Abstract
The combination of fibre-reinforced polymer (FRP) and high-volume fly ash self-compacting concrete (HVFA-SCC) reinforced is expected to solve the problem of steel corrosion in traditional structures and develop sustainable infrastructures. Bond behaviour has a strong effect on serviceability of FRP reinforced concrete structures. To achieve the acceptance of this novel composite structures in practical construction and design, it is significantly important to investigate the bond behaviour of FRP reinforced HVFA-SCC. In this study, a series of pull-out tests were carried out to investigate the bond behaviour of HVFA-SCC reinforced by FRP bar, which included bond strength, bond-slip response, and failure mode. The investigated experimental variables were reinforcing materials, surface treatment of FRP bars, bar diameters and concrete materials. The test results revealed that using HVFA-SCC resulted in higher average bond strength compared to those in the normal concrete test specimens. The reinforcing materials (steel vs. GFRP) had strong effect on bond behaviour, including bond strength, bond stiffness and failure mode. The failure mechanism of bond interaction between FRP and HVFA-SCC is dependent on friction and chemical adhesion. Subsequently, theoretical models for bond strength and development length were proposed. Finally, the parameters of analytical models of bond-slip curve are calibrated for GFRP reinforced HVFA-SCC by using the experimental data.
Highlights
The service life of steel reinforced concrete structures is reduced by the corrosion of steel bars, especially in marine or near aggressive environments [1]
The surface of GFRP reinforcing bar is damaged by the delamination of the resin-rich outer in the pull-out test for the HVFA-self-compacting concrete (SCC) test specimens, while the surface of the GFRP bar in normal concrete (NC) test specimens is almost intact and some residual concrete is attached to the reinforcement
The specimen reinforced by GFRP bar with large spiral leads to the increase of pores at the interface, which means that the chemical bond and friction effect are decreased at the interface of fibre reinforced polymer (FRP) bars and concrete
Summary
The service life of steel reinforced concrete structures is reduced by the corrosion of steel bars, especially in marine or near aggressive environments [1]. It has been reported that the SCC mixed with highvolume fly ash (50% or more) can produce an environmentally friendly concrete with high flowability and durability [6] These two engineering materials, high-volume fly ash-SCC (HVFA-SCC) and FRP, have attracted wide attention in the structural constructions [7]. It has been reported that the concrete compositions, including powder types and content, aggregate types and contents, and admixture, have a significant effect on the bond properties [16, 17] This means that the FRP/ steel reinforced HVFA-SCC, SCC and NC have different bond behaviour. It is of significantly important to fully study the bond-slip behaviour and bond failure process between GFRP bars and HVFASCC for establishing the prediction model of bond strength and development length This is beneficial for developing further study on the serviceability behaviour and establishing the design guidelines of FRP reinforced HVFA-SCC structures. The Ttst results indicate that the average bond strength of GFRP reinforced HVFA-SCC specimens is higher than that of GFRP reinforced NC specimens, especially in specimen of GFRP with a lower spiral height
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