CEMENT-TREATED BASES

CEMENT TREATED BASE /BTC/ CONSTRUCTION IN WASHINGTON STATE USES MOSTLY MANUFACTURED OR PROCESSED AGGREGATE. PLANT-MIX CONTROL OF AGGREGATE GRADATIONS IS OBTAINED USING SPECIFICATIONS FOR GRADING REQUIREMENTS FOR ROAD MIX AGGREGATES. FIELD INVESTIGATIONS ESTABLISHED THAT COMPRESSIVE STRENGTH OF THE CTB WAS HEAVILY DEPENDENT UPON ITS DENSITY. ALTHOUGH BATCH PLANTS ARE PERMITTED, MIXING IS GENERALLY ACCOMPLISHED IN CONTINUOUS TYPE PUG MULLS HAVING A CAPACITY IN THE ORDER OF 400 TONS PER HOUR. SPECIFICATIONS REQUIRE THAT THE CEMENT FLOW BE UNIFORM AND ACCURATE AND, AT ANY MOMENT, NOT LESS THAN 90 PERCENT OF THE DESIGN OR PLANNED AMOUNT. THIS SPECIFICATION REQUIREMENT IS MOST DIFFICULT TO OBTAIN. EXPERIENCE SHOWED THAT A CEMENT-TREATED BASE SECTION COULD NOT BE EXPECTED TO LAST WHEN IT HAD TO SERVE ON A FLOODED SUBBASE WHERE WATER WAS TRAPPED IN THE ROADWAY SECTION. THIS LED TO THE DISCOVERY OF THE NEED FOR EXTREMELY HIGH PERMEABILITY IN SHOULDER MATERIAL TO ALLOY LATERAL DRAINAGE OF WATER WHICH WOULD ACCUMULATE BENEATH PAVEMENTS. BENKELMAN BEAM DEFLECTION STUDIES WERE CONDUCTED THAT CTB WHICH WOULD DEFLECT IN EXCESS OF 0.012 IN. UNDER A 15,000 POUND AXLE LOAD WOULD BE SUBJECT TO EARLY DISTRESS. EXPERIENCE HAS SHOWN THAT CEMENT CONTENTS BELOW 4 PERCENT SHOULD NOT BE RECOMMENDED

  • Supplemental Notes:
    • Vol 41, No 12A, PP 38-43
  • Authors:
    • LeClerc, R V
  • Publication Date: 0

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  • Accession Number: 00231044
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 15 2004 2:41AM