Abstract
In this experimental work, four different curing methods were applied namely including water, air, water heated-air and water heated –water. The results showed that the highest compressive strengths are attributed to the air cured under room temperature after 20hrs curing in heated water at each age. To verify the effect of insoluble residue on the compressive strength of Portland cement, fine particles sand passing from sieve no. 200 and washing in hydrochloric acid were used as an insoluble residue. The Portland cement was replaced by insoluble residue which varied between (0 -7.0) % by weight. The results showed that the higher percentage of insoluble residue to 8.13% in cement mortar gives the lower the compressive strength by 12% of the control mortar compressive strength at 1 day .Although of this reduction of strength, it was found that the compressive strength was still higher than the limits given by ASTM ,BS and Iraqi standards.
