Assessment and Repair of Fire-Damaged High-Strength Concrete: Strength and Durability

Abstract

Strength and durability are two key factors influencing the safety and service life of fire-damaged concrete structures. To develop an assessment method for fire-damaged high-strength concrete (HSC) structures that is convenient for postfire repair, the effects of concrete strength and aggregate type on the postfire residual compressive strength of HSC were studied in this paper. Subsequently, the changes in durability and microstructures were investigated by the rapid chloride-ion penetrability test, the mercury intrusion porosimetry test, and scanning electron microscopy observation, respectively. Based on the test results and further analysis, estimation of the temperature distribution in the fire-damaged concrete element is established by the dichotomy and mercury intrusion porosimetry test and scanning electron microscopy observation. According to the estimated temperature distribution, the postfire residual compressive strength can be assessed by the strip method and postfire durability can be assessed by the “two-level” method, respectively. Based on the assessments, the repair method for fire-damaged HSC structures is recommended in steps.