Effect of Concentration of Sodium Hydroxide and Degree of Heat Curing on Fly Ash-Based Geopolymer Mortar

Abstract

Geopolymer concrete/mortar is the new development in the field of building constructions in which cement is totally replaced by pozzolanic material like fly ash and activated by alkaline solution. This paper presented the effect of concentration of sodium hydroxide, temperature, and duration of oven heating on compressive strength of fly ash-based geopolymer mortar. Sodium silicate solution containing Na 2 O of 16.45%, SiO 2 of 34.35%, and H 2 O of 49.20% and sodium hydroxide solution of 2. 91, 5.60, 8.10, 11.01, 13.11, and 15.08. Moles concentrations were used as alkaline activators. Geopolymer mortar mixes were prepared by considering solution-to-fly ash ratio of 0.35, 0.40, and 0.45. The temperature of oven curing was maintained at 40, 60, 90, and 120 ∘ C each for a heating period of 24 hours and tested for compressive strength at the age of 3 days as test period after specified degree of heating. Test results show that the workability and compressive strength both increase with increase in concentration of sodium hydroxide solution for all solution-to-fly ash ratios. Degree of heating also plays vital role in accelerating the strength; however there is no large change in compressive strength beyond test period of three days after specified period of oven heating.

Mix Design of Fly Ash Based Geopolymer Concrete

“…Fly ash Quantity and fineness of fly ash plays an important role in the activation process of geopolymer. It was already pointed out that the strength of geopolymer concrete increases with increase in quantity and fineness of fly ash [12]. Similarly higher fineness shows higher workability and strength with early duration of heating.…”

“…So, in the proposed mix design procedure, quantity of fly ash is selected from Fig. 1 on the basis of fineness of fly ash and target strength [12].…”

“…So, in the present investigation, geopolymer concrete mix design procedure is proposed on the basis of quantity and fineness of fly ash to achieve desired strength [12], quantity of water to achieve required degree of workability [13], grading of fine aggregate [14] and fine-to-total aggregate ratio by maintaining solution-to-fly ash ratio by mass of 0.35 [15], water-to-geopolymer binder ratio of 0.35 [16], sodium silicate-to-sodium hydroxide ratio by mass of 1 [17] and tested after oven heating at a temperature 60°C for duration of 24 h and tested after test period of 7 days [13].…”

Sustainable Use of Reservoir Sediment through Partial Application in Building Material

“…Also, reservoir sediments were chemically activated with the addition of sodium hydroxide as an activator into milling process. This activator was chosen based on the previous studies [43][44][45][46], which concluded that the inclusion of NaOH as chemical activator into geopolymer matrix increased the compressive strength of the hardened geopolymer concrete. Alkali activators transform the amorphous structure into a skeletal structure that exhibits cementitious properties [47].…”

Freeze-Thaw and Fire Resistance of Geopolymer Mortar Based on Natural and Waste Pozzolans

“…On the other hand, only limited information is available the use of natural zeolite in production of geopolymer concrete or mortar [9,10]. Up to now only a few studies have investigated the effect of the concentration of the alkaline solution on the strength and durability properties of the geopolymer concrete [11][12][13]. Moreover, there is limited literature describing the effects of alkaline activator ratios (Na 2 SiO 3 /NaOH) on durability properties of geopolymer mortar [14,15].…”