Enhancing the durability properties of concrete containing recycled aggregate by the use of pozzolanic materials

This study concerns properties of concrete containing Recycled Aggregate (RCA). To compensate for a reduction of properties for the RCA concrete, 30% Pulverised Fuel Ash (PFA) and 60% Ground Granulated Blast furnace Slag (GGBS) were used for replacement for Ordinary Portland Cement (OPC). The compressive strength for RCA concretes was measured for 180 days, and simultaneously the durability against chloride, frost and sulfate environment was evaluated. As a result, the RCA concrete always revealed the lower strength and resistance to chloride, frost and sulfate attack. However, the RCA concrete containing 30% PFA and 60% GGBS enhanced the strength to the level for control concrete containing natural aggregate. The rate of chloride transport was lowered by addition of 30% PFA and 60% GGBS in the RCA concretes after 91 days of curing, presumably due to the refinement of pore structure and further formation of hydration products. As for the frost damage, 30% PFA concrete containing the RCA showed the greatest resistance to frost, while 60% GGBS concrete containing RCA to the similar level of the control. It was found that the RCA concrete containing 30% PFA and 60% GGBS were slightly more resistant to sulfate attack than control.