Evaluation of Temperature Variation Effects on the Swelling Characteristics of Fine-graded Soils improvement with Sodium Alginate in Constant Volume condition

Abstract

In some regions with hot and dry climate conditions, the temperature varies greatly between day and night. Therefore, the materials used in construction projects are exposed to a large number of thermal cycles daily. In this research, the application of sodium alginate polymer as an eco-friendly additive for soil stabilization and improvement of its geotechnical characteristics is studied. The study involves conducting geotechnical tests on both control and stabilized soil samples (with and without sodium alginate polymer) such as standard compaction test, swelling tests, and measuring Atterberg limits, while specimens were subjected to the same temperature variations as those recorded in the Khuzestan province, in the southwest of Iran. In fact, this study aims to investigate the effect of temperature ranges on the changes in the swelling potential of high plasticity clayey soils stabilized with sodium alginate polymer. Consolidation tests were carried out on compacted clay samples - containing different concentrations of sodium alginate polymer with treatment durations of 1 and 14 days - in accordance with method C of ASTM standard. The temperature range considered in this research was 23 to 45℃ due to the simulation of the temperature in Khuzestan province in the spring and autumn seasons. Observations indicated an increase in the swelling potential up to %13 in a sigmoidal manner with the repetition of temperature ranges and the stabilization of swelling changes, or so-called aging of swelling, which occurs with the repetition of temperature fluctuations. Additionally, the samples were analyzed using X-ray Diffraction (XRD), and X-ray Fluorescence (XRF) techniques to investigate the changes in their compositions. These methods revealed the formation of palygorskite minerals in specimens. This mineral intensifies the soil's swelling potential and is considered one of the contributing factors to the observed increase in swelling in the stabilized soil samples containing sodium alginate polymer.

Keywords

• swelling potential
• clay soils
• expansive soils
• swelling pressure
• sodium alginate