Effect of glass fiber-reinforced polymer and epoxy injection on compressive strength of elevated temperature damaged concrete Ramazan Demirboğa 1,2, * ,† , Mehmet Akif Kaygusuz 3 and Rıza Polat 2 1 University Putra Malaysia, Engineering Faculty, Civil Engineering Department, Selangor, Malaysia 2 Ataturk University, Engineering Faculty, Civil Engineering Department, 25240-Erzurum, Turkey 3 State Hydraulic Works, 8th Regional Directorate, 25100-Erzurum, Turkey SUMMARY Glass fiber-reinforced polymer (GFRP) materials have received a great deal of interest among civil engineers during the past decade. This paper presents an overview of experimental studies carried out on GFRP- wrapped and epoxy-injected concrete samples exposed to elevated temperatures. For this purpose, 0.30, 0.35 and 0.40 water to binder (w/b) ratios were used. For each w/b ratio, normal aggregates were replaced by lightweight aggregates with a size fraction of 0–2 mm at three different volume fractions such as 10%, 20% and 30% of total aggregate volume. At the same time, a group of air-entrained samples was also cast for each w/b ratios. Prepared samples were exposed to 600  C for 3 h. The damaged samples were separately repaired by GFRP and epoxy injection. Before and after elevated temperature exposure, water absorption and compressive strength were tested. After repairing with GFRP and epoxy injection, only the compressive strength test was carried out. GFRP improved the compressive strength between 1–22% and 348–1403% for samples before and after being exposed to elevated temperatures, respectively. Epoxy injection increased the compressive strength of the samples, exposed to elevated temperature, between 1% and 123%. However, the epoxy injection process failed to recover the compressive strength of the samples before elevated temperature exposure. Copyright © 2012 John Wiley & Sons, Ltd. Received 15 March 2011; Revised 21 September 2011; Accepted 19 December 2011 KEY WORDS: compressive strength; elevated temperature; GFRP wrapping; epoxy injection; concrete strengthening and repair 1. INTRODUCTION Concrete structures are exposed to various external factors throughout their service life. These effects may be physical, chemical, biological or human induced. One of the main factors that jeopardizes the service life of concrete structures is fire damage. Deterioration of concrete in the majority of structures is manifested by cracking. Fire damage is one of the leading effects of crack development in concrete structures. Concrete is indubitably exposed to elevated temperatures during fire. The mechanical properties such as compressive strength, tensile strength and modulus of elasticity decrease dramatically during the period of exposure to elevated temperatures. These reductions can result in structural failures. During fire, temperature rises to 600  C in about 10 min, and thereafter, it will increase to approximately 1200  C. *Correspondence to: Ramazan Demirboğa, University Putra Malaysia, Engineering Faculty, Civil Engineering Department, Selangor, Malaysia. † E-mail: rdemirboga@eng.upm.edu.my; rdemirboga@yahoo.com; ramazan@atauni.edu.tr Copyright © 2012 John Wiley & Sons, Ltd. FIRE AND MATERIALS Fire Mater. (2012) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/fam.2116