Liquid carbon dioxide blasting technology as a new environmentally safe rock cracking technology has been widely used in mining, enhancing the permeability of coal seam, road construction, and other fields. In this study, a liquid carbon dioxide blasting experiment was conducted on a concrete specimen of size 500mm×500mm×400 mm firstly, and the crack distribution and blast hole morphology were observed. Then, the peridynamics model of rock fracturing under liquid carbon dioxide blasting was established, and the crack propagation in liquid carbon dioxide blasting and the influence of explosion pressure and numbers and radii of releasing holes on the liquid carbon dioxide blasting effects were analyzed. The results showed that the broken concrete specimen had no obvious smash district and the direction of crack propagation was perpendicular to that of carbon dioxide release after liquid carbon dioxide blasting. The failure of the specimen was only caused by the blasting stress wave, and the quasi-static effect of high-pressure carbon dioxide did not have sufficient time to play its role. With an increase in the stress wave strength and the numbers and radii of releasing holes, the fracturing velocity of liquid carbon blasting will increase. The cracks produced by liquid carbon dioxide blasting were mainly distributed in the middle of the adjacent releasing holes. The research results had a good guiding significance for understanding the mechanism of liquid carbon dioxide rock breaking and optimizing and improving the liquid carbon dioxide fracturing device.

The strength and consistency of cemented paste backfill (CPB) are of key concerns in the stope stability and cost control for underground mines. It is common practice to use additives, such as superplasticizer, to improve the performance of CPB. This study mainly focuses on the effects of superplasticizer on the hydration, consistency, and strength of CPB. In this study, a polynaphtalene sulfonate was used as the superplasticizer. The binder is a mix of 33.3% ordinary Portland cement and 66.7% fly ash. The CPB specimens with a tailings-binder ratio of 3:1 and a solid concentration of 70% were then tested by a low field nuclear magnetic resonance system after different hydration times. Effects of polynaphtalene sulfonate on the hydration, fluidity, and strength were investigated. Results showed that the polynaphtalene sulfonate has a strong influence on short-duration hydration, which may contribute to the strength increase of CPB. It has been demonstrated that the polynaphtalene sulfonate improved the fluidity of the CPB mixture. With the increased dosage of polynaphtalene sulfonate, the slump increased. It was also found that the polynaphtalene sulfonate dosage has a negligible effect on the 1 day (d) strength while it has a strengthening effect on the 7 d, 14 d, and 28 d strength of CPB specimens.