Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 57 8 2025 10 31 Investigation of the Effects of Weathering and Decay on Soil Stabilized with Rice Straw Fibers Investigation of the Effects of Weathering and Decay on Soil Stabilized with Rice Straw Fibers 1319 1342 5876 10.22060/ceej.2025.23771.8214 FA Mohammad Amin Ghasemi Alamshiri shahrood university of technology Mohsen Keramati Shahrood university of technology Hossein Moradi Moghaddam Amirkabir university of technology Journal Article 2024 12 26 This study investigates the effect of varying levels of rice straw fiber (RSF) decomposition on the unconfined compressive strength (UCS) of soil stabilized with different cement contents. The evaluation was conducted using the unconfined compressive strength test (UCS) and standard compaction tests (SCT). Additionally, the effect of weathering on the weight changes of soil samples containing different percentages of fibers was examined through freeze-thaw cycle tests. The variables in this research include: Fiber content (0%, 0.25%, 0.5%, and 1%), cement content (0%, 4%, 8%, and 12%) and curing time (0, 7, 14, and 28 days). The objective of examining the effects of decomposition and weathering on natural fibers is to achieve sustainability goals in geotechnical engineering. The results indicated that as the fiber content increased from 0% to 1%, the compressive strength of both dry and wet samples decreased, while the strain at failure increased. In decomposed samples, the compressive strength and strain at failure decreased by 39.28% and 80.69%, respectively. It is noteworthy that stabilized samples containing 12% cement exhibited higher compressive strength than those with 4% and 8% cement, although their strain at failure was lower. In the freeze-thaw cycle tests, the weight loss increased with a higher percentage of fibers, especially in the cured samples. The average R2 values of approximately 0.88 also demonstrate the effectiveness of the Response Surface Methodology (RSM) models. This study investigates the effect of varying levels of rice straw fiber (RSF) decomposition on the unconfined compressive strength (UCS) of soil stabilized with different cement contents. The evaluation was conducted using the unconfined compressive strength test (UCS) and standard compaction tests (SCT). Additionally, the effect of weathering on the weight changes of soil samples containing different percentages of fibers was examined through freeze-thaw cycle tests. The variables in this research include: Fiber content (0%, 0.25%, 0.5%, and 1%), cement content (0%, 4%, 8%, and 12%) and curing time (0, 7, 14, and 28 days). The objective of examining the effects of decomposition and weathering on natural fibers is to achieve sustainability goals in geotechnical engineering. The results indicated that as the fiber content increased from 0% to 1%, the compressive strength of both dry and wet samples decreased, while the strain at failure increased. In decomposed samples, the compressive strength and strain at failure decreased by 39.28% and 80.69%, respectively. It is noteworthy that stabilized samples containing 12% cement exhibited higher compressive strength than those with 4% and 8% cement, although their strain at failure was lower. In the freeze-thaw cycle tests, the weight loss increased with a higher percentage of fibers, especially in the cured samples. The average R2 values of approximately 0.88 also demonstrate the effectiveness of the Response Surface Methodology (RSM) models. https://ceej.aut.ac.ir/article_5876_fdc0eb412a84fa549afe68373d9087e9.pdf