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 Sulphoalu-minate (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 celcius.