SECTION 480 — BITUMINOUS SURFACE TREATMENT
480.1 DESCRIPTION —
This work is two applications of bituminous material, each immediately followed by an application of coarse aggregate.
480.2 MATERIAL —
(a) Bituminous Material.
(b) Coarse Aggregate.
Type A, No. 8 and No. 67, Section 703.2
Having the SRL designation as indicated in the bid proposal and supplied from acceptable sources for use in wearing courses. An aggregate designation or blends, equal to or better than that specified, may be supplied. Blends are 50% by weight and mixed by an approved method.
480.3 CONSTRUCTION —
At least two weeks before beginning work, submit a surface treatment design for review. Use the method in Appendix E of Bulletin 27 (Pennsylvania Design Method for Seal Coats and Surface Treatments).
(a) Conditioning Existing Surface.
(b) Application of Bituminous Material and Coarse Aggregate.
Section 470.3(b), except apply at the rates and place in the sequence, as follows:
Apply bituminous material at a rate of 0.25 to 0.50 gallon per square yard. Use a mechanical spreader and spread 25 to 45 pounds of No. 67 coarse aggregate per square yard, then roll thoroughly to set the aggregate. Sweep off loose material.
Apply bituminous material at a rate of 0.25 to 0.50 gallon per square yard. Use a mechanical spreader and spread 15 to 30 pounds of No. 8 coarse aggregate per square yard, then roll thoroughly to set the aggregate. Do not apply the second application until bituminous material in the first application is sufficiently cured.
Use sufficient pneumatic-tire rollers, as specified in Section 108.05(c)3.f, with contact pressure of 40-50 psi, to cover the width of stone spread during the first pass. Allow the surface to cure until it becomes tacky, then backroll with a pneumatic-tire roller or steel-wheel tandem roller until good adhesion is attained. If directed, eliminate backrolling. Rolling in the vibratory mode will not be permitted.
(d) Protection of Surface.
480.4 MEASUREMENT AND PAYMENT —
(a) Area Basis.
(b) Material Used Basis.
1. Coarse Aggregate.
2. Bituminous Material
(c) Crack Filling and Sealing.
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