Performance evaluation on engineering properties of sodium silicate binder as a precursor material for the development of cement-free concrete

Abstract

In emerging economies, huge stocks of industrial wastes are dumped in open landfills. Such wastes serve as a source for environmental pollution. Some of these materials such as Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBFS), Rice Husk Ash (RHA), and Palm Oil Fuel Shell Ash (POFA) can be used as binder materials to produce concrete mix. Aim of the study is to effectively utilize the Municipal Solid Waste (Sodium Silicate Waste (SSW)) powder as a partial replacement for FA in the development of Geopolymer Concrete (GPC). GPC requires heat curing for the attainment of early age strength. The development of GPC under heat curing conditions is a hard process in practice. To overcome such circumstances, an attempt was made to develop the GPC under ambient curing conditions with the aid of SSW. The influence of SSW on strength gain and microstructural characteristics of GPC is investigated. Mechanical properties of GPC such as compressive strength, tensile strength, and flexural strength are reported and discussed. This study focuses on the assessment of mechanical and microstructure characterization of eco-efficient GPC developed with SSW. The required optimum quantity of binder, alkali activator, alkaline liquid to binder ratio and aggregates was determined by appropriate trials. Following the properties of SSW, it is realistic to substitute up to 50% of SSW as the resulting binder mix falls within the requirements of the analyzed mix. Increase in the percentage of SSW decreases the fresh properties of GPC, such as setting time and workability; mix with 50% SSW exhibited the lowest initial and final setting time i.e., 77% and 81% than the control mix. Contrastingly, inclusion of SSW content enhances the mechanical properties of the mix. 12SSW50 mix produces the maximum compressive, tensile and flexural strength of 40.16 MPa, 2.8 MPa, and 4.18 MPa, respectively. Mix with 8 M concentration comprising 50% SSW possess higher cost efficiency than the mix with higher alkaline content. The main significance of this research work is, SSW can be used as a precursor material as an alternative for cementitious binder with better efficiency in terms of strength, microstructure, and sustainability. Therefore, GPC produced with SSW is an eco-friendly and sustainable building material. Effective use of waste materials such as fly ash and SSW for the development of GPC is another major research focus in the proposed investigation.