Attachment 4. Specification 416.pdf

416 – Road Mix Bituminous Pavement Description

416.01 This work shall consist of constructing one or more courses of road mix bituminous pavement on a prepared base or road surface that has been approved in writing by the engineer.

Material

416.02 The type and grade of bituminous material as shown in the schedule of items shall meet the requirements of the following Subsections:

Emulsified Asphalts 702.02 Surface Course Aggregate 703.05(c)

Aggregate shall be either new aggregate (Case 1 ) or aggregate scarified from existing roadbed (Case 2), or both as shown on the drawings. New aggregate shall meet requirements of Subsection 703.05. The contractor shall not be responsible for the grading or quality of the existing aggregate scarified from the roadbed except for removal of particles that are retained on a 1.5 inch sieve.

Construction Requirement

416.03 Weather & Temperature Limitations. Bituminous material shall be applied only when the atmospheric temperature in the shade is above 50°F and when the weather is not foggy or rain is anticipated within 24 hours of application, or when the ground is frozen. Apply when the ambient air temperature is 40° F or above.

416.04 Equipment. The equipment shall include scarifying, mixing, spreading, finishing and compacting equipment, and an asphalt distributor.

(a) Asphalt distributor. See Subsection 406.03

(b) Mixer. Use a tractor rotary tiller, blade graders, or other approved mixing device

(c) Roller.

(1) Self-propelled

(2) Pneumatic-tire rollers. See Subsection 407.05(c)

(3) Vibratory steel-wheel rollers weigh at least 6 tons, have amplitude and frequency controls

416.05 Preparation of Base.

(a) Case 1 (New Aggregate). When new aggregate is to be used for the road mix bituminous pavement, the existing base shall be scarify lightly, blade to uniform grade and shape to the cross section shown on the drawings. Depressions shall be filled and weak portions of the base strengthened with new aggregate.

(b) Case 2 (Salvaged Aggregate). When aggregate in the existing road surface is to be used for mixing, the surface shall first be scarified to a minimum depth of 3 inches, blade to uniform grade and shaped to the cross section shown on the drawings.

416.06 Placing Aggregate. New aggregate shall be spread and shaped in uniform layers not to exceed 4 inches compacted thickness or as shown on drawings whichever is less.

If the surface moisture of the aggregate is more than three percent of the dry weight of the aggregate, except when the bituminous material is emulsified asphalt, the aggregate shall be turned by blades or disc harrows or otherwise aerated until the moisture content is reduced to 3 percent or less. The aggregate shall then be spread smoothly and uniformly over half the road or other convenient width of the surface ready for the application of bituminous material, except that when a traveling mixing plant is used, the aggregate shall be formed into a uniform cross section.

416.07 Application.

(a) First Application. Apply the bituminous material with a distributor at a rate of 0.3 to 1.0 gallons per square yard as approved by the CO. The mixing equipment shall follow immediately behind the distributor to incorporate the bituminous material into the full width of loose material.

Shape the surface to line and grade and compact according to 416.09.

(b) Second Application. Apply the bituminous material to the finished surface with a distributor at a rate of 0.2 gallons per square yard as approved by the CO.

416.08 Mixing. If mixing is done with a blade grader, after the first application of bituminous material and partial mixing, the entire mass of the bituminous material and aggregate shall be windrowed on the road surface. Then the mass shall be mixed until all aggregate particles are coated with the bituminous material. The mixture shall have a uniform color and be free from fat or lean spots, or balls. During the mixing operations, care shall be taken to avoid cutting into the underlying course or contaminating the mixture with earth or other extraneous matter.

Should the mixture show an excess, deficiency, or uneven distribution of bituminous material, the condition shall be corrected by the addition of aggregate or bituminous material and remixing. If the mixture contains excess amount of moisture or volatile matter, it shall be bladed, aerated, or otherwise manipulated until the moisture and volatile content are satisfactory to CO. The spreading of the mix shall not be done until the surface to be covered is approved by the CO.

At the end of each day’s work, or when the work is interrupted by weather conditions or otherwise, all loose material shall be bladed into a windrow, whether mixing is completed or not, and shall be retained in a windrow until operations are resumed when liquid asphalts are used as the binder. Emulsion mixtures may be left in a windrow maximum of 6 hours before being spread and compacted.

When the mixing operations have been satisfactorily completed, the mixture shall be formed into a windrow of uniform cross section.

If traveling mix plants are used, the same requirement given above shall apply.

416.09 Spreading, Compaction, & Finishing. Spread the mixture on the surface in a uniform layer across the existing roadbed. Shape the mixture to the required line, grade, and cross-section. When spreading from the windrow, care shall be taken to avoid cutting into the underlying base.

After the material is spread, the surface shall be rolled. Rolling shall be parallel to the road centerline and shall commence at the outer edges of the road, overlapping the shoulders, and shall progress toward the center, overlapping on successive phases by at least one-half the width of the roller. On superelevated curves, rolling shall progress from the lower to the upper edge. Each pass shall terminate at least 3 feet in advance or to the rear of the end of the preceding pass.

Use pneumatic-tire rollers until no displacement is observed. Use steel-wheel rollers, either static or low-amplitude vibratory mode, to achieve final density and eliminate pneumatic-tire roller marks. Do not park or idle rollers on uncompacted material. Rolling shall be discontinued whenever it begins to produce excessive pulverizing of the aggregate or displacement of mixture.

When the compacted thickness of the road mix surface is to be more than 4 inches, the mixture shall be spread from the windrow and compacted in two layers. The first layer shall be bladed and rolled before the second layer is spread.

416.10 Surface Requirements. Produce a surface that is smooth, dense, and free of ruts, ridges, and loose material. Measure top surface using a 10-foot metal straightedge at right angles and parallel to the center. Defective areas are deviations between the surface and at any point on the bottom of the straightedge in excess of ½ inches.

416.11 Opening to Traffic. Keep traffic off the treated surface until the bituminous material have penetrated and cured to prevent excessive pickup under traffic.

416.12 Acceptance. Bituminous material will be evaluated under Subsection 106.03. Provide a commercial certification that includes the date, identification number (truck or trailer), net mass, and brand name with each shipment.

Application of road mix bituminous pavement will be evaluated under Subsection 106.02 and 106.04.

Measurement

416.13 Measure the Section 416 pay items in the bid schedule according to Subsection 109.02.

Payment

416.14 The accepted quantities will be paid at the contract price per unit of measurement for the Section 416 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05.

416 – Road Mix Bituminous Pavement