(e)ISSN 2656-8896 (p)ISSN 2656-890X Journal of Infrastructure and Facility Asset Management – Vol. 2, Issue. 2, September 2020 149 Effect of GGBS Slag on Setting Time and Compressive Strength of One-Part Geopolymer Binders Sani Haruna 1,2) , Bashar S. Mohammed 1) & M.M.A Wahab 1) 1) Dept. of Civil & Environmental Eng., Universiti Teknologi PETRONAS, Perak, Malaysia. 2) Civil Engineering Department, Bayero University Kano, Kano, Nigeria. Correspondent: sani_17000823@utp.edu.my ABSTRACT This paper investigated the influence of ground granulated blast furnace slag (GGBS) on the setting time and compressive strength of one-part geopolymer binders (OPGB). Powdered sodium metasilicate activator was utilized in the range of 8 – 16% by weight of the total binder. The central composite design method was used in designing the mixtures. Experimental investigation revealed that both the initial and final setting times of the OPGB decreased drastically with the increase in the GGBS and the activator content. The inclusion of GGBS in the binder influences the setting time of the binders thereby resulting in quick setting time. The variance analysis of the established models demonstrated that the setting and compressive strength models could be predicted using quadratic models with a high R 2 coefficient. Optimization results revealed that the optimum mixture can be obtained by substituting 95.8 % fly ash with GGBS and 13.4 % solid activator. Keywords : One-part geopolymer, GGBS, Setting time, Compressive strength INTRODUCTION Sustainable cementing binder systems have been widely discussed and promoted as a component of the current and future toolkit (Provis 2018). Geopolymer is regarded as an encouraging sustainable and environmentally favorable material substitute to Portland cement in construction applications. Portland cement generation increments worldwide greenhouse gas emissions outflows through the calcination of clinker in hydrocarbon warmed heaters. Generally, a decrease in cement utilization has been accomplished by the utilization of industrial by-products, for example, fly ash and ground granulated blast furnace slag (GGBS) as partial or complete replacement materials to Portland cement in concrete. Nowadays, various regulatory standards of using alkali-activated materials have been proposed in a different part of the world, for small and large scale production (Shi et al 2003, Provis and Van Deventer 2013). The key motivation behind the recognition of alkali activation for more than a century of sporadic use was identified with the potential reduction of CO2 emissions when alkali- activated materials are utilized instead of OPC based materials. Despite the numerous benefits possessed by geopolymer materials, the requirement for high temperature curing and dealing with a large volume of alkaline solutions makes it an issue for on-site applications. To address these problems, dry mixture is needed in such a way that only water will be added to the materials similar to that of OPC binders (Duxson & Provis 2008, Nematollahi, Sanjayan, et al. 2015). Therefore, one-part geopolymers can be well suited for both in-situ and precast applications. The production of one-part geopolymer consists of a dry mixture of a solid aluminosilicate precursor, and a solid alkali activator to which water is added, similar to the OPC preparation (Mohammed et al. 2019a, Mohammed et al. 2019b, Haruna et al. 2020). In