A THEORETICAL APPROACH TO DESIGN OF A ROAD JOINT SEAL

THEORETICAL AND EXPERIMENTAL STUDIES WERE CONDUCTED ON: (1) THE JOINT WIDTH, (2) SEALED DEPTH, (3) JOINT EXPANSION, AND (4) THE EXTENSIBILITY OF THE SEALER. THE THEORY PRESENTED IS BASED ON MAXIMUM STRAIN CALCULATIONS IN THE SEALER DUE TO JOINT WIDTH VARIATIONS. A PROCEDURE IS OUTLINED FOR ESTIMATING TENSION STRAINS IN A HOMOGENEOUS LIQUID-TYPE SEALER USED FOR SEALING JOINTS AND CRACKS IN PAVEMENTS. CONCLUSIONS REACHED IN THE STUDY ARE: (1) LABORATORY TESTS INDICATE THAT IF HOMOGENEOUS LIQUID TYPE SEALER IS PLACED IN A RECTANGULAR JOINT AND SUBJECTED TO STRAIN, THE CURVE-IN SURFACE CLOSELY FOLLOWS A PAROBOLIC CURVE, (2) MAXIMUM STRAINS IN THE SEALER CAN BE CALCULATED BY USING PARABOLIC EQUATIONS AND RELATIONSHIPS, (3) CALCULATIONS SHOW THAT FOR LIKE CONDITIONS, THE GREATER THE MINIMUM WIDTH OF THE JOINT, THE LESS THE SEALER WILL BE STRAINED FOR THE SAME PERCENTAGE OF JOINT OPENING, (4) THE SHALLOWER THE JOINT IS SEALED, THE LESS THE SEALER WILL BE STRAINED WHEN THE JOINT OPENS, OTHER CONDITIONS BEING THE SAME, (5) LABORATORY OBSERVATIONS SHOW THAT IF A SEALER DOES NOT FOLLOW THE PARABOLIC CURVE-IN LINE CLOSELY AND APPEARS SOUND FROM THE OUTSIDE, INNER COHESION SEPARATIONS AND FORMATION OF AIR SPACES ARE TAKING PLACE, (6) THE PRESENT BOND-DUCTILITY TEST DOES NOT INDICATE THE ACTUAL STRAIN CAPABILITIES OF A SEALER, AND (7) A BOND-DUCTILITY TEST IN WHICH THE SEALER IS STRAINED TO FAILURE SHOULD BE A BETTER WAY TO EVALUATE THE MATERIAL.