THE USE OF BITUMINOUS MATERIAL AS A CORRECTIVE MEASURE FOR PUMPING CONCRETE PAVEMENTS

A STUDY OF THE MOISTURE CONTENTS OF THE SUBGRADE AT VARIOUS DEPTHS INDICATES A MAXIMUM IMMEDIATELY BENEATH THE PAVEMENTS AND A DECREASE WITH DEPTH, INDICATING THAT SURFACE WATER IS THE CHIEF SOURCE OF THE SUBGRADE MOISTURE THAT CAUSES PUMPING. THE USE OF TRANSFER DEVICES AT JOINTS AND OF GRANULAR SUBGRADES HAS BEEN FOUND MOST EFFECTIVE IN THE PREVENTION OF PUMPING. THE USE OF FRENCH DRAINS IN THE SHOULDER WAS NOT EFFECTIVE IN STOPPING PUMPING. AFTER EXPERIMENTING WITH VARIOUS SOIL-BITUMINOUS, PORTLAND CEMENT MIXTURES AND SEVERAL GRADES OF SEMISOLID ASPHALTS, IT WAS FOUND THAT AN OIL ASPHALT FILLER HAVING A PENETRATION OF 30 TO 45 AT 77 F WAS MOST SATISFACTORY FOR FILLING THE VOIDS UNDER PUMPING CONCRETE SLABS. THIS MATERIAL IS FORCED UNDER THE PAVEMENT BY MEANS OF THE HAND SPRAY EQUIPMENT OF A STANDARD BITUMINOUS DISTRIBUTOR THROUGH HOLES DRILLED IN THE PAVEMENT WITH A STANDARD JACKHAMMER AND DRILL. THE BITUMINOUS MATERIAL FORMS A TIGHT SEAL BENEATH THE PAVEMENT AND PREVENTS THE ENTRANCE OF SURFACE WATER; ITS STABILITY IS NOT AFFECTED BY MOISTURE FROM THE SUBGRADE. ALTHOUGH THE COSTS OF THE ASPHALT IS SOMEWHAT HIGHER THAN ANY OF THE VARIOUS SOIL-MIXTURES, A PORTION OF THIS COST DIFFERENTIAL IS EQUALIZED IN THE LABOR SAVED ON THE ASSEMBLING AND MIXING OF THE VARIOUS MATERIALS USED IN SLURRIES. /AUTHOR/