Sustainable thermal insulating geopolymer blocks from palm oil waste and surgical face masks: effects of alumina and curing on performance

Following the global pandemic, there was a surge in surgical face masks (SFMs) waste, coupled with an increasing demand for sustainable building materials. Integrating industrial by-products and plastic waste into geopolymer composites represents an eco-friendly strategy to mitigate environmental impacts and promote a circular economy. This research determined the feasibility of producing thermally insulating geopolymer blocks using waste-based binders and aggregates. Palm oil ash (POA) was mixed with alumina powder (AP) and palm oil clinker (POC) was mixed with SFMs to serve as aggregate. SFMs were added at 0, 2, 4, and 6 wt% replacement of POC. Simultaneously, AP was replaced with POA at 0, 2.5, and 5% concentrations. The thermal insulation performance of blocks made of geopolymer with inserts of field Para rubber latex (FPRL) was also evaluated. The results showed that geopolymer mortar formulation with 2% SFMs and 2.5% AP achieved a compressive strength of 7.11 MPa after 28 days of heat curing. The bulk density of geopolymer mortar was 1,123–1,521 kg/m3 at the same age. The thermal conductivity of geopolymer mortar with SFMs was significantly lower than the thermal conductivity of conventional fired clay bricks and conventional concrete blocks, as confirmed by thermal insulation testing of blocks.