PROGRESS REPORT OF PROJECT COMMITTEE ON DISTORTION OF CONCRETE PAVEMENTS

DISTORTIONS ARE CAUSED BY THE UPLIFTING OF SLAB ENDS THROUGH SUBGRADE UPHEAVAL RESULTING FROM UNEQUAL SOIL MOISTURE DISTRIBTION AND NOT BY INTERNAL SLAB FORCES. SLABS PLACED ON DRY COMPACT CLAY SOILS (GENERALLY A 6 OR A 7) HAVE DISTORTED, WHILE ON REASONABLY MOIST CLAY OR ON SAND LOAMS, EXCEPT WHERE FROST IS A MAJOR FACTOR, THE SLABS HAVE NOT DISTORTED. DISTORTION MAY BE PREVENTED BY SUBGRADE TREATMENT TO INSURE MAINTENANCE OF UNIFORM MOISTURE CONTENT, BY TREATMENT TO CHANGE SUBGRADE CHARACTERISTICS SO MOISTURE EXPANSION IS PREVENTED, BY SELECTED SUBGRADE SOIL OR CONSTRUCTION FEATURES TO ELIMINATE MOISTURE ENTRANE INTO SUBGRADE. DISTORTED PAVEMENTS WERE LEVELLED BY MJD JACK AT REASONABLE COST IN TEXAS AND MISSOURI. /AUTHOR/