Investigation on strength and microstructure characteristics of nano-MgO admixed with cemented soft soil

Abstract

The effectiveness of nano-MgO in strength properties and microstructure characteristics of cement stabilized soft soil were analyzed in this study. Sulfuric acid attack was also taken into account, and the effects nano-MgO content and sulfuric acid concentration were mainly addressed. Based on a series of unconfined compression tests, it shows that nano-MgO content plays a significant role in the strength properties of the stabilized soil. For the cement content of 13%, the optimum nano-MgO content is 15‰ considering both with and without sulphate attack condition. The addition of nano-MgO not only improves the unconfined compressive strength (UCS) of the cement stabilized soil, but also tends to increase its ductility. Scanning electron microscopy (SEM) reveals that the addition of nano-MgO improves the microstructure of the stabilized soil, while overuse of nano-MgO may generate cracks inside of the structure. For the effect of sulfuric acid concentration, specimens under higher concentration solution will have lower strength and stiffness. Finally, the mechanism of sulfuric acid attack on cemented soil was revealed to be outside structure loss caused by sulfuric acid erosion and inside structure distortion caused by ettringite generation.