## 1 Introduction
have developed the marble-based geopolymer concrete and examined its physical/mechanical properties [24]. It was found that marble-based geopolymer concrete is an excellent material to be used in engineering applications. [PERSON] et al. (2019) have studied the effects of different parameters on the compressive strength, setting time, and workability of geopolymer pastes [25]. Based on the test results of compressive strength, setting time, and workability, the optimum mix design of geopolymer paste was found to have SG content of 40% and AAs content of 50%. The main limitation of this research is that it was carried out on the geopolymer cement pastes to find out the optimum mix. Furthermore, different concentrations of alkaline activating solution were not considered. The effect of slag content on the properties of ambient cured FS-GPC paste mixes may be affected by different molarities of NaOH solution. [PERSON] et al. (2019) have studied the influence of different parameters on the mechanical properties of alkali activated blast furnace slag concrete [26]. The main limitation of this research is that heat curing method was adopted for the specimens. The results of this study may be different to those of ambient cured specimens. Furthermore, the results of this study do not apply to the alkali activated fly ash and slag blended geopolymer concrete since only slag was used as a source material to produce GPC. [PERSON] et al. (2019) also explored the mechanical properties of fly ash and slag based alkali-activated geopolymer concrete [27]. It was found that GPC mixtures developed with 30% fly ash and 70% slag have better properties at 14 M of NaOH when cured in an oven for 24 h at 70 \({}^{\circ}\)C. However, it should be noted that the ambient curing conditions were not considered in selecting the optimal slag content and NaOH molarity. Furthermore, the optimal mixtures should also include alkaline activating solution content and SS/SH ratio in alkaline solution. It is therefore important to have comprehensive studies like the present study which should focus on the influence of all important parameters on fresh and mechanical properties of GPC to enhance the already available knowledge base. Figure 1: The contribution of each ingredient/activity in CO2 emissions as a percentage in the production of a cubic meter of GPC and OPC concrete. The workability and compressive strength are the two internationally accepted criteria for designing the OPC concrete mixes. However, the mix proportion of GPC is not that similar to OPC. There are more constituents involved in the production of GPC that makes its mix design process more complex. In OPC concrete, the strength of the mix is dependent, in general, on the ratio between cement, fine and coarse aggregates, water-cement ratio, fineness of cement, aggregates gradations, etc. The strength of GPC mix is dependent generally on various ingredients and their ratios, i.e., type of source materials like FA, SG, and alkaline activators, activating solution content, curing methods, mixing procedure, concentration of alkaline solution etc. ; this makes it challenging to design it against a specified target strength. GPC is still a relatively new material in terms of field application and has yet to secure international acceptance as a construction material. In order to effectively substitute the OPC concrete, GPC has yet to reach to a point where the constituents of the GPC mix with a specified target strength can be calculated confidently before mixing. However, this is only possible through a complete understanding of the parameters of the GPC mix. The fresh and hardened properties of GPC mix and the parameters affecting it must be thoroughly understood before its practical application to make sure that reliable and acceptable mixes can be proportioned with confidence.