Letter suffixes will be added to pay item number 406 (2) to designate alternative types of material to be bid on. Section 407.-TACK COAT Description 407.01 This work shall consist of preparing and treating an existing bituminous or concrete surface with bituminous material in accordance with these specifications and in reasonably close conformity with the lines shown on the plans or established by the Engineer. Materials 407.02 Bituminous Material. The type and grade of bituminous material will be specified in the bid schedule. The grade may be changed one step by the Engineer during construction at no change in unit price. The bituminous material may be conditionally accepted at the source, subject to the provisions of clause 10 of the General Provisions. The bituminous material shall be of the type and grade called for in the bid schedule and shall conform to the following subsections: Rapid-curing liquid asphalt (RC) Emulsified asphalt Tar Cationic Emulsified Asphalt Water 702.03 702.04 702.02 702.04 712.01 Application temperatures of bituminous materials shall conform to subsection 702.05. When the bid schedule calls for the use of emulsified asphalt, grade SS-1, water shall be added to the asphaltic emulsion material and thoroughly mixed therewith in such proportion that the resulting mixture will contain approximately 40 percent by volume of added water, the exact quantity of added water to be determined by the Engineer. Construction Requirements 407.03 Equipment. The Contractor shall provide equipment for heating and applying the bituminous material. This equipment shall meet the requirements of subsection 405.05. A power broom and/or power blower shall be provided for any required cleaning of the surface to be treated. 407.04 Preparation of Surface to be Treated. The existing surface shall be patched and cleaned and shall be free of irregularities to provide a reasonably smooth and uniform surface to receive the treatment. Unstable corrugated areas shall be removed and replaced with suitable patching materials. Payment for the patching will be made at the contract unit price for the various items used unless a reconditioning item is included in the contract. The edges of existing pavements, which are to be adjacent to new pavement, shall be cleaned to permit the adhesion of bituminous materials. 407.05 Application of Bituminous Material. The bituminous material shall be uniformly applied with a pressure distributor, within the 24 hours preceding placement of the covering course. The tack coat shall be applied in such manner as to offer the least inconvenience to traffic and to permit one-way traffic without pickup or tracking of the bituminous material. Tack coat shall not be applied during wet or cold weather, after sunset, or to a wet surface. The quantity, rate of application, temperature and areas to be treated shall be approved prior to application. The surfaces of structures and trees adjacent to the areas being treated shall be protected in such manner as to prevent their being spattered or marred. No bituminous material shall be discharged into a borrow pit, gutter, or stream. The surface shall be allowed to dry until it is in a proper condition of tackiness to receive the surface course. Tack coat shall be applied only so far in advance of surface course placement as is necessary to obtain this proper condition of tackiness. Until the surface course is placed, the Contractor shall protect the tack coat from damage. Method of Measurement 407.06 The bituminous material for tack coat will be measured by the ton or gallon. Water added to emulsified asphalt will not be measured for payment. Basis of Payment 407.07 The accepted quantities of tack coat, determined as provided above, will be paid for at the contract unit price per ton or gallon, as designated, for bituminous material complete in place, which price and payment will be full compensation for the work of this section. Payment will be made under: 408.01 This work shall consist of preparing and treating an existing surface with bituminous material, and blotter material, if required, in accordance with these specifications and in reasonably close conformity with the lines shown on the plans or established by the Engineer. Materials 408.02 Bituminous Material. The type and grade of bituminous material will be specified in the contract. The grade may be changed one step by the Engineer during construction at no change in unit price. The bituminous material may be conditionally accepted at the source, subject to the provisions of clause 10 of the General Provisions. The bituminous material shall be of the type and grade called for in the bid schedule and shall conform to the following subsections: Slow-curing liquid asphalt (SC) Medium-curing liquid asphalt (MC) 702.03 702.03 702.03 Application temperatures of bituminous materials shall conform to subsection 702.05. 408.03 Blotter Material. Blotter material shall meet the requirements of subsection 703.14. The material may be accepted in stockpile at the source, subject to the provisions of clause 10 of the General Provisions. Construction Requirements 408.04 Weather Limitations. Prime coat shall be applied only when the surface to be treated is dry or but slightly damp, when the atmospheric temperature in the shade is above 55° F. and rising or above 60° F. if falling, and when the weather is not foggy or rainy. 408.05 Equipment. The Contractor shall provide equipment for heating and applying the bituminous material and for applying blotter material. The equipment shall meet the requirements of subsection 405.05. 408.06 Preparation of Surface. Immediately before applying the bituminous material all loose dirt and other objectionable material shall be removed from the surface with a power broom and/or blower as required. If the Engineer so orders, the surface shall be lightly bladed and rolled immediately prior to the application of bituminous material, in which case brooming or blowing will not be required. When so ordered by the Engineer a light application of water shall be made just before the application of bituminous material. 408.07 Application of Bituminous Material. Bituminous material shall be applied to the width of the section to be primed by means of a pressure distributor in a uniform, continuous spread. When traffic is maintained, not more than 1⁄2 of the width of the section shall be treated in one application. Care shall be taken that the application of bituminous material at the junctions of spreads is not in excess of the specified amount. Excess bituminous material shall be squeegeed from the surface. Skipped areas or deficiencies shall be corrected. Building paper shall be placed over the end of the previous applications and the joining application shall start on the building paper. Building paper used shall be removed and satisfactorily disposed of. When traffic is maintained, one-way traffic shall be permitted on the untreated portion of the roadbed. As soon as the bituminous material has been absorbed by the surface and will not pick up, traffic shall be transferred to the treated portion and the remaining width of the section shall be primed. The quantities, rate of application, temperatures and areas to be treated shall be approved before application of the prime coat. The surfaces of structures and trees adjacent to the areas being treated shall be protected in such manner as to prevent their being spattered or marred. No bituminous material shall be discharged into a borrow pit, gutter, or stream. 408.08 Application of Blotter Material. If traffic must be routed over the primed surface before the bituminous material has penetrated sufficiently to prevent pickup by vehicles, or to minimize possible damage by rain before complete penetration, blotter material may be spread, as directed by the Engineer, to cover any unabsorbed bituminous material. Blotter material shall be spread so that no wheels or tracks will travel in uncovered wet bituminous material. Method of Measurement 408.09 Bituminous material will be measured by the ton or gallon and blotter material will be measured by the ton or cubic yard as provided in the bid schedule. When slag and stone (or gravel) are designated as alternative materials for pay items in the bid schedule and payment is by weight, the estimated quantities will be based on assumed average bulk specific gravities of available alternative materials. No adjustment in contract unit price will be made for variation in quantity due to differences in the specific gravity of the material actually used. Basis of Payment 408.10 The accepted quantities of seal coat, determined as provided above, will be paid for at the contract price per ton or gallon for bituminous material and per ton or cubic yard for blotter material complete in place, which price and payment will be full compensation for the work of this section. Payment will be made under: |