Fracture performance study of polypropylene-enforced steel slag concrete

Abstract

Concrete, a widely used construction material is prone to cracking and fracturing under various stress conditions, making its fracture performance a critical aspect of structural integrity. The use of steel slag, a sustainable byproduct of steel production, promotes environmental sustainability in concrete by optimizing the industrial waste, thus reducing the landfill dependency and conserving natural resources. The addition of steel slag and polypropylene fibers has been extensively studied for their effects on the mechanical and durability properties of concrete, but their impact on fracture behavior remains largely unexplored. Concrete specimens with different percentages of steel slag and polypropylene fibers are subjected to three-point bending tests under monotonic loading conditions. This study investigates the influence of these additives on the fracture performance of concrete utilizing the Digital Image Correlation (DIC) technique. The fracture behavior of the modified concrete is analyzed using DIC, providing high-resolution surface displacement and strain fields along with the crack propagation patterns and development of the FPZ. Microstructural analysis using Scanning Electron Microscopy (SEM) assesses the fiber–matrix interactions and distribution of polypropylene and steel slag. The study reveals that polypropylene fiber addition in concrete up to 0.6% by volume fraction optimally enhances the fracture characteristics. Beyond this threshold, fracture energy and peak load decline due to excessive fiber content in the concrete. The combined use of 50% steel slag and 0.6% volume fraction of polypropylene fibers has a synergistic effect on enhancing the FPZ and improving the post-peak behavior. For polypropylene fiber mixes (0.6% by volume), FPZ fully develops at 70%–60% of peak load in the post-peak region, compared to 85%–90% in conventional concrete. In conclusion, integrating steel slag and polypropylene fibers into concrete demonstrates a commitment to sustainable construction practices and enhances structural performance and integrity, thus establishing a standard for environmentally resilient engineering solutions.