CT characteristic analysis of sea-sand concrete exposed in simulated marine environment

Abstract

The deterioration mechanism of sea-sand concrete was different in different marine areas. An accelerated test chamber was designed to simulate the marine environment. Semi-immersion and drying – wetting cycle test were carried out on seawater and siliceous sea-sand concrete (SSC), coral aggregate seawater concrete (CASC) and tap water and desalted siliceous sea-sand concrete (DTC). Through the analysis of CT characteristics of sea-sand concrete in different parts and zones, the deterioration performance and safety comparison of sea-sand concrete were studied. The results were as follows: the types of sea salt attack to sea-sand concrete could be divided into internal sea salt attack (ISA), external sea salt attack (ESA) and physical sea salt attack (PSA). ESA, ISA and PSA could increase the cross-sectional area of the specimens and reduce the macropores. ISA, ESA and PSA could promote the expansion effect of each other. However, with the passage of time, the surface of the specimen affected by ESA would be damaged to a certain extent, resulting in the reduction of the cross-sectional area, which could be aggravated by ISA. The effect of ESA and PSA on mortar density first increased and then decreased, and ISA could increase the mortar density. ISA, ESA and PSA could reduce the macropores in concrete. With the same mix proportion (W/C = 0.52) of these three kinds of sea-sand concretes, at the bottom and middle part, DTC was the weakest concrete. In Zone 5 at the bottom part, SSC was also relatively weak. In Zone 1 at the top part, SSC was the safest concrete, while CASC was the weakest. In zone 5 at the top part, DTC was the weakest concrete, and CASC was the safest.