Mechanical and microstructural characteristics of geopolymer mortars at high temperatures produced with ceramic sanitaryware waste

Excessive amounts of solid wastes are generated by the ceramic sanitaryware sector in the world. Recycling ceramic wastes is one of the crucial solutions to ensure their elimination. This experimental study investigates the mechanical and microstructural characteristics of geopolymer mortars with recycled ceramic sanitaryware waste powder (CSW) exposed to high temperatures. The geopolymer mixtures are produced using CSW with four different molarity (10, 12, 14, and 16 M) of NaOH as alkali-activator and two water/binder ratios (0.45 and 0.50). The investigated properties of the CSW-based Mortars (CSW-M) are the flowability, unit weight, apparent porosity, flexural strength, compressive strength, phase, and microstructure utilizing X-ray diffractometry (XRD), and scanning electron microscopy (SEM/EDS). The increase in NaOH concentration is observed to improve the flow workability of CSW-M and reduce the apparent porosity and water absorption of specimens. Mechanical test results indicate that strength values of CSW-M increase with increasing NaOH molarity. The highest strength is obtained on the CSW-M made with 16 M NaOH and 0.45 w/b ratio. The crystalline phases are determined to be mullite, quartz and albite derived from ceramic sanitaryware waste. Additionally, zeolite is formed by the secondary reaction product after elevated temperatures. Performance analysis results reveal that using ceramic sanitaryware waste is a strong alternative material as a binder to produce geopolymer mortars and contributes to the elimination of the waste.