The Mechanical Properties of Kaolin-Based Geopolymer Concrete with Portland Cement Addition

In this study, Portland cement was added to a mixture to address low early strength challenges in kaolin-based geopolymers. The effects of various curing conditions were examined, including room temperature and elevated temperatures (60°C and 90°C), as well as the influence of Superplasticizer (SP) dosages (0–3%) on compressive and tensile strengths. The results showed that curing at 60°C for 24 hours provided the optimal balance between early and long-term strength development, achieving compressive strengths of 26.7 MPa at 28 days. Although curing at 90°C offered rapid early strength, it resulted in diminished long-term performance due to potential microstructural damage. SP addition improved workability and mechanical properties, with the optimal dosages being identified as 1% for room-temperature curing and 2% for elevated-temperature curing. The findings stress the importance of curing conditions and material composition in achieving high-performance geopolymer concrete. This type of concrete, when cured under controlled elevated temperatures, is suitable for precast applications where thermal curing is feasible, making it a promising eco-friendly alternative for structural elements in sustainable construction.