Cl- dissolution and mechanical properties of PVA, CSA modified coral sand

Due to high Cl- content and porosity in coral, coral-aggregate concretes usually present poor durability and mechanical properties. In this paper, two types of materials, polyvinyl alcohol (PVA) and Calcium Sulphoaluminate (CSA) clinker, were used to modify properties of coral sand and consequently inhibit leaching of Cl- from coral and improve mechanical properties of yield mortar. Results showed that the smaller the particle size, the greater Cl- dissolution rate of crushed coral sand. PVA and CSA materials could effectively inhibit the Cl- dissolution, and the most obvious decrease could reach 6% and 23%, respectively, in comparison of 35% prior to the modifications. However, mechanical properties of these two modified coral sand mortars were unsatisfactory under standard curing, which the CSA-modified specimens generate thaumasite resulting in a strength decrease and could be improved by a slight increase in curing temperature to 35 ℃.