S.O. Osuji

Concrete is one of the most widely used construction materials globally due to its high compressive strength, durability, and versatility. However, its inherent low tensile strength and brittle nature limit its performance under tensile and dynamic loading conditions. To overcome these limitations, fibre reinforcement has emerged as an effective technique for enhancing the mechanical and durability properties of concrete. This study examines the behaviour and performance of fibre-reinforced concrete, with particular emphasis on steel and synthetic fibres, which are among the most commonly used fibre types in modern construction. The study reviews the influence of fibre content, orientation, aspect ratio, and type on the mechanical properties of concrete, including strength, toughness, ductility, crack resistance, and residual load-bearing capacity. Findings indicate that the incorporation of fibres transforms concrete from a brittle material into a more ductile composite, thereby improving its structural performance and durability. Furthermore, the study highlights the growing application of Fiber-Reinforced Polymer (FRP) materials as alternatives to conventional steel reinforcement due to their lightweight nature, corrosion resistance, and enhanced toughness. The research concludes that fibre reinforcement significantly improves the overall performance of concrete and offers a promising solution for achieving more durable and resilient structures. It recommends further experimental investigations into the combined effects of different fibre types and mix designs to optimize the performance of fibre-reinforced concrete in various engineering applications.

This study examined the use of Crushed Concrete as a soil stabilizer to enhance the geotechnical properties of weak subgrade soils for road construction projects. The growing volume of construction waste and the environmental issues linked to traditional stabilizers such as cement and lime were key motivations for this research. The soil sample was mixed with varying amounts of CC i.e. at 6%, 12% and 18%. Laboratory tests were conducted and they include sieve analysis, Atterberg limits, compaction and CBR tests. The results were analyzed graphically using Microsoft Excel. The particle-size analysis categorized both the natural soil and the crushed concrete as fine sand to fine gravel. The Atterberg limits indicated that as CC content increased, both the liquid limit and plasticity index decreased, suggesting reduced cohesion and better workability. Compaction results revealed that the maximum dry density (MDD) increased from 1.85 g/cm³ at 0% to 1.92 g/cm³ at 12% CDW, while the optimum moisture content (OMC) decreased from 13.52% to 12.00%, indicating an improvement in compaction efficiency and a reduction in water demand. CBR results also showed significant increases in both soaked and unsoaked values with higher CC concentrations, which met the standards of the Federal Ministry of Works and Housing (FMWH, 2016). In summary, this study found that crushed concrete is a potent and environmentally sustainable soil stabilizer that can significantly strengthen and stabilize weak subgrade soils. It demonstrated that using CC can serve as a viable alternative to conventional stabilizers, reducing construction costs while promoting waste recycling. Further research is recommended to investigate the long-term durability and field performance of CDW- stabilized soils under traffic loads.