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Asphalt Compaction: coverage versus compaction value measurement

Better roads - Highway contractor 25

This is a very intersting article in the magazine Better Roads by Dan Brown. It is clearly stated that according to the research there is not a strong correlation between measured stiffness (with IC) and density. Another clear statement is on the value of pass counting or coverage measurement for asphalt compaction. It is quite intersting that different compactor manufacturers have completely different opinions on coverage versus compaction value measurement.

dshelstad 28.08.2012 23 2028
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  •  jhedderich: 
    Recently at the TRB session on Intelligent Compaction,
    Lee Gallivan was very clear that the development thus far is a Quality Control tool and NOT Quality Assurance.
    This is due to the fact that there is not correlation from the accelerometer data generated by the roller to density. Some comparisons to stiffness measurements have been made on the compaction of soils, but no one can relate the stiffness numbers from rollers to asphalt density.

    Other issues exist in even coming to any acceptable standard due to the fact that each roller manufacturer provides a diffferent measurement. In addition the vatriations in rollers must also be considered. The frequency, amplitude, unsprung weight of the drum, the eccentric weight and its relative position, down to the way the roller drum is shock mounted and even their relative condition will effect the results.

    Several customers have already show interest in our system for pass counting during this show at TRB.
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  •  sunyuyuan: 
    No, we do not have such publicly funded research project.
    0 points
  •  jutta: 
    Hello Yuyuan Sun, Are there also publicly funded research projects like in the US?
    0 points
  •  sunyuyuan: 
    In China IC is also a trend, just takes time like 3D.
    last year Trimble IC system (with GPS) was tested on a railway foundation layer, total 76.94KM.
    The result is like this:

    layers without IC (Qualified %) with IC (Qualified %)

    1st 94% 98%

    2nd 96% 99%

    3rd 95% 100%

    4th 94% 97%

    5th 93% 99%

    6th 96% 99%

    Average % 94.67% 98.77%

    labor cost contrast: without IC with IC

    (day pay Yuan) people numbers (day pay Yuan) people numbers

    Foundation indexK30,Ev2,Evd

    150 4.2

    150 4

    CMV indexK, Hole

    150 6.3
    150 6

    total Yuan 1575 1500

    labor cast saving 5%

    Moba China is convincing roller OEMs like Sany, Xuzhou to install our pass counting system, we tested it with SANY roller, generaly works fine, they will show it at shanghai Bauma show.
    I think it is good to have some figures like trimble did, if moba Germany already have, please inform us.
    if moba China have the chance to do it, we will inform you and share the numbers.
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  •  bmarx: 
    Each different roller needs its own calibration. This is fact. Measuring the stiffness allows you at least to stop compaction when additional passes could not improve the density and when they are only good to damage roller and material.
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