Flexural Strength of fiber-reinforced alkali-activated concrete beam made from locally available cementitious materials under monotonic load

Abstract

Concrete is a fundamental building material that was in demand for a very long time. Geopolymer concrete is considered an eco-friendly alternative to ordinary Portland cement (OPC). Because it is made using industrial waste materials such as fly ash and slag, which are by-products of other industrial processes. The addition of fibers to geopolymer concrete can enhance its mechanical properties. Research on fiber-reinforced geopolymer concrete beams has been ongoing since the early 2000s. The flexural strength of glass fiber-reinforced geopolymer concrete beams is an important area of research in the field of construction and civil engineering. The main aim of this research was to investigate the flexural strength of an alkali-activated concrete beam, which was produced using locally available white soil (Nech Afer), through the addition of fiber. The production of alkali-activated concrete involved a mixture of 50% white soil (Nech Afer) with 50% normal cement. In this study, plain normal concrete (control), plain alkali-activated (0%GF) concrete, and glass fiber-reinforced alkali-activated (0.2%GF, 0.4%GF, and 0.6%GF) concrete were cast. All specimens were tested for flexural strength on the 7th and 28th days, with different glass fiber percentages of 0.2%, 0.4%, and 0.6% by volume of concrete. Additionally, this study investigated workability, compressive, and split tensile strength tests. The strength of an alkali activated concrete was investigated for C-25 concrete grade in this paper. According to the experimental investigation, the workability of alkali-activated concrete decreased as the percentage of glass fiber increased. The compressive strength of glass fiber-reinforced alkali activated concrete showed an increment compared to the control concrete on the 7th and 28th tests. The split tensile strength showed an increment of 5.6% and 7% for 0%GF and 0.2%GF and it was below control for the rest mixes on 28th -day tests. In the study, it was observed that the addition of glass fibers greatly increased the flexural strength of the fiber-reinforced alkali-activated concrete beams. The increase in flexural strength was even greater than that of the control concrete beam. During the study, it was observed that the fiber-reinforced alkali-activated concrete exhibited additional load-carrying capacity after reaching peak load. Based on the study, it was concluded that the optimal percentage of glass fibers for the alkali-activated concrete was found to be 0.2.