A Study of Mechanism of Pressure Sensitivity Changes in CaO-Stabilized Red Clay Under Cyclic Loading Conditions

Abstract

To study the pressure sensitivity of CaO solidified red mud, the pressure sensitivity of CaO solidified red mud under different calcium oxide content and curing age conditions was tested. Through studying the porosity and pore size distribution, the internal relationship between pore structure and pressure sensitivity of materials was discussed. The results show that the compressive strength is the highest when the CaO content is 25%. The resistivity change rate is also better at 25%CaO content, and the pressure sensitivity of the material decreases with increasing curing age. With the increase of CaO content and curing age, the pores of large and small pore size increase at the same time, and the pressure sensitivity of the sample with small porosity changes more under cyclic load, which may be related to the sample being easy to compact and increases in the conductive path. The addition of CaO promoted the active substances in the red mud to participate in the hydration reaction, the generated C-(A)-S-H improved the skeleton structure, the small pore size increased, and the formation of calcium aluminate led to the increase of large pores, which confirmed the change of pore structure.