Experimental and Analytical Study on Rectangular Concrete Confined with Glass Chopped Strand Mats Under Axial Load

This study investigates the axial compressive behaviour of rectangular concrete specimens confined with low-cost Glass Chopped Strand Mat (GCSM) sheets. While the GCSM has been explored in other contexts, this is the first study specifically investigating its effects on rectangular concrete specimens. A total of 24 specimens were tested, grouped by different unconfined concrete strengths. Each group included unconfined specimens and GCSM-confined specimens wrapped with 2, 3, and 4 layers. The results demonstrate that GCSM confinement significantly enhances both compressive strength and ductility, particularly in low-strength concrete, where normalized gains in strength and strain exceeded 50% and 160%, respectively. The post-peak modulus decreased with increasing confinement ratio, indicating improved energy dissipation and delayed failure. Additionally, experimental elastic modulus values showed good agreement with ACI 318 predictions. Analytical models were developed to predict peak strength, peak strain, and post-peak modulus as functions of confinement pressure, achieving excellent correlation with experimental data (R2 > 0.98).