Sustainable development of geopolymer binder using sodium silicate synthesized from agricultural waste

摘要

Geopolymer binders have emerged as an innovative sustainable material with the prospective of substituting Portland cement in various circumstances with the possibility of reducing the carbon footprint up to 80% in the production of concrete. Conversely, there is a significant contribution to the carbon dioxide footprint and cost with the application of commercial activators in the production of geopolymer binders. This study investigates the viability of using an agro-industrial by-product rice husk ash based alkaline silicate as a substitute for silica-based activators in the production of geopolymer binders with ground granulated blast furnace slag (GGBFS) as source material. A hydrothermal process was utilized to extract the alkaline silicate powder to develop geopolymer binder with varying concentration of sodium hydroxide (ratio of RHA: NaOH of 1:0.5, 1:1.0 and 1:1.5) and process duration (1, 2 and 3 h) with constant process temperature of 100 degrees C. The paste samples were characterized for strength, mineralogy and microstructure for varying mix proportions. From the strength characteristics, the optimum process duration was found to be 2 h and the subsequent microstructural characteristics were assessed for the samples with process duration of 2 hat the age of 3, 7 and 28 days under ambient curing condition. Comparable development in the compressive strength results with improved microstructure characteristics was observed with the paste samples prepared with the RHA-based activators along with improved ecological properties in terms of energy requirement and carbon footprint in its production. (C) 2020 Elsevier Ltd. All rights reserved.