Strength and Carbonation Model of Rice Husk Ash Cement Mortar with Different Fineness

This paper presents a study of the strength and carbonation resistance of mortar made with portland rice husk ash cement by some accelerated short-term techniques in 5% carbon dioxide. Three finenesses of rice husk ashes, viz., original rice husk ash (RAO), medium rice husk ash (RA1) with 15–20% by weight retained on a sieve No. 325, and fine rice husk ash (RA2) with 1–3% by weight retained on a sieve No. 325. Ordinary portland cement was partially replaced with RAO, RA1, and RA2. Compressive strength, porosity, and carbonation depth were determined. The result indicated that the RA2 decreased the water requirement to a lesser extent as compared to that of the RA1 and RAO. The use of RA2 produced mixes with good strength and low porosity of mortar. The carbonation depth increased with an increase in the replacement level for all rice husk ashes. The carbonation depth of RA2 was lower than those of RA1 and RAO. The carbonation depth increased with a decrease in compressive strength and with an increase in amount of water requirement.