Effect of Temperature Variation and Pre-Sustained Loading on the Bond between Basalt FRP Sheets and Concrete.

Jun He,Yunfeng Pan,Guijun Xian,Sirong Tan,Zhongyu Lu,Tamon Ueda,Jianhe Xie

doi:10.3390/ma13071530

Abstract

The coupled effects of temperature variation and pre-sustained loading on the bond between basalt fiber reinforced polymer (BFRP) sheets and a concrete substrate were studied. Single lap-shear test specimens were exposed to temperatures of 15, 30, 40, 50, and 60 °C for 3 h with pre-sustained loading at 35% of the ultimate load capacity (Fu). Compared with the case of 15 °C, the interfacial fracture energy of the specimens at 30 and 40 °C increased by 46% and 11%, respectively, whereas those reduced by 73% and 77% at 50 and 60 °C, respectively. The coupled effects of temperature and pre-sustained loading on the effective bond length are insignificant for the specimens at both 15 and 30 °C and the effective bond length increased to 300 mm when the temperature exceeded 40 °C. The failure crack still occurred in the concrete substrate at the temperatures of 15 and 30 °C, and changed to the debonding of the adhesive layer from the concrete substrate at the temperature above 30 °C.

Highlights

Bonded fiber-reinforced polymer (FRP) sheets or plates have become popular for strengthening reinforced concrete structures in recent decades
With pre-sustained loading (Figure 3b,c), the failure mode is the same as that of the control specimen implying that the failure modes below 40 ◦ C are controlled by concrete tensile strength
Compared to the present duration of pre-sustained loading, longer durations accumulate the damage at the interface between adhesive layer and the concrete

Summary

Introduction

Bonded fiber-reinforced polymer (FRP) sheets or plates have become popular for strengthening reinforced concrete structures in recent decades. The effectiveness of this technique relies on the integrity of the bond between the FRP sheet/plate and concrete [1,2]. The harsh service environment of sustained loading, elevated service temperature (EST), and their combination deteriorates the FRP-to-concrete bond [7,8,9,10,11,12]. EST denotes the elevation of the matrix material and the bonding adhesive slightly above the glass transition temperature (Tg ) [13]. The bonding adhesive softens quickly around the Tg and the sustained loading may deteriorate the bond

Methods

Results

Conclusion