(A) Materials:
Coarse aggregate, deep strength, 20AA modified to
Minimum 50% crushed, div. 4.
Fine aggregate, 3fs, 3cs
Mineral filler 3mf
Bituminous materials - prime coat over aggregate bases shall be ms-op, or approved equal.
The contractor shall obtain approval from the structural/safety inspection division prior to starting work, on the source and particular type of course aggregate and bituminous materials he intends to use.
(B) Composition of mixture aggregate material:
Passing 3/4 inch sieve | 100% |
Passing ½ inch sieve | 95 - 100% |
Passing 3/8 inch sieve | 65 - 90% |
Passing No. 4 sieve | ----------- |
Passing No. 8 sieve | 45 - 70% |
Passing No. 30 sieve | 20 - 45% |
Passing No. 200 sieve | 2 - 10% |
Bitumen | 5 - 8% |
Slag aggregate may be used in the above mixtures provided the slag is air cooled blast furnace slag weighing not less than 85 lb. per cu. ft. (dry rolled material). Further, where slag is used, it can be anticipated that the mineral percentage used of bitumen by weight shall be 7%.
The proportions of composition of mixture shown hereinbefore may be varied between the percentage limits designated. A plant mix based on the marshal method of mix design, using a minimum stability of 1200, shall be established by a recognized, approved independent testing laboratory, such design to be approved by the structural/safety division, with all expenses associated therewith paid for by the contractor. The mix design shall be approved by the structural/safety division prior to the establishment of a paving schedule.
(C) Pavement thickness per course. For normal surfacing using asphaltic materials on aggregate base or existing asphalt surfaces, the minimum and maximum thickness per lift shall apply as set forth hereafter unless otherwise specified in supplemental specifications.
M.D.O.T. Designation | Minimum Thickness Inches | Maximum Thickness Inches |
20AA-NO. 1100 | 1.0 | 2.5 |
(D) Bond coat/prime coat. Bond coat for resurfacing shall be SSlh and shall be applied at the rate of 0.1 galons per sq. yard on existing concrete or asphalt pavement as well as between each course of new surfacing material. The material prime coat shall be applied on the compacted aggregate surface at a rate of 0.30 gallons per sq. yard. Bond coat and prime coat material shall be applied with a distributor to conform with specifications set forth in M.D.O.T. division 4.00.05 and at an application temperature in accordance with specifications in division 8.04.
(E) Testing.
(1) Mixture. Testing of the bituminous material in mixture shall be done in accordance with procedures set forth in division 4.00.14. The contractor shall bear the expense not only of removing the samples where directed by the structural/safety division but shall pay the cost of testing by a testing laboratory approved by the structural/safety division. Number and location of test samples shall be at the discretion of the structural/safety division, but shall not exceed two samples from each day’s work. Tests shall consist of a recovery test providing sieve analysis, asphalt content and percent of crushed aggregate.
(2) Cores. At the discretion of the structural/safety division a maximum of two cores shall be taken from any one site, or two cores per every 1000 sq. yards. Cores shall be taken to the full depth of the materials installed to verify thickness, asphalt content, graduation, percent crushed material and density. Costs for taking these cores and testing samples shall be borne by the contractor. If the cores indicate a deficiency in the thickness of any material, or if the materials do not meet the requirements of the specifications, no approval will be made until all deficiencies have been corrected to the satisfaction of the structural/safety division. Additional cores and material tests may be required to determine the extent of indicated deficiencies. Costs for these cores and subsequent testing shall be paid for by the contractor. Any additional aggregate thickness will not be a substitute for the specified thickness of the asphalt. The final thicknesses are considered as compacted thickness.
(F) Excavation. Earth excavation shall include all materials, asphalt, broken concrete, earth and miscellaneous fill that may be present. The area shall be excavated to the subgrade elevation to the exact cross section as shown on the plans and established in the field by the structural/safety division inspector. The subgrade shall be shaped to true and even lines by the use of patrol graders and rolled with minimum 10-ton rollers. Prior to placement of the subbase material, the structural/safety inspector shall approve the subgrade for elevation and compaction. If the subgrade is found not to be at the elevations as staked, the contractor shall degrade the area and the cost for rechecking the subgrade shall be paid for by the contractor. Excavated material shall be hauled from the site and disposed of by the contractor.
(G) Aggregate base course. This work shall consist of placing aggregate material on the prepared subgrade in accordance with the lines and grades shown on the plans. Base aggregate shall be limestone graded in accordance with and meeting the physical requirements of M.D.O.T., designation 22A, or 20AA aggregate. The total compacted thickness shall be as shown on the construction plans or as required by supplemental specifications. The compaction of the aggregate material shall be accomplished by means of vibrating type or pneumatic type roller, and balding aggregate surfacing with patrol graders, all in accordance with the construction method requirements of the current standard specifications of M.D.O.T. division 3, base course, articles 3.01.03, 3.01.04, 3.01.06, 3.01.07a and 3.01.08 except that the word “department” shall be replaced by “contractor”.
(H) Asphalt surface. After the aggregate subbase has been installed and approved by the structural/safety inspector a prime coat shall be applied as previously specified. Asphalt shall be M.D.O.T. No. 11Gc20AA modified to 50% crushed having a minimum stability of 1200. Asphalt shall be a minimum of two (2) separate lifts.
(I) Finished grade of asphalt. The finished elevation of the asphalt shall conform to the elevations as shown on the plans and established by the structural/safety division inspector in the field. Because of the need for proper drainage, asphalt not laid to such elevations may have to be removed and replaced by the contractor, at his expense.
(J) Weather and temperature. Asphalt mixture must arrive on the site at a temperature between 250°F and 325°F. No material shall be placed if it is raining, if the surface to be treated is wet or if rain is threatening. Material may only be placed if the ambient temperature at the construction site is 45°F and rising. No material shall be laid after November 1st or before May 1st except by request of the contractor and subsequent approval of the structural/safety division inspector.
(K) Traffic control. Traffic shall not be allowed on freshly laid asphalt until rolling operations are completed and until there is no marking under traffic loads.
(Ord. 775, passed 4-19-99)