Technical Report Documentation Page 1. Report No. FHWA/TX-05/0-4502-1 2. Government Accession No. 3. Recipient's Catalog No. 4. Title and Subtitle EFFECTIVENESS OF MINIMIZING REFLECTIVE CRACKING IN CEMENT-TREATED BASES BY MICROCRACKING 5. Report Date October 2004 6. Performing Organization Code 7. Author(s) Stephen Sebesta and Tom Scullion 8. Performing Organization Report No. Report 0-4502-1 10. Work Unit No. (TRAIS) 9. Performing Organization Name and Address Texas Transportation Institute The Texas A&M University System College Station, Texas 77843-3135 11. Contract or Grant No. Project 0-4502 13. Type of Report and Period Covered Technical Report: September 2002-August 2004 12. Sponsoring Agency Name and Address Texas Department of Transportation Research and Technology Implementation Office P. O. Box 5080 Austin, Texas 78763-5080 14. Sponsoring Agency Code 15. Supplementary Notes Project performed in cooperation with the Texas Department of Transportation and the Federal Highway Administration. Project Title: Microcracking Stabilized Bases During Construction to Minimize Shrinkage 16. Abstract This project focused on evaluating the effectiveness of the microcracking concept for reducing shrinkage cracking in cement-treated bases (CTB). Microcracking can be defined as the application of several vibratory roller passes to the cement treated base at a short curing stage, typically after 1 to 3 days, to create a fine network of cracks. In this project Texas Transportation Institute researchers monitored the performance of microcracking test sites on SH 47 and SH 16. Finally, the research team coordinated the construction and monitored the performance of controlled test sites constructed at Texas A&M’s Riverside Campus. Compared to moist curing alone, microcracking improved the performance of CTB by reducing the crack width and in some cases reducing the total crack length. Through these mechanisms, microcracking reduces the risk of reflective cracking through the surface layer. Microcracking did not cause pavement damage. The structural capacity of the CTB was not diminished, the strength of the material recovered, and surface damage did not occur. Microcracking with three passes of the same (or comparable tonnage) steel- wheel vibratory roller after 2 to 3 days cure, combined with a 3-day moist curing period, can be considered a valid method of reducing shrinkage-cracking problems in CTB. In this project microcracking was accomplished with the rollers vibrating at maximum amplitude and traveling at 2 to 3 mph. For maximum effectiveness, microcracking must be combined with a reduced strength mix design system. 17. Key Words Microcracking, Cement-Treated Base, Shrinkage Cracking, Reflective Cracking 18. Distribution Statement No restrictions. This document is available to the public through NTIS: National Technical Information Service Springfield, Virginia 22161 http://www.ntis.gov 19. Security Classif.(of this report) Unclassified 20. Security Classif.(of this page) Unclassified 21. No. of Pages 110 22. Price Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
EFFECTIVENESS OF MINIMIZING REFLECTIVE CRACKING IN CEMENT-TREATED BASES BY MICROCRACKING
May 19, 2023
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