Atch_2_Asphalt_Specs.pdf

Asphalt Specifications Aggregates - Aggregates shall consist of crushed stone, crushed gravel, crushed slag, screenings, natural sand and mineral filler, as required. The portion of material retained on the 4.75 mm (No. 4) sieve is coarse aggregate. The portion of material passing the 4.75 mm (No. 4) sieve and retained on the 0.075 mm (No. 200) sieve is fine aggregate. The portion passing the 0.075 mm (No. 200) sieve is defined as mineral filler. Aggregate testing shall have been performed within 90 days of performing the mix design.

Coarse Aggregate - Percentage of Wear (ASTM C131) must not exceed 40. Aggregates with a higher percentage of wear may be specified, provided a satisfactory record under similar conditions of service and exposure has been demonstrated. Coarse aggregate shall consist of sound, tough, durable particles, free from films of material that would prevent thorough coating and bonding with the asphalt material and free from organic matter and other deleterious substances. The coarse aggregate particles shall meet the following requirements:

The sodium sulfate soundness loss shall not exceed 12 percent, or the magnesium sulfate soundness loss shall not exceed 18 percent after five cycles when tested in accordance with ASTM C88.

At least 75 percent by weight of coarse aggregate shall have at least two or more fractured faces when tested in accordance with COE CRD-C 171. Fractured faces shall be produced by crushing.

The particle shape shall be essentially cubical and the aggregate shall not contain more than 20 percent, by weight, of flat and elongated particles (3:1 ratio of maximum to minimum) when tested in accordance with ASTM D4791.

Slag shall be air-cooled, blast furnace slag, and shall have a compacted weight of not less than 1200 kg/cubic meter 75 lb/cu ft when tested in accordance with ASTM C29/C29M.

Clay lumps and friable particles shall not exceed 0.3 percent, by weight, when tested in accordance with ASTM C142/C142M.

Fine Aggregate - Fine aggregate shall consist of clean, sound, tough, durable particles. The aggregate particles shall be free from coatings of clay, silt, or any objectionable material and shall contain no clay balls. The fine aggregate particles shall meet the following requirements:

The quantity of natural sand (noncrushed material) added to the aggregate blend shall not exceed 15 percent by weight of total aggregate. The individual fine aggregate sources shall have a sand equivalent value greater than 45 when tested in accordance with ASTM D2419. The fine aggregate portion of the blended aggregate shall have an uncompacted void content greater than 45.0 percent when tested in accordance with ASTM C1252 Method A.

Clay lumps and friable particles shall not exceed 0.3 percent, by weight, when tested in accordance with ASTM C142/C142M.

Mineral Filler - Mineral filler shall be nonplastic material meeting the requirements of ASTM D242/D242M.

Aggregate Gradation - The combined aggregate gradation shall conform to gradations specified in the Gradation Table below, when tested in accordance with ASTM C136 and ASTM C117, and shall not vary from the low limit on one sieve to the high limit on the adjacent sieve or vice versa, but grade uniformly from coarse to fine. The JMF shall be within the specification limits.

Gradations (Table 6) Sieve Size (mm / Sieve

Percent Passing by Mass (%)

Airfield Surface Course

25.0 / 1” 100 19 / 3/4” 100

12.5 / 1/2” 90-100

9.5 / 3/8” 69-89

4.75 / No. 4 53-73

2.36 / No. 8 38-60

1.18 / No. 16 26-48

0.60 / No. 30 18-38

0.30 / No. 50 11-27

0.15 / No. 100 6-18

0.075 / No. 200 3-6

ASPHALT BINDER - PG 67-22 binder is preferred however if another grade is typically used it will be taken into consideration for CO approval. Asphalt binder shall conform to AASHTO M 320 Performance Grade (PG) 67-22. Test data indicating grade certification shall be provided by the supplier at the time of delivery of each load to the mix plant. Copies of these certifications shall be submitted to the Contracting Officer. The supplier is defined as the last source of any modification to the binder. The Contracting Officer Engineer may sample and test the binder at the mix plant at any time before or during mix production. Samples for this verification testing shall be obtained in accordance with ASTM D140/D140M and in the presence of the Contracting Officer Engineer.

These samples shall be furnished to the Contracting Officer Engineer for the verification testing, which shall be at no cost to the Contractor.

MIX DESIGN - NOTE: Use 75 blow Marshall hand-held hammer or 75 gyration Superpave for all pavements designed for tire pressures of 690 kPa (100 psi) or higher.

Develop the mix design. The asphalt mix shall be composed of a mixture of well-graded aggregate, mineral filler if required, and asphalt material. The aggregate fractions shall be sized, handled in separate size groups, and combined in such proportions that the resulting mixture meets the grading requirements of Table 6. No hot-mix asphalt for payment shall be produced until a JMF has been approved. The hot-mix asphalt shall be designed using hand-held hammer procedures contained in AI MS-2 and the criteria shown in Table 7 or designed using the Superpave gyratory compactor set at 75 gyrations. Samples shall be prepared at various asphalt contents and compacted in accordance with ASTM D6925. Laboratory compaction temperatures for Polymer Modified Asphalts shall be as recommended by the asphalt cement manufacturer. If the Tensile Strength Ratio (TSR) of the composite mixture, as determined by ASTM D4867/D4867M is less than 75, the aggregates shall be rejected or the asphalt mixture treated with an anti-stripping agent.

The amount of anti-stripping agent added shall be sufficient to produce a TSR of not less than 75. If an antistrip agent is required, it shall be provided at no additional cost to the Government.

JMF Requirements Submittals:

Marshall Mix Design Criteria Test Property 75 Blow Mix

Stability (N / pounds minimum) 9560 / 2150(1) Flow (0.25 mm / 0.01 inch) 8-16(2) Percent Air voids 4% Dust Proportion(3) 0.8-1.2 TSR, Minimum Percent 75% TSR Conditioned Strength (minimum kPa/psi) 415 / 60 Percent Voids in Mineral Aggregate (minimum)

Intermediate Courses 13% Surface Course 14%

Notes:

1. This is a minimum requirement. The average during construction shall be significantly higher than this number to ensure compliance with the specifications.

2. The flow requirement is not applicable for Polymer Modified Asphalts.

3. Dust Proportion is calculated as the aggregate content, expressed as a percent of mass, passing the 0.075 mm (No. 200 sieve), divided by the effective asphalt content, in percent of total mass

4. Calculate VMA in accordance with AI MS-2, based on ASTM D2726/D2726M bulk specific gravity for the aggregate.

Use the properties from the 75 Blow Mix column only.

Use Gradation 2 requirements for table 8.

RECYCLED HOT MIX ASPHALT - The amount of RAP shall be limited so the asphalt binder from the RAP does not exceed 30 percent of the total asphalt content. Recycled HMA shall consist of reclaimed asphalt pavement (RAP), coarse aggregate, fine aggregate, mineral filler, and asphalt cement. The RAP shall be of a consistent gradation and asphalt content and properties. RAP stockpiles shall be free from contamination, including coal-tar sealers. When RAP is fed into the plant, the maximum RAP chunk size shall not exceed 50 mm (2 inches). The individual aggregates in a RAP chunk shall not exceed the maximum size aggregate of the gradation specified in Table 6. The recycled HMA mix shall be designed using procedures contained in AI MS-2. The job mix shall meet the requirements of paragraph MIX DESIGN. RAP shall only be used for intermediate courses. The amount of RAP shall be limited so the asphalt binder from the RAP does not exceed 30 percent of the total asphalt content.

RAP Aggregates and Asphalt Cement - The blend of aggregates used in the recycled mix shall meet the requirements of paragraph AGGREGATES. The percentage of asphalt in the RAP shall be established for the mixture design according to ASTM D2172/D2172M using the appropriate dust correction procedure.

RAP Mix - The blend of new asphalt cement and the RAP asphalt binder shall meet the viscosity requirements in paragraph ASPHALT CEMENT BINDER. For PG graded asphalt binders adjust as follows:

For 0-20 percent recycled binder content - no change in binder selection.

For 20+ to 30 percent recycled binder content - select binder one grade softer than normal.

Laboratory Air Voids and Theoretical Maximum Density - Laboratory air voids will be calculated in accordance with ASTM D3203/D3203M by determining the Marshall density of each lab compacted specimen using the laboratory-prepared, thoroughly dry method in ASTM D2726/D2726M and determining the theoretical maximum density (TMD) of two of the sublots using ASTM D2041/D2041M. Laboratory air void calculations for each lot will use the average theoretical maximum density values obtained for the lot. The mean absolute deviation of the four laboratory air void contents (one from each sublot) from the JMF air void content will be evaluated and a pay factor determined from Table 2. All laboratory air void tests will be completed and reported within 24 hours after completion of construction of each lot. The TMD is also used for computation of compaction, as required in paragraph: Mat and Joint Densities above.

Mean Absolute Deviation - An example of the computation of mean absolute deviation for laboratory air voids is as follows:

Assume that the laboratory air voids are determined from 4 random samples of a lot (where 3 specimens were compacted from each sample). The average laboratory air voids for each sublot sample are determined to be 3.5, 3.0, 4.0, and 3.7. Assume that the target air voids from the JMF is 4.0. The mean absolute deviation is then: Mean Absolute Deviation = (|3.5 - 4.0| + |3.0 - 4.0| + |4.0 - 4.0| + |3.7 - 4.0|)/4 = (0.5 + 1.0 + 0.0 + 0.3)/4 = (1.8)/4 = 0.45 The mean absolute deviation for laboratory air voids is determined to be 0.45.

It can be seen from Table 2 that the lot's pay factor based on laboratory air voids, is 100 percent.