This study investigates the permeability of concrete mixes composed of varying ratios of cement, gravel, and sand. The objective was to find the most permeable mixture while maintaining AASHTO specifications by testing different combinations of these materials.

            In this experiment, three different ratios were tested and compared to various pervious and standard concrete composites. Each of the tested ratios had a volume of 432 cubic inches. The ratios that were tested were formed by a volume percentage as follows: 50:50 cement to gravel, 50:45:5 cement to gravel to sand, and 50:35:15 cement to gravel to sand. For each mixture, the time was recorded for a gallon of water to fully pass through the slabs. The weight of each slab was measured before and after to see how much water was trapped by the concrete after the timer was stopped. The permeability of each sample was calculated using Darcy’s law.  

            In addition, a tensile test for each of the samples was run using a dog bone mold, poured separate from the original slabs. The results were converted from tensile to compressive strengths for trials 1-3 as follows: 4067 PSI, 11963 PSI, and 6961 PSI respectively.  

            The results of the test showed that the most permeable sample was the 50:50 ratio with an average permeability constant of , compared to the 50:45:5 which was   and 50:35:15 which was . The results show that a more permeable concrete contains less sand, as the sand fills the gaps between the concrete and gravel thus absorbing more water. 

            The findings of this study provide valuable insights between material proportions and concrete permeability, offering guidance for future concrete mix designs focused on preventing storm water flooding on roadways.