Influence of admixtures on the performance of soundless chemical demolition agents and implications for their utilization

Soundless Chemical Demolition Agents (SCDAs) are an environmentally friendly and safer alternative to traditional rock fragmentation methods. Admixtures are used to change the rheological properties and performance of SCDAs. This study aimed to investigate the effect of various concentrations of chemical accelerators (chloride salts) and viscosity enhancing agents (VEAs: Xanthan gum, Guar gum, and Gellan gum) on the fracture onset compared to an unmodified SCDA (BRISTAR 100®). All experiments were conducted on Portland Type 1 (OPC 1) cement blocks. The flowability of the mixtures was determined by mini-slump tests. Results show that 4wt% MgCl2 and 3wt% CaCl2 have accelerated the fracture onset by 47.4% and 61.2%, respectively. VEAs have a decelerating effect, which is mitigated by the addition of the aforementioned chloride salts. Combining 4wt% MgCl2 with 0.2wt% Xanthan gum reduced the fracture onset time by 66.8%. A cost analysis shows that the initial price of the SCDA mainly determines a potential cost reduction by using admixtures. For a low-cost SCDA, the focus is likely to shift to saving time. This study can serve as a basis for future studies to further improve performance and cost as well as diversify the range of applications for SCDAs.