An improved outer pipe method for expansive pressure measurement of static cracking agents

Static cracking agent (SCA) is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property. SCA can eliminate the negative effects of shock, noise and harmful gases encountered in explosive blasting processes. Accurate measurement and deep understanding of the expansive properties of SCAs are important in their industrial application. An improved outer pipe method (OPM), termed the upper end surface method (UESM), is proposed in this paper to overcome the shortcomings of the OPM in the expansive pressure measurement of SCAs. Numerical simulation is used to proof the concept and a mathematical model established to relate the internal pressure and the radial strains at different positions in the upper end surface method test equipment. The new equipment is calibrated using oil pressure and strain measurements. The calibrated equipment is then used to measure the expansion pressure of SCA at three different water contents to proof its potential. The differences in the measurements with OPM and UESM at three different moisture contents are less than 4%. The experimental results confirm the accuracy and applicability of the more user friendly and less expensive UESM in the measurement of the expansive pressures of SCAs.