1. HMA Construction Program Module 10 – Quality Control / Quality Assurance

2. Whenever you purchase a product, you have a certain level of expectation. Getting shortchanged means not getting what you expected: – –It breaks easily – –It does not last as long as you think it should, or – –It is a continuing source of costly problems (like a used car) This is where quality control and quality assurance come into play. All manufacturing processes, including HMA, must have a Quality Control (QC) system to measure its ability to produce a consistent product.

3. Module 10 Objectives Objective of Quality ControlObjective of Quality Control Objective of Quality AssuranceObjective of Quality Assurance Four Types of SpecificationsFour Types of Specifications Population, lot, sample, and specimenPopulation, lot, sample, and specimen Random sampling and testing plansRandom sampling and testing plans Control chartsControl charts Applicable QC/QA testsApplicable QC/QA tests

4. Present module objectives.

5. Quality Trends in Construction Customer-driven quality initiativesCustomer-driven quality initiatives ISO 9000-based quality systemsISO 9000-based quality systems Project-focused quality effortsProject-focused quality efforts Focus on customer satisfactionFocus on customer satisfaction The definition of “quality”The definition of “quality” Senior leadership involvementSenior leadership involvement

6. Quality trends in construction focus on the client. Private initiatives are focused on activities that increase product and/or service quality results. Public initiatives (Superpave) target quality results also, but also aim to differentiate among contractors without breaching anti-discrimination laws. Traditional tools to increase quality are developing cross-functional teams, opportunities for improvement gathering techniques, measurement, awards and recognition. Quality no longer means just the quality of the end product or service, but the quality of the process, relationship, and communications.

7. Quality Pavements: Don’t Begin and End with Material Inspection Pavement designPavement design Subgrade preparationSubgrade preparation Base constructionBase construction Management philosophyManagement philosophy

8. How many times have we heard, “The performance of the roadway is only as good as the material it is built on!” Engineers and contractors must insist on building to complete plans which detail the entire structure being built and the materials being specified. Senior managers have begun to understand that quality is a “line” responsibility and that quality has become strategic as leaders realize customers are demanding it – and getting it – from many contractors. Management philosophy – includes agency and industry, personnel and pavements (e.g. maintenance.)

9. Specification Evolution Method or Recipe (Past)Method or Recipe (Past) End Result (Quasi-Present)End Result (Quasi-Present) Quality Assurance (Present)Quality Assurance (Present) Performance Based (Future?)Performance Based (Future?)

10. The following is a brief comparison of the major specification types which discuss the evolution of specifications over the last 30 years. There are four principal types of specifications used today and each will be discussed in detail from philosophy through implementation issues.

11. Method or Recipe (Past) VILLAGE STATE CITY COUNTY Department of Transportation Library

12. A method or recipe type specification spells out exactly the equipment, methods, materials, and techniques a contractor is supposed to use.

13. Method Specification Owner designs project and sets specificationsOwner designs project and sets specifications Contractor identifies material sourcesContractor identifies material sources Contractor supplies representative samplesContractor supplies representative samples Agency conducts mix designAgency conducts mix design

14. This type of specification did not allow the contractor to be innovative or be rewarded for providing a higher quality product than called for in the specifications. The type of specification has been traditionally used in HMA production and construction.

15. Method Specification (continued) Contractor begins production of mixtureContractor begins production of mixture Agency conducts gradation and asphalt content tests at plant and makes plant adjustmentsAgency conducts gradation and asphalt content tests at plant and makes plant adjustments Agency checks pavement densityAgency checks pavement density Pay adjustments, if any, are madePay adjustments, if any, are made

16. The method specification, which was widely used in the 1940’s and 1950’s, puts maximum control and responsibility in the hands of the specifying agency. In effect, the agency rents the contractor’s personnel and equipment.

17. Problems with Method Specifications Mix design plant specificMix design – plant specific Types of tests inadequateTypes of tests inadequate Economic incentive materialsEconomic incentive – materials Adjustments at plant affect densityAdjustments at plant affect density Frequent disagreementsFrequent disagreements –Agency makes changes which affect pay –Referee testing often required

18. In the early use of the method specifications, little or no testing was done.In the early use of the method specifications, little or no testing was done. The specifying agency based acceptance primarily on inspection.The specifying agency based acceptance primarily on inspection. This type of specification is still used, but usually is accompanied by a greater degree of testing than in the 1950’s.This type of specification is still used, but usually is accompanied by a greater degree of testing than in the 1950’s.

19. End Result Specifications Specifying agency/contractorSpecifying agency/contractor –Sets limits –Defines the desired quality of the finished product

20. In 1958, the construction of the AASHO Road Test provided the first step toward end-result specifications.In 1958, the construction of the AASHO Road Test provided the first step toward end-result specifications. End result is a term that defines the desired quality of the finished product.End result is a term that defines the desired quality of the finished product. Many states are currently experimenting with end- result specifications.Many states are currently experimenting with end- result specifications. The end-results developed are often the result of input from many agencies, and might include segregation or smoothness, for example.The end-results developed are often the result of input from many agencies, and might include segregation or smoothness, for example.

21. End Result Specifications (continued) Becoming more prevalentBecoming more prevalent Agency or contractor designs project and provides expected results for:Agency or contractor designs project and provides expected results for: –Materials used, –Volumetrics, –Smoothness, and –Density

22. Most of the specifications specify the standard controlling mix properties, yield or thickness, density, and/or smoothness.Most of the specifications specify the standard controlling mix properties, yield or thickness, density, and/or smoothness. The difficulty with this specification is determining reasonable levels of acceptance, and determining the relationships between the controlling mix properties.The difficulty with this specification is determining reasonable levels of acceptance, and determining the relationships between the controlling mix properties.

23. End Result Specifications (continued) They typically require the:They typically require the: –Contractor to do quality control testing –Agency to do assurance testing and conduct an acceptance program for payment Consultants can play the role of either the contractor or the agency in terms of testing.Consultants can play the role of either the contractor or the agency in terms of testing.

24. This type of specification stresses testing, as opposed to inspection, as the main measure of contract compliance. The development of the acceptance limits used on the AASHO Road Test came from a panel of engineers who used their expertise to provide limits that they thought could be met by the contractor and which would lead to the desired product. The testing program undertaken at the AASHO Road Test proved that the limits generally could not be met consistently, some Marshall test properties were met with a relatively high frequency, while others were rarely met.

25. Common factors are used in end-result specifications for acceptance of materials and finished pavements

26. Reiterate that the agency sets limits for the contractor: – –JMF +/- tolerance – –Small standard deviations

27. Quality Assurance Specifications Separates responsibility for process control and product acceptanceSeparates responsibility for process control and product acceptance Ensures that inspection plays an essential roleEnsures that inspection plays an essential role QC Plan

28. Shrinking budgets deplete personnel reserves, agencies are moving more of the responsibility for the day-to-day process quality control to the contractor. QA specifications are characterized by a division of responsibility between contractor and agency and that the sampling and testing requirements are statistically-based.

29. Performance Based Specifications Performance of the final, in-place product, is measured; not how it was builtPerformance of the final, in-place product, is measured; not how it was built Performance-based test methods have not been fully developedPerformance-based test methods have not been fully developed

30. A true performance-based specification does not yet exist. In the true sense, the agency is concerned with the performance of the final, in-place product and not how it was built. These projects are similar to design-build and turn- key construction projects which have been used in building and rapid transit construction projects for decades. Examples include Koch’s warranty in New Mexico and the VMS project in Virginia.

31. Superpave Technology Superpave Technology Warranties Warranties Rut Testers Rut Testers Performance Based

32. Further development and validation of performance- based tests and specs are currently underway in the implementation of Superpave. Touch upon but don’t get too detailed with: – –PG binders – –Aggregate tests – –Coarser aggregate gradations – –Mixture tests – –Performance Models – –Test Track Facilities

33. The primary goal of a QUALITY ASSURANCE SYSTEM is to provide CONTROL and maintain ASSURANCE. This partnering approach will help to maintain program credibility. is to provide CONTROL and maintain ASSURANCE. This partnering approach will help to maintain program credibility.

34. The success or failure of any quality control organization will be a direct result of the commitment that top management makes to the program by supporting the quality control effort with adequate resources. – –This includes proper and sufficient testing equipment, adequate laboratory space, proper training, uniform materials, and a high level position in the management structure of the organization. The quality control effort cannot make good mixtures by itself, but it can provide the information necessary for a HMA producer to make the proper process adjustments to continuously produce a quality product.

35. Objectives of a Quality Control System Produce a quality productProduce a quality product Assure that the final product meets job specificationAssure that the final product meets job specification Satisfy the customer’s needs, as economically as possibleSatisfy the customer’s needs, as economically as possible

36. The objectives of a quality control system for HMA producers are to help: – –Produce a quality product – –Assure that the final product meets job specification – –Satisfy the customer’s needs, as economically as possible – –Increase efficiency and production – –Reduce operating costs – –Assist in learning to make reasonable adjustments to ever changing conditions

37. QC is the CONTROL portion of the inspection system. QC ensures the production of uniform materials that meet required specifications through periodic inspection and testing. QC is the producer’s responsibility!

38. Quality Control is the process of making tests and observations, monitoring these, and making adjustments to the production and laydown processes to ensure that the finished pavement will have a high level of compliance with the buyer’s specifications. The contractor is required to perform tests at specified frequencies and make the data available to the agency for review.

39. QA is the ASSURANCE portion of the inspection system. QA assures the owner that the producer’s test results are accurate. Random sampling and testing are at greater intervals than the producer’s process. QA is the buyer’s responsibility!

40. Assurance testing is the system the buyer uses to assure that the product meets the specifications. The agency may use the contractor’s data as part of the acceptance plan, which usually calls for the agency to make a certain number of acceptance tests to assure the quality of the product and to check the contractor’s test results. Assurance testing can be performed by technicians employed directly by the buyer, consultants hired by the buyer, or it may involve the buyer or their representative monitoring and observing quality control tests performed by the seller. (“Random” is first introduced here.)

41. Testing Responsibility Shifting from agency to contractorShifting from agency to contractor Certification training programsCertification training programs

42. Quality control personnel: – –Need to be developed over a long period of time through training and hands-on experience. – –Will be able to establish credibility with buyers once they have a good grasp of the quality control procedures and techniques. – –Must have the proper attitude towards testing. Training, training, and training are required to achieve and maintain an acceptable quality control workforce.

43. Quality Control Work Chart

44. Process Quality Control covers all production processes and tasks associated with meeting specification requirements. The functions involved in acceptance of a product include in-process inspection, monitoring of the supplier’s process control, and acceptance testing. Independent Assurance (IA) encompasses the actions and considerations included in both process quality control and acceptance sampling, testing, and inspection and is a management tool that requires a third party, not directly responsible for process control or acceptance, to provide an independent assessment of the product.

45. Typical QC/QA Sampling and Testing Procedures Pre-productionPre-production Job Mix Formula approval and verificationJob Mix Formula approval and verification QC during production by contractorQC during production by contractor Production and in-place acceptance by ownerProduction and in-place acceptance by owner

46. QC/QA areas from start to finish are all equally important within the overall QC plan.

47. Pre-Production QC/QA Plant ConsiderationsPlant Considerations Aggregate, asphalt cement, and additives for mix designAggregate, asphalt cement, and additives for mix design Consider anticipated process adjustmentsConsider anticipated process adjustments –Cause and effect –Economics

48. Plant type, materials used in the manufacture of the hot mix asphalt and anticipated process control variables are usually addressed in the pre-production stages. Economic issues are typically taken care of in this early stage of the QC process. Asphalt cement and additives are typically “controlled” by the agency or supplier.

49. Job Mix Formula Approval and Verification Aggregate gradationAggregate gradation Aggregate physical propertiesAggregate physical properties Asphalt contentAsphalt content Volumetric analysisVolumetric analysis Stability or strength testing, where applicableStability or strength testing, where applicable Moisture susceptibilityMoisture susceptibility

50. Job Mix Formula approval and verification is only achievable when a very specific set of processes are well defined by the approval authority. – –Mix designs are typically developed from aggregates being used at the hot mix facility already. – –Specific batching techniques usually are specified to ensure repeatable laboratory test results. Mix design formula approval requires that the JMF is within specifications when verified in the laboratory, has reasonably similar volumetric results to the mix design submitted by the contractor, and is a reproducible mixture. FHWA technical advisory stresses importance of volumetric design and field control. Volumetric criteria for controlling air voids, VMA, VFA, etc. for mixtures in field production are critical for Superpave, SMA, and conventional mixes.

51. QC During Production by Contractor Aggregate gradationAggregate gradation Asphalt contentAsphalt content Volumetric analysisVolumetric analysis In-place densityIn-place density

52. QC processes in hot mix asphalt usually require frequent sampling of incoming aggregates, asphalt, and the finished product. Process control is only as good as the timeliness of the test results; therefore it is recommended that completed test results be posted immediately and reviewed by the QC Manager. After a thorough review of all tests at the plant and in the field, the QC Manager may elect to make slight adjustments to the mixture at the asphalt plant or to the placement or compaction process in the field.

53. QA During Production by Agency Random production and in-place acceptance testing by the owner is similar to contractor testing, plus measurements of: –Thickness –Smoothness –Overall profile and workmanship

54. Currently these items are typically assurance items. Again, timeliness in reporting the results will allow for opportunity to adjust the existing process to improve on the final product. Partnering plans usually include these the test results as daily review items for the project. These items will discussed in greater detail towards the end of this module.

55. Independent Assurance In order for the QC/QA program to maintain the highest level of accuracy and credibility, owners should maintain an Independent Assurance Group. Typically separate, the group randomly reviews both parties’ procedures and addresses discrepancies.

56. Independent Assurance (IA) is an integral part of the QC/QA process. Reviewers must be familiar with specifications, processes, and roles and responsibilities Random process reviews occasionally lead to full blown process reviews when major discrepancies exist within the system, on either the contractor’s or owner’s side. These items will discussed in greater detail towards the end of this module.

57. Process Control Plan Assignment of QC responsibilitiesAssignment of QC responsibilities Type and frequency of testsType and frequency of tests Record of plant inspections and calibrationsRecord of plant inspections and calibrations DocumentationDocumentation Criteria for actionCriteria for action

58. The Process Control Plan is very detailed from the start to finish. The plan has been followed for years by agencies across the nation and are only now becoming the contractor’s responsibility. Certain individuals in the decision making process are relied upon to not just make changes, but to make the correct changes.

59. Assigning QC Responsibilities

60. A typical organization chart… The authority and responsibility of each person in the quality control system is related to the skill and technical capability of the people involved. People in the quality control system must know their duties, responsibilities, and authority. Each individual should clearly and distinctly see how their jobs and responsibilities for quality control fit with the work of others at the HMA facility. Ask: How are these assignments made here?

61. Type and Frequency of Tests Sampling and testing mix components (Plant)Sampling and testing mix components (Plant) Sampling and testing mixture produced (Plant/Field)Sampling and testing mixture produced (Plant/Field) Analysis of resultsAnalysis of results Evaluation of compliance with specification limitsEvaluation of compliance with specification limits

62. Quality control techniques are the procedures used to evaluate test results and observations. From these evaluations, the technician can decide whether or not the process is in control. If it is not, the quality control techniques will guide corrective actions.

63. HMA Sampling and Testing It is crucial that the producer and agency use the same test methods and equipment specifications in order to compare test results appropriately.

64. The sampling and testing of mix components and mixture produced shall be conducted according to the specific agency requirements. Testing equipment, methods, and personnel must be uniform in this system to minimize variability. If specific methods are not required by the specifications, then standard AASHTO or ASTM procedures should be used.

65. Analysis of Test Results Does the mix comply with specification limits?Does the mix comply with specification limits? –Current results vs. previous results –Job Mix Formula, JMF (+/-) –Single test vs. moving average

66. Job Mix Formula targets and tolerances are established prior to beginning production and must be known for the analysis process to be valid. It is necessary to understand how each test result compares with the results of tests performed previously. In some cases, the result will be compared to the tests that will be performed on subsequent samples. Several procedures are currently used. One is to observe the moving average of a series of samples, which reduces the influence of sampling and testing errors on the results, making it easy to identify trends.

67. Sample Process Control Chart Upper Control Limit Job Mix Formula Lower Control Limit  = Running Average  = Individual Test Results

68. The chart shown has an upper tolerance limit and a lower tolerance limit, this is the total range that the process control is allowed during production. As stated previously, a moving average reduces the influence of sampling and testing errors on the results, making it easy to identify trends. Another procedure is to observe the range or difference between the lowest and highest test result of a group of samples. A plot of moving ranges shows the variability between samples. If this variability tends to increase, problems may be present with the sampling and/or testing procedures.

69. Sample Process Control Chart Upper Job Mix Formula Lower

70. An example of an “out of control” process chart. There are data points outside of both limits, and the moving average is above the job mix formula.

71. Control Charts What is plotted?What is plotted? –Control sieves Max, 4.75 mm, 600 µm, 75 µm (#4, #30, #200)Max, 4.75 mm, 600 µm, 75 µm (#4, #30, #200) –Asphalt Content –Max. Theoretical Sp. Gr. –Laboratory Sp. Gr. –Voids and VMA –Pavement in-place density

72. Critical characteristics that are plotted are those which historically allow for adequate control of the production of HMA. The number of items analyzed and reviewed tends to increase with the reliability required for the project being built; i.e. an interstate roadway will require many more items of control than a large parking lot for a commercial development. Ask: What test items are plotted here?

73. Benefits of Control Charts

74. Ask: Why would you use control charts? Write down their answers on a flip chart. Then compare their answers to the list on the next slide.

75. Benefits of Control Charts Early detection of trendsEarly detection of trends Establish process capabilityEstablish process capability Decrease inspection frequencyDecrease inspection frequency Permanent record of qualityPermanent record of quality Provide a basis for acceptanceProvide a basis for acceptance Instill quality awarenessInstill quality awareness Taking corrective measuresTaking corrective measures Evaluating data for cost savingsEvaluating data for cost savings Recording and reportingRecording and reporting

76. The benefits of a quality control process is realized when a producer can dictate the frequency and type of testing required to maintain control of their facility. The ability of some producers to sell all finished HMA product as “Certified” increases their sales and marketability. Change needs to be evaluated and analyzed daily, weekly, and annually for producers to understand their process thoroughly and to be able to adjust accordingly to increase quality, production, and profits in the future.

77. Plant Inspections and Calibrations Control cold feeds and hot binsControl cold feeds and hot bins Facility operations and controlsFacility operations and controls

78. Internal housekeeping also includes reviewing the loading of cold feeds, the gradation of belt feeds and hot bins, as well as the “dialed in” values of the computer versus actual production numbers. NHI has the HMA Production Facilities course that is solely devoted to asphalt plants.

79. QC / QA DocumentationDocumentation –Day to day results –Problems with incoming products –Adjustments made to trend towards JMF –Others

80. Documentation must be made of corrective actions. Assigning blame to a specific product may be appropriate to a HMA producer, but controlling all incoming products will help ensure a quality finished product is produced for the owner. Ask: What “other” items are documented?

81. QC / QA Criteria for actionCriteria for action –Specification tolerances –Timely response for adjustments –Adjusted job mix formula –Others

82. Want to make changes daily, when they can have an effect. Ask: What “other” criteria for action are there?

83. Total Variability Variability – Everything variesVariability – Everything varies Assignable variability can be eliminated IF we identify the causeAssignable variability can be eliminated IF we identify the cause

84. It is important to understand that the Total Variability of a particular material is a sum of several definable variables. These are sampling, testing, production, and actual material variability. What is important is actual material variability. Variation of construction materials is inevitable and unavoidable. Control charts do not eliminate variability, but help distinguish between the inherent or chance causes of variability and assignable causes of variability. Ask: What would be an assignable cause of variability?

85. Scientific Tools to Use in the Treatment and Analysis of Data StatisticsStatistics Random samplingRandom sampling

86. The key components of a QC/QA plan can be summed up as: sampling, testing, analysis, and interpretation. A basic understanding of statistics is the first step in understanding how to use this tool in QC/QA and the materials testing associated with this program. Statistics is the science that deals with the treatment and analysis of numerical data. Random sampling is a sampling procedure where any specimen in the population has an equal chance of being sampled.

87. Statistics Central tendency or averageCentral tendency or average Dispersion or rangeDispersion or range Standard deviation or variabilityStandard deviation or variability Degrees of freedom (n-1)Degrees of freedom (n-1) OutliersOutliers Normal Distribution is most important for highway materials

88. Averages, ranges, variability and outliers are all important items to understand when utilizing statistics. (Later on the participants will do a homework problem utilizing these parts of statistics.) Outliers are not well defined but are typically results which exist because of an error in either the sampling or testing technique utilized; in some cases, outliers are discarded.

89. Statistics (continued) Sampling vs. complete enumerationSampling vs. complete enumeration –Population –Sample –Data Controlled conditionsControlled conditions

90. Population or lot is defined as all the measurements or counts that are obtainable from all the objects which possess common specified characteristics. A common definition of a lot is an isolated quantity of material produced essentially by the same process. A sample is a set of measurements or counts that constitute a part or all of the population. Data are the factual information (such as test results, measurements, or statistics) used as a basis for reasoning, discussion, or decision making.

91. Population or Lot

92. A large cube-shaped object can be thought of as a lot consisting of smaller cube-shaped blocks which represent potential specimens. Assume that the cube represents a lot of hot mix and that we wish to know the density of the hot mix in the lot. Obviously, to determine the “best” estimate of the density, every bit of material in the lot must be tested (complete enumeration). Since complete enumeration is not feasible, sampling is the practical solution.

93. Sample from the Population or Lot Sample #1 Sample #3 Sample #2

94. A sample can be selected from the lot of material, and data from the sample can be used to estimate the density of the hot mix in the lot in order to make a decision regarding its acceptability. The relationship between the properties of the sample and the properties of the population is an important aspect of statistical theory and practice since “good” estimates of the properties of a population require valid samples. Two concepts that are of particular importance for ensuring sample validity are random sampling and controlled conditions.

95. Random Sampling Any portion of the population has equal chance of being selectedAny portion of the population has equal chance of being selected Bias is introduced when judgment is usedBias is introduced when judgment is used Use random number tablesUse random number tables

96. “Random” does not mean “haphazard”; it means that the sample is selected without bias or choice.“Random” does not mean “haphazard”; it means that the sample is selected without bias or choice. In practice it may be difficult to train technicians who have been accustomed to inspection to randomly select samples without regard to quality.In practice it may be difficult to train technicians who have been accustomed to inspection to randomly select samples without regard to quality. Their tendency is to make sure that defective materials are represented in the sample, thus unconsciously biasing the sample.Their tendency is to make sure that defective materials are represented in the sample, thus unconsciously biasing the sample. Random sampling must be followed when using a statistically-based procedure, like Quality Assurance.Random sampling must be followed when using a statistically-based procedure, like Quality Assurance.

98. Slide showing technician laying out sampling location

99. Lots and Sublots LOT SUBLOT RandomSampling StratifiedRandomSampling

100. Random sampling ensures that each specimen in a lot has the same chance of being selected for the sample. Stratified random sampling additionally involves the selection of two or more defined sub-lots of a given lot. Stratified random sampling is used to ensure that the specimens for the sample are obtained from throughout the lot, and are not concentrated in one portion or sub-lot of the lot. It is possible, but not likely, that in a lot all of the random numbers could have us sample in the morning: we avoid this through the use of sub-lots.

102. Slide showing technician coring a roadway.

104. Slide showing nuclear density gauge.

106. Slide showing nuclear density gauge in the field.

107. QC / QA Sampling Example Lot size: 1,000 metersLot size: 1,000 meters Pavement width: 3.6 metersPavement width: 3.6 meters 5 cores per lot5 cores per lot Lot begins at Sta. 100+000Lot begins at Sta. 100+000

108. Sample problem to review with students.

109. LOT 100+000 5 equally sized sub-lots

110. Review of a stratified random sampling process. Sublot size may typically be 200 m.

111. Random Number Table 0.740.600.010.270.43 0.290.210.780.010.43 0.280.370.000.490.97 0.730.080.870.320.97 0.720.140.090.700.41 X (longitudinal) Y (transverse)

112. Use of random number tables assists us in developing unknown longitudinal and transverse measurements to make for sampling.

113. QC / QA Sampling Example ( cont’d) Sub-lot #1Sub-lot #1 –Length = 200 meters –Random numbers: 0.74 and 0.29 Measure up from Sta. 100+000Measure up from Sta. 100+000 –X = 0.74 x 200 meters = 148 meters –Y = 0.29 x 3.6 meters = 1.0 meters

114. Complete the sample problem with the students, using a chalkboard or flip chart.

116. Slide showing technician measuring distances for longitudinal sampling location.

118. Slide showing technician measuring distances for transverse sampling location

119. QC / QA Sampling Participant Example:Participant Example: –Lot size: 2,000 meters –Pavement width: 3.6 meters –5 cores per lot –Lot begins at Sta. 200+000

120. Student homework problem. Students should perform similar calculations prior to moving forward.

121. Random Number Table 0.740.600.010.270.43 0.290.210.780.010.43 0.280.370.000.490.97 0.730.080.870.320.97 0.720.140.090.70 0.41 X (longitudinal) Y (transverse)

122. Review use of random number table.

123. QC / QA Sampling Participant Example (cont’d.):Participant Example (cont’d.): –Sub-lot #1 Length = 400 metersLength = 400 meters Random numbers: 0.73 and 0.72Random numbers: 0.73 and 0.72 –Measure up from Sta. 200+000 X = 0.73 x 400 meters = 292 metersX = 0.73 x 400 meters = 292 meters Y = 0.72 x 3.6 meters = 2.6 metersY = 0.72 x 3.6 meters = 2.6 meters

124. Completion of homework problem. Have participants calculate test locations 2 through 5 based on the previously displayed random numbers.

125. Process Acceptance Criteria MaterialsMaterials Thickness toleranceThickness tolerance Pavement densityPavement density Pavement smoothnessPavement smoothness

126. Typically minimum standards are stated for each test, along with the method of measurement to be utilized by the owner to determine final payment percentages. Occasionally bonuses are paid for exceeding minimum requirements.

127. Materials Process control by contractorProcess control by contractor Assurance sampling and testing done randomly, and less frequently, by ownerAssurance sampling and testing done randomly, and less frequently, by owner

128. Comparison is typically “go - no go” criteria where when certain tolerances are achieved no further review of the contractor’s process is required. Material quality issues are set as minimums only.

129. Thickness Tolerance Can be checked with coresCan be checked with cores Yield checks during pavingYield checks during paving Use of stringlineUse of stringline –Initial HMA course –Ski used on subsequent courses Smooth surface to pave onSmooth surface to pave on

130. Contractors may elect to control the process by performing several of these tests themselves. Payment schedules are typically controlled by type of construction being done; i.e., full-depth pavement smoothness requirements usually exceed mill and fill construction project requirements.

131. Pavement Density Types of density specificationsTypes of density specifications –Laboratory density –Maximum theoretical density –Control strip –Method specification (ordinary compaction)

132. It is very important to understand which method of density is specified on a job by job basis.

133. Laboratory Density Compares cores to field-produced mix densityCompares cores to field-produced mix density –Field mix compaction same as mix design –Mix design properties verified –End result specification Percent Density = In-Place Density Laboratory Density Laboratory Density x 100

134. Slide is self explanatory

135. Maximum Theoretical Density (Rice) Unit weight of mix in “voidless” stateUnit weight of mix in “voidless” state Core density is compared to MTDCore density is compared to MTD Relative density is in-place air voidsRelative density is in-place air voids Percent of MTD = In-Place Density Max. Theor. Density x 100

136. Slide is self explanatory

137. Control Strip Density Requires control strip at start of each liftRequires control strip at start of each lift Minimum tonnage or areaMinimum tonnage or area After constructed, density tests takenAfter constructed, density tests taken Test results compared to lab or MTDTest results compared to lab or MTD –Number of tests is specified –Is compaction adequate? Field density is the reference targetField density is the reference target 100% of target is desired100% of target is desired

138. This is typically the most reasonable specification to use for commercial work and when the pavement structure being paved on is inadequately supported to achieve other minimum compaction levels. Minimum tonnage or area may be 250-300 tons or 500 ft.

139. Control Strip Precautions These factors can affect density:These factors can affect density: –Mix temperature –Asphalt content –Gradation –Rolling technique

140. Mixture type also plays a large role here. Interstate mixtures used on commercial projects are typically not capable of being compacted to any minimum desired level, unless the project has been designed using structural values. Same job, paved in both the summer and the fall with the same mixture, may cause difficulties because of different surface and air temperatures.

141. Reference Density Comparison In-PlaceAirVoids01 2 3 4 5 6 7 8 991 92 93 94 95 96 97 98 99100 % of MaximumTheoreticalDensity 100 99 98 97 96 95 LaboratoryDensity 100 99 Control Strip Density For 4% Voids Mix Design

142. Reference density comparison chart showing how each specification relates to the others. 8% is maximum in-place air voids.

143. Method Specification No reference densityNo reference density Spells out rolling operationSpells out rolling operation –Number of rollers –Types of rollers –Number of passes –Temperature measurements –“Free of roller marks” Very subjective specificationVery subjective specification

144. Obvious problems exist with this form of specification. These problems are shown here and were discussed earlier in this module.

145. Pavement Smoothness Provide better rideProvide better ride Less damage to pavementLess damage to pavement Measurements must be accurate, repeatable, and hopefully related to what we feel when we drive the roadMeasurements must be accurate, repeatable, and hopefully related to what we feel when we drive the road Specifications should be set to how much we can realistically improve the smoothness of a roadSpecifications should be set to how much we can realistically improve the smoothness of a road Corrections?Corrections?

146. Smoother is always better for performance and for the motoring public. (It is generally the requirement desired by the motorist.) The smoother the road, the better the paving contractor’s rating in almost every case. Current methods are being improved upon. Current levels of smoothness are always being challenged. Again, levels must be set to achievable amounts and vary based on type of construction; i.e. full-depth vs. mill and fill. Even with coarser mixes such as Superpave and SMA, smoothness criteria can be achieved. Ask: Is smoothness specified here?

147. Pavement Smoothness Measurements Straight edgeStraight edge ProfilographProfilograph ProfilometerProfilometer Mays MeterMays Meter LISALISA

148. Different types of measuring tools used across the nation are listed.

149. Pavement Smoothness Measurements (continued) Straight edgeStraight edge –Typically 3 meters long –Measure deviations > 6 mm –Some have wheels (rolling straight edge) Local requirements?Local requirements? –3 mm in 3 meters –6 mm in 3 meters (sidestreets) –5 mm in 5 meters

150. Slide is self explanatory

152. One type of straight edge. Ask: What are your local requirements for straightedge smoothness?

153. Pavement Smoothness Measurements (continued) ProfilographProfilograph –Most common is “California Style” 8 meter long aluminum truss8 meter long aluminum truss Center mounted measuring wheelCenter mounted measuring wheel –Standard testing distance = 0.15 km –Blanking band (5 mm) –Measurement in mm/km –Manual -vs- computer output –Local requirements?

154. Slide is self explanatory

156. Profilograph Ask: Who uses a profilograph for smoothness measurements? What are the local requirements?

158. Profilograph trace Usually, the higher the speed limit, the tighter the specification for smoothness. High type roadways, like interstates, are typically built with safety and performance in mind with large penalties being assigned for smoothness deficiencies.

159. Pavement Smoothness Measurements (continued) ProfilometerProfilometer –Self contained truck or trailer –Uses accelerometers and distance measuring equipment –Computer processed information –Used at highway speeds –High initial investment Not easy to correlate different methodsNot easy to correlate different methods

160. Slide is self explanatory.

161. Pavement Smoothness Measurements (continued) Mays Meter – trailer device for measuring roughnessMays Meter – trailer device for measuring roughness LISALISA –Lightweight inertial surface analyzer or quick response profilometer –Laser sensor and an accelerometer –Travels at 15 to 30 kph

162. Michigan DOT developed the lightweight inertial surface analyzer (LISA). The LISA uses a laser sensor and an accelerometer that feeds road profile data to a computer. Laser takes a profile reading every 75 mm and can measure fluctuations in the pavement as small as 0.0254 mm.

163. QC / QA Review The primary goal of a QUALITY ASSURANCE SYSTEM is to provide CONTROL and maintain ASSURANCE. This partnering approach will help to maintain program credibility. is to provide CONTROL and maintain ASSURANCE. This partnering approach will help to maintain program credibility.

164. The success or failure of any quality control organization will be a direct result of the commitment that top management makes to the program by supporting the quality control effort with adequate resources. – –This includes proper and sufficient testing equipment, adequate laboratory space, proper training, uniform materials, and a high level position in the management structure of the organization. The quality control effort can not make good mixtures by itself, but it can provide the information necessary for a HMA producer to make the proper process adjustments to continuously produce a quality product.

165. QC / QA Review Implementing a Quality CONTROL Program Management commitmentManagement commitment Quality statementQuality statement Developing a Quality Control manualDeveloping a Quality Control manual

166. The success or failure of any type of quality program is the responsibility of the company’s top management. Unless top management is committed to quality being more important than production, middle management and superintendents will continue to deal with everyday problems with the idea that production comes first. The corporate Quality Statement or plan should include the long term vision of where the company plans to be in the next ten years. The company quality manual should focus on the goals of that operation and the needs of its clients.

167. QC / QA Review Implementing a Quality ASSURANCE Program Process Quality ControlProcess Quality Control Acceptance sampling, testing and inspectionAcceptance sampling, testing and inspection Independent AssuranceIndependent Assurance

168. Everyone in the loop needs to know their role, their counterparts role, and how to react to make the system perform more efficiently the next time.

169. Quality Control with Quality Assurance Credibility is another way of saying, “You can believe me!”

170. Credibility is built by developing relationships over time. Credibility is built through providing competent technicians and inspectors at every stage of the QC process. Truly believing that increasing the performance of the finished product will benefit the client will help to build the contractor’s credibility.

171. Module 10 Objectives Review Objective of Quality ControlObjective of Quality Control Objective of Quality AssuranceObjective of Quality Assurance Four Types of SpecificationsFour Types of Specifications Population, lot, sample, and specimenPopulation, lot, sample, and specimen Random sampling and testing plansRandom sampling and testing plans Control chartsControl charts Applicable QC/QA testsApplicable QC/QA tests

172. Ask for specific responses to these questions. Use questions that will help draw out responses, such as: – –What do you remember? – –How is it related to what you know? – –How will you use this information in the future?