Improving capillary water absorption of high-volume fly ash mortar by curing temperature and limestone addition

Abstract

This work investigated the capillary water absorption performance of high volume fly ash cement mortar by increasing the curing temperature (20°C, 40 °C and 60 °C) and adding limestone powder (6% and 12%). Combined with XRD, chemically bound water, compressive strength and porosity test results, the effects of curing temperature and limestone powder on capillary water absorption of high volume fly ash cement mortar were discussed. The results indicated that when the fly ash content exceeded 30%, the capillary water absorption increased significantly. When the fly ash content reached 50%, raised the curing temperature to 40 °C or the limestone powder content reached 12%, the chemically bound water content increased greatly. Increasing the curing temperature or adding limestone powder increases the compressive strength. Otherwise the porosity and capillary water absorption of high volume fly ash cement mortar can be reduced at early age. Prediction of water penetration depth in high volume fly ash cement mortar and the results were consistent with the capillary water absorption results. The results highlight that improved curing temperature or addition of limestone powder could be an efficient way to improve the capillary water absorption performance of high volume fly ash cement mortar. Highlights: • The capillary water absorption performance of high volume fly ash cement mortar was improved by raised curing temperature or addition limestone powder. • Porosity was decreased by raised curing temperature or addition limestone powder. • Compressive strength and chemically bound water content was increased by raised curing temperature or addition limestone powder. • The prediction of water penetration depth was consistent with the capillary water absorption result.