Comparison of gravimetric methods to measure regional porosity distribution in porous concrete pavement

Porous concrete pavement requires exact determination of the regional porosity distribution (RPD) to better understand its hydraulic conductivity, mechanical strength, and clogging behaviour. This paper comparatively assessed the accuracy of three gravimetric methods in the determination of RPD of porous concrete: the incremental gravimetric method (IGM), nondemoulding cutting-gravimetric method (NCGM), and demoulding cutting-gravimetric method (DCGM). Capillarity in IGM causes the decreased porosity of approximately 0.93% for the top region 15–0 mm from specimen surface and causes the increased porosity of approximately 0.86% for the bottom region 120–105 mm, but the porosity for six other regions is hardly influenced by capillarity. A distinct knockout-related error (approximately 2.5%) is found in the overall porosity measurement via DCGM without mould protection. Mould protection in NCGM nearly eliminates the impact of knockout. Hence, NCGM is recommended as the best method to accurately measure RPD.