Mechanical and thermal properties of bottom ash-based porous geopolymer as thermal insulation material for construction

A geo-polymer is a cement-like material that can be used instead of Portland cement, requiring less energy, and emitting less CO2 in its production. It is made from solid wastes, such as fly ash and bottom ash. This work studied the physical, mechanical, and thermal insulation properties of bottom ash-based porous geo-polymers using two different foaming agents: aluminum powder (Al) and sodium lauryl ether sulfate (SLES). An alkaline activator (NaOH and Na2SiO3), bottom ash, and foaming agents (Al or SLES) were mixed to produce the porous geo-polymer samples, which were then cured for 28 days prior to testing at 27 & DEG;C (room temperature). X-ray diffractometry was used to determine the phase composition of the porous geo-polymer, and 3D digital video microscopy was used to determine the porous morphology. The compressive strength of the Al porous geo-polymer was in the range 1.27-2.37 MPa, whereas that of the geo-polymer added with SLES was in the ranged 0.75-6.86 MPa. The resulting samples were compared to some commercial products to evaluate their potential as building materials. The results showed that the thermal conductivity of commercial clay brick (TIS.77-2545) was 1.15 W/m.K while the porous geo-polymer using 5 wt% SLES had a lower thermal conductivity of 0.32 W/m.K and a high compressive strength of 6.86 MPa, making its suitable for use as a thermal insulation material for construction.