Abstract:By the experiments of ultrasonic pulse velocity, rebound and compression, the effect of steel fiber and nanosized materials on ultrasonic pulse velocity（UPV） and rebound number（RN) of fiber & nanosized materials reinforced concrete（FNMRC） before and after exposition to high temperature, and the relationship of compressive strength of FNMRC, the highest exposure temperature were investigated. Test data indicates that the suitable usage of steel fiber，polypropylene fiber and nanosized materials improves the microstructure of concrete, increases its UPV and RN in certain degree. Because there is a good regressive relationship between compressive strength and UPV & RN, the ultrasonic rebound combined method is suitable for evaluating compressive strength and the highest exposure temperature of FNMRC. Based on the regression analysis of test data, the ultrasonic rebound strength curve and the model for evaluating the highest exposure temperature were proposed.
