Investigation of the Compressive Strength, Ultrasonic Pulse Velocity, Calorimetric, Microstructural and Rheological Properties of the Calcined Laterite-Based Geopolymer Materials.

This study aims to investigate the compressive strengths, ultrasonic pulse velocity, calorimetric, microstructural and rheological properties of calcined laterite-based geopolymer materials. Calcined laterite has been used as an iron-rich aluminosilicate and the hardener containing various molar ratios SiO2/Na2O such as 1.6, 1.8, 2.0 and 2.2 have been used for the preparation of geopolymer materials. The 28-days compressive strengths of the geopolymer materials using sodium waterglass containing molar ratios SiO2/Na2O equal to 1.6, 1.8, 2.0 and 2.2 are 49.98, 48.19, 46.65 and 9.35 MPa, respectively. Their maximum ultrasonic pulse velocities are 3200, 2800, 2000 and 1600 m/s, respectively. Their total heat flows are 85.91, 68.42, 18.50 and 16.34 J/g, respectively. The rheological properties of the geopolymer materials indicate the destruction of the flocculation and the homogenization of the particles of calcined laterite during the formation of the fresh geopolymer prepared using hardeners containing the molar ratios SiO2/Na2O equal to 1.6, 1.8 and 2.0. The one from molar ratio SiO2/Na2O equal to 2.2 contains more flocculation and therefore inhibits the geopolymerization process. It was found that the compressive strengths decrease with decreasing the amorphous phase content, the ultrasonic pulse velocities, total heat flow and corroborate the rheological properties of calcined laterite-based geopolymer materials. [ABSTRACT FROM AUTHOR]