A study of alkali-activated concrete mixes in seawater environments

This paper assesses the performance in seawater environment of concrete mixes based on alkali-activated (AA) cements; these are proposed as an alternative to Ordinary Portland Cement (OPC) to address environmental footprint of cement production and to find new uses for waste materials. The proposed AA cements contained an industrial by-product, ground granulated blast furnace slag (GGBS) and a waste material, paper sludge ash (PSA). Mixes were made with fresh water and seawater respectively and were cured either in freshwater or seawater to simulate future exposure environments. The compressive strength at different curing times and a number of durability-related properties of AA mixes in marine environment were investigated and compared to those of OPC systems. The findings indicated that mixing with seawater rather than freshwater enhanced the performance of the AA mixes in terms of compressive strength and durability (resistance to chloride and sulphate attack). In a seawater environment the AA slag concrete mixes with PSA had the lowest porosity, which can be linked to their good durability performance. The study gives promise for the suitability of the tested alkali-activated concrete mixes in seawater environments.