Compressive strength and shrinkage of concrete containing calcium oxide (CaO) powder

Abstract

In this study, CaO powder was added in proportions (1, 1.5, 2, and 2.5) % by weight of cement to concrete mixtures with mixing ratios (1: 2: 4 and 1: 1.5: 3). The ratio of water to cement used in mixing was 0.48 and 0.25 with 2% of superplasticizer (KUT PLAST Sp 400). The results showed that when adding CaO to the mixture (1: 2: 4) the highest compressive strength was for samples containing 2% CaO. Where the percentage of increase was 69.23% at 28 days age compared to the reference specimen of mixture (1: 2:4). The lowest percentage of shrinkage for specimens containing 1.5% CaO in the laboratory atmosphere at 25° C and humidity was 65%, while the specimens that were in the outside atmosphere at 40° C and humidity 20 % were lower percentages (0.673 and 0.405) %, respectively, compared with reference specimen of the same mixture. The results also showed that when the mixing ratio (1:1.5:3), the highest compressive strength was for specimens containing 2.5% CaO, and the lowest shrinkage was for samples containing 1.5% CaO. As the percentage of increase in compressive strength reached (73.58) % at the age of 28 days compared to the reference specimen of mixture (1:1.5: 3) and the percentage of decrease in shrinkage for specimens that were in the laboratory and outside atmosphere (7.44 and 7.77) %, respectively, compared to the reference specimens.