Enhancing geopolymer mortars: The role of surgical face masks in modifying mechanical and thermal properties

Abstract

The primary aim of this study is to examine how expanded surgical face masks (SFMs) affect the mechanical properties, thermal conductivity, thermal insulation, and microstructure of geopolymer mortars. In the experimental phase, SFMs were used after removing the inner nose wires and ear loops, then cut into 5 mm × 5 mm pieces. These SFMs were added to various mixtures at different weight percentages (0%, 2%, 4%, and 6%), along with palm oil clinker (POC) and alkali activator. The mechanical properties of the mixtures, such as compressive strength, bulk density, and water absorption, underwent evaluation through testing. Moreover, thermal conductivity and thermal insulation measurements were carried out to gauge the effect of SFMs on this property. Microstructural analysis of the mixtures was conducted using scanning electron microscopy SEM to examine the impact of SFMs on mortar microstructure. The test results indicated that geopolymer mortar containing 2% SFM achieved a compressive strength of 67.3 ksc at 28 days, with an alkaline to fly ash ratio of 0.8 and POC to fly ash ratio of 3. The geopolymer mortars with POC containing SFMs had a bulk density ranging from 1,233 to 1533 kg/m³ at 28 days. Notably, the use of SFMs resulted in a substantial enhancement in thermal conductivity and thermal insulation. Additionally, a strong correlation was found between thermal conductivity and bulk density, suggesting a potential relationship between these properties.