Durability of recycled aggregate concrete incorporating slag

This paper presents the results of experimental research on the durability and performance of various mixes of recycled aggregate concrete (RAC) incorporating 25% ground-granulated blast-furnace slag (GGBS) as a cement replacement. The compressive strength, drying shrinkage, water penetration, water absorption, alkali-aggregate reactivity and sulfate content of the concrete mixes were tested. The results indicated that the addition of mineral slag improved the mechanical properties and durability characteristics of the RACs. The addition of 25% GGBS proved to be efficient in reducing water absorption, alkali-silica reactivity and sulfate attack in RAC. However, the test results showed that the introduction of 25% GGBS is not effective enough to prevent the excessive expansion of the alkali-carbonate reaction in RAC after 1 year of testing. Furthermore, it has an adverse impact on resisting the water penetration and drying shrinkage of the RAC mixes.