REDUCING CRACKS OF THE WHITE PORTLAND CEMENT MORTAR

Three types of additive: limestone powder and two kinds of water-soluble polymers (Carboxymethyl-cellulose (CMC), and polyvinyl alcohol (PVA)) have used in this research to study their effect on physical and mechanicalproperties of White Cement mortar. The mixing ratio was 1:3 for (cement: sand) of White cement mortar. The limestone powder ratios are (4%, 8%, and 12%) by weight of the mixture. While the Carboxymethyl-celluloseratios are (0.25%, 0.5%, and 1%) by weight of the mixture and the polyvinyl alcohol ratios are (1%, 3%, and 5%) by weight of mixture. This research investigates compressive and flexural strength, water absorption and dryingshrinkage were also examined of the modified mortar. Moreover, a nondestructive test of ultrasonic pulse velocity was used in this research. The test results show that using limestone powder within White cement mortar isnot proposed because it has negative effect on both mechanical and physical properties of cement mortar. Furthermore, reducing cracks of White cementmortar is meaningfully improved by using polymer additives such as PVA and CMC. Also, the optimum percentages of polymer addition are 3% and 0.25% of PVA and CMC, respectively.

Keywords:

Carboxymethyl-cellulose , reducing cracks , limestone , polyvinyl alcohol , white cement