Effect of Alkaline Activators Concentration to the Strength and Morphological Properties of Wastepaper-Based Geopolymer Mortars

Abstract

Waste paper sludge ash (WPSA) is a byproduct that has potential to replace Ordinary Portland Cement (OPC) as a building material. The purpose of this study is to investigate the effect of NaOH concentration on the strength of Waste Paper Sludge Ash (WPSA)-based geopolymer mortar. Initially, the WPSA samples were been analyzed using X-ray Fluorescence (XRF) to determine the chemical composition. From the XRF analysis, the by-product WPSA containing higher amount of calcium, silica and alumina. Alkaline solution are from soluble sodium-based used in geopolymerization are combination of Sodium Hydroxide (NaOH) and Sodium Silicate (Na2SiO3). The mortars samples were cast with various concentration of NaOH and ratio of Na2SiO3 /NaOH which is 2.5. The specimens were carried out on size 50x50x50 mm cube and fresh mortar were been cured at 70 ̊c oven temperature and ambient temperature. The compressive strength tests were conducted after aging the specimen at 3, 7, 14, and 28 days. The results revealed that as the concentration of NaOH increased, the compressive strength of geopolymer mortar increases. However, the optimum NaOH concentration of geopolymer mortar is at 12M. More than 12M concentrations of NaOH were produced high porosity and decreasing the strength. Moreover, curing of fresh geopolymer mortar is performed mostly at an oven temperature compared to ambient temperature due to heat being a reaction accelerator. This paper also present on the morphology, and Energy dispersive x-Ray (EDX) composition analysis of WPSA based geopolymer mortar.