10-31 1010 -2 Aggregate for Plan T Mixed Cement Treated Base Course
Provide a ggregate meeting Article 1010 -1, except as modified herein . Sources of aggregate will not be approved unless the material has a percentage of wear of not greater than 65% . AGGREGATE FOR ASPHALT PAVE MENTS AND SURFACE TREATMENTS 1012 -1 AGGREGATE FOR ASPHALT PLANT MIXES
A.General Design the asphalt plant mix with coarse and fine aggregate that meet Section 1005, except as noted herein. Size, uniformly grade and combine the aggregate fractions in such proportions that the resulting mixture meets the grading and physical requirement s of these specifications for the specified mix type. Materials that will not produce a mixture within the design criteria required by these s pecifications will be rejected, unless otherwise approved by the Engineer . The consensus property criteria in Tab le 1012- 1 apply to the design aggregate blend. Source property criteria apply to individual aggregate sources. For all dense -graded surface course mixes, that are the top or final layer, limit the amount of coarse aggregate or fine aggregate produced from crystalline limestone, crystalline - dolomitic limestone or marble to no more than 50% of the total amount of coarse aggregate or fine aggregate in the asphalt mixture. For open- graded asphalt friction course and ultra - thin bonded wearing course, do not us e aggregates produced from crystalline limestone, crystalline -dolomitic limestone or marble.
B.Coarse Aggregate
1.General Use coarse aggregate consisting of crushed stone, crushed gravel, a mixture of uncrushed gravel with either crushed stone or crushed grave l or other inert material having similar characteristics. Provide coarse aggregate composed of clean, tough, durable fragments free from an excess of flat or elongated pieces and free of organic matter and deleterious substances. Use coarse aggregate from sources participating in the Department ’s Aggregate QC/QA Program as described in Section 1006. A list of sources participating in the Department ’s Aggregate QC/QA Program in North Carolina and adjoining states is available from the Materials and Tests U nit in Raleigh.
2.Gradation Use standard size coarse aggregate meeting Table 1005 -1 and these Standard Specifications unless otherwise approved by the Engineer .
3.Coarse Aggregate Angularity (Fractured Faces) Use coarse aggregate meeting Table 1012 -1 for coars e aggregate angularity (fractured faces) when tested in accordance with ASTM D5821.
4.Flat and Elongated Pieces Use coarse aggregate meeting Table 1012 -1 for flat and elongated pieces when tested in accordance with ASTM D4791 on the No. 4 sieve and larger wi th a 5:1 aspect ratio (maximum to minimum) for all pavement types, except there is no requirement for Types S4.75A and S9.5B.
10-32 (5) Soundness
The maximum weighted average soundness loss of individual coarse aggregate sources when subjected to 5 cycles using sodi um sulfate when tested in accordance with AASHTO T 104 is 15%. TABLE 1012 -1 AGGREGATE CONSENSUS PROPERTIESA Mix Type Coarse Aggregate AngularityB Fine Aggregate Angularity % Minimum Sand Equivalent % Minimum Flat and Elongated 5 : 1 Ratio % Maximum Test Method ASTM D5821 AASHTO T 304 AASHTO T 176 ASTM D4791 S4.75A ; S9.5B 75 / - 40 40 - S9.5C ; I19.0C; B25.0C 95 / 90 45 45 S9.5D 100 / 100 45 50 OGFC 100 / 100 45 45 UBWC 100 / 85 45 45
A.Requirements apply to the design aggregate blend.
B.95/90 denotes that 95% of the coarse aggregate has one fractured face and 90% has 2 or more fractured faces.
6.Toughness (Resistance to Abrasion) The maximum allowable percentage of loss of each individual coarse aggregate source for all plant mix types except open- graded asphalt friction course, shall be 55% when tested in accordance with AASHTO T 96. The maximum percentage loss for aggregate used in OGFC shall be 45%. The percentage loss for aggregate used in UBWC shall be no more than 35%.
7.Deleterious Materials The maximum allowable percentage by weight of clay lumps and friable particles in individual aggregate sources shall be 1 % when tested i n accordance with AASHTO T 112.
8.Durability (Micro -Deval test) The maximum allowable abrasion loss for aggregate used in UBWC shall be 18% when tested in accordance with AASHTO T 327.
C.Fine Aggregate
1.General Use fine aggregate that is consistently graded from coarse to fine and consists of natural sand, stone screenings, or a blend of natural sand and stone screenings. Use aggregate composed of rough surfaced and angular grains of quartz or other hard durabl e rock. Use fine aggregate f rom sources participating in the Department ’s Aggregate QC/QA Program as described in Section 1006. A list of sources participating in the Department ’s QC/QA Program in North Carolina and adjoining states is available from the Department ’s Materials and T ests Unit in Raleigh. If a natural sand source is owned by the same owner as the asphalt plant where the material is used, participation in the Aggregate QC/QA Program is not required.
10-33 Furnish sand from approved sources. Do not use sources contaminated by industrial
waste. A sufficient number of samples of fine aggregate, but in no case less than three , will be taken to indicate any variation within any stockpile or source of supply. Do not use fine aggregate containing sticks, roots, trash, visible lumps of clay, or other unsatisfactory material unless all undesirable material is removed to the satisfaction of the Engineer before the aggregate is used in the asphalt mixture. Use natural sand that is non- plastic when tested in accordance with AASHTO T 90. Produce stone screenings from stone that has a maximum percentage of wear of 55 % when tested in accordance with AASHTO T 96 using test grading A.
2.Gradation Use stone screenings that are consistently graded with not more than 20% by weight passing the No. 200 sieve when tested by dry sieving in accordance with AASHTO T 27. Use natural sand that is consistently graded.
3.Clay Content (Sand Equivalent) Use a fine aggregate blend that has a minimum sand equivalent percentage as indicated in Table 1012- 1 when te sted in accordance with AASHTO T 176.
4.Soundness The maximum weighted average soundness loss of individual fine aggregate sources when subjected to 5 cycles using sodium sulfate shall be 15% when tested in accordance with AASHTO T 104 . Natural sand that contains grains of questionable hardness will be subjected to 5 cycles of the soundness test. The weighted average loss shall be not more than 15%. The soundness test will be performed before establishing the mix design.
5.Deleterious Materials The maximum percentage by weight of clay lumps and friable particles in individual fine aggregate sources shall be 1 % when tested in accordance with AASHTO T 112.
6.Fine Aggregate Angularity Use a fine aggregate blend that has a minimum fine aggregate angularity as indicated in Table 1012- 1 when tested in accordance with AASHTO T 304, Method A.
D.Mineral Filler Use mineral filler consisting of limestone dust, dolomite dust, Portland cement, or other inert mineral matter that conforms to AASHTO M 17.
E.Reclaimed A sphalt Shingles (RAS) For use in asphalt mix, Reclaimed Asphalt Shingles (RAS) can be either manufacturer - waste shingles or post -consumer shingles that have been processed into a product that meets the requirements of this section. Manufacture r-waste RAS (MRAS) are processed shingle materials discarded from the manufacturing of new asphalt shingles. It may include asphalt shingles or shingle tabs that have been rejected by the shingle manufacturer. Post-consumer RAS (PRAS) are processed shingle materials r ecovered from mixed roofing material scrap removed from existing structures. Tear -off shingle scrap must be sorted and other r oofing debris, including nails, plastic, metal, wood, coal tar epoxy, rubber materials, or other undesirable components, shall be removed. This sorting of the scrap must be done prior to grinding of the PRAS for use in asphalt production.
10-34 Sample and test PRAS for asbestos and provide results demonstrating that the bulk samples
contain less than one percent of asbestos containing material in accordance with Federal, State of North Carolina , and Local regulations. Use NC -accredited Asbestos Inspectors or Roofing Supervisors to sample the PRAS to meet the above criteria. Maintain records on- site indicating shingle source (s), asbestos operation plan approved by Division of Public Health’s Health Hazards Control Unit, and all asbestos analytical reports. All documentation will be subject to review by the Department . Process RAS by ambient grinding or granulating methods such that 100% of the particles will pass the 9.50 mm (3/8 inch) sieve when tested in accordance with AASHTO T27. Perform sieve analysis on processed asphalt shingles prior to ignition or solvent extraction testing . RAS shall contain no more than 0.5% by total cumulative weight of d eleterious materials . These materials include, but are not limited to, excessive dirt, debris, concrete, metals, glass, paper, rubber, wood, plastic, soil, brick, tars, or other contaminating substances. Blend RAS with fine aggregate, meeting the requirements of this Section, if needed to keep the processed material workable. Any stockpile containing RAS will be considere d a RAS stockpile and will be limited in mixtures as prescribed in Article 610-3. MRAS and PRAS shall not be blended together for the production of hot mix asphalt.
1.Mix Design RAS Incorporate RAS from stockpiles that have been tested for uniformity of gradation and binder content prior to use in an asphalt mix design.
2.Mix Production RAS New Source RAS is defined as acceptable material which was not included in the stockpile when samples were taken for mix design purposes. Process new source RAS so that all materials will meet the gradation requirements prior to introduction into the plant mixer unit. After a stockpile of processed RAS has been sampled and mix designs made from these samples, do not add new source RAS to the original stockpile without prior field testing to e nsure gradation and binder uniformity. Sample and test new source RAS before blending with the existing stockpile. Store new source RAS in a separate stockpile until the material can be sampled and tested for comparison with the origina l recycled mix design data. New source RAS may also be placed against the existing stockpile in a linear manner provided it is sampled for mix design conformity prior to its use in the recycled mix. Store RAS materials in such a manner as to prevent conta mination. Field approval of new source RAS will be based on T able 1012- 2 and volumetric mix properties on the mix with the new source RAS included. Provided these tolerances are met, volumetric properties of the new mix will then be performed. If all vol umetric mix properties meet the mix design criteria for that mix type, the new source RAS may continue to be used. If the gradation, binder content, or any of the volumetric mix properties are not within the allowable tolerances of T able 1012- 2, do not us e the new source RAS unless approved by the Engineer. The Contractor may elect to either not use the stockpile, to request an adjustment to the JMF, or to redesign the mix.
10-35 Table 1012 -2
NEW SOURCE RAS BINDER AND GRADATION TOLERANCES (Apply Tolerances to Mix Design Data) Pb % ± 2.5 Sieve Size, mm Tolerance 4.75 ± 2.36 ± 1.18 ± 0.300 ± 0.150 ± 0.075 ± 2.0
F.Reclaimed Asphalt Pavement (RAP)
1.RAP Classifications During production i ncorporate RAP from stockpiles or other sources tested for uniformity of gradation and binder content before use in an asphalt mix. Ensure that no deleterious material is allowed in any stockpile. When multiple stockpi les of recycled material are used during production, erect and maintain signs satisfactory to the Engineer properly identifying each stockpile. Use RAP that meets all requirements specified for the following classifications.
a.Millings Existing RAP that is r emoved from its original location by a milling process as specified in Section 607. Millings shall have a uniform gradation and binder content and all materials must pass a 1 1/2 inch sieve before introduction into the plant mixer unit.
b.Processed RAP RAP that is processed by crushing, screening and/or blending to produce a uniform gradation and binder content. Process ed RAP shall have a uniform gradation and binder content and will pass a 1 inch sieve before introduction into the plant mixer unit.
c.Fractio nated RAP RAP that is processed by crushing, screening and/or blending into one or two stockpiles . When only one fractionated RAP stockpile is used, the stockpile shall only contain material passing the 5/8 inch sieve. If a second coarse fraction is used, the coarse stockpile shall only contain material passing the 1 inch sieve and retained on the 5/8 inch sieve . The Engineer may allow the Contractor to use an alternate screen to fractionate the RAP. The maximum percentages of fractionated RAP may be co mprised of coarse, fine, or the combination of both. Use a separate cold feed bin for each stockpile of fractionated RAP introduced into the plant mixer unit . Perform gradation and asphalt content tests at a rate of one per 1 ,000 tons of RAP, with at least five tests per stockpile to determine the asphalt content and gradation. Assure that no deleterious material is allowed to contaminate any stockpile. The Engineer may reject by visual inspection any stockpiles that are not kept clean, separated and free of foreign materials. For the Fractionated RAP to be considered for approval, the gradation and asphalt content shall be uniform. Individual test results, when compared to the target, will be accepted if within the tolerance s listed in Table 1012 -3.
10-36 Table 1012 -3
FRACTIONATED RAP GRADATION AND BINDER TOLERANCESA (Apply Tolerances to Mix Design Data) Pb % ± 0.3% Sieve Size, mm Tolerance 25.0 ± 5% 19.0 ± 5% 12.5 ± 5% 9.50 ± 5% 4.75 ± 5% 2.36 ± 4% 1.18 ± 4% 0.300 ± 4% 0.150 ± 4% 0.075 ± 1.5%
A.If more than 20% of the individual sieves are out of the gradation tolerances, or if more than 20% of the asphalt binder content test results fall outside the appropriate tolerances, the RAP shall not be used in asphalt mix unless the RAP representing the failing tests is removed from the stockpile. Do not add additional material to any fractionated RAP stockpile, unless otherwise approved by the Engineer. Maintain a record system for all fractionated RAP stockpiles at the plant site. Include at a minimum the following: Stockpile identification and a sketch of all stockpile areas at the plant site; all RAP test results (including asphalt content, gradation and asphalt binder characteristics).
2.RAP Management During Production New source RAP is any acceptable material that was not included in the stockpile or other source when samples were taken for mix design purposes . After a stockpile of millings, processed RAP or fractionated RAP has been sampled and mix designs made from these samples, do not add new source RAP to the original stockpile without prior field testing to insure gradation and binder uniformity. Sample and test new source RAP to ensure it meets one of the RAP Classifications in Subarticle 1012- 1(F)(1) before bl ending with the existing stockpile. Store new source RAP in a separate stockpile until the material can be sampled and tested for comparison with the original recycled mix design data. New source RAP may also be placed against the existing stockpile in a linear manner provided it is sampled for mix design conformity before its use in the recycled mix. Unprocessed RAP is asphalt material that was not milled and/or has not been processed to obtain a uniform gradation and binder content and is not representat ive of the RAP used during the applicable mix design. Unprocessed RAP shall not be incorporated into any JMFs before processing. Different sources of unprocessed RAP may be stockpiled together provided it is generally free of contamination and will be processed before use in a recycled mix. RAP contamination in the form of excessive dirt, debris, clean stone, concrete, etc. will not be allowed. Incidental amounts of dirt, concrete and clean stone may be acceptable. Unprocessed RAP may be processed and then classified as a new source RAP as described above. Field approval of new source RAP will be based on Table 1012- 4 and volumetric mix properties in the mix with the new source RAP included. Provided the Table 1012- 3 tolerances are met, volumetric prop erties of the new mix will then be performed. If all volumetric mix properties meet the mix design criteria for that mix type, the new source RAP may continue to be used.
10-37 If the gradation, binder content, or any of the volumetric mix properties are not wi thin
the allowable tolerances of Table 1012 -4, do not use the new source RAP unless approved by the Engineer. The Contractor may elect to either not use the stockpile, to request an adjustment to the JMF, or to redesign the mix. TABLE 1012 -4 NEW SOURCE RAP GRADATION AND BINDER TOLERANCES (Apply Tolerances To Mix Design Data) 0 - 20% RAP 20 - 30 % RAP > 30 % RAP Pb, % ± 0.7% ± 0.4% ± 0.3% Sieve Size, mm Mix Type Mix Type Mix Type Base Inter. Surf. Base Inter. Surf. Base Inter. Surf. 25.0 ±10 - - ±7 - - ±5 - - 19.0 ±10 ±10 - ±7 ±7 - ±5 ±5 - 12.5 - ±10 ±6 - ±7 ±3 - ±5 ±2 9.50 - - ±8 - - ±5 - - ±4 4.75 ±10 - ±10 ±7 - ±7 ±5 - ±5 2.36 ±8 ±8 ±8 ±5 ±5 ±5 ±4 ±4 ±4 1.18 ±8 ±8 ±8 ±5 ±5 ±5 ±4 ±4 ±4 0.300 ±8 ±8 ±8 ±5 ±5 ±5 ±4 ±4 ±4 0.150 - - ±8 - - ±5 - - ±4 0.075 ±4 ±4 ±4 ±2 ±2 ±2 ±1.5 ±1.5 ±1.5 1012 -2 AGGREGATES FOR ASPHALT SURFACE TREATMENT
A.General Use coarse aggregate consisting of crushed stone, crushed gravel, or other inert material having similar characteristics. Adequately wash coarse aggregate so it is free from clay, loam, dust and other adherent materia ls. Adequately clean all fine aggregate so it is free from sticks, roots, visible lumps of clay or other unsatisfactory material before use.
B.Gradation Use coarse aggregate for mat and seal coat and AST as required by Section 660, unless otherwise required by the contract. Use aggregate meeting the applicable gradation requirements of Table 1005- 1. Remix aggregate that has become segregated until it meets the applicable gradation requirements.
C.Fractured Faces Use coarse aggregate that contains at least 75 % by weight of crushed pieces having 2 or more fractured faces and at least 90 % by weight of crushed pieces having one or more fractured faces on that portion retained on the No. 4 sieve.
D.Soundness The maximum weighted average loss of either coarse or fine aggregate when subjected to 5 cycles using sodium sulfate when tested in accordance with AASHTO T 104 is 15%.
E.Toughness (Resistance to Abrasion) The maximum percentage loss of co arse aggregate for asphalt surface treatment wh en tested in accordance with AASHTO T 96 is 55%.
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 447–453 of 857.