Design and test of porosity testing apparatus for granular materials

Abstract

In order to improve the accuracy and reliability of porosity measurement of granular materials, on the basis of equation of state of ideal gas and gas displacement method, a rapid measurement apparatus for porosity of granular materials with constant volume was studied and an automatic detection control system was developed. Within measurement range of 0.1∼ 0.4 MPa, the standard stainless-steel spheres, plastic quadrangular prisms, cobblestones and fine gravels with different shapes accurately measurable were adopted, and it was found that the higher the inflation pressure of the system, the smaller the measurement error and the better the repeatability. Using standard stainless-steel sphere and cylinder with porosity of 16.02%, 25.14%, 35.57%, 49.05%, 58.42%, 67.79%, 76.57%, 85.36% and 94.14% respectively, the formula of compensation coefficient was given. The measurement error was 0.3%, which proved the reliability of the measurement results.