The Effect of Moist Curing on the Properties of Concretes Made by Pozzolanic Cements

The strength development and permeability properties of two concretes prepared with natural pozzolanic cements, Trass Cement (TC) and Blended Cement (BC), were investigated and compared with those of an Ordinary Portland Cement (PC) concrete under varying water-curing periods. The mix design of concretes was made with an equal strength base at 28 days age under standard curing. The compressive strength tests were carried out at the ages of 3, 7, 14, 28, 90, and 180 days. The curing regimes include initial curing periods between continuous in-air and continuous in-water. Strengths of all concretes increased orderly with the initial water-curing duration time; however the difference between the air-cured and water-cured specimens was the highest for the TC concretes and the lowest for the PC concretes. Sorptivity tests were made to indicate the permeability properties of concretes at the age of 90 days. Although the difference between the sorptivities of air-cured specimens for all cement types is maximum 20 percent, under the water-curing conditions the differences between the TC concrete, and BC and PC concretes become 3.4 and 3.0 times, in the favor of the former, respectively. Also larger difference is obtained for the TC concrete between the air-cured and continuous water-cured specimens, comparing with those of BC and PC concretes.