Durability analysis of metakaolin recycled concrete under sulphate dry and wet cycle

Abstract To improve the durability, performance, cost-effectiveness and sustainability of recycled fine aggregate concrete (RFAC) under the combined effects of wet and dry cycle and sulfate erosion. Dry and wet cycling tests in 5% sulfate erosion environment were carried out after incorporating content of metakaolin and 15% fly ash mixture (M)) in RFAC. Study of 0%, 30%, 60% and 90% recycled fine aggregate replacement of natural fine aggregate on RFAC mass loss, cubic compressive strength, relative dynamic modulus test, damage modeling and prediction of damage life of concrete. The results revealed that in the early cycles, the specimens exhibited significant improvements in compressive strength, mass, and dynamic modulus. However, in the later cycles, the performance of the specimens deteriorated. Optimal performance was achieved with a 15% MK content and a 60% replacement rate of recycled fine aggregate. The application of the Weibull function modeling estimated the longest service life of M15RAC60 under 5% sulfate dry-wet cycles to be approximately 578 cycles.