Influence of curing time on the chloride penetration resistance of concrete containing rice husk ash: A technical and economical feasibility study

This study investigates the influence of the curing time on the chloride penetration behavior of concrete produced with different concentrations of rice husk ash. Compressive strength and chloride penetration at 91 days were assessed according to ASTM C1202. Concentrations of 10%, 20% and 30% of rice husk ash were used and the results were compared with a reference mix with 100% Portland cement and with two other binary mixes with 35% fly ash and 50% ground blast furnace slag. Increases in rice husk ash content produced lower Coulomb charge values. Longer curing times reduced Coulomb charges values for all mixes investigated. However, the extent of the effect of curing times on compressive strength and chloride penetration in concrete is related to the type of mineral addition, the concentration of the substitutions used, the w/b ratio and the curing time used. This behavior points at an optimal curing period for each type of binder to meet specific technical and economical criteria, namely durability and compressive strength specifications for the structure.