Effect of vibration duration on strength and permeability of pervious concrete with recycled aggregate and low-carbon cements

This study investigates the effect of vibration duration on the porosity, permeability, and compressive strength of pervious concrete incorporating 50% recycled concrete aggregate. Mixtures were prepared with Portland cement (CEM I) and blended cement (CEM II), and compacted by tamping or table vibration for durations ranging from 10 to 60 s. A refined falling-head permeability test was developed, using a novel circumferential heat-shrink sealing to eliminate lateral flow and ensure axial water penetration. Pore structure and connectivity were characterized using optical microscopy and X-ray micro-computed tomography. Increasing vibration duration reduced porosity and permeability while enhancing compressive strength. An optimal compaction window of approximately 30 s, corresponding to a normalized vibration dose of 226, provided the best balance between hydraulic and structural performance. Micro-computed tomography confirmed a highly interconnected pore network and strong agreement with effective porosity, demonstrating the value of three-dimensional metrics in mix design. The results show that combining recycled aggregate with low-carbon blended cements can meet functional performance targets while reducing cradle-to-gate carbon dioxide emissions by up to 25%. These findings offer practical guidance on compaction regimes and testing protocols, supporting reproducible and sustainable applications of pervious concrete in pavement infrastructure.