Investigation on mechanical and micro properties of concrete incorporating seawater and sea sand in carbonized environment

Abstract This study aims to explore the mechanical and micro performance of seawater and sea sand concrete under accelerated carbonization environment. This study designed a total of 8 mix ratios, mainly to explore the effects of different water-cement ratios and different mineral admixtures (FA and LC2) on the properties of seawater and sea sand concrete after carbonization. To better evaluate and understand the mechanical properties, the micro morphology analysis was carried out by SEM, the hydration product analysis was carried out by TGA and XRD, and the pore structure was studied by MIP. The results show that the standard curing of seawater and sea sand concrete for 28 days can increase the compressive strength by about 10% compared with ordinary concrete, but the final mechanical strength is similar to ordinary concrete under the condition of long-term accelerated carbonization. The carbonation resistance performance of seawater and sea sand concrete is approximately twice that of ordinary concrete, but when FA and LC2 are added, the property of carbonation resistance will be reduced by more than two times. The large amount of chloride ions added into the concrete by seawater and sea sand will reduce the total porosity of the concrete by about 13% and improve the pore size distribution. In general, to improve the current shortage of natural resources such as river water and river sand, it is feasible to consider adding seawater and sea sand into ordinary concrete.