Based on visual examinations, petrographic evaluation, and an application of materials models, the deterioration of concrete highway pavements in Iowa appears to be related to a freeze-thaw failure of the coarse aggregate and the mortar. Surface cracks traceable into the coarse aggregate, cracking of coarse aggregate and crack patterns sub-parallel to the concrete surface transecting the mortar fraction and the coarse aggregate are indicative of freeze-thaw damage of these constituents.
The entrained air void system was marginal to substandard, according to recommendations provided in ACI 201. Filling of the finer-sized (< 125 µm) entrained air voids further degraded the air void system. The filling approaches up to 2 % by volume resulting in an increase in void spacing factor and decrease in specific surface values generally in excess of those considered necessary for freeze-thaw exposure.