Improvement of the collapsibility of gypseous soil by adding carbon fiber.

The presence of gypsum within the soil mass leads to considerable construction problems when the soil underneath is exposed to water. This study's main goal is to improve gypseous soil's potential to collapse using carbon fiber additive. Three percentages of carbon fiber (i.e., 1%, 2%, and 4%) were added to the highly gypseous soil brought from Al-Ramadi city in Iraq with gypsum content of 70%. The soil deformation and collapsibility treatment were investigated by using an oedometer device and Soil-Model Apparatus with dimensions (30*30*30 cm3). All test models were prepared with an initial density of 1.3 gm/cm3and moisture content of 2%. The results of the tests showed a significant reduction in the collapse potential of the soil sample upon treatment with fiber carbon additives. It was noted that the result of collapsibility of Soil-Model Apparatus for 0%, 1%, 2% and 4 % percentages of carbon fiber addition is 4.8%, 3%, 4.1%, and 3.1%. The best results are the lowest percentage of collapse potential at 1% additive is 2.9% in Soil-Model Apparatus. Collapse potential of Oedometer device of 0%, 1%, 2%, and 4% percentages of carbon fiber addition is 4.5%, 3.2%, 3.8%, and 2.9%. [ABSTRACT FROM AUTHOR]