Influence of Recycled Aggregates on Mechanical and Permeability Properties of Pervious Concrete

Abstract

Objectives: This research seeks to compare the mechanical properties and permeability of recycled pervious concrete (RPC) to regular concrete, with particular focus on its suitability for sustainable urban infrastructure applications. Method: Three different aggregate sizes, fixed aggregate-to-cement ratio, fine aggregate inclusion, compressive strength, split tensile strength and permeability were evaluated using Multiple Linear Regression (MLR) and Artificial Neural Network (ANN) strength prediction models as means to gauge strength variation and accuracy. Concrete specimens were prepared following ASTM C192 guidelines, with aggregate-to-cement ratios between 3:1 and 7:1, and water-to-cement ratios ranging between 0.35 and 0.38. Cylindrical (100 mm x 200 mm) and cubic samples (15mmx150mmx150mm) from each curing cycle were tested for compressive strength, split tensile strength, and permeability after seven, fourteen, and 28-days curing using compressive strength tests, constant head permeability tests; MLR and ANN models were employed to predict strength properties and compare performance over time. Findings: RPC compression strength ranged from 6.8 MPa to 22.15 MPa, approximately 8-15% lower than conventional concrete under comparable conditions. Permeability increased significantly from 3.0 mm/s to 4.2 mm/s - 35%-50% higher than traditional pervious concrete, making this material perfect for stormwater management applications. Porosity values ranged between 15% and 25%, having an effect both on strength and permeability. An optimal equilibrium was reached at 20% porosity where compressive strength reached 20.04 MPa while permeability reached 3.8 mm/s. MLR models achieved an R2 value of 0.803 when it came to compressive strength prediction, while ANN models outshone them by having an MPE of 2.1% for compressive strength prediction and 1.2% for split tensile strength predictions respectively. Recycled aggregates helped RPC lower its carbon footprint by about 15% compared to regular concrete. Novelty: This research develops an innovative mix design strategy to systematically optimize strength-permeability tradeoffs for recycled pervious concrete (RPC), using a novel mix design approach. Unlike previous studies, it integrates life cycle analysis, carbon footprint reduction metrics and AI-based predictive modeling for better sustainability and performance evaluation. Additionally, its comprehensive experimental and statistical approaches yield new insight into optimizing RPC for urban applications like mitigating urban heat island effects and improving stormwater drainage. Keywords: Pervious Concrete, Recycled Aggregates, Mechanical Properties, Permeability, Sustainable Construction, Stormwater Management and Strength Prediction Models