The impact of accelerated maintenance system on alkali-activated mortar incorporating ultra-fine dredged sand

Abstract

Alkali-activated concrete mixed with waste dredged sand (DS) is a new type of green concrete. In addition to reducing resource consumption and CO2 emissions, this approach is also cost-effective. Therefore, the ongoing research on its application in real industrial production is of great importance. This study examined the impact of the steam curing system on the mechanical properties and microstructure of alkali-activated dredged-sand concrete (AADSC). Different alkali equivalents and DS contents were used to produce AADSCs, and such AADSCs were cured using different steam curing schemes. The results show that steam curing significantly improves the early strength and 28-day strength under low alkali equivalent. The curing promotes the 1-day strength at 3% alkali equivalent from 2.1 MPa to 27 MPa after steam curing, and the 28-day strength increase was 7.8%. It is also found that the rise in compressive strength does not have a direct correlation with the energy consumption of steam curing. Even though the energy consumed by steam curing at 40 °C was 67% more than that at 60 °C, the 1 d strength under 40 °C steam curing was 7.5% lower. However, low-temperature steam curing retains more room for concrete strength increase. These results indicate the importance of a reasonable steam curing regime for the strength of AADSC.