PROPERTIES OF SELF-CONSOLIDATING CONCRETE OF DIFFERENT MIX DESIGN APPROACHES

摘要

Cement-based materials used in repair of concrete infrastructures should have high impermeability and low chloride-ion permeability to reduce the risk of corrosion and enhance service life.In this study,the chloride-ion permeability and pore-size distribution using mercury intrusion porosimetry were determined for a number of self-consolidating concrete(SCC)mixtures developed for repair applications.The mixtures were prepared with two design approaches that can yield proper stability: SCC with water-to-cementitious material ratio(w/cm)of 0.35 and SCC with 0.42 w/cm with viscosity-enhancing admixture(VEA).The mixtures were proportioned with three different binder and four high-range water reducing admixture(HRWRA)types.Test results show that the volume of capillary pores having apparent diameter greater than 50 nm and the total pore volume have marked effect on rapid chloride-ion permeability(RCP).SCC mixtures proportioned with 0.42 w/cm and VEA can develop approximately 30% greater volume of total capillary pores and 40% higher RCP value compared to those prepared with 0.35 w/cm.Binder type is shown to have significant influence on pore-size distribution and chloride-ion permeability of SCC.SCC mixtures made with quaternary cement containing fly ash,blast furnace slag,and silica fume yield the lowest volume of large capillary pores and level of RCP.A relationship can be established between the RCP values and volume of large capillary pores for the tested SCC mixtures.