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

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.