Precast segmental beams made of fibre-reinforced geopolymer concrete and FRP tendons against impact loads

In the open literature, there is no investigation into the impact behaviour of prefabricated segmental concrete beams (PSCBs) cast with low CO2-emission fibre-reinforced geopolymer concrete (GPC), reinforced with non-corrodible basalt fibre-reinforced polymer (BFRP) reinforcement, and post-tensioned with carbon FRP (CFRP) tendons. This research, hence, aims to close this existing gap of knowledge. The primary goals are to investigate the effect of dispersed fibres on the impact response of PSCBs and to compare the performance of CFRP versus steel tendons. The experimental results reveal that the PSCBs fail due to excessive joint openings that lead to concrete spalling and flying concrete debris. The inclusion of dispersed fibres in the concrete postpones crack development, reduces reinforcement strain, and effectively mitigates concrete spalling and stiffness degradation of the beams. While fibres show limited influence on the deflection response of PSCBs, as the deformation of segmental beams is predominantly governed by joint openings with no fibres bridging across the joints, they play a crucial role in preventing severe damage during impact events. The impact response of beams post-tensioned with CFRP tendons is analogous to those with steel tendons. Notably, both the CFRP tendon and BFRP reinforcement remain intact even when the beam fails under impact loads. This implies that CFRP tendons and BFRP reinforcement can be successfully employed in constructing durable and sustainable segmental GPC beams capable of withstanding impact loading. A high-fidelity numerical model of PSCBs made of GPC and FRP tendons and reinforcement subjected to impact loads is also developed, for the first time, to supplement the discussions of experimental findings.