Mechanical and vegetation performance of porous concrete with recycled aggregate in riparian buffer area

This study is to evaluate the potential application of porous concrete with recycled coarse aggregate (RA) in riparian buffer area from two aspects: mechanical behaviour and vegetation performance. The effect of curing duration, RA grading, water/cement ratio (W/C) and cement paste/RA ratio (CP/RA) on the porosity and strength of RA porous concrete were determined by effective porosity and compressive strength tests, followed with evaluating the durability by wetting-drying (W-D) cycle tests. The vegetation performance of the porous concrete was evaluated, and then a tank leaching test was carried out to investigate the absorption capacity for total nitrogen (T-N) and total phosphorus (T-P). The results show that the compressive strength strongly depends on the bonding capacity among RA grains and slightly depends on RA grading; CP/RA ratio has a greater effect on effective porosity than other variables since diluted cement paste is more liable to fill the pores in the concrete; the mass transport (MT) values when suffering different W-D regimes ranges from 0.98 to 2.36%, indicating that porous concrete can maintain the structural integrity. Porous concrete with the RA grading (20-25 mm) is more suitable for vegetation growth than other grading, and incorporating with plants exhibits a considerable removal efficiency for T-N and T-P in wastewater, with maximum values of 59.82% and 61.99%, respectively. In general, the porous concrete with RA investigated in this research can offer a prominent technical advantage when applied in riparian buffer zones considering its structural improvement and reducing environmental load.