Concrete Composition and Its Effects on Properties and Performance

Concrete is a critical component for construction due to its strength in compression, low cost, and durability. The relative proportions of its components – coarse aggregate, fine aggregate, cement, air, water, and admixtures – determine its properties and thus suitability for a variety of applications. This research focused on creating a concrete mixture that exhibited high compressive strength and high permeability for potential applications as a low-cost and low-tech drinking water filter or a permeable surface for stormwater management. Concrete mixtures were made from a variety of ratios of standard Quikrete® concrete mix, pea gravel, and water, and placed in 100 mm (4") diameter molds and allowed to cure for one week to reach the 7-day strength as an indicator of ultimate strength. Various amounts of pea gravel were used to determine the ideal ratio for water flow through the porous cured concrete, while maintaining compressive strength. Cured samples were fully saturated and then the times to drain 200 mL of water were measured. The samples were allowed to air dry and tested for compressive strength using a hydraulic press. Results were largely inconclusive, but generally show that concrete mixture permeability is enhanced by higher water concentrations. It is hoped that the results of this research will allow for the development of a concrete for use in civil applications that can filter contaminants out of storm and groundwater.