ITEM 304 – BITUMINOUS SURFACE TREATEMENT

304. 1 Description

This Item shall consist of either a single application of bituminous material followed by a single spreading aggregate (single surface treatment) or two applications of bituminous material each followed by a spreading of aggregate (double surface treatment) in accordance with the Plans and Specifications.

304.2 Material Requirements

304.2.1 Quantities of Materials

The approximate amounts of materials per square meter and sequence of operations for single and double surface treatment shall be as provided in table 304.1 and 304.2, whichever is called for in the Bill of Quantities.

The quantities given in the Tables are those of aggregates having a bulk specific gravity of 2.65 as determined by AASHTO T 84 and T 85. Proportionate corrections will be made when the aggregate furnished on the job has a bulk specific gravity above 2.75 or below 2.55. In such case, the corrected amount will be the product of the quantity shown in the tables and the ratio of the bulk specific gravity of aggregate to 2.65.

The amounts given in the Tables are approximate and the exact amounts will be set by the Engineer. Total amount of bituminous material per square meter may be varied by the Engineer as necessary to fit conditions, but the total amount of aggregate per square meter, after adjusting for specific gravity will not be changed.

Table 304.1 – Quantities of Materials and Sequence of Operations Using Cut-Back Asphalt or Asphalt Cement

Aggregate Grading and Sequence of Operations	Single S.T.	Double S.T.
First Course:    Apply bituminous material, L/m2 Spread Aggregate:    Grading A, kg/m2    Grading B, kg/m2 Second Course:     Apply bituminous material, L/m2 ¬Spread Aggregate:     Grading C, kg/m2	0.7 – 1.1 AC 0.9 0 1.5 MC 11.0 – 14.0	1.6 – 2.0 AC 1.8 – 2.3 MC 22.0 – 27.0 2.3 – 2.7 AC 2.8 – 3.5 MC 11.0 – 14.0

Table 304.2 – Quantities of Materials and Sequence of Operations Using Emulsified Asphalt

Aggregate Grading and Sequence of Operations	Single S.T.	Double S.T.
First Course:    Apply bituminous material, L/m2 Spread Aggregate:    Grading A, kg/m2    Grading B, kg/m2 Second Course:     Apply bituminous material, L/m2 ¬Spread Aggregate:     Grading C, kg/m2	0.9 – 1.6 11.0 – 14.0	1.4 – 2.0 14.0 – 19.0 2.1 – 3.0 5.0 – 8.0

304.2.2 Bituminous Materials

Bituminous materials shall be either CRS-1 (Cationic Rapid Setting), CRS-2 (Cationic Rapid Setting), RS-1 (Rapid Setting), RS-2 (Rapid Setting), AC 120-150 (Asphalt cement), MC 250-800 (Medium Curing), whichever is called for in the Bill of Quantities. It shall conform to the requirements of Item 702, Bituminous Materials, Penetration Grade No. of asphalt cement, the type and grade of cut-back and emulsified asphalt will be specified in the Special Provisions.

304.2.3 Aggregates

The aggregates shall be crushed stone, crushed slag, or crushed gravel. Only one type of aggregate shall be used in a project unless alternative types are approved. The gradation shall conform to Table 304.3.

Table 304.3 – Aggregate Grading Requirements

Sieve Designation		Mass Percent Passing
Standard,mm	Alternate US Standard	Grading A	Grading B	Grading C
25.0 19.0 12.5 9.5 4.75 2.36 1.18 0.300	1” ¾” ½” 3/8” No. 4 No. 8 No. 16 No. 50	100 90 - 100 20 – 55 0 – 15 0 – 5 - - -	- - 100 85 – 100 10 – 30 0 – 10 0 – 5 -	- - - 100 85 – 100 10 – 40 0 – 10 0 - 5

The aggregate shall have a mass percent of wear not exceeding 40 when tested by AASHTO T 96.

When crushed gravel is used, not less than 50 mass percent of the particles retained on the 4.75 mm (No. 4) sieve shall have at least one fractured face.

When crushed slag is used, it shall be uniform density and quality, and shall have a density not less than 960 kg/m3 as determined by AASHTO T 19.

304.3 Construction Requirements

304.3.1 Rates of Application/Spreading of Asphalt and Aggregate

The rates of application/spreading of asphalt and aggregate shall be within the range in Table 304.1 and 304.2 respectively. These quantities are given as guide only and will vary considerably according to the type and condition of the surface, the grading, type, shape and absorbency of the aggregate, the weather condition and the traffic. The actual quantities to be used for surface treatment shall be determined by the Contractor in accordance with the design methods for one-size aggregate given in the Asphalt Institute Manual (MS-13), Asphalt Surface Treatment. The proposed design shall be subject to the approval of the Engineer.

The Contractor shall furnish the Engineer a certified vendor’s certificate in duplicate immediately upon delivery of asphaltic material to the Site.

The Contractor shall provide weighing equipment on the Site to control the application of aggregates. The weighing equipment shall have an approved multiple beam type scale with indicator and other necessary dials for accurately weighing the aggregate. The scale shall be protected by a weather-proof house with a floor area not less than 10m². The Contractor shall, at his own expense, have the scale tested and approved by the Department of Public Works and Highways.

304.3.2 Equipment

Equipment for applying the bituminous material shall conform to the requirements of Subsection 301.3.2, Equipment of Item 301, Bituminous Prime Coat. A mechanical spreader shall be used for spreading the aggregates. It shall be capable of spreading the aggregate uniformly over the full width of the area being treated and shall have controls to regulate the feed gates, the feed roll, the auger and the truck hatch. The equipment shall be subject to the approval of the Engineer.

304.3.3 Application of Bituminous Material

The application of bituminous material shall be done when the weather is warm and dry.

The required asphaltic material shall be applied to the surface at least twenty four (24) hours after it has been prime coated, or until the prime coat has sufficiently cured as determined by the Engineer.

Prior to applying the asphaltic material, dirt and other objectionable materials shall be removed from the surface. If so directed by the Engineer, the surface shall be cleaned by power broom until all dust and loose materials are removed. Asphaltic material shall be applied on dry surface whenever cut-back or asphalt cement is used; moist surface when emulsified asphalt is used.

Spraying shall not be done unless the road temperature has been above 200C for at least one hour prior to the commencement of spraying operations, and the temperature shall not be less than 200C during the spraying.

The application temperature asphalt cement shall be within the range that produces a viscosity of 10 to 60 second Saybolt Furol, and for cut-back asphalt shall be within the range given in Item 702, Bituminous Material. The temperature shall be such that no fogging occurs.

304.3.4 Spreading of Aggregate

Immediately after applying the asphaltic material, dry aggregate shall be uniformly and evenly distributed over the treated surface from an approved mechanical aggregate spreader. The truck carrying the aggregate shall move backwards as it spreads the aggregate so as to prevent the tires of the truck and the mechanical aggregate spreader from driving directly on the newly sprayed asphalt.

No portion of the sprayed surface shall remain uncovered for a period in excess of 2 minutes. Immediately after spreading the aggregate, the treated surface shall be rolled with an approved pneumatic-tire roller.

Where asphaltic material is exposed during rolling, the area shall be covered with additional aggregate and further rolled until an even surface results.

304.3.5 Control of Traffic

The Contractor shall take all steps necessary to control traffic over newly-laid bituminous surface treatment so that the surface is not damaged in any way. Traffic shall be prohibited from traveling at speeds in excess of 40 km/h until the asphaltic material has set. The Contractor shall ensure that no vehicles, including those delivering aggregates, shall be permitted to turn around on newly-laid material.

304.4 Method of Measurement

Bituminous material and aggregate for Bituminous Surface Treatment will be measured by the tonne (t). The quantity to be paid for shall be the number of tonnes of bituminous material and aggregate used and accepted in the completed work.

304.5 Basis of Payment

The accepted quantities, measured as prescribed in Section 304.4, shall be paid for at the contract unit price for Bituminous Surface Treatment, which price and payment shall be full compensation for furnishing and placing all materials and for all labor, equipment, tools and incidentals necessary to complete this Item.

Payment will be made under:

Pay  Item Number	Description	Unit of Measurement
304 304 (1) 304 (2) 304 (3) 304 (4) 304 (5)	Bituminous Surface Treatment Aggregate Grading Asphalt Cement Pen. Grade RC ___ Cut-back Asphalt MC ___ Cut-back Asphalt Emulsified Aspahlt	Tonne Tonne Tonne Tonne Tonne Tonne