Relationship between the micro texture and strength development of cement-treated clay under high pressure environmental condition.

Bentonite and a cement-based hardener were mixed and cured under high water pressure simulating deep sea conditions. The relationship between the microstructure of the generated phases and the mechanical strength of the cured cementitious soil was investigated. Samples were cured under hydrostatic pressures ranging from atmospheric pressure to 50 MPa and at a constant temperature of 20°C. The microstructure, chemical composition, and crystalline phases were investigated by scanning electron microscope (SEM), X-ray fluorescence (XRF), and X‐ray diffraction (XRD), and their relationship with the curing characteristics was examined. Samples cured at high pressure tended to have higher strength than those cured at atmospheric pressure for the same curing period. An unknown phase, presumed to be Layered Double Hydroxide (LDH)-type cement hydrate, showed a stronger correlation with the uniaxial compressive strength than an ettringite-type phase, which has been reported to affect the strength of cement-improved soils.