Study of the disintegration of loess modified with fly ash and Roadyes

Abstract

The disintegration property of loess is the wetting and subsequent disintegration of loess in water, which is generally an important index for resistance to erosion and disintegration of wet loess slopes and foundations. In this study, a disintegration instrument is developed in this laboratory and used to study the disintegration properties of fly ash-modified loess in foundations and Roadyes-modified loess in subgrades. Disintegration tests are used to compare samples of loess modified with different amounts of fly ash and Roadyes, different water contents and different dry densities; the influence of fly ash and Roadyes content on the disintegration of modified loess is analyzed. The differences in disintegration properties between the pure loess and modified loess are compared to explore the evolution of disintegration properties of modified loess and the optimal incorporation levels of fly ash and Roadyes. The experimental results show that the incorporation of fly ash reduces the disintegration of loess, while the incorporation of Roadyes likewise decreases the disintegration of loess. The disintegration of the loess modified with the two curing agents is better than that of the pure loess and loess mixed with a single curing agent; the optimal incorporation levels are 15% fly ash and 0.5‰ Roadyes. Comparing the evolution of the disintegration curves of samples of loess with different modifications shows is a linear relationship between time and amount of disintegration for pure loess and Roadyes-modified loess. Thus, a linear disintegration model is established in which the parameter P is the disintegration rate. According to the exponential relationship between time and amount of disintegration of fly ash-modified loess and loess modified with both fly ash and Roadyes, an exponential disintegration model is established in which the water stability parameter Q affects the strong and weak disintegration of the modified loess. The relationship between the water stability of the loess (modified with added fly ash and Roadyes) in water and the initial water content and dry density is analyzed. The water stability of the loess first increases and then decreases with increasing initial water content and gradually increases with increasing dry density. When the sample density is the maximum dry density, the sample has the best water stability. These research results provide a basis for the application of loess modified with added fly ash and Roadyes.