THE USE OF BUNA-LATEX S 213 FOR THE MODIFICATION OF BITUMINOUS MIXTURES

ON THE BASIS OF EXTENSIVE LABORATORY STUDIES FOR THE CHECKING OF THE SUITABILITY OF BUNA LATEX S 213 AS AN ADMIXTURE FOR BITUMEN AND BITUMINOUS MIXTURES, A LARGE NUMBER OF EXPERIMENTAL ROADS WERE LAID IN THE MAGDEBURG AREA. APPROXIMATELY 40000 T OF MODIFIED BITUMINOUS MIXTURES WERE APPLIED. BY MEANS OF THE ADDITION OF RUBBER IN LATEX FORM, THE PLASTICITY RANGE OF THE BITUMEN INCLUDING THE RESISTANCE TO HIGH AND LOW TEMPERATURES IS IMPROVED. THIS MAKES IT POSSIBLE IN BUILDING OPERATIONS TO PRODUCE BITUMINOUS MIXTURES OF THE REQUIRED QUALITY PROPERTIES, WITHOUT THE NEED FOR ORDERING SPECIALLY PREPARED BITUMENS. SLIGHT PROBLEMS IN LAYING BECAUSE OF INCREASED ADHESIVE POWER, ARE BALANCED BY THE QUICKER SETTING CAPABILITIES OF THE MODIFIED BITUMEN MIXTURES. THE CLOSURE TIME FOR INDIVIDUAL FINISHER LANES WHERE HALF THE WIDTH IS OBSTRUCTED OVER THE AREA OF LAYING ARE ALSO REDUCED AT HIGH AIR TEMPERATURES. THE REQUIRED COMPACTION TEMPERATURES OF 120 DEG TO 130 DEG C MUST BE ENSURED BY MEANS OF A TECHNICALLY PERFECTLY COORDINATED LAYING RHYTHM. FOR THIS REASON THE LAYING TIME FOR THE WEARING COURSES SHOULD BE RESTRICTED TO THE MONTHS OF JUNE, JULY AND AUGUST. THE OPERATING EXPERIMENTAL ROAD DISPLAY A LOW LEVEL OF MORTAR LOSS AT THE SURFACE (WEAR DUE TO CHEMICAL DE-ICING SALTS) AND A HIGH LEVEL OF PERMANENT ROUGHNESS ARISING FROM REDUCED AMOUNT OF SUBSEQUENT COMPACTION DURING THE SUMMER MONTHS. IT IS SHOWN THE AMOUNT OF REAL POSSIBILITIES HIGHWAY AUTHORITIES HAVE, FOR IMPROVING THE PROPERTIES OF THE ROAD STRUCTURE IN USE CONSIDERABLY, BY MEANS OF ADMIXTURES INTRODUCED TO THE MIXING PLANT. A PROBLEM WHICH STILL REMAINS TO BE CLARIFIED IN THE FIELD OF THE COMPACTION OF MODIFIED BITUMINOUS MIXTURES BY RUBBER ROLLERS IS TO ACHIEVE A SOLUTION, SO THAT THE MATERIALS SUPPLIED WILL HAVE A VOIDS CONTENT OF NOT LESS THAN 2.5%.