ASPHALTopics | Summer 2014 | VOL 27 | NO3

More documents

Recommendations

Info

occasions when the results for one or two labs cause the standard deviation to be very high. There are statistical tests that are applied and, if justified, one or two of the results could be removed as outliers and the results are re-analyzed. That has happened with some of the testing. The next thing to look at is the co-efficient of variation (COV). This is just the standard deviation divided by the mean and it gives an indication of the variability of the test procedure. A lower COV indicates that there is not much distribution of the results around the mean and is one way of looking at the acceptability of a test procedure. But if you’re writing a specification, you have to look at the d2s value. This is part of the precision statement that is included in almost all ASTM specifications. You look at that because you need to know how far apart the results could be from one another if identical samples are sent to two different approved laboratories. This is expressed in terms of the test units and is calculated by multiplying the COV by 2.8 and then by the mean value measured. The effect of doing this calculation is shown on the attached tables. Only the highlighted results have been included in the average d2s. What does this mean in terms of the results of something like the DENT test? The average value for the d2s since 2012 is 5.5 mm. That means if you sent a sample to a lab and received a result of 8 mm when the specified value was 10 mm, would you know that the result had failed? Not necessarily. If you sent the sample to another lab you could get 3 mm (likely the sample failed) or 13 mm (likely the sample did not fail) and that would be within the normal variability of the test. The typical way of dealing with this in a purchase specification is to allow for a tolerance. For instance, if the tolerance of 4 mm were selected, results down to 6 mm would be accepted but the supplier would be advised that the results were low and could be asked to respond. Between 4 mm and 6 mm would be a borderline zone where action might be taken by the agency; below 4 mm the material would be rejected. In the latter case there is no statistical evidence that would indicate that the sample might pass the specified value of 10 mm if sent to another lab. Fair purchase specifications are difficult to write without an understanding of the variability of the test and the degree of reliance that should be placed on a single test result. The precision section of a specification is the curriculum vitae of the test method. It provides validation for the test method and ensures that it can do what it purports – distinguish between materials that we expect to perform well and those that we expect won’t perform well. RESULTS OF MTO ROUND ROBIN TESTING · DENT d2s average value is 5.5 mm Standard Coefficient of d2S d2S Date Grade Labs Mean CTOD (mm) Deviation Variation (%) (mm) May 2014-1a 16 21.44 4.071 19.0% 53.2% 11.4 May 2014-1b 14 20.17 2.155 10.7% 30.0% 6.0 64-34 May 2014-2a 16 22.21 4.101 18.5% 51.8% 11.5 May 2014-2b 14 21.47 2.946 13.7% 38.4% 8.2 Nov 2013-1 15 4.58 1.303 28.4% 79.5% 3.6 70-28 Nov 2013-2 15 5.29 1.262 23.9% 66.9% 3.5 Jun 2013-1 15 6.61 1.454 22.0% 61.6% 4.1 58-34 Jun 2013-2 15 7.16 1.275 17.8% 49.8% 3.6 Dec 2012-1 14 14.44 2.991 20.7% 58.0% 8.4 Dec 2012-2a 46-34 14 13.52 5.988 44.3% 124.0% 16.8 Dec 2012-2b 14 15.60 2.370 15.2% 42.6% 6.6 Aug 2012-1 13 26.66 5.360 20.1% 56.3% 15.0 64-34 Aug 2012-2 13 27.42 8.335 30.4% 85.1% 23.3 RESULTS OF MTO ROUND ROBIN TESTING · ExBBR LTLG d2s average value is 3.9°C LTLG Standard Coefficient of d2S d2S Date Grade Labs (°C) Deviation Variation (%) (°C) May 2014-1 17 -32.95 0.698 -2.1% -5.9% 1.94 64-34 May 2014-2 17 -33.17 0.885 -2.6% -7.3% 2.41 Nov 2013-1 14 -18.73 7.074 -37.8% -105.8% 19.82 70-28 Nov 2013-2 14 -21.28 2.938 -13.8% -38.6% 8.22 Jun 2013-1 14 -25.21 1.929 -7.7% -21.6% 5.44 58-34 Jun 2013-2 14 -25.86 1.588 -6.1% -17.1% 4.42 Dec 2012-1 12 -34.54 1.392 -4.0% -11.2% 3.87 Dec 2012-2a 46-34 12 -34.61 1.676 -4.8% -13.4% 4.65 Dec 2012-2b 10 -34.98 1.156 -3.3% -9.2% 3.23 Aug 2012-1 13 -33.18 1.047 -3.2% -9.0% 2.97 64-34 Aug 2012-2 13 -33.58 0.785 -2.3% -6.4% 2.16 60 OHMPA | ASPHALTOPICS
RESULTS OF MTO ROUND ROBIN TESTING · ExBBR Loss d2s average value is 3.3°C Date Grade Labs Loss (°C) Standard Deviation Coefficient of Variation d2S (%) d2S (°C) May 2014-1 17 -2.83 0.746 -26.4% -73.9% 2.1 64-34 May 2014-2 17 -2.53 0.812 -32.1% -89.9% 2.3 Nov 2013-1a 14 -7.85 1.996 -25.4% -71.1% 5.6 Nov 2013-1b 70-28 11 -7.49 0.631 -8.4% -23.5% 1.8 Nov 2013-2 14 -6.78 1.684 -24.8% -69.4% 4.7 Jun 2013-1a 14 -7.25 4.944 -68.2% -191.0% 13.8 Jun 2013-1b 13 -8.48 1.835 -21.6% -60.5% 5.1 58-34 Jun 2013-2a 14 -7.17 4.847 -67.6% -189.3% 13.6 Jun 2013-2b 13 -7.82 1.331 -17.0% -47.6% 3.7 Dec 2012-1a 12 -2.54 2.743 -107.8% -301.8% 7.7 Dec 2012-1b 10 -2.81 0.715 -25.5% -71.4% 2.0 46-34 Dec 2012-2a 12 -2.75 2.703 -98.3% -275.2% 7.6 Dec 2012-2b 10 -2.89 0.951 -32.9% -92.1% 2.7 Aug 2012-1a 13 -1.37 3.343 -244.6% -684.9% 9.4 Aug 2012-1b 10 -3.00 0.956 -31.9% -89.3% 2.7 64-34 Aug 2012-2a 13 -1.54 3.303 -215.1% -602.3% 9.3 Aug 2012-2b 10 -2.25 2.173 -96.7% -270.8% 6.1 RESULTS OF MTO ROUND ROBIN TESTING · MSCR Jnr d2s average value is 0.20 kPa -1 Date Grade Labs Mean MSCR Jnr (kPa -1 ) Standard Deviation Coefficient of Variation d2S (%) d2S (kPa -1 ) May 2014-1 22 0.564 0.066 11.8% 33.0% 0.186 64-34 May 2014-2 22 0.579 0.063 10.9% 30.5% 0.177 Nov 2013-1a 20 0.068 0.027 39.3% 110.0% 0.075 Nov 2013-1b 18 0.061 0.012 20.0% 56.0% 0.034 70-28 Nov 2013-2a 20 0.069 0.026 38.2% 107.0% 0.074 Nov 2013-2b 18 0.062 0.012 18.7% 52.4% 0.032 Jun 2013-1a 19 0.540 0.142 26.4% 73.9% 0.399 Jun 2013-1b 18 0.566 0.088 15.6% 43.7% 0.247 58-34 Jun 2013-2a 19 0.539 0.145 26.9% 75.3% 0.406 Jun 2013-2b 18 0.565 0.093 16.4% 45.9% 0.259 Dec 2012-1a 19 3.730 1.233 33.0% 92.4% 3.447 Dec 2012-1b 16 4.050 0.319 7.9% 22.1% 0.896 46-34 Dec 2012-2a 19 3.740 1.153 30.9% 86.5% 3.236 Dec 2012-2b 16 4.100 0.310 7.6% 21.3% 0.872 Aug 2012-1a 19 0.890 0.543 60.9% 170.5% 1.518 Aug 2012-1b 16 0.760 0.100 13.1% 36.7% 0.279 64-34 Aug 2012-2a 19 0.890 0.553 62.0% 173.6% 1.545 Aug 2012-2b 16 0.750 0.105 13.9% 38.9% 0.292 RESULTS OF MTO ROUND ROBIN TESTING · MSCR % Recovery d2s average value is 8% Date Grade Labs Mean MSCR Recovery (%) Standard Deviation Coefficient of Variation d2S (%) d2S (% Rec) May 2014-1 22 58.27 3.986 6.8% 19.0% 11.1 64-34 May 2014-2 22 58.40 3.068 5.3% 14.8% 8.7 Nov 2013-1 20 86.90 2.280 2.6% 7.3% 6.3 Nov 2013-2a 70-28 20 86.79 2.551 2.9% 8.1% 7.0 Nov 2013-2b 20 87.15 2.003 2.3% 6.4% 5.6 Jun 2013-1a 19 54.59 13.031 23.9% 66.9% 36.5 Jun 2013-1b 16 57.17 2.781 4.9% 13.7% 7.8 58-34 Jun 2013-2a 19 54.90 12.372 22.5% 63.0% 34.6 Jun 2013-2b 16 57.21 3.474 6.1% 17.1% 9.8 Dec 2012-1a 19 5.28 17.140 324.5% 908.6% 48.0 Dec 2012-1b 18 1.84 2.087 113.2% 317.0% 5.8 46-34 Dec 2012-2a 19 5.36 17.329 323.3% 905.2% 48.5 Dec 2012-2b 18 1.88 2.317 123.5% 345.8% 6.5 Aug 2012-1 19 39.66 12.355 31.2% 87.4% 34.6 Aug 2012-2a 64-34 19 39.43 11.607 29.4% 82.3% 32.5 Aug 2012-2b 18 37.69 9.012 23.9% 66.9% 25.2 FALL 2014 61
Page 1:
FALL 2014 | VOL27 | NO3 th Annivers
Page 4 and 5:
WE DARE TO BE DIFFERENT, SO YOU CAN
Page 6 and 7:
Congratulations on 40 years of comm
Page 8 and 9:
WE KNOW THE ROAD. WE’VE BEEN ON I
Page 10 and 11: THE STRAIGHT GOODS 10 OHMPA | ASPHA
Page 12 and 13: For approximately 30 years, Vacuum
Page 14 and 15: that there was no real difference i
Page 16 and 17: 16 OHMPA | ASPHALTOPICS
Page 18 and 19: For the last 15 years, consumers ha
Page 20 and 21: “When you don’t have to stop fo
Page 22 and 23: An all-Canadian connected car is un
Page 24 and 25: Ladies on a paver. Undated photo fr
Page 26 and 27: 26 OHMPA | ASPHALTOPICS HMA plant f
Page 28 and 29: Multiple Stress Creep Recovery proc
Page 30 and 31: The MSCR test uses the creep and re
Page 32 and 33: 32 OHMPA | ASPHALTOPICS
Page 34 and 35: Only Astec has the patented Double
Page 36 and 37: Pennsylvania State Route 462 in Lan
Page 38 and 39: The Ohio Department of Transportati
Page 40 and 41: One of OHMPA’s most significant c
Page 42 and 43: 1987 1988 1989 1990 1991-92 1986 La
Page 44 and 45: 1998 1999 2000 2001 1998 Teri McKib
Page 46 and 47: 2007 2008 2009 2010 2011 2012 2013
Page 48 and 49: Asphalt Cement Specifications in On
Page 50 and 51: currently known. It has been adopte
Page 52 and 53: Special Profile Eddie DeToro, found
Page 54 and 55: 50 stability machines. Call, write,
Page 56 and 57: Albarrie’s Door Seals & Dryer/Dru
Page 58 and 59: The effect of polymer modification
Page 62 and 63: ENVIRONMENT COMMITTEE A commitment
Page 64 and 65: Why OHMPA? We asked some of our mem
Page 66: THE LAST WORD by Gerry Chaput Succe
show all

ASPHALTopics | Summer 2014 | VOL 27 | NO3

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?