Evaluation of a Hybrid-Polymer Pervious Mortar and Optimization of Its Mix Design

The utilization of permeable pavement has notably increased in urban areas. However, the conventional bonding layer composed of ordinary mortar or coarse sand can lead to challenges such as easy-loosening and a pseudo-permeable effect. To tackle this problem, this study utilized a hybrid polymer additive (HPA) to develop a novel hybrid-polymer pervious mortar (HPPM). An orthogonal experiment with the Composite Scoring Method (CSM) was conducted to determine the optimal mix design for HPPM, and the effect of the HPA content water-to-binder (W/B) ratio on the mechanical and bonding properties was analyzed. The CSM result revealed that the HPA content presented a higher significant impact than the W/B ratio, and the optimal combination was B3A2 - HPA content of 6 % (B3) and W/B of 0.3 (A2). Under this optimal combination, HPPM was able to enhance the compressive strength, flexural strength, tensile bond strength, and workability compared with the pervious mortar without HPA. Simultaneously, this study revealed that HPPM exhibited a higher ratio of interconnect voids compared to ordinary mortar, and demonstrated HPPM was able to achieve a good permeable function. In addition, according to the life-cycle cost and eco-efficiency analysis, the cost of permeable pavement using HPPM was lower than that of ordinary mortar, while HPPM represented savings in resource consumption and in energy consumption. Consequently, these results demonstrated the feasibility of using HPPM as an eco-friendly alternative to mitigate the pseudo-permeable issue of permeable pavement.