A step towards sustainable glass fiber reinforced concrete utilizing silica fume and waste coconut shell aggregate

Abstract

Today, it’s getting harder to find natural resources for concrete production. Utilization of the waste materials not just helps in getting them used in concrete, cement, and other construction materials, but also has various secondary advantages, for example, saving in energy, decrease in landfill cost, and protecting climate from pollution. Considering this in the development of modern structural design, utilizing waste materials instead of natural aggregate is a good option to make concrete that is sustainable and eco-friendly. The present research aims to find the impact of adding glass fiber into sustainable concrete made with silica fume, as a partial replacement of cement, and coconut shell added with different ratios as a replacement of coarse aggregate, on concrete mechanical and durability aspects. Various blends were made, with coconut shell as a substitution of coarse aggregates with different ratios. Portland cement was substituted with silica fume at 5%, 10%, 15%, and 20% by cement weight in all concrete blends. The volume ratios of glass fibers utilized in this study were 0.5%, 1.0%, 1.5% and 2.0%. Adding glass fibers increases concrete density to some extent and then marginally reduces the density of coconut shell concrete. When the percentage of glass fibers increases, the compressive, flexural and split tensile strength of coconut shell concrete also increases. From the lab results and SEM images of the present research display that glass fibers might be utilized in coconut shell concrete to enhance its mechanical and durability attributes, to accomplish sustainable concrete with acceptable strength with ease.

Effects of Steel Fibers (SF) and Ground Granulated Blast Furnace Slag (GGBS) on Recycled Aggregate Concrete

“…The second objective of this study was to add GGBS into recycling coarse aggregate concrete to offset its porous nature by filling voids and by the pozzolanic reaction, which enhances the mechanical performance of recycled coarse aggregate concrete. Zaid et al showed that although pozzolanic materials improved the compressive strength of concrete, however, the concrete still had less tensile capacity, resulting in brittle failure that is unacceptable [4]. Further research was recommended in [4] where fibers must be added to GGBS recycled aggregate concrete to achieve high strength, durable, and ductile concrete.…”

“…Zaid et al showed that although pozzolanic materials improved the compressive strength of concrete, however, the concrete still had less tensile capacity, resulting in brittle failure that is unacceptable [4]. Further research was recommended in [4] where fibers must be added to GGBS recycled aggregate concrete to achieve high strength, durable, and ductile concrete. Therefore, the final objective of this study was to add steel fiber to GGBS recycled coarse aggregate concrete to obtain high-strength durable concrete.…”

“…This is due to the physical nature of RCA, which absorbs more water, leading to porous concrete, resulting in less compressive strength. It has also been reported that the compressive strength of recycled aggregate concrete is due to unreactive cement [4]. RCA absorbs water from concrete and no water is available for the hydration process.…”

“…The additional binder produced by the GGBS reaction with available lime allows concrete to continue to gain strength over time. However, at a higher dosage of GGBS (beyond 20% by weight of cement), strength reduces because of the dilution effect, which leads to the alkali-silica reaction due to a higher quantity of unreactive silica available with the high quantity of GGBS [4]. Additionally, GGBS fills the voids in the recycled aggregate, leading to denser concrete, which resulted in an improvement in the compressive strength of concrete.…”

“…Therefore, it is recommended that it is necessary to use cementitious materials in recycled aggregate concrete to improve its permeance [3]. It has also been recommended that it is necessary to add secondary cementitious materials such as fly ash, silica fume, and GGBS into the recycled aggregate concrete to improve their performance [4].…”