USE OF MARSHALL STABILITY TEST IN ASPHALT PAVING MIX DESIGN
A CONTINUING PROBLEM IN THE DESIGN OF BITUMINOUS PAVEMENTS IS THE SPECIFICATION OF THE PROPERTIES OF THE MIX SO THAT IT WILL HAVE SUFFICIENT STABILITY TO RESIST DISPLACEMENT UNDER TRAFFIC. THIS PROBLEM HAS BEEN MADE MORE ACUTE BY THE DEMANDS OF HEAVIER WHEEL LOADS WHICH ARE ANTICIPATED FOR MODERN HIGHWAYS AND AIRFIELDS. THUS, TO AID MIX FORMULATION THERE IS A PRESSING NEED FOR SPECIFICATIONS IN TERMS OF THE RESULTS OF LABORATORY TESTS. AN ANALYSIS OF THE MARSHALL STABILITY TEST SHOWS THAT THE BEARING CAPACITY OF A PAVING MIX CAN BE RELATED TO MARSHALL STABILITY AND FLOW BY THE FOLLOWING EQUATION: BEARING CAPACITY (PSI) = 1/5 STABILITY / FLOW X(Z+K) F IN WHICH K=1 + SIN PHI /1-SIN SPHI AND F=(1-0. 055K). DERIVATION OF THIS EQUATION IS BASED ON TWO IMPORTANT ASSUMPTIONS: (1) ALLOWABLE DESIGN STRESS CORRESPONDS TO THE STRESS CALCULATED AT 1 PERCENT STRAIN IN THE MARSHALL TEST, (2) CONFINING PRESSURE IN THE PAVEMENT IS EQUAL TO 50 PERCENT OF UNCONFINED COMPRESSIVE STRENGTH (CONFINEMENT IS PROPORTIONAL TO LATERAL STRAIN. THIS IS 50 PERCENT OF VERTICAL STRAIN FOR MATERIALS THAT DO NOT CHANGE VOLUME). A CONVENIENT APPROXIMATION OF ABOVE EQUATION IS GIVEN BY BEARING CAPACITY (PSI) = STABILITY /FLOW X (120-FLOW) 100. THE DESIGN CURVES REPRESENTING THE ABOVE RELATIONSHIPS EMPHASIZE THAT THE LOAD-CARRYING ABILITY OF AN ASPHALTIC MIX IS A FUNCTION OF THE FLOW VALUE AS WELL AS THE STABILITY AND REVEAL THE INADEQUACY OF THE USUAL SPECIFICATIONS WHICH CALL FOR ONLY A MINIMUM STABILITY AND MAXIMUM FLOW VALUE. A SINGLE BEARING CAPACITY FOR ANY MIX CAN BE CALCULATED FROM THE COMBINATION OF STABILITY AND FLOW. MARSHALL STABILITY ALONE, HOWEVER, IS NOT AN ABSOLUTE MEASURE OF STRENGTH. IT IS BELIEVED THAT THE RESULTS OF THIS ANALYSIS WILL BE VERY USEFUL IN HIGHWAY AND AIRFIELD DESIGN. /AUTHOR/
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Supplemental Notes:
- No 234, pp 12-22, 10 FIG, 2 TAB, 15 REF Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
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Authors:
- Metcalf, C T
- Publication Date: 1959
Media Info
- Media Type: Digital/other
- Pagination: 11p
- Monograph Title: Performance and tests of asphaltic concrete
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Serial:
- Highway Research Board Bulletin
- Issue Number: 234
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Airports; Asphalt; Bearing capacity; Bituminous pavements; Compressive strength; Equations; Highway design; Laboratory tests; Marshall test; Mix design; Strain (Mechanics); Stresses; Wheel loads
- Old TRIS Terms: Marshall stability marshall stability & flow test flow; Strains
- Subject Areas: Aviation; Highways; Materials; Terminals and Facilities;
Filing Info
- Accession Number: 00211325
- Record Type: Publication
- Files: TRIS, TRB
- Created Date: Sep 9 1994 12:00AM