Studying the physical an‎d consolidation properties an‎d unconfined compressive strength of the unstabilized an‎d stabilized Savadkouh peat soil

11/16/2025 12:00:00 AM

Peat soils, due to their high organic matter content, high porosity, natural moisture content, an‎d poor mechanical performance, are considered problematic soils in geotechnical engineering. These types of soils are widely found in various regions of Iran, including the Hyrcanian forests of the north, wetlan‎ds, an‎d humid an‎d fertile areas. Owing to their low bearing capacity an‎d high compressibility, they are usually removed during construction projects. However, in areas where the thickness of the peat soil layer is significant an‎d its removal is neither economically nor technically feasible, stabilization with cementitious materials can be an effective method for improving its engineering properties. In this study, to investigate the possibility of improving the peat soil of the Lafur region in Savadkuh County, a series of index tests, consolidation tests, an‎d unconfined compressive strength (UCS) tests were conducted. The natural soil examined had a maximum dry unit weight of about 15 kN/m³, fiber an‎d organic matter contents of approximately 17% an‎d 38%, respectively, an‎d a UCS value of around 30 kPa. For soil improvement, samples were prepared with different weight percentages of Type I Portlan‎d cement an‎d cured under moist an‎d submerged conditions for curing periods ranging from 3 to 60 days. The consolidation test indicated that the compression index (Cc) of the natural soil was close to 1. The unconfined compressive strength of the soil after stabilization with 5%, 10%, 15%, an‎d 20% cement increased by approximately 4.5, 15, 26, an‎d 32 times, respectively. The effect of curing conditions showed that samples containing 10% cement an‎d cured under moist conditions achieved about 14% higher strength than submerged samples, whereas samples containing 15% cement performed about 4% better under submerged curing than under moist curing. Based on engineering analyses, the optimal cement content for stabilizing the peat soil of the Lafur region was determined to be about 10–15%, with a relative compaction of 90% during construction an‎d a moisture content of 30% at the time of mixing, ensuring adequate strength while keeping costs an‎d environmental impacts within acceptable limits.

خاك گياهي سوادكوه , بهسازي خاك با سيمان , مقاومت فشاري تك‌محوري , تحكيم يك بعدي

Savadkuh peat soil , cement soil stabilization , unconfined compressive strength , one-dimensional consolidation

Mehdi Molaei Raeisi

Dr. Heshmati