Damage and deterioration characteristics of basic magnesium sulfate cement-coral aggregate concrete exposed to elevated temperature

Abstract

Different proportions of coral aggregate, coral sand and basic magnesium sulfate cement (BMSC) were used to prepare the basic magnesium sulfate cement-coral aggregate concrete (BMSC-CAC), which was applied in the island and marine engineering as a brand new type of concrete. The specimens of BMSC-CAC exposed to elevated temperature (100°C, 300°C, 500°C, 700°C, and 900°C) were tested by the non-destructive method to obtain the surface characteristics at different temperatures. A new parameter, elevated temperature damage (D), derived from continuous damage mechanics (CDM) was applied to indicate the degree of concrete damage after being exposed to elevated temperature. The surface characteristics of the specimen were changed significantly at different temperatures, especially the aggregate colours. The fitting relationship between ultrasonic velocity and temperature was established, which can be well used to fit different types of concrete. The elevated temperature damage degree (D) was defined by damage mechanics, and the mathematical relationship between D and the residual compressive strength was discussed.