Activation of Cementless Binder Based on Volcanic ash and Calcium Carbide Residue

This study assessed the performance of a cementless binder comprising volcanic ash (VA) and calcium carbide residue (CCR) with different activation methods. The binder was made of 95% VA and 5% CCR and activated by physical, chemical, thermal, and combinations of the methods. While the physical activation included using CCR of nominal particle size of 45 μm, the chemical activation involved adding 1% NaOH by binder mass to the paste, and thermal activation comprised curing the paste in an oven at 65℃ for 24 hours. The performance evaluation was based on flowability, compressive strength, and bulk electrical resistivity. The flowability increased by chemical activation and subsequent physical and chemical activation but decreased with physical activation alone. Meanwhile, all activation methods improved the compressive strength and bulk resistivity. In particular, binders activated by subsequent physical and thermal techniques achieved the highest compressive strength, exceeding 30 MPa at 28 days. In contrast, subsequent chemical and thermal activation produced superior bulk resistivity of 193 Ω.m at 28 days compared to other activation techniques. The study illustrated the feasibility of using low-carbon materials to form sustainable cementless binders for different applications in construction.