MAINTENANCE OF JOINTS IN CONCRETE PAVEMENTS AS RELATED TO THE PUMPING ACTION OF THE SLABS

THE CORRECTION OF PUMPING AT JOINTS IN CONCRETE PAVEMENTS, BY THE USE OF A SEMIFLUID SOIL-CEMENT MIXTURE FORCED UNDER THE SLAB WITH A MUDJACK IS DESCRIBED. THE SLURRY USED CONSISTED OF FOUR SACKS OF CEMENT PER CUBIC YARD OF TOPSOIL AND 50 TO 55% WATER. THE SPACING OF THE HOLES FOR ELIMINATION OF PUMPING AND CORRECTION OF FAULTING IS DISCUSSED. THE EQUIPMENT AND PERSONNEL REQUIRED IS GIVEN IN DETAIL. IN A STUDY OF THE DEFLECTIONS OF THE PAVEMENT UNDER MOVING LOADS, IT WAS NOTED THAT DEFLECTIONS INCREASED IMMEDIATELY AFTER FILLING THE VOIDS UNDER THE PAVEMENT WITH THE SOIL-CEMENT SLURRY AND THEN DECREASED AFTER A PERIOD OF TIME HAD ELAPSED. IT WAS FOUND THAT A FEW OF THE MUDJACKED SLABS RESUMED PUMPING AND THAT THE WORK HAD TO BE SUPPLEMENTED WITH JOINT AND CRACK WATER-PROOFING TO KEEP SURFACE WATER FROM REACHING THE SUBGRADE. ON PAVEMENTS THAT WERE CRACKED EXTENSIVELY, THE BEST METHOD OF WATERPROOFING JOINTS WAS BY THE USE OF A SUBSTANTIAL BITUMINOUS SURFACE OR UPPER DECK NOT LESS THAN 1-IN. IN THICKNESS. AFTER A STUDY OF DESIGN FEATURES FROM THE VIEWPOINT OF A MAINTENANCE ENGINEER, THE AUTHOR CONCLUDES THAT EXPANSION OR CONTRACTION JOINTS SHOULD NOT BE USED IN CONCRETE PAVEMENTS EXCEPT AT HIGHWAY INTERSECTIONS, BRIDGE ENDS OR OTHER LOCATIONS WHERE THE PAVEMENT ABUTTS A FIXED OBJECT. THE RELATION OF THE TYPE OF AGGREGATE TO THE CRACK INTERVAL IN CONCRETE PAVEMENTS IN WHICH NO JOINTS WERE PLACED IS DISCUSSED. /AUTHOR/