SECTION 408 MICROSURFACING

408.01 Description

Apply microsurfacing material to an existing road surface.

408.02 Material

A. Polymer-Modified Emulsified Asphalt.

1. Use emulsified asphalt cationic Type CSS-1H as specified in Section 702.01.

2. Meet AASHTO M 316 polymer requirements.

3. Ensure the mixed emulsified asphalt will not separate.

4. Formulate with a [2.5] percent minimum polymer content.

5. Formulate so a 1-in. (25-mm) thick application, at a maximum [50] percent humidity and 75°F (25°C) minimum ambient air temperature, supports rolling traffic without surface damage after a 1-hour cure.

B. Aggregate. Meet ASTM D 6372.

C. Filler. Use any recognized brand of smooth non-air-entrained portland cement Type I.

A. The Engineer will measure emulsified or cutback asphalt by the amount of residual asphalt.

406.05 Payment

The Agency will pay for accepted quantities at the contract unit price as follows:

Pay Item Pay Unit

(A) Asphalt binder for chip seal ton (Mg), gal (L) (B) Cutback asphalt for chip seal ton (Mg), gal (L) (C) Emulsified asphalt for chip seal ton (Mg), gal (L) (D) Cover coat material size ton (Mg), yd³ (m³)

Such payment is full compensation for furnishing all materials, equipment, labor, and incidentals to complete the work as specified.

SECTION 407

Reserved

SECTION 408 MICROSURFACING

408.01 Description

Apply microsurfacing material to an existing road surface.

408.02 Material

A. Polymer-Modified Emulsified Asphalt.

1. Use emulsified asphalt cationic Type CSS-1H as specified in Section 702.01.

2. Meet AASHTO M 316 polymer requirements.

3. Ensure the mixed emulsified asphalt will not separate.

4. Formulate with a [2.5] percent minimum polymer content.

5. Formulate so a 1-in. (25-mm) thick application, at a maximum [50] percent humidity and 75°F (25°C) minimum ambient air temperature, supports rolling traffic without surface damage after a 1-hour cure.

B. Aggregate. Meet ASTM D 6372.

C. Filler. Use any recognized brand of smooth non-air-entrained portland cement Type I.

D. Water. Use potable water.

A. The Engineer will measure emulsified or cutback asphalt by the amount of residual asphalt.

406.05 Payment

The Agency will pay for accepted quantities at the contract unit price as follows:

Pay Item Pay Unit

(A) Asphalt binder for chip seal ton (Mg), gal (L) (B) Cutback asphalt for chip seal ton (Mg), gal (L) (C) Emulsified asphalt for chip seal ton (Mg), gal (L) (D) Cover coat material size ton (Mg), yd³ (m³)

Such payment is full compensation for furnishing all materials, equipment, labor, and incidentals to complete the work as specified.

SECTION 407

Reserved

SECTION 408 MICROSURFACING

408.01 Description

Apply microsurfacing material to an existing road surface.

408.02 Material

A. Polymer-Modified Emulsified Asphalt.

1. Use emulsified asphalt cationic Type CSS-1H as specified in Section 702.01.

2. Meet AASHTO M 316 polymer requirements.

3. Ensure the mixed emulsified asphalt will not separate.

4. Formulate with a [2.5] percent minimum polymer content.

5. Formulate so a 1-in. (25-mm) thick application, at a maximum [50] percent humidity and 75°F (25°C) minimum ambient air temperature, supports rolling traffic without surface damage after a 1-hour cure.

B. Aggregate. Meet ASTM D 6372.

C. Filler. Use any recognized brand of smooth non-air-entrained portland cement Type I.

E. Set Time Additives. Meet emulsion manufacturer’s recommendations.

408.03 Construction

A. Weather Limitations. Place microsurfacing material when the following conditions apply:

1. Minimum air temperature is 50°F (10°C) and rising;

2. The surface must be dry;

3. 24 hour forecast predicts temperatures above 32°F (0°C); and 4. Surface temperature is at least 50°F (10°C).

B. Mix Design. Develop a job-mix formula using Agency procedure _______. Submit test results for review a minimum of [3] days before application. Include aggregate type and gradation and percentages of polymer-modified emulsion, water, and cement by dry aggregate weight (mass).

C. Proportioning. Proportion as follows:

Aggregate lb/yd² dry weight (kg/m² dry mass)

[10 to 15 lb (4.5 to 7 kg)]

Polymer-modified emulsion (residual) [6.5 to 7] percent

Filler [2] percent by weight (mass) of dry aggregate

Additive As required

D. Aggregate and Asphalt. Weigh aggregate before delivery to roadway. Proportion emulsified asphalt by weight (mass) or volume.

E. Preparing Existing Surface. Clear the roadway surface of all loose aggregate and foreign material. Pre-wet the surface immediately before applying the microsurfacing materials.

Fill cracks and potholes with the mixture to restore roadway cross section.

F. Equipment:

1. Mixing Equipment. Use a self-propelled, multiblade dual mixer. Ensure accurate proportioning. Provide adequate mixer storage capacity to ensure continuous operation and to eliminate unnecessary construction joints.

Calibrate and properly mark proportioning controls for easy verification.

Weigh the aggregate before delivery to roadway.

Proportion emulsified asphalt by weight (mass) or volume.

Equip the mixing machine with a pressure water system and nozzle-type spray bar(s) to provide a water spray immediately ahead of and outside the spreader box.

Add filler at the loading facility or at the roadway. Provide a documented record of filler weight (mass). Add set time additives according to the manufacturer’s recommendations to meet field conditions.

2. Spreading Equipment. Spread the mixture uniformly with a mechanical-type laydown box attached to the mixer. Equip the laydown box with agitation paddles. Ensure the mixture does not form lumps or set up in the box. Use flexible seals, front and rear, to prevent loss of material from the laydown box. Use an adjustable steel strike-off plate when filling ruts.

G. Applying Mixture. Apply mixture in a uniform consistent flow without skips, lumps, or tears in the finished surface. Use hand methods to spread the mixture in areas

inaccessible by mechanical spreaders. Ensure full coverage. Make a neat seam at joints.

Remove all excess material, lumps, balls, or unmixed aggregate prior to set.

H. Maintaining Traffic. Meet traffic control plan.

Protect the microsurfacing material from traffic damage until the mixture cures and will not be damaged by traffic. Repair traffic damage to the microsurfacing application before acceptance and at no cost to the Agency.

408.04 Measurement

The Engineer will measure work acceptably completed as specified in Subsection 109.01 and as follows:

A. The Engineer will not measure mix water or water used to pre-wet the pavement surface.

408.05 Payment

The Agency will pay for accepted quantities at the contract unit price as follows:

Pay Item Pay Unit

(A) Aggregate for microsurfacing ton (Mg)

(B) Emulsified asphalt (polymer) ton (Mg), gal (L)

(C) Filler ton (Mg)

Such payment is full compensation for furnishing all materials, equipment, labor, and incidentals to complete the work as specified.

SECTION 409