Long-term mechanical and durability properties of recycled aggregate concrete prepared with the incorporation of fly ash

This paper presents the findings of a long-term study on the mechanical and durability properties of concrete prepared with 0%, 50% and 100% recycled concrete aggregate that were cured in water or outdoor exposure conditions for 10 years. The recycled aggregate concrete (RAC) was prepared by using 25%, 35% and 55% class-F fly ash, as cement replacements. It was found that, after 10 years, the compressive strength and modulus of elasticity of the concrete prepared with 100% recycled concrete aggregate was still lower than that of the control concrete. Over this period, the highest gain in compressive strength and modulus of elasticity was recorded for the concrete mixture prepared with 55% fly ash. Fly ash improved the resistance to chloride ion penetration but it also increased the carbonation depth of the concrete.