Mechanical and microstructural behavior of high strength geopolymer concrete inclusion of various industrial wastes

The experimental work is intended to identify the mix proportion of M100 grade of High-Strength Geopolymer Concrete (HSGPC) by a targeted strength-based method. Concrete ingredients are Ground Granulated Blast Furnace Slag (GGBS), Microfine (MF), Fly Ash (FA), Silica Fume (SF) as a binder, 10 mm natural coarse aggregate, and river sand. Eight different mix proportions of M100-grade concrete were calculated and tested by considering the different fractions of binders. Fresh concrete workability was assessed by a slump test. The compressive, indirect tensile, flexural, and shear strength were evaluated at the age of 7 and 28 days to find the optimum mix proportion of M100 concrete. Technique for Order Preference by Similarity to Ideal Solution analysis was incorporated to find the optimum proportion of M100 concrete with due weightage of sufficient slump value and high mechanical properties. The experimental analysis includes the microstructural behavior of the HSGPC. The results represented that incorporating the SF and MF reduces the workability by approximately 28% but increases the mechanical properties by up to 22%. The promising compressive strength for M100 grade was observed at 28 days with a binders fraction of 55% GGBS, 25% FA, 10% SF, and 10% MF concrete sample as 104 MPa, the highest compressive strength compared to other mixes. Microstructural analysis of HSGPC revealed that mechanical properties were enhanced due to a dense microstructure of different gel formations like C–S–H, Ca–S–H, and Na–S–H gel.