Process for manufacturing asphaltrubber blends

Claim 1

IN A PROCESS FOR PREPARING ASPHALT-RUBBER BLENDS FREE OF MINERAL AGGREGATE, SAID BLENDS BEING CHARACTERIZED BY GOOD DUCTILITY AND LOW TEMPERATURE PROPERTIES, THE IMPROVEMENT WHICH COMPRISES: MAINTAINING A MOLTEN ASPHALT SUPPLY BODY FOR RUBBERIZING AT TEMPERATURE BETWEEN 275* AND 375* F., THE ASPHALT IN SAID SUPPLY BODY HAVING SECOND FUROL VISCOSITY LESS THAN 100 AT SAID TEMPERATURE, CIRCULATING AN ASPHALTIC STREAM FROM SAID SUPPLY BODY THROUGH AN EXTERNAL MIXING ZONE WHEREIN ASPHALTIC SURFACE IS EXPOSED AND BACK TO SAID SUPPLY BODY, DURING THE CIRCULATING PERIOD ADDING AN AQUEOUS SUSPENSION OF RUBBER LATEX ON TO THE EXPOSED ASPHALTIC SURFACE IN SAID MIXING ZONE AT RATE BETWEEN 0.02 AND 0.5 GALLON PER MINUTE OF SUSPENSION PER SQUARE FOOT OF EXPOSED ASPHALT AREA IN SAID MIXING ZONE, SAID SUSPENSION HAVING SOLIDS CONCENTRACTIO FROM 15-50% OF RUBBER LATEX SELECTED FROM THE GROUP CONSISTING OF A BUTADIENE-STYRENE COPOLYMER RUBBER, NATURAL RUBBER, POLYISOBUTYLENE RUBBER, AND POLYBUTADIENE, TERMINATING LATEX ADDITION WHEN THE RESULTING ASPHALT-RUBBER BLEND CONTAINS BETWEEN 1 AND 3.5% RUBBER ON A WATER-FREE BASIS, AND CONTINUING MAINTENANCE OF TEMPERATURE BETWEEN 275* AND 375* F., IN SAID RESULTING ASPHALT-RUBBER BLEND AT LEAST UNTIL SUBSTANTIALLY ALL OF THE WATER HAS BEEN REMOVED THEREFROM.