# An Experimental Study for Swelling Effect on Repairing of Cracks in Fine-Grained Clayey Soils
###### Abstract  
Earth-dam failure starts with cracking in the clay core, and this cracking is not easy to detect and prevent. Therefore, swellable clay is a feasible solution, which helps to close the cracks automatically based on the self-healing process. The presented study utilizes experimental procedures to analyze the swelling behavior of fine-grained clayey soils to prevent structural failure regarding crack generations. In this regard, the clayey materials were modified using Kaolin and Bentonite mixed with various weight percentages (2.5, 5.0, 7.5, 10.0, and 12.5%) and extracted the geotechnical characteristics of the studied soils, which included 90 specimens and 85 tests, such as physical properties, consolidation, particle-size analysis, hydrometry, Arterberg limits, compaction, odometer, and pinhole. The experimental results revealed that the swelling of the Bentonite is more than Kaolin satisfied for self-healing features in clayey soils. Regarding the numerous swelling tests, Bentonite provides optimum results (attained 10%) compared to Kaolin. As a verification procedure, the pinhole test was performed on samples, which revealed that Bentonite was dominant in controlling the water flow through the samples. geotechnical characteristics; cracks; swelling effect; self-healing process; clayey soils Article  
An Experimental Study for Swelling Effect on Cracks in Fine-Grained Clayey Soils. _Applied_  
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M.N.N. of clay content to provide the self-stabilization-based self-healing process concerning the environmental conditions [7]. Regarding the fact that the initial stage of the appearance of the cracks inside the earth-fill dam's core with fine-grained clayey soil is not possible to recognize after finishing the construction, it is improbable to prevent the crack generation, propagation, or repair them [11]. In the meantime, applying self-healable materials like swellable clay can be useful to control the crack generation at the dam's core, which helps to close the cracks automatically based on the self-healing process [12]. [PERSON] and [PERSON] [13] mentioned that the swelling behavior of fine-grained soils can be used to control the dispersion of compacted clayey soils, which is potentially applied for earth-fill dam core stabilization. According to the results, the swelling is directly controlled by clay minerals type, plasticity (\(10\leq\text{PI}<50\)), clay particles, degree of compaction, and density of soil. [PERSON] and [PERSON] [14] provided experimental methods to understand the self-healing progressive erosion process of cracks in earth dams' cores. The results of the experiments indicate that the finest content of more than 85% (\(\text{D}_{15\text{F}}/\text{d}_{\text{e}}\)) should be less than 9. [PERSON] et al. [15] investigated the Bentonite impact on the sand-bentonite mixture's compaction characteristics and shear strength parameters. According to the results, the adequate bentonite percentage should be 12% to 15% until hydraulic conductivity is reduced to \(10^{-6}\) cm/s and the shear strength is improved. [PERSON] et al. [12] stated that using the clay particles for self-healing in a five-layer embankment dam can prevent the critical flow rate for crack propagation in the dam's core. In their experiments, the results indicate that the crack's self-healing is induced under 300 kPa of water pressure. The critical flow rate through the sample before the self-healing of the crack is different in the experiments, but it increases with the increase of the crack depth or/and the \(\text{D}_{15}/\text{d}_{85}\) value. [PERSON] et al. [16] used the drying shrinkage relationship with pore moisture and mechanical properties to understand the swelling potential and soil activity under different percentages of bentonite. Based on the results, it shows that using 50 gr/lit NaCl to 250 gr/lit CaCl can improve the uniaxial strength of swellable soils up to 10 kPa. [PERSON] et al. [17] used the swellable clays to control the crack generation and propagation on concrete-faced rockfill dams (CFRDs).