THE PERFORMANCE AND COST OF SEALS LAID ON WESTERN AUSTRALIA ROADS DURING THE PERIOD 1934-1958

A DETAILED ANALYSIS HAS BEEN MADE OF THE PERFORMANCE AND COST OF SEALS LAID ON RELATIVELY LIGHTLY TRAFFICKED ROADS IN WESTERN AUSTRALIA, DURING THE PERIOD 1934 TO 1958. MOST OF THE INFORMATION OBTAINED WAS FOR INITIAL SEALS (LAID ON NEWLY CONSTRUCTED OR RECONSTRUCTED ROADS). IN GENERAL, THESE WERE PLACED AS A STAGE CONSTRUCTION TREATMENT IN WHICH A PRIMER SAND SEAL WAS FOLLOWED AT AN INTERVAL OF 3 TO 18 MONTHS, EITHER BY ONE APPLICATION OF BITUMEN AND STONE (SINGLE SEAL) OR BY A DOUBLE APPLICATION OF BITUMEN AND STONE (DOUBLE SEAL). SOME INFORMATION WAS OBTAINED ON SINGLE RESEALS LAID IN THE PERIOD 1950 TO 1955. THE AVERAGE LIFE OF THE INITIAL SINGLE SEALS RANGED FROM SIX AND ONE-HALF YEARS (FOR SAND) TO 17 YEARS (FOR 3/4 TO 1/2 IN. STONE), THE LIFE INCREASING WITH THE SIZE OF THE COVER STONE USED. DOUBLE SEALING WITH A FIRST STONE APPLICATION SIZE OF 3/4 TO 1/2 IN. INCREASED THE AVERAGE LIFE, OVER THAT OF THE CORRESPONDING SINGLE SEAL, BY ONLY TWO YEARS. ENRICHMENT OF THE SINGLE SEALS (A FOG SPRAY OF DILUTED BITUMEN EMULSION APPLIED TOWARDS THE END OF THE EXPECTED LIFE) EXTENDED THEIR AVERAGE SERVICE PERIOD BY THREE YEARS. COST RATE DATA INDICATE THAT THE CHEAPEST INITIAL SEALING TREATMENT WAS A SINGLE SEAL, WITH EITHER 1/2 TO 3/8 IN, OR 3/8 TO 3/16 IN. SIZED STONE. SUBSEQUENT RESEALING OR ENRICHMENT TREATMENTS SIGNIFICANTLY REDUCE COST RATES. DOUBLE SEALS, WITH OR WITHOUT ADDITIONAL TREATMENT, WERE RELATIVELY COSTLY. SMALL BUT SIGNIFICANT DIFFERENCES IN PERFORMANCE WERE FOUND FOR INITIAL SEALS LAID WITH DIFFERENT TYPES OF CRUSHED ROCK AGGREGATES IN DIFFERENT CLIMATIC ZONES. THE AVERAGE TRAFFIC DENSITY FOR THE RETIRED SEALS RANGED FROM ABOUT 50 TO 600 VEH/DAY, AND BITUMENS FROM MANY DIFFERENT CRUDE SOURCES WERE USED DURING THE INITIAL SEAL LAYING PERIOD UNDER CONSIDERATION. NEITHER FACTOR APPEARS TO HAVE AFFECTED INITIAL SEAL LIFE. THE LIVES OF RESEALS WERE FOUND TO BE SIMILAR TO THOSE LAID IN VICTORIA ON MORE HEAVILY TRAFFICKED ROADS. /AUTHOR/

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  • Accession Number: 00210746
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 18 1994 12:00AM