In this paper, the impact of temperature and admixture-based salts on the mechanical and rheological properties, and composition of geopolymers was studied. Neat geopolymer and Class-G cement, manufactured by Dyckerhoff, were used as reference samples at elevated temperatures. To enhance the additive properties of the geopolymer slurry, a combination of K and Zn was examined with a variety of K:Zn ratio ranging from ∼0.15 to ∼0.25. The workability of samples was tested by using an atmospheric consistometer, while other rheological properties were examined by running fluid loss test, and rotational viscometer test. The sample with the best workability was cured for 1, 3, and 7 days at bottomhole static temperatures of 70 and 80°C and pressure of 140 MPa where the mechanical properties were examined by ultrasonic cement analyzer and uniaxial compressive strength test. X-ray diffraction was used to analyze the composition of samples at different curing times and temperatures.
The obtained results showed that the salt derivative admixtures have a significant impact on the oligomerization and polycondensation phases, where it distinctively elongated the setting time, enhanced strength, and strength development. On the other hand, the temperature effect was clearly observed by reducing rheological properties, while maintaining similar mechanical properties.