Experimental study on expansion and cracking properties of static cracking agents in different assembly states

Abstract

Rolled static cracking agent (RSCA) can solve the intractable problem of traditional bulk static cracking agent (BSCA) in engineering applications. This paper innovatively studies the rational water-cement ratio of BSCA and the immersion soaking time of RSCA under the condition of controlling temperature. Through the expansion and cracking performance experiments, the development characteristics of expansion pressure, the cracking effect of the single-hole specimen and the performance of hole spraying prevention under the action of BSCA and RSCA were compared and analyzed. The results show that: (1) The volume growth rate of static cracking agent decreases with the increase of water-cement ratio, and the fluidity increases with the increase of water-cement ratio. The rational water-cement ratio for BSCA application is 0.3, and the rational immersion time of RSCA is 2–2.5 min; (2) Under the bore diameters of 30, 35, 40 and 45 mm, the expansion pressure of BSCA with a water-cement ratio of 0.3 is 38.2, 52.3, 61.5 and 68 MPa, and the expansion pressure of RSCA immersed in water for 2.5 min is 43.5, 58.8, 69.5 and 75.1 MPa, respectively. Among them, the development speed of expansion pressure of BSCA is higher than that of RSCA, and the arrival time of the peak expansion pressure of RSCA is 1.7 times that of BSCA; (3) The crack initiation speed of single-hole specimen under the action of RSCA is 10.3 % lower than that under the action of BSCA, but the cracking speed of the former is 72.6 % higher than that of the latter; (4) The hole spraying occurs in BSCA under the bore diameter of 50, 55 and 60 mm, while the hole spraying occurs in RSCA under the bore diameter of 60 mm. In terms of bore diameter, the hole spraying prevention of the RSCA is better than that of BSCA. The research results enrich the static blasting technology and provide data support and theoretical reference for field application.