Effect of silica fume and recycled concrete aggregate on the mechanical properties of GGBS based geopolymer concrete

The present work investigates the mechanical and chemical characteristics and durability of high-strength geopolymer concrete (HSGPC) developed using high-volume copper slag and micro silica. The objective of the study was to explore the feasibility of deploying high-volume copper slag as a replacement for river sand in the fabrication of high-strength geopolymer concrete. In total, 11 different trials were cast by varying copper slag up to 100% as a potential alternative for the river sand. The mixture of alkaline activators for the preparation of the geopolymer concrete (GPC), such as sodium silicate (Na2SiO3) and sodium hydroxide (12 M NaOH), was used in the ratio 2.5:1. The optimum mix was selected from different copper slag dosages based on the characteristics of the HSGPC, such as mechanical strength and workability. For the selected optimized mix, micro silica was added up to 5% by volume of the binder (i.e., 1%, 2%, 3%, 4% and 5%) to improve the particle packing density of the developed HSGPC mix which in turn further enhances the strength and durability properties. Two different curing methods, including (a) ambient curing and (b) steam curing at 80 °C, were deployed for achieving the polymerization reaction (i.e., the formation of Na-Al-Si-H gel). Experimental outcomes reveal a maximum compressive strength of 79.0 MPa when 2% micro silica was added to the optimized GPC mix. In addition to the mechanical tests, the quality of the developed HSGPC was assessed using the ultrasonic pulse velocity (UPV) tests, water-absorption tests, sorptivity tests and microstructural analyses.

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Development of High-Strength Geopolymer Concrete Incorporating High-Volume Copper Slag and Micro Silica

Relative Performance of Limestone, Marble, and Basalt Powders in Replacement of a Recycled Fine Aggregate from Red Mud and Metakaolin-Based Geopolymer Mortar

This study focused on the reliability assessment of ground-granulated blast furnace slag (GGBS) and cow bone ash (CBA) based geopolymer concrete (GPC). To produce the GPC, sodium silicate (Na2SiO3) was mixed with sodium hydroxide of 12M at a 2.5:1 ratio and used as the alkaline activator. The mechanical properties of the GPC were examined at 7, 14, 28, 56, and 90 days of ambient curing. Microstructural analyses were also carried out to investigate the microstructural properties that influence the mechanical performance of the GPC. Following these, a reliability assessment was carried out to establish the reliability of GPC using the constant failure model method. The results of the mechanical tests showed that GPC with GGBS composition that is ≥ 60% and CBA that is ≤ 40% performed better than the conventional concrete. At 28 days of curing, the GPC optimum mix attained a compressive strength of 40.13 MPa against 33.14 MPa attained by the conventional concrete. Also, the reliability analyses established that GPC mixes with GGBS composition that is ≥ 60% and CBA that is ≤ 40% are reliable up to the expected 50 years of service for structures. Hence, GPC is reliable as well as conventional concrete. 

K. Tamilarasan

Papers

Exploration on geopolymer concrete using GGBS and silica fume