Mitigating Drying Shrinkage in High-Strength Concrete Using Glass and Polypropylene Fibers with Diatomaceous Earth as Cement Substitute

Abstract In recent decades, the demand for high-strength concrete has surged due to its enhanced workability and durability. However, the high cement content in such concrete impacts its hardening properties, particularly causing drying shrinkage strain, which affects structural performance and durability. Adding fibers like glass and polypropylene can mitigate this drying shrinkage by improving tensile and flexural strength, ductility, and crack control. High cement content also raises environmental concerns, including increased CO2 emissions. Diatomaceous earth, an eco-friendly and cost-effective cement substitute, can address these issues. This study explores the effects of glass and polypropylene fibers on concrete drying shrinkage and the impact of diatomaceous earth. Concrete specimens (100 mm × 100 mm × 400 mm) with 0% and 10% diatomaceous earth and varying fiber contents (0%, 0.2%, 0.4%, 0.8%, 1%) were tested. Drying shrinkage data over 60 days were recorded using dial gauges. Results indicate that both types of fibers effectively reduce drying shrinkage, with glass fibers being more effective. Additionally, the usage of 10% diatomaceous earth also reduces drying shrinkage. A modified B4-Bazant model incorporating coefficients for diatomaceous earth (Kd), fiber type (Kf), and fiber volume (Kvf) was developed. Further research with different fiber proportions is recommended for more accurate modeling.