404.01Design of Asphalt Mixtures. (a) General. The
Contractor shall furnish one mix design for each of the particular asphalt mixtures listed on the plans or in the Cont ract. The mix design shall be performed by a laboratory that is o n the Department’s QPL of approved asphalt mix design lab oratories and shall include the following: • Type of mix (e.g., ACHM Base, Binder, and Surface C ourse). • Design values for asphalt binder content, air voids , voids in mineral aggregate, gradation, and wheel tracking te st.
245 • Source of each material to be used in production of the mix. • Designation of the asphalt plant to be used for pro duction of the mix. • Name(s) of individual(s) who performed the sampling , testing, and preparation of the mix design and the name of the laboratory used. • Optimum laboratory mixing and compacting temperatures. • Temperature viscosity curves for the asphalt binder to be used in the mix. • A one gallon sample of performance grade asphalt bi nder to be used in the mix. • Copies of all test results and mix design work pape rs. • Nine (9) blended aggregate samples. • A Certification by the Contractor that the mix desi gn was prepared according to the specifications and that t he materials to be used are from sources approved by the Enginee r. The mix design shall be submitted to the Engineer o f Materials for review. After completion of the review, the En gineer of Materials will accept or reject, in writing, the mi x design. A mix design will be accepted only for a specific type of mix, materials sources, and the plant to be used. A change in any materials source will require a different mix design. Mix designs w ill be approved for a period of five years from the original approval date provided satisfactory results are obtained during production and placement. The Engineer of Materials will accept a maximum of three (3) mix designs for a particular type mix, materials source , and plant combination at any time. Mix designs submitted in excess of three will not be considered until the number of accepted mix designs is reduced by declaring one or more of them invalid. All mix designs accepted by the Engineer of Materials become the pr operty of the Department. The Contractor shall notify the Resident Engineer i n writing of the accepted mix design proposed for use on a speci fic project and provide copies of the mix design to the Resident En gineer. The Resident Engineer will approve an accepted mix desi gn for use on each project. Only one mix design for each type of mix will be active (approved for use on highway projects) at an y one plant at any time. A maximum of two other accepted mix desi gns for each type of mix will be considered inactive. If a chan ge of mix design is
246 desired, the Contractor shall notify the Resident E ngineer and request permission to change the mix design. Arbit rary changes of the active mix design will not be approved. The Engineer will not perform any pre-bid testing o f materials. It will be the Contractor's responsibility to obtain m aterial sources approved by the Engineer unless sources are designa ted on the plans or in the Contract. Additives shall be selected fr om those on the Qualified Products List. If asphalt binder or aggr egate sources proposed for use are not on the Qualified Products List, at least 10 business days must be allowed for sampling and testing before beginning the mix review process. At least five (5 ) business days shall be allowed for the review of the mix design.
laboratory analysis according to the requirements o f the specifications. Each mix design will establish a m ix gradation for the aggregates (based on the weight of material pas sing specified screen sizes), an optimum asphalt binder content (e xpressed as a percentage of the total mix weight), an optimum lab oratory mixing temperature, and an optimum laboratory compaction t emperature. Optimum laboratory mixing and compaction temperatures shall be established based on temperature-viscosity curves o f the asphalt binder to be used in the mix. The optimum asphalt content is the asphalt binder content at 4% Air Voids (AV) for PG 76-22 mixes and 4.5% Air Voids (AV) for PG 64-22 and PG 70-22 m ixes. The mix design will be designed in accordance with the volumetric mix design procedures contained in AASHTO M 323, its re ferenced standards, and the exceptions below: • PG 64-22 and PG 70-22 mixes will be designed using 4.5% air voids; • the fine aggregate angularity will be determined i n accordance with AASHTO T 304 using the aggregate bl end specific gravity of the minus No. 8 (2.36 mm) sieve through plus No. 100 (0.15 mm) sieve material; • if any part of an ACHM Binder Course or an ACHM Ba se Course is within four inches (100 mm) of the paveme nt surface, the binder or base course lift shall compl y with the angularity requirements for the top four inches (10 0 mm) of pavement;
247 • the gyratory compactor used in design, quality con trol, and acceptance testing must be a type evaluated by a Su perpave Center and must meet the testing protocols for gyra tory compactors. Gyratory compactors shall be calibrate d in accordance with AASHTO T 312 and the manufacturer’s recommendations. Documentation of calibration shal l be made available to the Engineer upon request. • the Voids in Mineral Aggregate (VMA) ranges will be as shown in Tables 405-1, 406-1, 407-1, or 407-2, as appropriate; • the minimum requirement for one fractured aggregate face will be 98% and 80% for two fractured faces; • wheel tracking test results will be determined usin g AHTD Test Method 480. • water sensitivity will be determined using AHTD Tes t Method 455A. Copies of AHTD Test Methods are available from the Department. The maximum number of gyrations (N max ) will be shown on the plans. Asphalt binder shall comply with the requirements o f AASHTO M 320 Table 1, except the Direct Tension requiremen ts are deleted, and shall be from sources that have executed a cert ification agreement with the Department. PG 70-22 and PG 76- 22 asphalt binders shall be production straight run binders th at are modified by using either a SB, SBS or SBR to achieve the specif ied grade. PG 70-22 and PG 76-22 asphalt binders shall meet a minimum elongation recovery of 40% and 50%, respectively, w hen tested on the original binder at 77º F (± 1º F) [25º C (± 0.5 º C)], in accordance with AASHTO T 301. Additives shall be approved by the Engineer. If an anti-strip additive is needed, a heat stable liquid anti-strip additive from the Qualified Products List shall be added at the rate of 0.5% or 0.75% by weight of the asphalt binder as determined by laboratory analysis. The maximum theoretical densit y computed from the specific gravity as determined by the Rice method (AASHTO T 209) shall be included in the mix designs . The Contractor shall compute the effective specific gra vity. A correction factor, accounting for the difference in the VMA(ac tual) determined by bulk specific gravity and the VMA(effective) det ermined by the effective specific gravity, shall be shown on the m ix design. The mix design for each type of asphalt mix shall meet the design
248 criteria for asphalt binder content, Air Voids (AV) , Voids in Mineral Aggregate (VMA), fines to asphalt ratio, aggregate gradation, water sensitivity, and wheel tracking test. The Contractor certified mix design shall provide f or the design requirements for asphalt binder content, AV, VMA, f ines to asphalt ratio, aggregate gradation, and water sensitivitys pecified for the particular mix. The mix design gradation must fall within the maste r gradation limits for the specified type of mix. If an acceptable pavement is not produced and it is determined that the accepted mix design is at fault, paving op erations shall be stopped and the Contractor shall prepare a new mix design. The processing of proposed changes or new designs shall follow the same procedures as the initial mix designs.
404.02Mixture Requirements. Asphalt mixtures will be
designed and tested to meet the requirements specif ied in Sections 405, 406, and 407.
404.03Mixture Substitutions. Substitutions of specified
courses will be allowed only on shoulders, leveling , and incidental or temporary construction as follows: 1) ACHM Base Course (1-1/2 ″ [ 37.5 mm ]) may be replaced with: ACHM Binder Course (1 ″ [25 mm]) ACHM Surface Course (1/2 ″ [ 12.5 mm ]) ACHM Surface Course (3/8 ″ [ 9.5 mm ]) 2) ACHM Binder Course (1 ″ [25 mm]) may be replaced with: ACHM Surface Course (1/2 ″ [ 12.5 mm ]) ACHM Surface Course (3/8 ″ [ 9.5 mm ]) 3) ACHM Surface Course (1/2 ″ [ 12.5 mm ]) may be replaced with: ACHM Surface Course (3/8 ″ [ 9.5 mm ]) Mixture substitution will be at the planned rate fo r the material for which the substitution is being made and shall use the specified asphalt binder grade. Measurement for payment of a ll components of the mix will be based on the accepted mix design for the type specified on the plans or on the accepted mix desig n for the type used, whichever results in the lower cost per ton ( metric ton) of mix to the Department. If no accepted mix design for t he type specified on the plans is available, the mixture composition for payment will be based on the composition shown on the plans as t he basis of estimate for the plan type or on the accepted mix d esign for the mix
249 actually used, whichever results in the lower cost per ton (metric ton) of mix to the Department.
404.04Quality Control of Asphalt Mixtures. The Contractor
shall perform all applicable quality control sampli ng and testing of the asphalt mixtures used on the project. The Contractor is responsible for product quality c ontrol during handling, blending, mixing, storing, transporting, and placement operations, and for necessary adjustments in propor tioning of the materials to produce the accepted mix design within the tolerances specified for the mix. Adjustments to the accepted mix design to conform to actual production values without re-desi gn of the mixture shall be based on production of the mixture at a target value of 4.0% Air Voids (AV) for PG 76-22 mixes and 4.5% Air Voids
binder content not less than that specified in the accepted mix design. The VMA shall be within the specified limi ts for the adjustment to be acceptable. The accepted mix design shall be field verified by the Contractor at the start of mix production or after an interruption of more than 90 calendar days. The asphalt mixture shall be verified by testing mix that has been produced through the plant using the aggregate proportions shown on the accepted mix design. The mix will be considered to be verified if test v alues for air voids, asphalt binder content, and VMA are within t he compliance limits shown in Table 410-1, and when the accepted mix design has been produced within the gradation tolerances accor ding to Subsection 404.04. After verification of the initial design, the Contr actor may elect to make adjustments in aggregate proportions to vary t he accepted mix design gradations and bring the mix properties near the center of the compliance limits. If these adjustments are made a nd the plant produced mix has the desired properties, the Contra ctor may request that a field mix design be accepted by the Engineer . If this is acceptable to the Engineer, the Contractor will be notified in writing. If other changes to the accepted mix design are des irable, the Contractor must first produce another laboratory mi x design, submit it to the Engineer for review and acceptance, and f ollow the verification procedures that are described above.
250 The Contractor shall perform all applicable quality control sampling and testing required to ensure that the co mpleted asphalt pavement complies with all requirements of the spec ifications. Quality control sampling and testing by the Contrac tor shall be performed in a qualified laboratory by a certified technician. Requirements for technician certification and labor atory qualification are contained in the Department’s Manual of Field Sampling and Testing Procedures . Quality control sampling and testing shall be accom plished in a timely manner. Sampling and testing shall be planned and conducted so that a representative sample is obtained and tested. The Contractor shall determine the specific locatio ns for samples and frequency of sampling for quality control, exce pt the minimum frequency which is listed below for aggregate gradation shall be used. In addition, the Contractor shall be require d to perform acceptance sampling and testing at specific times a nd/or locations specified by the Engineer according to Subsection 4 10.09. The Contractor may use the results of these required te sts in their quality control program. If the accepted mix design is not being produced as defined by the accepted mix design, and if the mix cannot be a djusted within the tolerances of the accepted mix design to achiev e the specified mix properties, production shall be discontinued. A new mix design shall be developed and submitted for review and acc eptance. Sieve tolerances shall be as tabulated below. Mix Design Tolerances Sieve Size (mm) Tolerance (%) 1" (25.0) ±7.0 3/4" (19.0) ±7.0 1/2" (12.5) ±7.0 #4 (4.75) ±7.0 #8 (2.36) ±7.0 #16 (1.18) ±4.0 #30 (0.60) ±4.0 #50 (0.30) ±4.0 #100 (0.15) ±4.0 Sampling shall be performed according to AASHTO T 1 68 and AHTD 465, except that the number and locations for sampling shall
251 be as specified in this Subsection and in Subsectio n 410.09. Test methods shall be as shown below: Property Test Method(s) (NOTE 1) Aggregate Gradation AASHTO T 30, AHTD 460, or AASHTO T 308 1 per 750 metric tons (750 tons) minimum Asphalt Binder Content (NOTE 4) AHTD 449/449A or AASHTO T 308 Stability AASHTO T 245 Air Voids (AV) (NOTE 2) AASHTO T 269 Voids in Mineral Aggregate (VMA) AHTD 464 Density - Maximum Theoretical AASHTO T 209 Density (Field) AASHTO T 166 or AHTD 461 Water Sensitivity (NOTE 3) AHTD 455A Wheel Tracking Test AHTD 480
NOTE 1: Where alternate test methods are shown, the metho d used shall be at the Contractor's option. All testing for quality control and acceptance shall be performed on samples of the plant mixed product. Field densities and samples to inve stigate segregation shall be taken from the roadway after c ompaction; all other samples shall be taken from trucks at the pla nt. NOTE 2: Test for AV on samples prepared by gyratory compactor according to the volumetric mix design pr ocedures in AASHTO M 323. NOTE 3: The Water Sensitivity shall be determined at leas t once during the first three days of production of e ach type mix; during the first three days of production of any ne w mix design; and/or during the first three days of production af ter an interruption of 90 calendar days or more. If the water sensitiv ity falls more than 10 percentage points below that specified for the t ype mix, production shall cease and a new mix design will be required. NOTE 4: Department test results for asphalt binder conten t will be determined by AHTD 449/449A (nuclear asphalt con tent gauge) exclusively. In the event of disagreement between the test results from a nuclear gauge and test results from an ignition oven, the
252 nuclear gauge results shall take precedence over th e ignition oven results. Sampling and testing for acceptance and adjustment of payment will be performed as specified in Subsection 410.09 . The Contractor shall furnish a building for the use of the Department's plant inspector according to Subsectio n 409.03(h). This building shall be separate and independent of the Contractor's facilities and equipment for performing quality con trol sampling and testing. The "separate and independent" requiremen t may be met by space in a building that is also used by the Contra ctor or supplier, provided that the space otherwise meets all requirements of Subsection 409.03(h); is physically separated from the rest of the building by a solid wall; and has an outside entrance with all keys placed in the custody of the Engineer. The Contractor shall provide an opportunity for the Engineer to observe all quality control sampling and testing pr ocedures. The Contractor's quality control personnel may observe the AHTD project personnel during acceptance sampling and te sting for the purpose of comparing sampling and testing procedures. The Contractor shall maintain a daily plot of all t est results, and make the plots available to the Engineer. Upon com pletion of work on the item these plots shall be furnished to the R esident Engineer for inclusion in the project files. The Resident E ngineer will make acceptance test results available to the Contractor 's personnel. If the test results show that the material is outsi de the mix design limits, is widely varying, or is consistently margi nal, corrective action shall be taken. Corrective actions taken sh all be based on the Contractor's quality control test results. The Dep artment's asphalt plant inspector will be notified of all proposed co rrective actions before their implementation. Each individual aggre gate cold feed may be adjusted no more than an amount that is suff icient to produce the specified AV and VMA and that is within the tolerances for the accepted mix design. If excessive changes are required, production will be suspended and a new mix designs hall be developed according to the applicable specifications. Use of nuclear asphalt content gauges is regulated by the Radiation Control and Emergency Management Programs of the Arkansas State Department of Health. If the Contra ctor elects to use a nuclear gauge in his quality control program, he shall be 405 253 responsible for meeting and following all licensing and use requirements.
404.05Method of Measurement and Basis of Payment. Design
and Quality Control of Asphalt Mixtures will not be paid for separately, but full compensation therefor will be considered included in the contract unit prices bid for the va rious types of asphalt concrete hot mix used on the project.