SPECIAL PROVISION TO SPECIAL SPECIFICATION Quality Control/Quality Assurance of Hot Mix Asphalt

Transcription

1 1993 Specifications CSJ SPECIAL PROVISION TO SPECIAL SPECIFICATION Quality Control/Quality Assurance of Hot Mix Asphalt For this project, Special Specification Item 3146, Quality Control/Quality Assurance of Hot Mix Asphalt, is hereby amended with respect to the clauses cited below, and no other clauses or requirements of this Item are waived or changed hereby. Article Materials, Subarticle (1), Aggregate, Section (A) Coarse Aggregate Stockpile. The fourth and fifth paragraphs are voided and replaced by the following: Coarse aggregates to be used in surface courses shall have a minimum surface aggregate classification as shown on the plans. Unless otherwise shown on the plans, the surface aggregate classification requirement will apply only to aggregate used on travel lanes. Aggregates in locations other than travel lanes shall meet the requirements in Table 1. The surface aggregate classifications for sources on the Aggregate Quality Monitoring Program (AQMP) are listed in the Rated Source Quality Catalog (RSQC). When aggregates are supplied from a source which is not on the AQMP, the aggregate will be sampled and tested prior to use. The procedures will be in accordance with the AQMP. Blending of Class "B" aggregate with a Class "A" aggregate will be allowed in order to meet requirements for Class "A" materials. At least 50 percent (by weight) of the material retained on the No. 4 sieve must come from a Class "A" aggregate source. The aggregates must be blended by volume if the bulk specific gravity of the Class "A" and Class "B" aggregates differ by more than Class "C" and "D" aggregates will not be allowed for blending. Article Job Mix Formula is supplemented by the following: Evaluate the mixture proposed for use for moisture susceptibility by Test Method Tex-242-F, Hamburg Wheel-Tracking Test in lieu of Tex-531-C for mix design verification (JMF1), JMF2 and during production Contractor s Responsibilities. Use a Department-approved AMRL accredited laboratory to perform the Hamburg Wheel test and provide results with the mixture design or provide the laboratory mixture and request that the Department perform the Hamburg Wheel test. The engineer will be allowed 10 working days to provide the Contractor with Hamburg Wheel test results on the laboratory mixture design. If necessary for Hamburg Wheel testing, obtain the list of Department-approved laboratories from the Construction Division

2 If opting to have the Department perform the Hamburg Wheel test on the laboratory mixture, provide the Engineer with approximately 10,000 grams of design mixture and request on the mixture design report that the Department perform the Hamburg Wheel test. Test the trial batch to ensure the mixture produced using to proposed JMF1 meets the verification testing requirements for gradation, asphalt content, laboratory density and is in compliance with the Hamburg Wheel test requirement in Table A. Use a Department-approved AMRL accredited laboratory to perform the Hamburg Wheel test on the trial batch mixture or request that the Department perform the Hamburg Wheel test. The Engineer will be allowed 10 working days to provide the Contractor with Hamburg Wheel test results on the trial batch. Provide the Engineer with a copy of the trial batch test results. After receiving approval for JMF2 and receiving a passing result from the Department s or a Department-approved laboratory s Hamburg Wheel test on the trial batch, use JMF2 to produce Lot 1. As an option, once JMF2 is approved, proceed to Lot 1 production at your own risk without receiving the results from the Department s Hamburg Wheel test on the trial batch. If electing to proceed without Hamburg Wheel test results form the trial batch, notify the Engineer. Note that the Engineer may require up to the entire sublot of any mixture failing the Hamburg Wheel test be removed and replaced at the Contractor s expense. Engineer s Responsibilities. If the Contractor request the option to have the Department perform the Hamburg Wheel test on the laboratory mixture, the Engineer will mold samples in accordance with Test Method Tex- 242-F to verify compliance with the Hamburg Wheel test requirement in Table A. The Engineer will submit the molded samples of to the Materials and Pavements Section of the Construction Division for testing. The Engineer will authorize the Contractor to proceed with Lot 1 production as soon as a passing result is achieved from the Department s or a Department-approved laboratory s Hamburg Wheel test on the trial batch. As an option, the Contractor may at their own risk, proceed with Lot 1 production without the results from the Hamburg Wheel test on the trial batch. If the Department s or Department-approved laboratory s sample from the trial batch fails the Hamburg Wheel test, the Engineer will suspend production until further Hamburg Wheel tests meet the specified values. The Engineer may require up to the entire sublot of any mixture failing Hamburg Wheel test be removed and replaced at the Contractor s expense

3 Table A Hamburg Wheel Track Requirements High Temperature Minimum # of 0.5" Rut Test Method Binder Grade Depth F PG 64 Tex-242-F 10,000 1 PG 70 Tex-242-F 15,000 1 PG 76 or higher Tex-242-F 20, May be decreased or eliminated when shown on the plans. The Engineer may perform a Hamburg Wheel test at any time during production. In addition to testing production samples, the Engineer may obtain cores and perform Hamburg Wheel tests on any areas of the roadway where rutting is observed. When the production or core samples fail the Hamburg Wheel test criteria in Table A, suspend production until further Hamburg Wheel tests meet the specified values. Core samples if taken will be obtained from the center of the finished mat or other areas excluding the vehicle wheel paths. The Engineer may require up to the entire sublot of any mixture failing the Hamburg Wheel test be removed and replaced at the Contractor s expense. If the Department s or Department-approved laboratory s Hamburg Wheel test results in a remove and replace condition, the Contractor may request the Department confirm the results by retesting the failing material. The Construction Division will perform the Hamburg Wheel tests and determine the final disposition of the material in question based on the Department s test results. Article Construction Methods, Subarticle (6), Placing. The first paragraph is supplemented by the following: If segregation or irregularities occur in the pavement surface, the Contractor shall review the plant, hauling and paving operations and take corrective action. A "Segregation Check Points" list is available from the Engineer. Segregation will be identified in accordance with Test Method Tex-207-F, Part V "Determination of Mat Segregation Using a Nuclear Density Gauge". The Contractor shall perform a minimum of four segregation checks each day for each mix type used on the project. The density profile must meet the criteria shown in Table 1 to be considered acceptable. The profile location shall be recorded to permit future evaluation of the segregation section. At the start of the project, the paving unit will be allowed to pave for a distance of 1,000 linear feet with each individual mix designation before implementing a profile analysis. Any visibly identifiable segregated areas shall be profiled unless both the Contractor and the Engineer agree that segregation does exist and the Contractor agrees to immediate mitigation of the problem. A segregation profile starting point shall be established at each point location where the screed stops due to discontinuous mix delivery. If the lay down operation continues to progress without stopping and no visible segregation is noted and four consecutive profiles are within established tolerances, then the test frequency will be reduced to one profile per placement lot. The Engineer may further reduce the frequency of testing at the Contractor's request

4 Table 1 Density Profile Acceptance Criteria Nominal Max. Aggregate Size Maximum Allowable Density Range (highest to lowest) Maximum Allowable Density Range (average to lowest) 5/8 or less 6.0 lbs./c.f. 3.0 lbs./c.f. 5/8 or greater 8.0 lbs./c.f. 5.0 lbs./c.f. The Engineer will be provided results of the segregation profiles as they are completed. Whenever one of the profiles fails the acceptance criteria, the Contractor will be allowed to make changes to the operations before the next profile evaluation is made. Any changes must be made within the first hour of production following determination of a failing evaluation. Production of the hot mix asphalt shall cease whenever two consecutive profiles fail unless otherwise approved by the Engineer. The Contractor shall make changes to the mix or process before production is restarted. The Contractor may produce enough mixture to place approximately 2,000 linear feet of pavement one paver width wide. Two segregation profiles shall be taken within these 2,000 linear feet of production and if both profiles meet the acceptance criteria, the Contractor may resume normal operations. However, if one or both of the segregation profiles fail, the Contractor shall make additional changes as approved by the Engineer and an additional 2,000 linear feet of pavement shall be laid and evaluated as before. This procedure of placing and evaluating 2,000 linear feet sections will be continued until both segregation profiles pass. The Engineer may require the Contractor to provide specialized mixing or material transfer devices for remixing of the mixture prior to placement if the segregation has not been eliminated through plant and process adjustments. Normal production and segregation checks will resume when both profile results pass. Although it will be the Contractor's responsibility to perform the segregation check described above using the nuclear density gauge, the Engineer may make as many independent or confirmation nuclear density checks as deemed necessary. The Engineer's results will be used to determine segregated sections when available. Article Construction Methods, is supplemented by the following: (9) Longitudinal Joint Density. The Contractor shall perform a joint density evaluation for each sublot at the random sample locations selected for in place air void testing. At each location, the Contractor shall perform a nuclear density gauge reading with the center of the gauge placed at 8 in. from a mat edge that will become a longitudinal joint. This reading will be compared to a nuclear density gauge reading taken on the interior of the mat more than 2 ft. from the mat edge. When the density at the 8 in. offset from the mat edge is more than 3 lb. per cubic foot below the interior mat density, the evaluation fails. The Contractor shall investigate the cause of failure and take corrective actions during production to improve the joint density. Production of the hot mix asphalt shall cease when 2 consecutive evaluations fail unless otherwise approved by the Engineer. The Contractor shall make changes to the hot mix or the placement process before production is resumed. The Contractor may produce enough mixture to place approximately 2,000 linear feet of pavement 1 paver width wide. Two joint density evaluations shall be performed within these 2,000 linear feet of production and if both evaluations are acceptable, the Contractor may resume normal operations. However, if 1 or both of the joint density evaluations fail, the Contractor shall make additional changes as approved by the Engineer and an additional 2,000 linear feet of pavement shall be laid and evaluated as

5 before. This procedure of placing and evaluating 2,000 linear feet sections will be continued until both joint density evaluations pass. The Engineer may require the Contractor to implement different joint construction methods or provide special joint making equipment to improve joint density. Normal production and joint density verification will resume when both joint density evaluations pass. Although it is the Contractor s responsibility to perform joint density evaluations, the Engineer may make as many independent joint density verifications as deemed necessary at the random sample locations. The Engineer s results will be used to determine joint density when available. Article Measurement, Subarticle (1) Composite Mass Method. The first sentence of the first paragraph is voided and replaced by the following: Hot mix will be measured by the ton of the composite hot mix of the type actually used in the completed and accepted work in accordance with the plans and specifications for the project. Article Table 6 Placement Pay Adjustment Factors for In-Place Density is voided and replaced by the following table. Table 6 Placement Pay Adjustment Factors for In-Place Air Voids In-Place Air Voids Pay Adjustment Factor In-Place Air Voids Pay Adjustment Factor <3.0 Remove & Replace >10.0* Remove & Replace

6 * Operations shall cease when the average sublot in-place air voids exceeds 10%. Operations will not resume until the Engineer is satisfied that the next mix placed will be equal to or less than 7.5% air voids