Investigating The Effect of Replacing Diatomite Powder with Quartz Powder on The Mechanical Properties of Reactive Powder Concrete

Reactive Powder Concrete (RPC) is recognized as one of the most innovative types of concrete, notable for its exceptional strength and durability. This type of concrete is composed of essential components such as cement, silica fume, quartz powder, silica sand, superplasticizer, and water. Due to its superior mechanical properties, RPC is widely utilized in specialized projects and structures that require outstanding strength and durability. However, the high cost of its components, particularly quartz powder, significantly increases the overall production cost, limiting its widespread application in larger, cost-sensitive projects. Quartz powder is scarce in the Azerbaijan region of Iran and is often sourced from mines in Hamedan and Isfahan. By replacing it with more locally available, affordable materials, final production costs can be reduced. To address this issue and optimize the use of available resources, the possibility of substituting quartz powder with local, cheaper, and more accessible materials has been explored. Micronized quartz powder is crystalline, though some of its finer particles have a minor pozzolanic effect. In contrast, diatomite powder, which contains both amorphous and crystalline particles with a high percentage of amorphous silica, exhibits significantly greater pozzolanic activity. These enhanced reactions contribute to the formation of a denser and stronger concrete matrix, improving its mechanical properties. The purpose of this study was to investigate the feasibility of replacing quartz powder with diatomite powder in different proportions—specifically 25%, 50%, 75%, and 100%. The goal was to evaluate how this substitution affects the concrete's strength while also reducing overall production costs. In this research, concrete samples were tested at various curing ages, including 7, 14, and 28 days. Mechanical tests such as compressive strength and tensile strength were conducted to assess the effects of the substitution on the concrete's performance. Additionally, parameters such as standard water absorption, water absorption during curing, density, and consistency were measured. To simulate real-world construction conditions and avoid the use of specialized equipment, the samples were cured in a water tank at 25°C. This curing method not only eliminated the need for expensive equipment like autoclaves but also made the concrete more applicable to typical site conditions, further lowering production costs. The test results were promising. The strength of the modified concrete mixtures improved significantly when diatomite powder replaced quartz powder. In samples where 100% of the quartz powder was substituted with diatomite, the compressive strength increased from 543 MPa to 806 MPa (approximately 49%), and the tensile strength increased from 543 MPa to 806 MPa (approximately 18%) at 28 days. In addition to the improvements in mechanical properties, the use of diatomite powder offers significant economic advantages. Diatomite is abundantly available in various regions, and its accessibility reduces both production and transportation costs. As a result, the overall production cost of the concrete is significantly lowered, which is especially beneficial for large-scale construction projects where cost efficiency is critical. In conclusion, replacing quartz powder with diatomite powder is a practical solution that brings both technical and economic benefits. The enhanced strength of the concrete, coupled with reduced production costs and the efficient utilization of local resources, makes this approach a practical and effective method for producing high-performance concrete.