OAPA

1. OAPA 2007 ANNUAL CONFERENCE WHEN TO WORRY ABOUT TEST RESULTS Danny Gierhart, P.E. ODOT Bituminous Engineer

2. ANSWER: ALWAYS! (However, you need to worry about some more than others)

4. Test results are often used to document the degree out of specification so that a corresponding financial penalty can be assessed. The very best use of test results is to track the ongoing quality of a project and make corrections as necessary to ensure a quality pavement.

6. 1.15 ASPHALT BINDER TEST – DYNAMIC SHEAR RHEOMETER (DSR)

7. ASPHALT BINDER TEST – DYNAMIC SHEAR RHEOMETER (DSR) The purpose of the test is to address potential rutting due to binder stiffness. Typical failing DSR tests reveal increased rutting and/or cracking potential. from negligible up to an average of 1/4”. They can also indicate whether or not the binder has sufficient polymer.

8. ASPHALT BINDER TEST – DYNAMIC SHEAR RHEOMETER (DSR) A typical failing DSR test indicates relatively minor problems. Large deviations can indicate significant problems. DSR tests that are slightly low (running 0.90 to 0.99) are minor. Tests that are ½ the target indicate a lower grade of binder was sampled.

9. 1.15 20 - 100 22 77 ASPHALT EMULSION TEST – SAYBOLT-FUROL VISCOSITY

10. ASPHALT EMULSION TEST – SAYBOLT-FUROL VISCOSITY The purpose of the test is to show the as-delivered viscosity, or fluidity of the material. Failing tack coat results will often be on the low side, indicating a deficiency of residual asphalt. This could cause slippage between lifts. For chip seal emulsions, a low value could mean that aggregate particles will not stick well. Results on the high side may be caused by an old sample.

11. Slippage between lifts as a result of insufficient adhesion.

12. ASPHALT EMULSION TEST – SAYBOLT-FUROL VISCOSITY Failing viscosity tests that are an accurate indicator of low residual asphalt content can, under the right circumstances, have serious ramifications. Field application has a significant effect on performance. It is very difficult to establish how big the problem is based on test results alone.

13. RED FLAG ALERT!

14. 30 - 60 45 ASPHALT CUTBACK TEST – KINEMATIC VISCOSITY

15. ASPHALT CUTBACK TEST – KINEMATIC VISCOSITY This test also shows the as-delivered viscosity, or fluidity of the material. It tells the supplier about the uniformity of shipments. Low test results indicate a higher ratio of diluent to asphalt cement. The prime may not provide the moisture barrier intended. High test results indicate a lower ratio of diluent to asphalt cement.

16. ASPHALT CUTBACK TEST – KINEMATIC VISCOSITY Failing viscosity tests have a minimal effect on the quality of prime. For example, both MC-30 and MC-70 are acceptable for use as prime coat. An out-of-spec high MC-30 may meet or be low for MC-70. Out-of-spec on the high side should not have a major effect. Tests for MC-30 that are significantly low will likely result in an ineffective moisture barrier.

17. AGGREGATE TEST - GRADATION Comparison

18. Comparison

19. Comparison

20. AGGREGATE TEST – GRADATION (Max. Agg. Size) The maximum aggregate size influences allowable pavement thickness, susceptibility to segregation, asphalt content, and volumetric requirements. A gradation on the maximum sieve size that is less than 100% indicates the presence of over-sized particles. This could result in compaction difficulties, segregation, and asphalt content problems.

21. AGGREGATE TEST – GRADATION (Max. Agg. Size) Gradations results showing less that 100% passing the maximum sieve size are rare and usually only slightly less than 100%. Potential ramifications are minimal. Results deviating by 10% or more indicate that a different type of HMA was sampled than expected.

22. Comparison

23. AGGREGATE TEST – GRADATION (% Passing # 200) The % passing the # 200 sieve influences compaction, asphalt content, and volumetric requirements. A low % passing the # 200 may result in high air voids, permeability, and a lower AC demand. A high value may result in low air voids and VMA, a higher AC demand, and a tender mix.

24. Check cracking as a result of a high % passing the #200 sieve combined with a low binder content

25. High % passing the #200 gives the HMA a lighter appearance, indicating a lower film thickness and lower durability.

26. AGGREGATE TEST – GRADATION (% Passing # 200) High dust portions can have major ramifications on the longevity of a roadway. They are typically accompanied by lower than necessary binder contents which reduce pavement durability. Deviations inside the tolerance of 2% typically don’t have too much of an effect. Deviations greater than 2% should be addressed immediately.

27. Comparison

28. AGGREGATE TEST – GRADATION (% Passing # 8) The % passing the # 8 sieve has a major influence on voids and permeability. A low % passing the # 8 sieve may result in a permeable mix. A high value is not as worrisome as a low value.

29. Low % passing the # 8 indicates a mix that is subject to permeability, which in turn can lead to stripping.

30. AGGREGATE TEST – GRADATION (% Passing # 8) A low % passing the # 8 sieve can have major ramifications on the longevity of a roadway. They are often accompanied by permeability issues which can lead to stripping. Gradations near the lower broad band are especially of concern when accompanied by a low % passing the # 200 sieve.

31. AGGREGATE TEST – SAND EQUIVALENT

32. AGGREGATE TEST – SAND EQUIVALENT The test is intended to show the relative proportions of fine dust or clay-like material in the aggregate. A low sand equivalent result indicates a high percentage by volume of clay-like fines. These fines may cause the asphalt binder to debond from the aggregate in the presence of moisture.

33. Low sand equivalents indicate a high percentage of clay-like fines, which can cause a poor bond with the asphalt binder.

34. AGGREGATE TEST – SAND EQUIVALENT Although extremely rare, a failing sand equivalent test indicates a very poor aggregate quality, which can have major ramifications to the longevity of the pavement. Sand equivalent results do not have to be much out of spec to be a cause for concern.

35. HOT MIX ASPHALT TEST – TENSILE STRENGTH RATIO

36. HOT MIX ASPHALT TEST – TENSILE STRENGTH RATIO The test is intended to show the susceptibility of the HMA to moisture damage. A failing TSR indicates the mix is inherently susceptible to stripping and raveling.

37. Tensile Strength Ratio AASHTO T 283 • Moisture Sensitivity • Prepare set of 6 specimens • 6.5 to 7.5% voids • Represents anticipated in-service voids • Use 3 specimens as controls • Remaining 3 specimens are vacuum saturated 70 to 80% • Min. 16 hour freezing at 0oF • 24 Hours in 140oF water bath • Bring all specimens to test temperature (77oF) and determine indirect tensile strength

38. Tensile Strength Ratio AASHTO T 283 Saturating Specimens Freezing Specimens Specimens in Hot Water Bath

39. Avg. wet tensile strength TSR = Avg. dry tensile strength Moisture SensitivityAASHTO T 283 Determine the indirect tensile strengths of both sets of 3 specimens Calculate the Tensile Strength Ratio (TSR) Minimum of 75% required for field tests

40. HOT MIX ASPHALT TEST – TENSILE STRENGTH RATIO The ramifications of a failing TSR can be severe. Because the test procedure is not one of the most repeatable, results down to around 70% should be confirmed by further testing. TSR results less than 65% would be just cause for immediate work stoppage to investigate and fix the problem.

41. HOT MIX ASPHALT TEST – ASPHALT BINDER CONTENT Result JMF Comparison

42. HOT MIX ASPHALT TEST – ASPHALT BINDER CONTENT The test shows the percent of asphalt binder by weight of the total mix. A low binder content can lead to premature aging of the pavement, stripping, or raveling. A high binder content can lead to flushing or bleeding in the pavement.

43. Low binder contents can lead to raveling, stripping, and premature aging.

44. High binder contents can lead to flushing or bleeding.

45. HOT MIX ASPHALT TEST – ASPHALT BINDER CONTENT The ramifications would likely be different depending on the degree out of spec. Whether any of the potential pavement distresses occur also depend on other factors. Binder content is one of several parameters that affect each other. However, binder contents very far out of spec should be a major cause for concern.

46. HOT MIX ASPHALT TEST – AIR VOID CONTENT Specimen 1 Specimen 2 Average

47. HOT MIX ASPHALT TEST – AIR VOID CONTENT The test shows the percent air voids in lab-molded specimens. This test indicates a mix property, not in-place air voids. With a low air void content, the pavement is susceptible to rutting, flushing, and bleeding. For high air void contents, the pavement is susceptible to premature aging, raveling, and stripping.

48. HOT MIX ASPHALT TEST – AIR VOID CONTENT The ramifications can be severe depending on the degree out of specification. Whether any of the potential pavement distresses occur also depend on other factors. All failing void contents need some type of action. Mixes that are 1% or more out of spec indicate a need for immediate shutdown for more trials.

49. HOT MIX ASPHALT TEST – VOIDS IN MINERAL AGGREGATE (VMA) Specimen 1 Specimen 2 Average

50. HOT MIX ASPHALT TEST – VOIDS IN MINERAL AGGREGATE (VMA) VMA is calculated from the binder content test and lab-molded specimens. It tells about the total volume of the voids created by aggregates. Samples with low VMA do not have enough void space to provide the proper amount of binder and the proper amount of air. Low VMA, depending on the reason, could result in many distress types.