INVESTIGATION OF HIGH-STRENGTH FROST-RESISTANT CONCRETE.

This study was conducted to determine if reduction in air content by vibration of a well proportioned concrete mixture of relatively high cement content reduces the frost resistance of the hardened concrete and also to determine the effect of such reduction in air content on compressive strength. One 3/4-in. maximum-size crushed limestone aggregate concrete mixture was proportioned to have a compressive strength of approximately 5500 psi at 28 days age. The mixture had an air content of 8 plus or minus 1 percent. Various vibration times were used to reduce the air content until the damples had an air content as low as could be practically obtained. Specimens were cast for determining compressive strength, resistance to freezing and thawing, and air void parameters to evaluate the effect of reduction in air content of the concrete on strength and frost resistance.