SECTION 305 — BITUMINOUS CONCRETE BASE
COURSE (STANDARD) AND BITUMINOUS CONCRETE BASE COURSE (HEAVY DUTY)
305.1 DESCRIPTION —
This work is construction of a plant-mixed standard bituminous concrete base course and heavy duty bituminous concrete base course. When placed on subgrade, it includes the preparation of subgrade as specified in Section 210.
305.2 MATERIAL —
(a) Bituminous Material.
One of the following:
1. Virgin or Recycled Mix containing 5 to 15% RAP.
Asphalt Cement, Class AC-20, Section 702. Asphalt Cement, Class AC-10, Section 702 may be used in lieu of AC-20 in Districts 1-0, 2-0, 3-0, 4-0, 9-0, 10-0, 11-0, 12-0 and 5-0 (Monroe, Carbon, and Schuylkill Counties only), for standard bituminous mixture.
2. Recycled Mix containing 16% or more RAP.
1. Fine Aggregate.
Section 703.1. Use 75% manufactured sand in the fine aggregate portion of the heavy duty bituminous mixture. Increase or decrease this percentage to meet other specification criteria when approved by the Engineer.
2. Coarse Aggregate.
Type A or Type B, Section 703.2. Coarse aggregate may be obtained from more than one source; however, start and complete any portion of the base course with aggregate from one source, or with an acceptable blend. Type A, No. 2A coarse aggregate may be used if the combined gradation meets the requirements in Table A.
3. Reclaimed Asphalt Pavement Material or Reclaimed Aggregate Material.
Section 403.2(b) or (c)
(c) Filler for Use in Heavy Duty Bituminous Mixture.
Section 703.1(c)1. Do not use flyash as a filler for heavy duty bituminous mixture.
(d) Composition of Mixture.
As follows, except conform to Section 403.2(d) for recycled mix.
1. Review of Quality Control Plan and Job-Mix Formulas.
Prepare a quality control plan, as specified in Section 106, and submit it for review at the start of the project and at least annually thereafter. Do not start actual work until the quality control plan has been reviewed and the job-mix formula has been submitted.
If the source of material changes, have a new job-mix formula submitted before using the new material.
When unsatisfactory results or other conditions make it necessary, a new job-mix formula may be required.
Establish and use the job-mix formula within the limits of Table A. Conform to the following Marshall values, when tested in accordance with PTM No. 705:
1.a Bituminous Concrete Base Course (Standard).
Stability Value at 140F
not less than 700 pounds, when maximum aggregate size is not over 1 1/2-inches, with a 4-inch test specimen, or
not less than 1,500 pounds, when maximum aggregate size is over 1 1/2-inches, with a 6-inch test specimen.
6 to 16 inclusive, with a 4-inch test specimen; or
9 to 24 inclusive, with a 6-inch test specimen.
These values are not required for daily plant control.
1.b Bituminous Concrete Base Course (Heavy Duty).
Vary the percentage of material passing the No. 200 and/or No. 8 Sieves in the heavy duty bituminous concrete base course mixture (if required for the job-mix formula) within the tolerance band specified in Table A, with the approval of the Engineer.
Compact Marshall specimens with 75 blows on each side. Control all operations in design and production of bituminous mixtures to comply with the following Marshall values:
Stability Value at 140F
not less than 2,000 pounds with a 4-inch test specimen, or
not less than 4,500 pounds with a 6-inch test specimen, for the job-mix formula; and
not less than 1,800 pounds with a 4-inch test specimen, or
not less than 4,000 pounds with a 6-inch test specimen, during production.
not less than 6 nor more than 16 with a 4-inch test specimen, or
not less than 9 nor more than 24 with a 6-inch test specimen.
Percentage of unfilled voids to be 5.0% for the job-mix formula. Voids in daily plant compacted Marshall specimens not to exceed the master range of 3.5% to 6.5% voids. Compliance with these criteria is acceptable if 90% of the determinations per project are within the specified tolerance band.
Provide minimum percent VMA (Voids in Mineral Aggregate) of 13 for the job-mix formula. Provide minimum percent VMA of 12.0 during production. Compliance with these criteria is acceptable, if 90% of the determinations per project meet the stated minimums.
The composition limits in Table A are to govern mixtures and are the maximum and minimum allowed. Analyze samples of the completed mixture, in accordance with the reviewed quality control plan, for compliance with Table A.
Perform the test specified in PTM No. 740, daily until no problems are evident; then testing may be reduced to once a week unless a significant change is determined in accordance with the requirements of Bulletin 27. Provide the project with the running average of the last five consecutive values. Show this value on the density sample identification form submitted from the project. Use the maximum specific gravity value to calculate the theoretical density of the paving mixture.
2.a. Standard Bituminous Concrete Base Course Mixture.
Maintain the bitumen content within ±0.8 of one percentage point of the job-mix formula for individual test samples (n = 1) and within ±0.5 of one percentage point for multiple test samples (n = 3 to n = 7).
2.b. Heavy Duty Bituminous Concrete Base Course Mixture.
Produce the bituminous mix within the job-mix formula tolerances specified in Section .401.2(d)2., Table B.
Composition of Mixture — Table A
(Mass Percent Passing Square Openings,
Based on Laboratory Sieve Tests)
Required Composition of Mixture
Bitumen % by Weight
Stone or Gravel
3. Acceptance of Mixture.
3.a. Standard Bituminous Concrete Base Course.
Obtain material certification from the material producer. Send certification to the Inspector-in-Charge within one working day following quality control tests for bitumen determination and sieve analysis of the mixture.
The mixture will be accepted by certification at the plant when quality control tests conform to the job-mix formula within the tolerance specified in Section 305.2(d)2. Acceptance by certification may be suspended as specified in Section 401.3(q).
The acceptance values will be:
asphalt percent by weight, and
percent passing the No. 8 sieve.
If at any time during the course of the work either of the acceptance values deviates in consecutive tests, immediately make necessary changes to comply with the job-mix formula. If the material cannot be brought into compliance within 150 tons of production, suspend operations and notify the Inspector-in-Charge. Do not resume production for the project until the Engineer has reviewed any corrective action.
If the asphalt (bitumen) content deviates from the tolerances specified in Section 305.2(d)2., the material represented by such testing will be considered defective and acceptance will be determined as specified in Section 401.3(p).
3.b. Heavy Duty Bituminous Concrete Base Course.
305.3 CONSTRUCTION —
Section 401.3 or 403.3 with additions and modifications as follows:
(a) Weather Limitations.
Replace with the following:
Do not place base course on surfaces that are wet or at a temperature of 35F or lower, or when the air temperature is 35F or lower. When work is halted
because of weather conditions, limited tonnage en route to the project may be placed, if permitted.
Spreading and Finishing.
Add the following:
If the base course is more than 5 inches in compacted depth, place in two or more layers of approximately equal depth, with no layer less than 2 1/2-inches nor more than 5 inches in depth. Place the base course in layers not less than 4 inches in depth when the air temperature is below 40F.
(k) Surface Tolerance.
Replace the requirement for correcting irregularities with the following:
Satisfactorily correct irregularities of more than 1/4-inch.
(m) Tests for Depth.
Replace with the following:
Drill one test hole, where directed, for each 3,000 square yards, or less, of completed base course.
The Engineer will measure the depth of the base course.
Remove and satisfactorily replace sections in which the depth is 1/2-inch or more deficient.
After depth measurements have been completed, backfill test holes with acceptable material, compact and seal. Additional test holes may be required to determine the extent of deficient areas.
In sections deficient in depth, start immediate correction at the point of determined deficiency. Proceed longitudinally and transversely until the depth meets the requirements.
(n) Protection of Courses.
Add the following:
Artificial cooling of completed heavy duty bituminous concrete base courses is prohibited.
305.4 MEASUREMENT AND PAYMENT —
(a) Bituminous Concrete Base Course (Standard).
Square Yard or Ton
(b) Bituminous Concrete Base Course (Heavy Duty).
Square Yard or Ton
Most Current Supplement
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