Effect and microscopic mechanism of nano-oxide modified cement solidified silty soft soil

Abstract To enhance the engineering properties of cement solidified silty soft soil, nano-oxides such as nano-SiO2(NS), nano-Al2O3(NA), nano-MgO(NM) and nano-Fe3O4(NF) were selected for modification. The unconfined compressive strength, one-dimensional consolidation and water stability tests were carried out, and the microstructure was analyzed by X-ray diffraction, scanning electron microscopy and mercury intrusion tests. The test results show that nano-oxides can significantly improve the compressive strength of cement solidified silty soft soil. After curing for 28 days, The unconfined compressive strength of samples modified with 1.5% NS, NA, NF, and NM increased by 187.44%, 171.67%, 122.55%, and 189.37%, respectively, compared to that of pure cement soil. With the increase of nano-oxide content, the void ratio and compression coefficient of the sample gradually decrease, and the strength residual coefficient gradually increases. Microscopic test analysis shows that the addition of nano-oxides causes the difference in the type and quantity of hydration products in cement solidified soil, promotes the formation of an effective whole of soil particles wrapped by gel products, transforms the pores from inter-particle pores into intra-particle pores, and improves the integrity of microstructure. Furthermore, the microscopic mechanism of nano-oxide modified cement solidified silty soft soil is established, which can provide theoretical guidance for related research and engineering.