Sharif University of Technology Sharif Journal of Civil Engineering 2676-4768 41 2 2025 09 22 Investigating the Effect of Gorgan Bay’s Sludge Ash on the Mechanical Parameters of Gorgan Loess Soil at Different Moisture Content and the Same Compaction Energy Investigating the Effect of Gorgan Bay’s Sludge Ash on the Mechanical Parameters of Gorgan Loess Soil at Different Moisture Content and the Same Compaction Energy 114 123 23653 10.24200/j30.2024.64158.3314 FA Vahid Pesarakloo Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran Seyed Hamid LAJEVARDI Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran Hossein MolaAbasi Department of Civil Engineering, Gonbad Kavous University, Gonbad Kavous, Iran 0000-0002-4552-5551 Seyed Mohammad MIrHosseini Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran Journal Article 2024 04 15 The objective of this study is to examine the mechanical properties of Gorgan loess enhanced with sludge pond ash (SPA) from Gorgan Gulf under different conditions. To achieve this, different proportions of SPA were mixed with the loess to obtain accurate findings on the efficacy of SPA addition on the unconfined compressive strength (UCS), cohesion (C), friction angle (f), compression (Cc), and recompression (Cs) index of the loess. Firstly, the sludge from a pond burned at 1000°C, which was the optimal temperature determined by X-ray fluorescence analysis (XRF), was added to the mixture as 0, 2, 4, 6, 8, and 10% of the soil's dry weight, respectively. The studied samples were prepared with the same energy (equivalent to the standard Proctor test) at different moisture contents (16, 18.5, 21, 23.5, and 26%) and were tested in unconfined compressive strength, direct shear, and consolidation devices at 56 days of curing in a humid room with a temperature of 24°C. It was found that adding SPA to the base soil increases the maximum strength measured in unconfined compressive strength, which is defined as unconfined compressive strength (UCS). On the other hand, it decreased with increasing moisture content. The addition of SPA as an additive material to the loess mixture was found to exert a significant effect on the shear strength properties (C and f) of the loess. The changes in moisture percentage for this test were not specific due to soil saturation and consolidation, and did not have a great effect on the increase of shear strength parameters with the increase of SPA. Examining the graphs of the consolidation test shows that the addition of 2% of SPA to the loess caused a noticeable decrease in the amount of Cc of the sample under the test after processing. Increasing the amount of SPA up to 10% caused a further decrease in the Cc value of the samples. This trend is also noticeable for the re-compression index, which showed a greater intensity with the increase in the amount of SPA. Accordingly, adding SPA to the soil caused a sharp decrease in Cs in the samples compared to the base soil. At the end, the results of macro-scale analyses collectively confirm the superior efficacy of the SPA replacement in enhancing various strength and stiffness properties of the loess. The objective of this study is to examine the mechanical properties of Gorgan loess enhanced with sludge pond ash (SPA) from Gorgan Gulf under different conditions. To achieve this, different proportions of SPA were mixed with the loess to obtain accurate findings on the efficacy of SPA addition on the unconfined compressive strength (UCS), cohesion (C), friction angle (f), compression (Cc), and recompression (Cs) index of the loess. Firstly, the sludge from a pond burned at 1000°C, which was the optimal temperature determined by X-ray fluorescence analysis (XRF), was added to the mixture as 0, 2, 4, 6, 8, and 10% of the soil's dry weight, respectively. The studied samples were prepared with the same energy (equivalent to the standard Proctor test) at different moisture contents (16, 18.5, 21, 23.5, and 26%) and were tested in unconfined compressive strength, direct shear, and consolidation devices at 56 days of curing in a humid room with a temperature of 24°C. It was found that adding SPA to the base soil increases the maximum strength measured in unconfined compressive strength, which is defined as unconfined compressive strength (UCS). On the other hand, it decreased with increasing moisture content. The addition of SPA as an additive material to the loess mixture was found to exert a significant effect on the shear strength properties (C and f) of the loess. The changes in moisture percentage for this test were not specific due to soil saturation and consolidation, and did not have a great effect on the increase of shear strength parameters with the increase of SPA. Examining the graphs of the consolidation test shows that the addition of 2% of SPA to the loess caused a noticeable decrease in the amount of Cc of the sample under the test after processing. Increasing the amount of SPA up to 10% caused a further decrease in the Cc value of the samples. This trend is also noticeable for the re-compression index, which showed a greater intensity with the increase in the amount of SPA. Accordingly, adding SPA to the soil caused a sharp decrease in Cs in the samples compared to the base soil. At the end, the results of macro-scale analyses collectively confirm the superior efficacy of the SPA replacement in enhancing various strength and stiffness properties of the loess.

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