Experimental study on tensile strength of remolded loess in Xinjiang Ili valley

To study the tensile strength change characteristics and the formation process of tensile crack of Ili loess, a self-made tensile strength measure apparatus was used, and the particle image velocimetry (PIV) system, nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) were employed to test the remolded Ili loess with different dry density and water content indoor. Results show that tensile strength of the remolded loess is related to the dry density and water content. With the decrease of water content, the tensile strength increases, and there is a critical water content wc of 18% (close to the plastic limit). The NMR and SEM revealed the influencing mechanism of water content on the tensile strength of Ili loess in terms of water phase variation and microstructure evolution. When water content is higher than wc, the decrease of water content corresponds to the loss of a large amount of free capillary water, and the increase of matric suction and the a small amount of aggregated clay at this stage contribute to the slow increase of tensile strength. When water content is no higher than wc, the clay is aggregated by the rapid decrease of the loosely bound water, and the aggregated clay cements the loess particles and fills the macropores partly. Meanwhile, physico-chemical force from water film increases significantly, thus facilitating the rapid increase in the tensile strength of the remolded Ili loess. © 2021, Editorial Board of Journal of Huazhong University of Science and Technology. All right reserved.