Volume 5, Issue 2 (February 2008)
A Novel Approach to Characterize Entrained Air Content in Pervious Concrete
The current pervious concrete placed in cold climates generally contains air entrainment but, unlike traditional concrete, the evaluation of entrained air is not performed. This paper presents results from a study that characterized the entrained air voids in pervious concrete using a RapidAir system. The RapidAir system is an automatic device that determines the air void properties of hardened concrete according to ASTM C457, “Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete.” Two types of aggregates, i.e., crushed limestone and rounded river gravel (pea gravel), and two types of air entraining agents, i.e., natural and synthetic, were used. The air entrainment dosage rates varied from zero to double the manufacturer’s recommended dosage. Compressive strength, tensile strength, and freeze-thaw durability (ASTM C666A) of the pervious concrete were tested. The results show that use of air entrainment improves workability of pervious concrete, thus reducing the overall porosity and increasing unit weight of the pervious concrete. The strength and freeze-thaw durability also increases with the level of entrained air in pervious concrete.