Effects of heating on compositional, structural, and physicochemical properties of loess under laboratory conditions

Wildfires are swept-wing across the world is increasing in recent time, causing serious environmental, ecological and socioeconomic impacts due to alterations in soil properties. Currently, wildfires are increasing in landscapes over the Chinese Loess Plateau. This study examined the changes in loess properties at laboratory temperatures ranging from 20 to 1000 °C. Various tests were performed on the raw and heated loess, including mineral and chemical compositions, color, scanning electron microscopy (SEM), particle size distribution, bulk and particle densities, particle flow velocity, specific surface area (SSA) and cation exchange capacity (CEC), along with electric conductivity (CE) and pH of its 1:5 extracts. The test results showed that heating couldn't produce notable changes in various loess properties below 400 °C, although slight changes have been observed resulting from loss of physically free and absorbed water. In contrast, higher temperature heating can induce important changes in loess properties due to the formation of aggregation as a result of changes in structure and composition. The analysis of results indicated that there has a close relation between microscopic characteristics of heated samples and its macroscopic behaviors. These findings are important to an initial understanding of wildfire-induced alterations in loess properties and then can afford useful posthoc estimate to such as erosion and debris flow geohazard processing in the fire-affected loess areas.