Effect of pore forming agents on geopolymer porosity and mechanical properties

Abstract

Generation of industrial waste materials such as fly ash and slag in bulk provides an opportunity to convert these wastes into eco-friendly, value-added products. A geopolymer, a strong, porous and environmentally friendly material, was synthesized by mixing fly-ash with an alkaline activator, followed by addition of a pore forming agent (PFA) which created voids of varied pore sizes within the mixture. This polymer has potential applications as an adsorbent or membrane material; however, there is no established technology to regulate the pore size. Corn oil, waste palm oil and starch were investigated as potential organic additives to produce geopolymer materials with pore sizes suitable for water treatment membranes. Geopolymer without additives had a compressive strength of 30.93 MPa. Corn oil induced the highest porosity of up to 26.6 % with a compressive strength of 9.9 MPa, waste palm oil at 21.3 % and 9.0 MPa and starch at 17.9 % and 20.41 MPa. SEM analysis revealed that the voids and tunnels formation increased with increased PFA dosage.