WATER IN CUTBACK ASPHALT STABILIZATION OF SOIL

THE PRESENCE OF WATER DURING THE MIXING AND THE COMPACTION PHASES OF ASPHALT SOIL STABILIZATION HAS LONG BEEN RECOGNIZED AS AN IMPORTANT FACTOR. DURING MIXING, WATER FACILITATES THE EVEN DISTRIBUTION OF ASPHALT THROUGHOUT THE MASS. THE AMOUNT OF MOISTURE REQUIRED FOR THOROUGH DISTRIBUTION OF CUTBACK ASPHALT APPARENTLY INCREASES AS THE AMOUNT OF FINE MATERIAL IN THE SOIL INCREASES. DURING THE COMPACTION PHASE THE AMOUNT OF WATER BECOMES IMPORTANT MAINLY BECAUSE OF ITS EFFECT ON DENSITY. THE AMOUNT OF MOISTURE REQUIRED FOR MAXIMUM DENSITY OF THE SOIL-ASPHALT MIXTURE IS NOT THE SAME AS THAT FOR THE SOIL ALONE. THE DESIRABLE MOISTURE CONTENTS OF A SOIL-CUTBACK ASPHALT MIXTURE DURING MIXING AND DURING COMPACTION ARE MAJOR FACTORS THAT HAVE BEEN INVESTIGATED. A LITERATURE REVIEW INDICATES THAT THESE MOISTURE CONTENTS ARE CONTROVERSIAL, TO SAY THE LEAST. DIFFERENT CONCEPTS OF THE RELATION OF CUTBACK ASPHALT CONTENT TO WATER CONTENT USED VARY FROM THE BELIEF THAT 2 PERCENT CUTBACK ASPHALT REPLACES 1 PERCENT WATER, TO THE BELIEF THAT CUTBACK ASPHALT AND WATER HAVE AN EQUIVALENT LUBRICATION EFFECT ON SOIL GRAINS DURING COMPACTION. VARIOUS MIXTURES OF SOIL, CUTBACK ASPHALT AND WATER WERE STUDIED. ANALYSIS OF THE RESULTING DATA SHOWS THAT THE PERCENTAGE OF STRENGTH, MAXIMUM STANDARD PROCTOR DENSITY, MINIMUM STANDARD PROCTOR DENSITY, MINIMUM MOISTURE ABSORPTION DURING IMMERSION, AND MINIMUM SWELLING IS DIFFERENT FOR EACH PROPERTY MENTIONED. HOWEVER, A COMPROMISE MOISTURE CONTENT (CMC) FOR MIXING WAS FOUND AT WHICH THE VARIANCE OF THE AFOREMENTIONED PROPERTIES IS A MINIMUM. THE CMC WAS FOUND TO BE MOST ADVANTAGEOUSLY DETERMINED BY MINIMIZATION USING THE METHOD OF FIRST POWERS. THE CMC WAS ALSO FOUND TO OCCUR VERY NEAR THE MIXING MOISTURE CONTENT REQUIRED TO PRODUCE MAXIMUM STANDARD PROCTOR DENSITY OF THE SOIL-CUTBACK ASPHALT-WATER SYSTEM. /AUTHOR/