Impact, Cause, and Remedies for Excessive Cracking in CRC Pavement

US Transportation Collection2009PDFTech ReportJohnston, DanSouth Dakota. Dept. of Transportation. Office of ResearchUnited States. Department of Transportation. Federal Highway AdministrationSouth Dakota. Dept. of Transportation. Office of ResearchSouth DakotaUnited StatesAsphalt concrete pavementsBindersCold weatherCores (Specimens)Low temperatureRheometersTension testsTransverse crackingCrackingPerformanceContinuously Reinforced Concrete Pavements (CRCP)PunchoutsSD2004-07-FFinal ReportNewer continuously reinforced concrete pavements (CRCP) in South Dakota have exhibited undesirable levels and types of transverse cracking. This poor performance was not expected under the current recommended design practices. Research was undertaken to identify design, construction and material issues that may be contributing to the undesirable cracking. After preliminary surveys of existing projects and analysis of the available Long Term Pavement Performance CRCP data, a systematic construction program was initiated whereby changes in design and materials were incorporated and monitored for any beneficial effects. Beneficial changes were incorporated into projects scheduled for construction the following year and new parameters modified to understand how critical the effects on the cracking behavior any given parameter was with minimum ambiguity. The results are a series of recommended changes in design, construction and materials yielding much more normal and desirable cracking patterns. They include using an optimized 1\ubd\u201d maximum coarse aggregate concrete mix, reducing steel content to 0.6% regardless of thickness, requiring a nominal steel depth of 3\ube\u201d for all new CRCP pavements, using a modified chair configuration providing more support near centerline to reduce steel settlement, increasing the minimum cement content to 512 lbs/yd3 with 112 lbs/ yd3 modified Class F fly ash, wetting down aggregate stockpiles the night before paving if temperatures above 80\ub0F are expected and increasing the curing compound application rate to 1.5 gal/125 ft2 .143