The effectiveness of the fly-ash slurry injection method to eliminate depressed transverse cracks.

1124905316329101Final reportPDFTech ReportFHWA-KS-07-6Asphalt pavementsFly ashSlurryTransverse crackingKansasKansas. Dept. of TransportationFelker, VictoriaParcells Jr, William H.Kansas. Dept. of TransportationNTL-HIGHWAY/ROAD TRANSPORTATION-Construction and MaintenanceNTL-HIGHWAY/ROAD TRANSPORTATION-DesignNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceUS Transportation CollectionOne of the primary causes of increasing roughness in asphalt pavements in Kansas has been naturally occurring transverse cracks. Maintenance forces continually tried to seal the cracks; however, the cracks continued to grow wider and the depressions deeper. A review of the history of transverse cracking on I-70 in the western half of Kansas reveals that very wide cracks (top down) developed in cold weather and no suitable treatments were available from the 1960s through the 1980s. It was common to have cracks about 60 ft apart, 4 to 5 in. wide, depressed 2 to 3 in. and extended across all lanes. In this study, the nature and extent of transverse cracking in asphalt pavements on I-70 in Kansas was determined. A pavement investigation was conducted to determine the effectiveness of the Fly Ash Slurry Injection (FASI) method (a crack stabilization procedure) to eliminate or minimize the depression (bump) caused by the depressed pavement on both sides of the transverse cracks. The intent of the FASI was to fill the subsurface voids at severely distressed transverse cracks to delay depression and reflective cracking, because the pavements were structurally sufficient for the traffic loading. The initial objective of the study was to find a low-cost "maintenance" approach to improve ride by filling the transverse cracks and their associated depression. A variety of products and application procedures were attempted, with variable results. Most attempts re-cracked within a year, and depression soon followed