Studies on the mechanical and durability performance of textile reinforced geopolymer concrete beams

Abstract

The steel reinforcements used in structural elements are prone to corrosion due to adverse environmental effects. Hence, in recent years, the development of sustainable materials to replace steel reinforcement in concrete has been under research. In this paper, the mechanical and durability characteristics of Geopolymer Concrete (GC) and Epoxy-coated Carbon (EC) yarn against chemical attack were investigated. Tension tests were conducted on EC yarns immersed in acid, sulfate, marine water, and alkaline solution over an exposure period of 1 year. The test results reveal that better durability was achieved for GC specimens compared to cement concrete (CC) specimens in terms of water absorption, acid resistance, sulfate resistance, marine water attack, and chloride diffusion. Compressive strength and flexural strength obtained were 2.6–7.7 times and 1.65–2.36 times higher in GC compared to CC after immersion in various chemical solutions for 6 months. The chemical resistance of EC yarns over an exposure period of 1 year was measured with respect to loss in tensile strength and the reduction in strength was obtained as 29.6% for EC yarns immersed in acid solution, 14.71% in sulfate solution, 7.06% in alkali, and 3.82% in marine water. The study also investigated the flexural behavior of Textile Reinforced Geopolymer Concrete (TRGC) beams (100 × 100 × 500 mm) subjected to monotonic loading. The effectiveness of textile yarn spacing and the number of carbon textile layers to improve the load-bearing behavior of GC beams were evaluated. The reinforcing benefits of TRGC can be confirmed from the load-deflection graph in terms of ultimate load-carrying capacity, post-peak behavior, and failure mode. An energy absorption capacity of 80.06% was found for TRGC-4 L beams compared to TRGC-1 L beam specimens (43.76%), i.e., TRGC specimens with 4 layers showed improved strength and ductility compared to one layer of carbon textile. The failure surface of the TRGC sample was examined using Scanning Electron Microscope (SEM), and fiber-matrix interaction was identified. Hence, despite the high cost of carbon yarn, TRGC can be used for special applications where corrosion protection and durability are controlling parameters.