Application of organic additives as pore forming agents for geopolymer composites

Abstract

Geopolymer is a relatively new type of material derivable from aluminosilicate precursors such as fly-ash, clays and mining slags is often regarded as a green material. The structure of geopolymer consists of a negatively charged aluminosilicate network where the charge balancing cations (Na + , K + , or Ca 2+ ) can be exchanged from solution, therefore offers adjustable properties. Due to its porosity, geopolymer is a good adsorbent material. The porosity can be enhanced using pore forming agents, however research in this field remains limited. This work investigated the potential of corn oil, waste cooking oil (palm) and starch as organic pore forming agents (POF) for fly-ash geopolymers to create pores of various size ranges in the matrices. Highlights of results include pristine geopolymer had a compressive strength of 30.93 MPa, corn oil as PFA induced the highest porosity of 26.6% with compressive strength of 9.9 MPa, followed by palm oil at 21.3 % and 9.0 MPa and starch at 17.9 % and 20.41 MPa. The pores were combination of voids and tunnels in the composites as confirmed by SEM.