Axial compression of corroded square RC columns strengthened with combined basalt fibre and ECC

This paper presents an experimental study on the compressive behaviour of corroded square RC columns strengthened with basalt fibre-reinforced ECC (BFRE). Axial compression tests were conducted on fourteen specimens, with key parameters including the number of basalt fibre grid layers, corrosion schemes and steel corrosion ratio. The results showed that BFRE systems effectively enhanced the compressive behaviour of corrosion-damaged columns. Specifically, BFRE layers restored 90% of their initial axial capacity when the stirrup corrosion ratio was below 16.23% (stirrup-corrosion only), while a axial capacity gain of 1.3%-10.5% when the longitudinal bar corrosion ratio was under 9.86% (longitudinal bar-corrosion only). Additionally, BFRE significantly improved deformability, increasing ductility by 42.8%-327.7% compared to corroded columns and 12.1%-139.6% compared to intact columns. Stirrup corrosion was found to have a more adverse effect on the deformation capacity than longitudinal bar corrosion, particularly in the post-peak stage. Based on the test results, a predictive model for the load-carrying capacity of BFRE-strengthened square RC columns is proposed. • Axial compressive tests of BFRE-strengthened corroded columns with square cross section. • Effectiveness of BFRE systems in improving the load-carrying capacity and deformbility of corroded-damaged columns. • A predictive model for buckling mode of longitudinal bars under the confining of of stirrup and BFRE layer. • A predictive model for load-carrying capacity of BFRE-strengthened columns considering the bar buckling behaviour.