Effect of Air-Entrained Agent on Fresh and Hardened Properties of Cement Mortar

Abstract

Freezing and thawing action is the main cause of the deterioration of the reinforced concrete structures. It decreases its durability if appropriate precaution is not taken into account. In order to minimize the effect of freezing and thawing action, generally 4∼7 % of air content by volume of concrete is introduced into the concrete. Air content in the concrete is considered as the combination of the entrapped air and entrained air. Entrapped air is minimized as less as possible during the compaction process of concrete and instead, the microscopic air cells are entrained into the concrete by using air entrained agent during the mixing. This paper is focused on the content of highly effective air-entrained agent (AE 303A), on the fresh and hardened cement mortar. The air content of mortar was increased from 2.7% to 10.5% while using 0.01% of AE 303A by weight of cement. The density of fresh mortar was decreased from 2.261 g/cm 3 to 2.078 g/cm 3 and that of hardened mortar was from 2.238 g/cm 3 to 2.039 g/cm 3 . With similar trend of decreasing densities, seven days compressive strength was decreased from 43.12 MPa to 27.37 MPa. However, no significant difference was observed on the workability of mortar, measured in table flow value while increasing the AE 303A content.