The Effect of Oyster Shell Powder on the High-Temperature-Properties of Slag-Ceramic Powder-Based Geopolymer

Current research lacks clarity on how oyster shell powder (OSP) affects geopolymer concrete under high temperatures. It is already known that geopolymer binders can withstand elevated temperatures, but their performance with added waste materials remains understudied. This gap motivated the investigation into OSP as a potential additive to improve thermal resistance. The environmental impact of OSP waste has not been fully explored in the context of construction materials. Prior research has shown that OSP contains calcium carbonate, which may influence geopolymerization. However, no prior work had resolved how OSP affects phase transitions in alkali-activated systems. The need to reduce industrial and marine waste drives interest in OSP’s role in sustainable construction. This paper’s contribution lies in linking OSP’s thermal properties to geopolymer durability.

The study aimed to evaluate how oyster shell powder influences the high-temperature performance of alkali-activated slag-ceramic powder mixtures. A specific problem is the lack of application of eco-friendly building materials and the environmental burden of OSP waste. The motivation stems from the need to repurpose OSP as a construction additive. Researchers tested OSP at 10% and 20% replacement levels for granulated blast furnace slag and ceramic powder. The focus was on how OSP affects geopolymer properties at 400°C, 600°C, and 800°C. The goal was to assess compressive strength, phase transitions, and shrinkage resistance. This study sought to determine if OSP improves thermal resilience in geopolymer systems. The broader aim is to promote sustainable construction through waste utilization.

The study used alkali-activated slag-ceramic powder mixtures with OSP as a replacement material. The OSP was added at 10% and 20% by weight of the binder. Mixes were cured for 180 days before being heated to 400°C, 600°C, and 800°C. Thermogravimetric analysis (TGA) measured weight changes during heating. Compressive strength and ultrasonic pulse velocity (UPV) were tested post-heating. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyzed phase transitions. Visual inspection and size change measurements documented physical effects. The experimental design compared OSP20 and OSP0 (control) samples. The methods focused on quantifying thermal degradation and structural changes.

The thermogravimetric analysis showed that OSP20 samples produced more CASH gels than the control OSP0. As temperature increased, compressive strength and UPV both declined in all samples. At 800°C, the mixture underwent a phase transition, as observed via FTIR and XRD. The OSP20 mix exhibited a different phase transition compared to the control. The addition of OSP reduced shrinkage in the heated samples. Calcium carbonate in OSP decomposed into CaO, which appeared as off-white residue. The results suggest that OSP enhances thermal resistance in geopolymer systems. The most significant finding is that OSP20 mitigates high-temperature damage more effectively than OSP0.

The authors propose that OSP improves the thermal resistance of alkali-activated binders at 800°C. The study suggests that OSP20 produces more CASH gels than the control. The phase transition observed at 800°C was different in OSP20 compared to OSP0. The findings suggest that OSP inhibits shrinkage and stabilizes the structure during heating. The decomposition of calcium carbonate into CaO is a key mechanism in this process. The authors state that OSP can be used to reduce the environmental impact of construction materials. The results support the use of OSP as a sustainable additive in geopolymer systems. The study concludes that OSP enhances high-temperature performance without compromising structural integrity.