Effect of different fibre reinforcements on the strength and acid attack resistance of alkali-activated concrete

The effects of steel, polyvinyl alcohol, polypropylene and glass fibre reinforcements on alkali-activated concrete (AAC) were investigated by conducting various mechanical strength tests. The fibre dosage was 0.1–0.3% by volume of AAC. Furthermore, the effects of acidic exposure on the strength of fibre-reinforced alkali-activated concretes (FRAACs) were examined by immersing samples in 10% v/v solutions of hydrogen chloride, sulfuric acid or nitric acid for 28 days. It was found that fibre additions improved the compressive and flexural strength by up to 13% and 27%, respectively, while the modulus of elasticity was significantly improved by up to 52%. Acid attack tests on AAC specimens demonstrated sulfuric acid to be highly detrimental to the mechanical and chemical properties of AACs. The strength loss in FRAAC after acidic exposure was up to 50% less than that of the plain AAC. The glass-fibre-reinforced AACs were found to be highly resistant to acid attack, whereas the steel-fibre-reinforced AACs had less resistance. These findings were further validated by scanning electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy, which showed the changes in the microstructure of the specimens subjected to acidic environments. Overall, the fibre reinforcements improved the mechanical and durability properties of AACs.