Mechanical properties and engineering applications of low-dosage cement/lime-stabilized loess improved with nano-MgO and nan-SiO2

Abstract

Loess has poor engineering performance and needs to be improved for engineering applications by adding a large amount of lime or cement, which is not consistent with the goal of “carbon peaking and carbon neutrality”. In this study, nano-SiO₂ (NS) and nano-MgO (NM) were applied to improve the engineering performance of low-dosage lime/cement- stabilized loess. The improvement mechanisms of each binder on loess were analyzed by X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) tests. The impact of binder dosage and curing time (T) on unconfined compressive strength (UCS), resilient moduli (M_R), California bearing ratio (CBR), internal friction angle (φ), cohesion (c), and compression coefficient (a_1-2) of each stabilized loess were also explored by conducting a range of laboratory experiments. The results show that the addition of NS did not result in the formation of new substances. However, the formation of MH was noted with the addition of NM. The combination of lime and NS can significantly enhance the UCS, CBR, M_R, and c of the stabilized loess, followed by the combination of cement and NS. With the increasing NM content, the above mechanical indices first increased and then decreased for the stabilized loess. Both the binder content and type caused a lesser impact on the φ and a_1-2 than on other mechanical indices. Moreover, the mix ratio and feasibility of each stabilized loess applied in various engineering fields were analyzed based on relevant standards and the construction requirements of lime and cement. Finally, estimation models were established for the above mechanical indices of lime-NS stabilized loess, which can provide a reference for engineering design and quality control.