2.02 (a) ASPHALT EMULSION
Asphalt emulsion shall be homogenous and shall be a polymer modified quick-setting, quick- traffic cationic asphalt emulsion conforming to the requirements of Section 94 “Asphalt Emulsions” and these Special Provisions. The polymer material shall be milled or blended into the asphalt or blended into the emulsifier solution prior to the emulsification process. The asphalt emulsion manufacturer shall certify that the emulsion contains a minimum of 3% polymer solids based on the mass of asphalt (asphalt residual) within the emulsion. The emulsion, upon standing undisturbed for a period of twenty-four (24) hours, shall show no white or milky colored substance on its surface, and shall be a homogeneous brown color throughout.

The polymer modified quick-setting quick-traffic asphalt emulsion shall conform to the following requirements when tested in accordance with the specified test method.

The aggregate, prior to the addition of emulsion shall conform to the requirements of this section. If aggregates are blended each component aggregate shall meet the sand equivalency and abrasion resistance and shall be 100% crushed as tested in accordance with California Test 205. The definition of a crushed particle in California Test 205 Section D, is amended to read: “Any particle having 2 or more fresh mechanically fractured faces shall be considered a crushed particle.”

The percentage composition by mass of the aggregate shall meet the following grading requirements when tested in conformance with California Test 202:

If the results of the Sand Equivalent test for aggregate does not meet the requirement specified, the microsurfacing represented by the test shall be removed. However, if requested in writing by the Contractor and approved by the Engineer, the microsurfacing may remain in place and the Contractor shall pay to the State $2.00 per tonne for the aggregate represented by the test and left in place.

When the results of both the aggregate grading and the Sand Equivalent test do not conform to the requirements specified, both payments to the state shall apply. The Department may deduct these amounts due from any moneys due, or that may become due, the Contractor under the contract. No single aggregate grading or Sand Equivalent test shall represent more than 275 tonnes or one day’s production, whichever is smaller.

The tests and mix design shall be performed by a laboratory capable of performing the applicable International Slurry Surfacing Association (ISSA) tests. The proposed microsurfacing mixture shall conform to the requirements specified when tested in accordance with the following tests:

All the component materials used in the mix design shall be representative of the materials proposed by the contractor to be used on the project.

The percentages of each individual material required shall be shown in the laboratory report. Adjustments may be required during the construction, based on field conditions. The component materials shall be within the following limits:

The Contractor shall furnish an aggregate moisture determination from the stockpile prior to placing the microsurfacing and shall be retested if weather conditions have changed the aggregate moisture content appreciably. Aggregate moisture will be accounted for in determining the aggregate/bitumen ratio to be used during placement. Portable acetylene moisture determination kits will be allowed for determining moisture contents.

The aggregate shall be proportioned using a belt feeder operated with an adjustable cutoff gate. The height of the gate opening shall be readily determinable. The emulsion shall be proportioned by a positive displacement pump. Any variable rate emulsion pump, if used, shall be calibrated and sealed in it’s calibrated condition in accordance with California Test 109 prior to usage.

Uniformity of distribution of asphalt will be determined by extraction test in accordance with California Test 310. The bitumen ratio (kg of asphalt per 100 kg of dry aggregates) shall not vary more than 0.5 percent of asphalt above or 0.5 percent of asphalt below the amount based on the dry aggregate mass approved by the Engineer.

The delivery rate of aggregate and emulsion per revolution of the aggregate feeder shall be calibrated at the appropriate gate settings for each mixer-spreader truck used on the project in accordance with California Test 109 and the requirements of these special provisions.

The aggregate belt feeder shall deliver aggregate to the pugmill with such volumetric consistency that the deviation for any individual aggregate delivery rate check-run shall not exceed 2.0 percent of the mathematical average of three runs of at least 3 tonnes in duration each. The emulsion pump shall deliver emulsion to the pugmill with such volumetric consistency that the deviation for any individual delivery rate check-run shall be within 2.0 percent of the mathematical average of three runs of at least 1135 liters each in duration. The water pump shall deliver water to the pugmill with such volumetric consistency that the deviation for any individual delivery rate check-run shall be within 2.0 percent of the mathematical average of three runs of at least 1135 liters each in duration.

The emulsion storage located immediately before the emulsion pump shall be equipped with a device which will automatically shut down the power to the emulsion pump and aggregate belt feeder when the emulsion level is lowered sufficiently to expose the pump suction line.

A temperature-indicating device shall be installed in the emulsion storage tank at the pump suction level. The device shall indicate temperature of the emulsion and shall be accurate to within 5°C.

The belt delivering the aggregate to the pugmill shall be equipped with a device to monitor the depth of aggregate being delivered to the pugmill. Said device for monitoring depth of aggregate shall automatically shut down the power to the aggregate belt feeder whenever the depth of aggregate is less than the target depth of flow. A second device shall be located where it will monitor movement of the aggregate belt by detecting revolutions of the belt feeder. The device for monitoring no flow or belt movement, as the case may be, shall automatically shut down the power to the aggregate belt when aggregate belt movement is interrupted. This second device will not be required where the aggregate delivery belt is an integral part of its drive chain. To avoid erroneous shutdown by normal fluctuation, a delay of 3 seconds between sensing and shutdown of the operation will be permitted.

A minimum of two operational mixing machines of 12 cubic yard capacity, or larger, shall be maintained on the project. The mixed material retention time in the pug mill shall be less than three seconds. No retention of mixed material shall be allowed within the pug mill by gate shut-off or other mechanical means. Any machines with pugmill retention or shut-off gates shall have them removed prior to being used on this project. The mixing machine shall have sufficient storage capacity of aggregate, emulsified asphalt, and water to maintain an adequate supply to the proportioning controls. All indicators required in the section entitled “Proportioning” shall be in working order prior to commencing mixing and spreading operations.

Mixer-spreader trucks shall be equipped to proportion emulsion, water, aggregate, and set-control additives by volume. All rotating and reciprocating equipment on mixer-spreader trucks shall be covered with metal guards.

The mixer-spreader truck shall not be operated unless all low-flow and no-flow devices and revolution counters are in good working condition and functioning and all metal guards are in place. All indicators required by these special provisions shall be visible while walking alongside the mixer-spreader truck.

Aggregate feeders shall be connected directly to the drive on the emulsion pump. The drive shaft of the aggregate feeder shall be equipped with a revolution counter reading to the nearest one-tenth of a revolution.

In addition to the requirements of the fourth paragraph of Section 5-1.10, “Equipment and Plants,” of the Standard Specifications, the identifying number of mixer-spreader trucks shall be at least 2 inches in height, located on the front and rear of the vehicle.

The microsurfacing mixture shall be spread by means of a spreader box conforming to the following requirements:

The spreader box shall have a double strike-off blade design at the rear of the box. The first strike-off blade shall be made of steel or stiff rubber and the second strike-off blade (attached to the first blade) shall be made of a flexible material. Rear flexible strike-off blades shall make close contact with the pavement, and shall be capable of being adjusted to the various crown shapes so as to apply a uniform microsurfacing coat. A secondary strike-off blade attached to the rear of the spreader box (located behind the double strike-off blades at the rear of the spreader box) shall be provided and shall be adjustable. It shall be designed and operated such that a uniform texture is achieved in the finished surface of the microsurfacing.

Flexible fabric drags attached to the rear of the spreader box shall not be allowed. Strike-off blades (rubber) shall be cleaned or changed daily if problems with cleanliness and longitudinal scouring occur.

The microsurfacing spreader box in use shall be clean and free of microsurfacing and emulsion, at the start of each work shift.

Microsurfacing mixture, to be spread in areas inaccessible to the controlled spreader box, may be spread by other methods approved by the Engineer.

Microsurfacing shall only be placed when the ambient and pavement surface temperature is 10°C minimum and rising. Microsurfacing shall not be placed if rain is falling or is imminent or if there is the possibility that the finished product will freeze within 24 hours.

Before placing the microsurfacing, the pavement surface shall be cleaned by sweeping, flushing or other means necessary to remove all loose particles of paving, all dirt and all other extraneous material.

When wheel path depressions have a cross section that is deformed 12.5 mm or more the individual wheel paths must first be filled utilizing a wheel path depression box meeting the requirements of these special provisions. Filling of wheel path depressions shall be accomplished using Type lll aggregate. Wheel path depression spread rates will vary with depression depth. Maximum single application for wheel path depressions shall be 37.5 mm. Greater depths may require multiple applications in each depression.

Wheel path depression repair shall be constructed with a slight crown to permit initial traffic compaction of the microsurfacing.

At least 12 hours of traffic compaction shall be allowed on freshly filled wheel path depressions before additional lifts are applied as surface courses. This may be replaced by rolling with an unballasted pneumatic tyred roller at the discretion of the contractor supervisor.

When there is a contract item of asphalt emulsion to be used for paint binder, the pavement surface shall be coated with an SS,CSS or CQS (-1 or -1h) grade asphalt emulsion meeting the requirements of Section 94, “Asphalt Emulsions” of the Standard Specifications. The asphalt emulsion shall be mixed in the proportion of one part of emulsion to three parts water. The mixture shall be applied at the approximate rate of 0.16 to 0.32 liters per square meter. The paint binder shall be allowed to cure before application of microsurfacing.

When used for full lane width passes microsurfacing mixture shall be spread at a rate within 7.0 to 10.0 kg of dry aggregate per square meter. The exact rate will be determined by the Engineer after taking into account the surface demand of the pavement, the size of the largest particles of aggregate and using the specific mass of the aggregate determined in the mix design. The completed spread will be within 10 percent of the rate determined by the mix design.

(When using Type lll aggregate.)

When used for full lane width passes microsurfacing mixture shall be spread at a rate within 13.0 to 17.0 kg of dry aggregate per square meter. The exact rate will be determined by the Engineer after taking into account the surface demand of the pavement, the size of the largest particles of aggregate and using the specific mass of the aggregate determined in the mix design. The completed spread will be within 10 percent of the rate determined by the mix design.

On concrete pavements (bridge decks and roadways) the microsurfacing mixture shall be spread at a minimum rate of 16.0 kg of dry aggregate per square meter. A paint binder shall be placed on new concrete surfaces, highly polished concrete surfaces or when designated by the Engineer.

Longitudinal joints shall correspond with the edges of traffic lanes. The Engineer may permit other patterns of longitudinal joints, if such patterns will not adversely affect the quality of the finished product, as determined by the Engineer.

Longitudinal joints common to two driving lanes, shall be butt joints with overlaps not to exceed 76.2 mm. Building paper shall be placed at transverse joints, over previously placed microsurfacing, or other suitable methods, approved by the Engineer, used to avoid double placement of microsurfacing. Hand tools shall be available in order to remove spillage. Ridges or bumps in the finished surface shall not be permitted.

The mixture shall be uniform and homogeneous after spreading on the surfacing and shall not show separation of the emulsion and aggregate after setting.

Adequate means shall be provided to protect the microsurfacing from damage by traffic until such time that the mixture has cured sufficiently so that the microsurfacing will not adhere to and be picked up by the tires of vehicles.

Rolling of the surface will be required with a pneumatic roller- unballasted at the discretion of the contractor supervisor.