GGBS based alkali activated fine aggregate in concrete - Properties at fresh and hardened state

Abstract

Scarcity of the construction materials, peculiarly the natural river sand has become a serious threat in the construction industry. Though many researchers of developed and developing countries are trying to find alternative sources for the same, the complete replacement of the fine aggregate in concrete is crucial. Geopolymer sand developed from the Industrial waste (Ground granulated blast furnace slag - GGBS) is an effective alternative for the complete replacement of the natural sand. The GGBS based geopolymer sand (G-GFA) was tested for physical and chemical properties. Upon the successful achievement of the properties in par with the natural river sand, the fresh properties (fresh concrete density & slump) and hardened properties (compressive strength, tensile strength & flexural strength) of the concrete specimens developed with G-GFA were studied. The G-GFA is obtained by both air drying (AD-G-GFA) and oven drying (OD-F-GFA) after the dry mixing of the alkaline solution and GGBS for about 10 min. Thus, developed fine aggregates were studied separately for the fresh and hardened concrete to optimize the feasible one. Superplasticizer of 0.4% is included in the concrete mix to compensate the sightly hydrophilic nature of the fine aggregates produced. The mechanical properties of the concrete with G-GFA are observed to be more than 90% close to that of the concrete developed with natural river sand. Thus, both the fresh and mechanical properties of the G-GFA concrete specimens resulted in findings similar to those of the control specimen developed with natural river sand reflecting the plausibility of G-GFA as a complete replacement choice to the fine aggregate in the concrete industry. The flaky GGBS particles merge well with the alkaline solution at room temperature itself since the former gets dried at elevated temperatures. Thus, more feasible fresh concrete properties and mechanical properties were recorded for the AD-G-GFA than the OD-G-GFA.

Experimental Investigation on Partially Replacing the Fine Aggregate by using Ground Granulated Blast Furnace Slag in Cement Concrete

“…Ashita sing et.al. (2019) studied on optimization of cement and fine agrregate by blast furnace slag in M30 grade concrete [3]. It is concluded that cement can be replaced by GGBS upto 55% and sand can be replaced by GGBS upto 50% without affecting compressive strength.…”

Evaluating the performance of alkali activated concrete with fly ash, lime and GGBS

“…The development of AAM utilizes alkali activators and supplementary materials like fly ash, silica fume, steel slag, and GGBS [6][7][8][9]. The hardened paste has been generated and improves the strength and durability in AAC, by the chemical reaction between a solid alumina silicate and an alkali activator [10,11].…”

“…Many researchers have explored the effect of slag on performance of AAC considering type, dosage of activator, water content and curing conditions [3,21]. The slag source and replacement level for fly ash can dominantly influence the properties of AAC [3,22].…”