Influence of Solid Activator on Setting Time and Compressive Strength Properties of Fly Ash/Slag-Based One-Part Geopolymer Pastes

Geopolymerization has transformed industrial wastes into strong and durable construction materials such as geopolymer binders to minimise CO₂ emissions during ordinary Portland cement (OPC) production. These geopolymer binders, on the other hand, are derived from aluminosilicate waste products and alkali activators. The activator solutions show some drawbacks in transportation, storage, preparation and execution stage. In this research, a new one-part or just-add water geopolymer binder was developed by dry blending the aluminosilicate precursors, alkali activators in powder form and free water, similar to OPC. The impact of solid activator on the fly ash/slag based OPG mixes with respect to setting time and compressive properties was studied. The solid activator content was considered from 6 to 16% at an interval of 2%. Microstructure and mineral phase evolution of the mixtures were investigated using scanning electron microscopy and x-ray diffraction. The test results revealed that prolonged setting times were recorded at lower activator content. The lower compressive strength was recorded at 6% activator and higher strength was noticed at 12% activator content. The mix with 12% activator performed better than all other mixes with respect to setting time and compressive strength properties and also exhibits dense and compacted microstructure properties.