Analysis of the Influence of Polypropylene Fiber Addition on Permeable Concrete

Abstract

Objective – This study aims to investigate the influence of polypropylene fiber addition on the mechanical and functional properties of permeable concretes containing 10% silica fume, assessing their potential for application in sustainable urban pavements. To this end, the effects of incorporating different fiber contents (1, 2, 3, and 4 kg/m³) on permeability, void content, and mechanical strengths (axial compression, splitting tensile strength, and flexural tensile strength) were evaluated. Furthermore, variations in the modulus of elasticity and post-peak deformation capacity were analyzed, comparing the results with a reference mixture to determine the feasibility of using these compositions in urban infrastructure.

Methodology – The study was conducted in a laboratory setting following an experimental approach to assess the effects of polypropylene fiber addition in permeable concretes containing 10% silica fume. Initially, the constituent materials were selected, including Portland cement, aggregates, silica fume, and polypropylene fibers. The mixtures were prepared with varying fiber contents (1, 2, 3, and 4 kg/m³), along with a reference mixture without fibers for comparison. Specimens were cast and subjected to tests to determine their physical and mechanical properties. Bulk density, permeability, and void content were evaluated to characterize the porous structure of the concrete. Mechanical strength was analyzed through axial compression, splitting tensile, and flexural tensile strength tests. The modulus of elasticity and post-peak deformation capacity were also investigated to understand the structural behavior of the samples. The results were compared among the different mixtures, allowing an assessment of the influence of fiber incorporation on the mechanical strength and functionality of permeable concrete. The findings contribute to the development of more sustainable and durable urban pavements.

Originality/Relevance – The rapid urbanization process has exacerbated issues such as soil impermeabilization, increased stormwater runoff, and the urban heat island effect, necessitating sustainable solutions for urban drainage. In Brazil, urban drainage prioritizes hydraulic efficiency, often at the expense of environmental impacts. Permeable concrete emerges as a viable alternative, as it reduces surface runoff and improves water quality. However, its high porosity compromises mechanical strength, limiting its application in traffic areas. Recent studies have explored modifications in cementitious composites to address this limitation, such as the use of silica fume and polymeric fibers. Nevertheless, there is a gap in the literature regarding the impact of polypropylene fiber incorporation in permeable concretes containing silica fume, particularly in relation to the balance between permeability, mechanical strength, and post-cracking behavior. This study contributes to advancing knowledge by investigating different dosages of polypropylene fibers (1, 2, 3, and 4 kg/m³) in permeable concretes with 10% cement replacement by silica fume, evaluating their influence on mechanical and functional performance. The results may support the development of stronger and more durable concretes, expanding their practical application in sustainable urban infrastructure.

Results – The results demonstrated that the addition of polypropylene fibers significantly influenced the physical and mechanical properties of permeable concrete. The incorporation of fibers reduced bulk density while increasing permeability and void content, indicating greater pore connectivity. In mechanical tests, axial compressive strength and splitting tensile strength did not exhibit significant variations among different fiber dosages. However, flexural tensile strength increased with the addition of 1 kg/m³ of fibers, suggesting a positive effect on the concrete's ability to withstand bending stresses. For higher fiber dosages (2, 3, and 4 kg/m³), a slight reduction in flexural strength was observed, possibly due to increased porosity and difficulties in achieving homogeneous fiber dispersion within the cementitious matrix.

Theoretical/Methodological Contributions – This study contributes to the scientific literature by deepening the understanding of the impact of polypropylene fiber addition in permeable concretes modified with silica fume. The detailed analysis of the material's physical and mechanical properties, particularly concerning permeability, flexural strength, and modulus of elasticity, fills a research gap regarding the structural viability of this type of concrete for urban infrastructure applications. From a methodological perspective, the research stands out for its systematic experimental approach, evaluating different fiber contents (1, 2, 3, and 4 kg/m³) and comparing their effects on the porous structure and mechanical behavior of permeable concrete. The combined use of strength tests, modulus of elasticity assessment, and post-peak deformation capacity analysis provides a more comprehensive understanding of fiber-matrix interactions, enabling a more precise determination of optimal reinforcement conditions. Additionally, the results of this study offer a methodological foundation for future research aimed at optimizing permeable concretes with polymeric reinforcements, contributing to the development of more efficient and sustainable materials for the construction sector.

Social and Environmental Contributions – The use of permeable concrete with polypropylene fibers contributes to urban sustainability by reducing surface runoff, aiding in flood control, and enhancing groundwater recharge. Additionally, its application can mitigate the urban heat island effect, promoting improved thermal comfort. Socially, the adoption of this material supports the development of more resilient cities, reducing the need for conventional drainage infrastructure and its associated maintenance costs. This study fosters the advancement of sustainable construction technologies aligned with sustainability principles.