# Performance Testing and Evaluation of Double-Layer Pervious Concrete Based on Recycled Aggregates

## TL;DR

This paper explores using recycled aggregates in double-layer pervious concrete to improve slope protection while balancing strength and water permeability.

## Contribution

The study introduces a double-layer pervious concrete system using recycled aggregates that optimizes both mechanical and hydraulic performance.

## Key findings

- A 45% recycled fine aggregate replacement ratio balances permeability and compressive strength in single-layer concrete.
- A paste-to-coarse aggregate ratio of 0.45 in double-layer concrete achieves optimal compressive strength and permeability.
- The double-layer system improves water retention and infiltration control for ecological slope protection.

## Abstract

A double-layer pervious concrete composite structure incorporating recycled fine aggregates derived from construction waste was developed to advance ecological slope protection performance. Single-factor experimental investigations on single-layer pervious concrete examined the effects of recycled fine aggregate replacement ratios (0–60%) and water–cement ratios (0.27–0.39) on material properties. The experimental results established 0.36 as the optimal water–cement ratio, while a 45% replacement ratio achieved an effective balance between permeability and compressive strength. Subsequently, parametric studies on double-layer composite concrete evaluated paste-to-coarse aggregate ratios ranging from 0.3 to 0.55. A paste-to-coarse aggregate ratio of 0.45 yielded optimal compressive strength while preserving favorable permeability characteristics, thereby achieving an effective balance between hydraulic and mechanical performance. Field tests of slope protection demonstrated that the double-layer configuration exhibited superior water retention capacity within the planting layer, while the fine particle layer effectively attenuated infiltration rates. Interlayer capillary mechanisms facilitated vertical moisture redistribution, ensuring equilibrated moisture distribution across soil strata. These findings provide a theoretical framework and experimental validation for implementing recycled fine aggregates in sustainable ecological slope protection engineering.