(A) Description. Bituminous surface treatment of flexible type base courses shall consist of a light wearing surface, composed of applications of bitumen covered with aggregate, constructed on a prepared base, in accordance with these specifications and in conformity with the lines, grades, and typical cross-sections shown on the accepted drawings.
(B) Materials. All materials shall comply with state specifications.
(1) Aggregate. Aggregates shall comply with state specifications § 612 and shall consist of particles of clean, hard, tough, durable, uncoated fragments of crushed stone or gravel, reasonably free from an excess of flat, elongated, soft, or disintegrated pieces, organic or other objectionable matter, and shall be free from lumps of clay.
(2) Gradation. The aggregate, when tested by means of laboratory sieves, shall meet the following requirements of size eight for cover coats and size 11 for seal coats.
(3) Bituminous materials. Bituminous materials shall conform with current state specifications for the following grades.
Designation | Asphalt Grades | Tar Grades |
Prime coat | RC-1, RC-2, MC-0, or MC-1 | RT-1, RT-2, or RT-3 |
Cover coats and Seal coat | RC-3, RC-4, MC-4, MC-5, or SC-5n | RT-6, RT-7, RT-8, or RT-9 |
Note: The MC and SC asphalts, and the heavier tars should be used only when the air temperature in the shade and the temperature of the base is 70°F or above. | ||
(4) Proportions. Bituminous material shall be proportioned per square yard as follows.
Application | Gals. of Bitumen | Lbs. of Aggregate |
Prime coat | 0.25 to 0.50 | --- |
First cover coat | 0.20 to 0.25 | 20 - 30 |
Second cover coat | 0.25 to 0.30 | 25 - 35 |
Seal coat | 0.25 to 0.30 | 25 - 35 |
Note: Weights of stone and gravel aggregate based on a specific gravity of 2.65. | ||
(C) Construction methods.
(1) Preparation of base. The base to be treated shall be thoroughly compacted, true to the lines, grades, and typical cross-sections shown on the accepted drawings. The base shall be swept or otherwise cleaned of all dust, mud, and foreign matter, and shall be thoroughly dry before any bituminous material is applied.
(2) Application of bitumen. Bituminous material shall be applied uniformly at the rates specified in division (B)(4) above, with a power distributor or approved type under a pressure of not less than 30 to 40 pounds per square inch.
(3) Spreading aggregate. The aggregate shall be uniformly spread at the rates specified in division (B)(4) above, by means of spreader boxes, other approved mechanical equipment, or from moving vehicles equipped to distribute the material in a uniform layer.
(4) Prime coat. Bituminous material for the prime coat shall be applied uniformly at the rate specified in division (B)(4) above, and in a manner outlined in division (C)(2) above. Traffic shall not be permitted on the primed base until the bitumen has penetrated, dried, and will not pick up under traffic.
(5) First cover coat. Bituminous material for the first cover coat shall be applied uniformly at the rate specified in division (B)(4) above, and in the manner outlined in division (C)(2) above. Immediately after the first cover coat application of bitumen has been applied, aggregate for the first cover coat shall be spread at the rate specified in division (B)(4) above, and in the manner outlined in division (C)(3) above.
(6) Rolling first cover coat. Immediately after the aggregate for the first cover coat has been spread it shall be compacted for the full width of the base by means of a dual wheel truck. Compacting shall continue until the aggregate is thoroughly keyed into the bitumen. At the end of one year from the completion of construction, such compacting shall be repeated until the aggregate is thoroughly keyed into the bitumen.
(2005 Code, § 91.47) (Ord. 69, passed 8-2-1966) Penalty, see § 91.99