Assessing different methods of salt removal techniques from offshore sand

Abstract

Usage of offshore sand as an alternative to inland river sand is beneficial due to the various environmental impacts of river sand mining in Sri Lanka. However, higher amount of chloride ions in the sea sand can corrode the reinforcements of the concrete. Therefore it's necessary to identify suitable, low cost and efficient method to remove cl* ions from the sea sand. In this study, three different salt removal techniques; mechanical washing, natural washing and recently introduced grain to grain collision were evaluated using samples from beach sand, river sand, offshore sand and old stock piled offshore sand. Relative salt content and absolute cl* content were measured using conductivity measurements and titration, respectively. Mean grain size and other textural parameters were calculated using sieve analysis. Results indicate lOOg of sand soaked in 200ml of water, required approximately 10 minuets to remove salt from sea sand. Natural removal of chloride by rainwater shows one year of Monsoon rain is more than sufficient to remove salt from even 10 m thick piles of sea sand. However, grain to grain collision does not show significant capacity to remove salt.