Evaluating damaged concrete depth in reinforced concrete structures under different fire exposure times by means of NDT and DT techniques

Abstract

After a severe fire, concrete structures are generally capable of being repaired rather than demolished. To determine whether the fire-damaged structure can be repaired, an assessment of structural integrity must be conducted. In this research, a laboratory assessment of fire-damaged reinforced concrete (RC) slabs was carried out by using Destructive Testing (DT) and Non-Destructive Testing (NDT) techniques. The study aimed to evaluate the depth of damaged concrete in RC slabs exposed to fire for different periods of time (30, 60, 90 and 120 minutes) based on the correlation between the experimental results of DT and NDT methods. The experiment was conducted with two concrete grades of 24 and 35 MPa. Limestone aggregates were used in this study. The experimental results indicated that 30 minutes of heating time did not show severe effects on reinforced concrete slabs in comparison with the other cases. A damaged concrete layer of 30 - 45 mm was observed for slabs exposed to fire in 60 and 90 minutes. Besides, 24 MPa slabs also showed a lower damage level compared with 35 MPa slabs.