The Effect of Using Various Types of Clay on the Mechanical Properties of Plastic Concrete

J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 77 Journal of Civil Engineering and Materials Application http://jcema.comJournal home page: Received: 04 March 2025 • Revised: 09 May 2025 • Accepted: 22 May 2025 doi: 10.22034/jcema.2025.229295 The Effect of Using Various Types of Clay on the Mechanical Properties of Plastic Concrete Milad Saedi 1*, Amin Dadashi Beilankouhi 2, Ata Ashrafi 3, Vahid Taheri 4 1 Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran. 2 Department of Civil Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran, 3 Faculty of Civil Engineering, Seraj Institute of Higher Education, Tabriz, Iran, 4 Faculty of Civil Engineering, Sahand University of Technology, Tabriz, Iran, *Correspondence should be addressed to Milad Saedi, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran. ; Email: [email protected] Copyright © 2025, Milad Saedi. This is an open access paper distributed under the Creative Commons Attribution License. Journal of Civil Engineering and Materials Application is published by (ISNet); Journal p-ISSN 2676-332X; Journal e-ISSN 2588-2880. 1. INTRODUCTION Dams are typically made in high permeability areas. Therefore, controlling groundwater and their leakage is one of the most important issues in the stability of dams, tunnels and many concrete structures related to soil. Due to the accumulation of large amounts of water behind the dam, one of the ways to reduce and control the water leakage from the back of the dam is to use the cut-off walls. The cut-off walls must have high plasticity and low permeability [1]. For this reason, plastic concrete could be one of the solutions. Plastic concrete has a higher formability, but lower compressive strength and permeability, resulting from the usage of clay slurry in the concrete D ABSTRACT Plastic concrete, as a construction material with high workability and low permeability, is widely used in the construction of hydraulic structures. Clay, as one of the main components of plastic concrete, plays an important role in improving its properties. However, plastic concrete faces challenges such as longer curing time and low strength. Moreover, permeability in plastic concrete is one of the key issues that needs to be studied. Therefore, this study investigates the mechanical properties and permeability of plastic concrete made with two types of clay: clay from the Baghmisheh region of Tabriz and the same clay that has been processed for use in ceramic clay. Clay was used to replace cement at three different percentages: 10%, 20%, and 30% and a sample without clay was prepared for comparison. The prepared samples were evaluated through a series of tests, including compressive, tensile, flexural strength, water absorption, and permeability. The results indicate that Baghmisheh clay, due to its higher plasticity, had negative impact on the mechanical properties compared to Ceramic clay. By increasing in the content of both types of clay, compressive, tensile, and flexural strengths were significantly reduced. This reduction is attributed to the partial replacement of cement with clay, which increased porosity of the concrete, and decreased bonding between its particles. Water absorption and permeability coefficient of the concrete increased considerably with higher clay content, particularly in mixes containing Baghmisheh clay. Overall, concrete containing Baghmisheh clay exhibited lower strength and was more vulnerable to water and chemical penetration. Keywords: plastic concrete, plasticity, clay, permeability, mechanical properties, smartphone sensor J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 78 mix design [2]. Plastic concrete consists of aggregate, cement, water, and clay mixed at a high water cement ratio to produce a ductile material than conventional structural concrete [2]. Plastic concrete shows great promise for satisfying the strength, stiffness, and permeability requirements for remedial cut-off wall construction [3]. In general, using higher water to cement ratio in the mixing design increases plasticity and reduces permeability. However, this case cause aggregates to be separated from cement. For this reason, at these ratios, we use clay in mix designs. Clay acts as a stabilizing agent in plastic concrete and prevents aggregate from having separated from cement and it creates a homogeneous mixture. The properties of clay include plasticity, ion succession and ionic contraction. While using in concrete, clay acts as an ion exchange. This makes the mixture homogeneous and stable, which in addition to preventing the separation of aggregate from the cement, it results in the uniformity of the molecular arrangement of the mixture and increases the plasticity and decreases permeability [4,5]. Clay has high water absorption and swells about 300% after combining with water. These properties make saturated clay workable in plastic concrete in order to eliminate the damaging effects of high water absorption of dry bentonite [6]. Amlashi et al. (2019) investigated the soft computing based formulations for slump, compressive strength, and elastic modulus of bentonite plastic concrete (BPC). Parametric study indicated that increasing clay contents leads to the reduction of slump, compressive strength, and elastic modulus due to the adsorption of water by clay particles. Moreover, at constant amounts of clay, increasing the ratio of gravel to sand improves the strength parameters of BPC. While increasing the amount of water increases the slump of BPC, the slope of this ascending trend turn into zero at water contents greater than 0.34 Kg/m3. There is an inverse correlation between water content and strength parameters of BPC. At constant amounts of water, increasing the clay to cement ratio leads to an increase in slump and reduces compressive strength and elastic modulus [7]. Shepherd et al. (2020) reviewed about plastic concrete for cut-off walls. The review presented here confirms that Plastic Concrete may be considered to be a low-strength, low-stiffness impervious concrete with high deformation capacity under load, but also supports the need for further investigations into the mechanical and hydraulic material properties [8]. Taher Shamsi et al. (2009) investigated the effect of two types of clay minerals on the compressive strength of plastic concrete made from them. The results of this research indicated that if the compressive strength criterion of the samples is used to evaluate the extent of the effect of the clay type on the mechanical properties of plastic concrete, the addition of bentonite clay has more favorable consequences than kaolinite clay in plastic concrete [9]. Fadaie et al. (2019) investigated the effect of dry and saturated bentonite on plastic concrete. In order to saturate bentonite clay, plastic concretes must be mixed with water at least 24 hours before usage and then they must be blended by special blades. This process costs huge time and money. Therefore, in this research, dry bentonite has been added to the mixer with particular method. It can be seen saving time and money and the properties of plastic concrete such as compressive strength, tensile strength, slump and permeability will not be slightly changed [1]. Memon et al. (2012) examined Pakistani bentonite as a part of Portland cement. They examined the use of bentonite as pozzolan is an environmental friendly option. Technically and financially, bentonite has lots of potentials to be used as pozzolan in the concrete construction industry. They also indicated that the workability, density and water absorption decrease by replacing bentonite with cement Kaci et al. (2011) investigated the influence of bentonite clay on the rheological behavior of fresh mortars, and more particularly on the ability of the material to recover yield stress after being sheared at high rates. By determining the flow curves at controlled stresses, the mortars initially showed a rheopectic behavior. This rheopectic aspect was attributed to the diminution of the lubricating effects of the fine particles suspensions due to their shearthinning property. It was found that bentonite increases both the level of yield stress recovered after shear and the kinetics of the microstructure rebuild up. Adding more bentonite can enhance the shear induced thickening effect [10]. Abbaslou et al. (2014) investigated effect of sepiolite clay mineral on the compressive strength of plastic concrete. The research aimed to evaluate sepiolite clay as a replacement for bentonite and investigate its workability. Compressive strength results showed that replacing bentonite with sepiolite, despite J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 79 having plasticity, leads to higher optimal strength. Laboratory findings regarding the impact of the mineralogical structure of different clays on the strength properties of plastic concrete, which are important for dam construction applications, indicate a significant difference between the tested samples [11]. In this article, plastic concrete samples were made with two types of clays: clay from the Baghmisheh region of Tabriz and clay from the Baghmisheh region that has been processed for use in ceramic clay. For this purpose, the clay soils replaced the Portland cement in three percentages of 10, 20, and 30, and were cured for 7 and 28 days. Compressive strength, tensile strength and flexural strength tests for mechanical properties, water absorption and permeability tests in terms of durability were conducted on the plastic concrete samples. The results were then compared. 2. MATERIALS AND METHODS 2.1. Cement The cement used in this research is Portland Cement Type 2 of Soufian Cement Plant (East Azerbaijan), the chemical and physical requirements are shown in Table 1 and 2. Table 1. Chemical Analysis of Soufian Cement L.O.I I.R. K2O Na2O SO3-2 MgO CaO Fe2O3 Al2O3 SiO2 Component 1.36 0.62 0.58 0.22 2.00 2.22 64.44 3.74 5.22 21.70 Percent (%) Table 2. Physical Analysis of Soufian Cement Compressive Strength (Kg/cm2) Density (Kg/m3) Final Setting Time (min) Initial Setting Time (min) Autoclave Expansion (%) Residue on 90 µ Sieve (%) Fineness (Blaine) (cm2/g) 28 days 7 days 3 days 2 days 465 345 240 172 3160 185 115 0.18 3.86 3230 2.2. Clay Based on the project objectives and research methodology, the effectiveness of two types of clay soil in plastic concrete was investigated. Both types of clay have been extracted from the Baghmisheh region of Tabriz. However, clay type A has undergone processing for use in ceramic clay, while type B is the raw, unprocessed clay as extracted. Clay is a fundamental raw material in the production of traditional and decorative tiles, requiring specific properties such as suitable plasticity, high adhesiveness, and resistance to cracking. Ceramic clay is extracted from natural deposits and undergoes processing to remove impurities and enhance its usability. Initially, coarse particles and organic materials are separated through screening and, if necessary, sedimentation. The clay is then dried and may be ground to achieve a finer texture. Additives such as grog (fired and ground clay) or silica may be incorporated to improve its technical properties. Finally, the clay is kneaded and homogenized to produce a material ready for tile production [12]. The Baghmisheh region of Tabriz is one of the sources of ceramic clay in Iran, where the extracted clay, once processed, is widely used in the making of traditional tiles. Table 3 shows the LL, PL, PI and special gravity (GS) of clays. Table 3. Physical Analysis of Clays GS (Kg/m3) PI PL LL Clay Type 2581 7% 22% 29% Ceramic clay 2691 17% 17.6% 34.7% Baghmesheh region Clay J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 80 2.3. Aggregate The aggregate used in this research was fine and coarse aggregate of the Marand Qara Qoum Mine and their particle size distribution charts are shown in Figures 1 and 2. Figure 1. Fine Aggregate Particle size Figure 2. Coarse Aggregate Particle size 2.4. Water to Cement Ratio One of the characteristics of plastic concrete is the high ratio of water to cement. This high ratio added to clay increase deformation and decrease permeability and compressive strength. In this study, the water to cement ratio was considered to be 0.75. 2.5. Mix Design Given that the aim of this research is to investigate the effect of adding two types of clay in different percentages, the volumetric method was used for the mix design of the prepared samples. The plastic concrete samples were grouped into two samples that include: A) Ceramic clay and B) Baghmesheh region clay. Table 4 shows the weight of the materials used in the mix design. Table 4. Mix Design Fine Aggregate (Kg/m3) Coarse Aggregate (Kg/m3) W/C Water (Kg/m3) Clay (Kg/m3) Cement (Kg/m3) Sample Name 1438.1 606.4 0.45 146.2 0 297.0 CL0 (Control) 1269.0 535.1 0.75 234.8 29.7 267.3 CLA10 1265.1 533.4 0.75 234.8 59.4 237.6 CLA20 1261.2 531.8 0.75 234.8 89.1 207.9 CLA30 1269.9 535.4 0.75 234.9 29.7 267.3 CLB10 1266.8 534.2 0.75 234.9 59.4 237.6 CLB20 1263.8 532.9 0.75 234.9 89.1 207.9 CLB30 0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 Passing percentage Particle size (mm) Fine Aggregate Particle size 0 10 20 30 40 50 60 70 80 90 100 0.001 0.01 0.1 1 10 100 Passing percentage Particle size (mm) Coarse Aggregate Particle size J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 81 2.6. CONSTRUCTION METHOD AND EXPERIMENTS 2.6.1. Plastic Concrete with Clay For the mix design of this research, the required clay was initially saturated in a portion of the mixing water for 24 hours. In the next step, coarse aggregate and one-third of the mixing water were added to the mixer, and mixing continued for 5 minutes. Then, cement and another one-third of the mixing water were added to the mixer, and the mixing operation was continued again for 5 minutes. In the following step, fine aggregate along with the remaining onethird of the mixing water were added to the mixer, and the mixing operation continued for 5 minutes. Finally, the clay was added to the mixer, and the mixing operation continued for 10 minutes. After 10 minutes, the samples were molded and kept at ±22°C temperature for 24 hours. 2.6.2. Curing of Samples Curing of specimens was done according to ASTM C192 (13) in the cure box. The water temperature in cure box was 20°C to 23°C. The samples were completely soaked in water. 2.7. Compressive Strength Test Compressive strength is one of the most important properties of hardened concrete for classification in international standards. This test is performed according to ASTM C39 (14) on 10x10x10 cm cubic samples as shown in Figure 3. The specimens were broken at 7 and 28 days. To obtain the compressive strength of the specimens, the maximum applied force is divided by the cross-sectional area of the sample. The Results were showed in Table 5. Figure 3. Compressive Strength Test on Samples 2.8. Tensile Strength Test This test, known as the splitting tensile strength of concrete or the Brazilian test and is performed according to ASTM C496 [15]. For the tensile strength test in this research, three cylindrical specimen with dimensions of 10x20 cm were used for each sample as shown in Figure 4. According to ASTM C496, the tensile strength of the specimen is calculated using Eqs. (1): 𝑇 = 2P 𝜋𝐿D (1) In which T is the tensile strength of the specimen in MPa, P is the compressive force in N, L is the length of the specimen in mm and D is the diameter of the cylindrical specimen in mm. Figure 4. Tensile Strength Test on Samples J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 82 2.9. Flexural Strength Test For the flexural strength test in this research, three prismatic beams with dimensions of 10x10x45 cm were used for each sample as shown in Figure 5. This test is performed according to ASTM C78[16]. Considering the static stability of the beam, pure bending exists in the middle third of the beam. If a newly formed crack on the tension surface is within the middle third of the span length, we use Eqs. (2): 𝑅 = PL 𝑏𝑑2 (2) In which R is the flexural strength of the specimen in MPa, P is the compressive force in N, L is the span length of the specimen, which is 390 mm, b is the width of the beam cross-section which is 100 mm and d is the height (depth) of the beam cross-section which is 100 mm. If the crack that occurs on the tension surface is outside the middle third of the span length but not more than 5 percent of the span length, the modulus of rupture is obtained from Eqs. (3): 𝑅 = 3PL 2𝑏𝑑2 (3) In which R is the flexural strength of the specimen in MPa, P is the compressive force in N, L is the span length of the specimen, which is 390 mm, b is the width of the beam cross-section which is 100 mm and d is the height (depth) of the beam cross-section which is 100 mm. The specimens were broken at 28 day and the Results were showed in Table 5. Figure 5. Flexural Strength Test on Samples 3. RESULTS AND DISCUSSION 3.1. Flexural Strength Referring to Figure 6, the analysis of the 28 day flexural strength test results on samples containing Ceramic clay and Baghmisheh region clay shows that with an increase in the amount of clay, the flexural strength of the samples has decreased compared to the CL0. The lowest flexural strength of Ceramic clay samples was related to CLA30 with value of 1.37 MPa, and the highest was related to CLA10 with value of 2.87 MPa. Furthermore, regarding samples of Baghmisheh region clay, the lowest flexural strength was related to CLB30 with value 1.11 MPa, and the highest was related to CLB10 with value 2.13 MPa. Compared to the CL0, the samples containing 10, 20, and 30 percent Ceramic clay showed a reduction in strength of 49.98%, 62.94%, 76.09%, and samples containing 10, 20, and 30 percent Baghmisheh region clay showed a reduction in strength of 62.84%, 74.84%, and 80.60%. In general, increasing the amount of clay leads to an increase in the proportion of a weaker phase, changes in the microstructure, and disruption of the cement hydration process, also it can weaken the structural integrity and internal cohesion of the concrete, consequently reducing its resistance to flexural strength of the samples. Table 5, shows the results of flexural strength. J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 83 Table 5. Flexural Strength Results 28 day (MPa) Sample Name 5.73 CL0 (Control) 2.87 CLA10 2.12 CLA20 1.37 CLA30 2.13 CLB10 1.44 CLB20 1.11 CLB30 Comparing the strength of samples containing Ceramic clay and Baghmisheh region clay, it has been observed that the strength of samples with Ceramic clay was higher than the strength of samples with Baghmisheh region clay. Specifically, samples with 10, 20, and 30 percent Baghmisheh region clay, a reduction of 25.71%, 32.11%, and 18.88% was observed compared to Ceramic clay samples. In summary, the difference in the flexural strength results of concrete samples containing Ceramic clay and Baghmisheh region clay is likely due to differences in their chemical and mineral composition, physical properties, pozzolanic reactivity, and plasticity characteristics. Figure 6. Result of Plastic Concrete Flexural Strength 3.2. Water Absorption Test Referring to Figure 7, the analysis of the 28 day water absorption test results on samples containing Ceramic clay and Baghmisheh region clay shows that with an increase in the amount of clay, the water absorption of the samples has increased compared to the CL0. The lowest water absorption of Ceramic clay samples was related to CLA10 with a value of 0.93%, and the highest was related to CLA30 with a value of 5.32%. Furthermore, regarding samples of Baghmisheh region clay, the lowest water absorption was related to CLB10 with value of 3.39%, and the highest was related to CLB30 with value of 6.02%. Therefore, increasing the percentage of clay, especially clay with high hydrophilicity, and in the absence of proper mixing and curing management, can lead to a significant increase in water absorption in concrete samples by increasing porosity, specific surface area, and creating more porous structures. This can negatively affect the durability and other long-term properties of the concrete. Table 6, shows the results of flexural strength. CL0 CLA10 CLA20 CLA30 CLB10 CLB20 CLB30 28 5.73 2.87 2.12 1.37 2.13 1.44 1.11 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 Flexural Strength (MPa) Flexural Strength Resualts 28 J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 84 Table 6. Water Absorption Results Water Absorption Sample Name 0.93% CL0 (Control) 3.28% CLA10 5.23% CLA20 5.32% CLA30 3.39% CLB10 5.72% CLB20 6.02% CLB30 Comparing the water absorption of samples containing Ceramic clay and Baghmisheh region clay, it has been observed that the water absorption of samples with Ceramic clay was lower than the water absorption of samples with Baghmisheh region clay. Specifically, samples with 10, 20, and 30 percent Baghmisheh region clay showed increases of 3.30%, 9.40%, and 13.08%, respectively, compared to the ceramic clay samples. In summary, the difference in the water absorption of concrete containing two different types of clay stems from variations in their mineral and chemical composition, physical properties (especially inherent water absorption capacity and specific surface area), and their impact on the microstructure of the concrete (particularly porosity and the interfacial transition zone). Figure 7. Result of Plastic Concrete Water Absorption 3.3. Permeability Test Referring to Figure 8, the analysis of the 28 day permeability test results on samples containing Ceramic clay and Baghmisheh region clay shows that with an increase in the amount of clay, the permeability coefficient of the samples has increased compared to the CL0. The lowest permeability coefficient of Ceramic clay samples was related to CLA10 with a value of 1.10E-08, and the highest was related to CLA30 with a value of 2.39E-08. Furthermore, regarding samples of Baghmisheh region clay, the lowest permeability coefficient was related to CLB10 with value of 1.71E-08, and the highest was related to CLB30 with value of 2.65E-08. Therefore, increasing the percentage of clay, especially clay with high hydrophilicity, and in the absence of proper mixing and curing management, can lead to a significant increase in permeability coefficient in concrete samples by increasing porosity, specific surface area, and creating more porous structures. This can CL0 CLA10 CLA20 CLA30 CLB10 CLB20 CLB30 Water Absorption 0.93% 3.28% 5.23% 5.32% 3.39% 5.72% 6.02% 0.00% 1.00% 2.00% 3.00% 4.00% 5.00% 6.00% 7.00% Water Absorption (%) Water Absorptio Results Water Absorption J. Civil Eng. Mater.App. 2025 (June); 9(2): 77-87 ························································································· 85 negatively affect the durability and other long-term properties of the concrete. Table 7, shows the results of permeability coefficient. Table 7. Permeability Coefficient Results Permeability Coefficient Sample Name 9.10E-10 CL0 (Control) 1.10E-08 CLA10 1.46E-08 CLA20 2.39E-08 CLA30 1.71E-08 CLB10 2.16E-08 CLB20 2.65E-08 CLB30 Comparing the permeability coefficient of samples containing Ceramic clay and Baghmisheh region clay, it has been observed that the permeability coefficient of samples with Ceramic clay was lower than the permeability coefficient of samples with Baghmisheh region clay. Specifically, samples with 10, 20, and 30 percent Baghmisheh region clay showed increases of 56.45%, 47.93%, and 10.70%, respectively, compared to the ceramic clay samples. In summary, the difference in the permeability coefficient of concrete containing two different types of clay stems from variations in their mineral and chemical composition, physical properties, and their impact on the microstructure of the concrete. Figure 8. Result of Plastic Concrete Permeability Coefficient CL0 CLA10 CLA20 CLA30 CLB10 CLB20 CLB30 Water Absorption 0.93% 3.28% 5.23% 5.32% 3.39% 5.72% 6.02% 0.00% 1.00% 2.00% 3.00% 4.00% 5.00% 6.00% 7.00% Water Absorption (%) Water Absorptio Results Water Absorption