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ITEM P-401. QUALITY CONTROL More Makes Money Less Leads Losses. Introduction . The “good old days.” When yelling and cursing was an accepted management style. Firings increased until morale improved. Corners were cut to increase profits. Quality Control was imposed from outside.
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ITEM P-401 QUALITY CONTROL More Makes Money Less Leads Losses
Introduction • The “good old days.” • When yelling and cursing was an accepted management style. • Firings increased until morale improved. • Corners were cut to increase profits. • Quality Control was imposed from outside. • Fortunately, the “good old days” are no longer with us.
Introduction • The local governments said: • Do your own quality control and we will review and approve if it meets specifications. • Still, the attitude is in many cases to do the least amount of testing to get by. The test result meet the spec., didn’t it? or • The lab ran the tests wrong. • Fortunately, the “good old days” are no longer with us?
Introduction • Less Leads Losses • Today’s production: 2000 tons P-401. • First sublot: 440 tons, 20th truck load. • Another hour + until the air void test results. • If the air voids are less than 2.0 then at least one forth of the days production is below the specified limits with a maximum PWL of 71 for the entire 2000 tons.
Introduction • More Makes Money • Today’s production: 2000 tons P-401. • First sublot: 440 tons, 20th truck load. • QC personnel obtain a sample from the cold feed early on for gradation and sample the first truck load shipped to test for temperature, air voids, and (if available) nuclear asphalt content.
Introduction • More Makes Money • By now 150 tons or less is on the ground instead of over 550 tons. • Production is stopped, adjustments are made and when the first random sample is obtained and tested PWL = 100 • If you have over 440 tons already made for that day, some hard decisions must be made quickly.
Introduction • More Makes Money • If you trust and listen to your QC staff. • Less Leads Losses • You don’t listen to and trust your QC staff.
Overview • Quality Control: an aggregate of activities (as design analysis and inspection for defects) designed to ensure adequate quality especially in manufactured products • We will learn which analyses and inspections are required by the Specifications and ERLPM.
Overview • 401‑6.1 GENERAL. The Contractor shall develop a Quality Control Program in accordance with Section 100 of the General Provisions. The program shall address all elements which effect the quality of the pavement including, but not limited to: a. Mix Design f. Mixing and Transportation b. Aggregate Grading g. Placing and Finishing c. Quality of Materials h. Joints d. Stockpile Management i. Compaction e. Proportioning j. Surface smoothness
Overview • Part 7 and Item 401-6.1 refer specifically to Contractor Quality Control, for sampling, testing, and reporting.
ERLPM Part 7, P-401 Item 6Quality Control • Sampling - ASTM D 75, ERLPM & Spec. • 7.1 Asphalt Content • 7.2 Gradation Analyses • 7.3 Temperature • Reports - P-401Specifications • Questions? and Answers!
Sampling IT ALL BEGINS WITH OBTAINING SAMPLES: From ASTM D 75 - Practice for Sampling Aggregates No amount of testing will yield correct answers if the samples are carelessly taken and do not represent the material sampled. It is better not to test a material improperly sampled because erroneous conclusions can be drawn from the test results. In any sampling system there are perhaps four stages, each of which requires careful attention and planning:
Sampling (1) selection of a sampling plan which will provide the greatest amount of information at the least cost; (2) physical selection or gathering of samples in accordance with predetermined procedures for the preselected locations; (3) testing; and (4) analysis of the data obtained.
Sampling Strictly speaking, there is no such thing as a representative sample. All materials are subject to periodic variation. Different shipments, lots, truck loads, car loads, or batches from a given supply will vary to some extent. In addition, the material comprising any of the specific units will seldom be precisely homogeneous.
Sampling • However, a successful sampling plan can establish the average characteristic of the material and determine the nature and extent of variability. As data become available it is possible to detect trends and decide if changes in production procedures or processes are required to deliver materials of acceptable quality with reasonably low percentages of defective or substandard material.
Sampling • The ERLPM and the Specification (Item P-401) delineates sampling methods that meet the intent of ASTM D 75
7.1 Asphalt Content • 7.1.1 General Information • 7.1.2 Sampling Procedure & Frequency • 7.1.3 Equipment & Test Procedure – Bitumen • 7.1.4 Moisture Content – Mixture • 7.1.5 Weight of Ash
7.1.1 General Information • General Information - Extraction test shall be performed by the contractor as part of his required quality control testing. The purpose of the test is to determine the bitumen content and aggregate gradation in the pavement mixture.
Extraction Test ? ? ? • How many laboratories still perform chemical extraction tests? • Regardless of the type of test the frequency is still the same.
7.1.2 Sampling Procedure & Frequency • The sampling procedure shall be in accordance with the method described in Section 6 of this manual and a minimum of two extraction tests per lot shall be performed. • If the nuclear or ignition-oven method is used the sample can be taken from the same sublot sample obtained for acceptance testing.
7.1.3 Equipment & Test Procedure – Bitumen • Equipment and Test Procedure - Bitumen Content - The equipment required and the test procedure to be followed for the determination of the bitumen content in paving mixture shall be in accordance with ASTM D 2172 – Quantitative Extraction of Bitumen from Bituminous Paving Mixtures.
7.1.3 Equipment & Test Procedure – Bitumen • Equipment and Test Procedure - Bitumen Content - Extraction equipment and test procedures approved by State testing agencies shall also be acceptable: • ASTM D 4125 Asphalt content of Bituminous Mixtures by Nuclear Method • Accepted in AC 150/5370-10B, with calibration • D6307-05 Standard Test Method for Asphalt Content of Hot-Mix Asphalt by Ignition Method • Method listed in AC 150/5370-10B
7.1.4 Moisture Content – Mixture • The determination of the moisture content of the paving mixture shall be determined once per lot and in accordance with ASTM D 1461 – Moisture or Volatile Distillates in Bituminous Paving Mixtures.
7.1.4 Moisture Content – Mixture I’ve never seen one of these much less used it! How many of you perform this test on a regular basis? Use xylene or a blend of xylene and toluene.
7.1.5 Weight of Ash • The weight of ash portion of the extraction test, as described in ASTM D 2172 shall be determined as part of the first extraction test performed at the beginning of plant production, and as part of every tenth extraction test performed thereafter for the duration of plant production for the project. The last weight of ash value obtained from the extraction test shall be used, where applicable, in the calculation of bitumen content of the mixture.
7.2 Gradation Analyses • 7.2.1 General Information • 7.2.2 Sampling Procedure & Frequency • 7.2.3 Equipment & Test Procedure • 7.2.4 Moisture Content of Aggregate
7.2.1 General Information • Gradation analyses shall be performed by the contractor as part of his required quality control plan. The purpose of the test is to determine the aggregate gradation of the mixture as produced by the plant. When the asphalt content of the mixture is determined by a method other than the extraction test, the aggregate gradation shall be determined from samples taken from hot bins on batch plants or cold feed on drum mix or continuous plants.
7.2.2 Sampling Procedure & Frequency • The sampling procedure shall be in accordance with the method described in Section 6 of this manual and a minimum of two extraction tests per lot shall be performed. • If chemical extraction or ignition-oven methods are used the sample can be taken from the same sublot sample obtained for acceptance testing. • Hot bin or cold feed samples can be taken at the same sublot tonnages during production.
7.2.3 Equipment & Test Procedure • The equipment required and the test procedure to be followed for the determination of the particle size distribution of aggregates, extracted from the mixture or sampled from the plant, shall be in accordance with ASTM C 136. Dry sieving only shall be utilized. • However:
7.2.3 Equipment & Test Procedure • The ERLPM and latest Specifications indicate only the dry sieve procedure is to be used. • The liquid (bitumen) cannot read the specifications and doesn’t know that it is not to be used in coating the material passing the #200 sieve that was not detected by the dry sieve process. What?
7.2.3 Equipment & Test Procedure • How many labs use the wash procedure specified in ASTM D 136, D 5444 and AASHTO T 30? • How can you control the voids, permeability, and other characteristics of the mix without an accurate measurement of the material passing the #200 sieve (P 200)?
7.2.4 Moisture Content of Aggregate • The moisture content of the aggregates shall be determined a minimum of once per lot in accordance with ASTM C 566 – Total Evaporative Moisture Content of Aggregate by Drying. • Typically done once in the morning to determine drying time as the aggregates run through the dryer-drum, and • To adjust the weighing on the load bridges to correct for the weight of moisture.
7.3 Temperature • 7.3.1 General Information • 7.3.2 Frequency of Measurements • 7.3.3 Equipment & Procedure • 7.3.4 Use of Standard Forms
7.3.1 General Information • Temperature measurements shall be made by the contractor as part of his required quality control testing. The purpose of the measurements is to: • check the temperature of the dryer, • bitumen in the storage tank, • mixture in the trucks at the plant, and • mixture at the spreader at the job site.
7.3.2 Frequency of Measurements • The temperatures shall be checked at least four times per lot
7.3.3 Equipment & Procedure • The thermometers shall be reliable and accurate instruments, appropriate as to type and sensitivity for the particular measurements required. Armored glass, dial-type with metal stem, or remote sensing element with shield and associated indicator are typical examples. They shall be properly calibrated at a minimum by comparative readings with accurate, calibrated thermometers.
7.3.4 Use of Standard Forms • Standard forms for extraction test data and calculations, gradation analyses and calculations and the recording the required temperatures measurement, are included in Appendix C.
Reports – P-401 Specification • 401‑6.5 CONTROL CHARTS. The Contractor shall maintain linear control charts both for individual measurements and range (i.e., difference between highest and lowest measurements) for aggregate gradation and asphalt content.
Individual Measurements CONTROL CHART LIMITS FOR INDIVIDUAL MEASUREMENTS Sieve Action Limit Suspension Limit ¾ inch (19.0 mm) 0% 0% ½ inch (12.5 mm) ±6% ±9% d inch (9.5 mm) ±6% ±9% No. 4 (4.75 mm) ±6% ±9% No. 16 (1.18 mm) ±5% ±7.5% No. 50 (0.30 mm) ±3% ±4.5% No. 200 (0.075 mm) ±2% ±3% Asphalt Content ±0.45% ±0.70%
Range (based on n = 2) CONTROL CHART LIMITS BASED ON RANGE Sieve Suspension Limit ½ inch (12.5 mm) 11 percent d inch (9.5 mm) 11 percent No. 4 (4.75 mm) 11 percent No. 16 (1.18 mm) 9 percent No. 50 (0.30 mm 6 percent No. 200 (0.075 mm) 3.5 percent Asphalt Content 0.8 percent
401‑6.6 QUALITY CONTROL REPORTS • The Contractor shall maintain records and shall submit reports of quality control activities daily, in accordance with the Contractor Quality Control Program described in General Provisions, Section 100.
Daily Inspection Reports • Each Contractor quality control technician shall maintain a daily log of all inspections performed for both Contractor and subcontractor operations . . . and shall, as a minimum, include the following:
Daily Inspection Reports (1) Technical specification item number and description; (2) Compliance with approved submittals; (3) Proper storage of materials and equipment; (4) Proper operation of all equipment; (5) Adherence to plans and technical specifications; (6) Review of quality control tests; and (7) Safety inspection.
Daily Inspection Reports • The daily inspection reports shall identify inspections conducted, results of inspections, location and nature of defects found, causes for rejection, and remedial or corrective actions taken or proposed. • The Engineer shall be provided at least one copy of each daily inspection report on the work day following the day of record.
Daily Test Reports Daily test reports shall document the following information: (1) Technical specification item number and description; (2) Test designation; (3) Location; (4) Date of test; (5) Control requirements; (6) Test results; (7) Causes for rejection; (8) Recommended remedial actions; and (9) Retests.
Daily Test Reports • Test results from each day's work period shall be submitted to the Engineer prior to the start of the next day's work period.
Summary • State what has been learned • Define ways to apply training • Request feedback of training session