Aggregate Freeze-Thaw Testing and D-Cracking Field Performance: 30 Years Later.

摘要

Premature deterioration of concrete pavement due to D-cracking has been a problem in Kansas since the 1930s. Kansas geology includes mineable limestone coarse aggregates with variable durability in the eastern portion of the state. Due to this variability and historically poor D-cracking field performance, the Kansas DOT initiated intensive identification and tracking of individual mined beds, as well as frequent durability testing during production in the 1980s. Dcracking field performance of concrete pavements containing limestone coarse aggregates was investigated in 2010- 2012. Results of this investigation indicate that the rate of D-cracking decreased, but the minimum rate of D-cracking presence in concrete pavements is more than 30%. In reaction to these results, KDOT implemented changes aimed at mitigating the risk of D-cracking. Implementation actions included increasing the number of freeze-thaw cycles for aggregate in concrete prisms from 300 to 660 cycles, freeze-thaw testing of all aggregate types (not just limestone) in concrete, focusing aggregate sampling at the point of concrete production, and including an acceptable field-performance history criterion for concrete aggregates. Ongoing research is being conducted to develop new methods to identify durable aggregates and faster testing techniques.