INFLUENCE OF FINENESS MODULUS AND PREHEATED SAND ON COMPRESSIVE STRENGTH OF ALKALI ACTIVATED GEOPOLYMER MORTAR

Abstract

Geopolymer mortar is a complex material, and its strength and durability fundamentally depend on its main constituent properties, grading and grain size distribution of a fine aggregate. The Fineness Modulus (FM) of fine aggregates (sand) is an empirical figure obtained by adding the total percentage of the sample of sand retained on each of a specified series of sieves and dividing the sum by 100. The purpose of this research is to analyze the effect of the Fineness Modulus (FM) of preheated sand at 100°C on geopolymer material (GPM) compressive strength (Cs). The current research used natural river sands of fineness modulus 1.85, 2.41, 2.79, 3.32 to prepare geopolymer material paste. The 36 cube specimens of 50 x 50 x 50 mm size were used to calculate the Cs of GPM paste at 3 h, 1 d, and 7 d. All specimens were kept in hot curing at 40°C for 3 h. The outcomes of the research showed that the sand fineness modulus has a significant impact on the GPM flow rate (%). The results indicated that rising the fineness modulus of sand enhanced the flow rate (%) of GPM paste. The GPM paste made with preheated sand of FM 1.85 (fine sand), and FM 2.79 (medium sand) at 100°C attended the highest compressive strength growth rate (%)and showed up to 47% and 51%, 85.6% and 87.27% increased in compressive strength in 3 h and 1 d, accordingly. Additionally, the fineness modulus has a significant impact on the Cs of GPM paste in the case of preheated sand. Fine sand and mild sand are the best type of fine aggregate to develop early-high-strength geopolymer material.