الفهرس 
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Abstract
Fly ash based geopolymer concrete (GPC) is an environmentally friendly concrete made from alkali activated aluminosilicate and aggregate. Generally, geopolymer concrete needs several approaches before and after casting which limits its in-field applications. Development of geopolymer concrete become a demand to widen its application beyond precast concrete. This study aims to study the influence of fly ash content (350, 400 and 450 kg/m3), adding Portland cement (5, 10 and 15 %), alkaline solution resting time (30 minutes and 24 hrs), curing period (24, 48 and 72 hrs), and curing temperature (28, 50, 70 and 90 o C) on fly ash based geopolymer concrete. Also, study the influence of additional water content (10, 20, 30 and 35 kg/m3) , chemical admixture content (2.5, 5, 7.5 and 10.5 kg/m3), sodium hydroxide solution molarity (12, 16 and 18 M), alkaline solution to fly ash ratio (0.3, 0.35, 0.4 and 0.45) and sodium hydroxide to sodium silicate ratio (0.3, 0.4 and 0.5) on fly ash based geopolymer concrete. The evaluated properties of (GPC) were workability, compressive strength, splitting tensile strength, modulus of elasticity, absorption, thermal gravimetric analysis (TGA), acid resistance and drying shrink age. The study results show that, generally, adding cement improves all fly ash based geopolymer properties except workability. The increase of fly ash content enhances geopolymer concrete properties. Using 30 minutes solution resting time has a significant effect on geopolymer properties compared with using 24 hrs solution resting time. Geopolymer concrete properties significantly affected by curing approaches represented in curing time and temperature. The study also show that, generally, increasing additional water content increased workability, but decreased other fly ash based geopolymer properties and the optimum dose of additional water content was found to be 30 kg /m3 which has slight effect on geopolymer properties. The increase of chemical admixture content up to 10.5 kg/m3 had acceptable effects on geopolymer concrete properties due to improved workability. The optimum molarity of sodium hydroxide solution was found to be 16 M. Geopolymer concrete properties significantly affected by alkaline solution to fly ash ratio and 0.40 was expected to be the optimum ratio. Increasing sodium hydroxide solution to sodium silicate solution ratio reduces geopolymer concrete properties; nevertheless, low ratio is not economic due to sodium silicate solution cost.