Effects of intrinsic granular porosity and mineral admixtures on durability and transport properties of recycled aggregate concretes

Sustainably using raw materials including the use of local/recycled aggregates has been attracting a lot of attention in recent years. However, local/recycled aggregates can be porous and low quality. It is generally believed that the intrinsic porosity of aggregates affects the transport properties and durability of concrete, but to what extent is still a question. The objective of the paper is to analyze the impact of intrinsic coarse aggregate porosity on the durability and performance of concrete incorporated with various mineral admixtures. The main factors to be investigated were the coarse aggregate nature (i.e. porous and non-porous aggregates and recycled aggregate) and the binder nature (i.e. cement substituted by 15 % metakaolin, 30 % blast furnace slag, 25 % limestone filler). The results show that the porosity of aggregate significantly affects the water accessible porosity and air permeability of concrete whatever the nature of binder. The use of recycled aggregates results in a good impact on the densification of the cementitious matrix and slightly improve the resistance of concrete to carbonation. The addition of mineral admixture significantly influences the hardened properties and durability of concretes with porous aggregates rather than concrete with non-porous aggregate.