Experiment on Interface Shear Properties of Previous Concrete-MgO Stabilized Soils of MgO-carbonated Composite Piles
The MgO-carbonated composite pile is a novel composite pile consisting of a previous concrete pile(inner core)in a deep magnesia mixing column(outer core)formed by carbonation with the magnesia-soil admixture.The frictional characteristics of the inner and outer cores interfaces are crucial factors influencing the load transfer pattern of carbonized composite piles.To study the shear behavior of the interface between the inner and outer cores of this composite pile,direct shear tests were conducted on pervious concrete-magnesia(MgO)-treated soil under different normal stresses.In addition,the effects of the carbonation time(Tc),MgO dosage(wm),and initial moisture content(ww)on the interface shear characteristics of the specimens were analyzed.The tested results showed that as the carbonization time increases,the curve type transfers from"ideal elastic-plastic mode"to"shear-softening mode,"and the shear strength of the optimal specimen with an optimal carbonation time of 6 h is 311 kPa.However,an excessively long carbonation time can result in the formation of cracks within the soil mass,leading to a decrease in the overall strength.Compared with the specimen with wm of 10％,the shear strength of the specimen with an optimal wm of 20％increased by 37％.The shear strength of the specimen with ww=25％was 257 kPa.A low moisture content is unfavorable for hydration and carbonization reactions,which also affects the shear strength of the specimen.For specimens with ww=28％,water molecules filled the pores,resulting in a decrease in the gas diffusion rate.Additionally,water molecules formed a film on the surface of the particles,thereby reducing the cohesion and strength of the MgO-treated soil.The interfacial shear strength has an approximately linear relationship with the normal stress and the unconfined compressive strength of the carbonized soil,and the shear failure of the interface conforms to the Mohr-Coulomb criterion.
NETL
NSTL
万方数据
