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MICROSURFACING Microsurfacing shall consist of mixing a polymer modified, cationic microsurfacing emulsion (MSE), aggregate, mineral filler, set-control additives, and water and spreading the mixture on a pavement surface where shown on the plans, in conformance with the provisions in these special provisions, and as directed by the Engineer. Attention is directed to "Damage Claims," "Order
of Work," "Cold Plane Existing Pavement," "Maintaining
Traffic," and "Closure Requirements and Conditions"
of these special provisions. MATERIAL The material for microsurfacing shall conform to the following requirements: Microsurfacing Emulsion (MSE) Microsurfacing Emulsion (MSE) shall be homogenous and shall conform to the provisions of these special provisions. The polymer shall be milled or blended into the asphalt or blended into the emulsifier solution prior to the emulsification process. The MSE shall conform to the following requirements when tested
in conformance with the following test methods:
Water and Additives Mineral Filler 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 (including
mineral filler) shall conform to the following grading requirements
when tested in conformance with California Test 202:
The aggregate (excluding mineral filler) shall conform to the following quality requirements:
If the results of the aggregate grading do not meet the specified gradation, 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 ton (tonne) for the aggregate represented by the tests and left in place. If the results of the Sand Equivalent test for aggregate do not meet the specified requirement, 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 ton (tonne) for the aggregate represented by the tests and left in place. When the results of both the aggregate grading and the Sand Equivalent tests do not conform to the specified requirements, both payments to the State shall apply. The Department may deduct these amounts from any moneys due or to become due the Contractor. No single aggregate grading or Sand Equivalent test shall represent more than (275 tonnes) or one day's production, whichever is smaller. MIX DESIGN At least 7 working days before the microsurfacing placement commences, the Contractor shall submit for approval of the Engineer a laboratory report of tests and a proposed mix design covering the specific materials proposed for use on the project. The percentages of each individual material proposed in the mix
design shall be shown in the laboratory report. Individual materials
shall be within the following limits:
Adjustments may be required during construction based on field conditions. The mix design and aggregate tests 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 specified requirements when tested in conformance
with the following tests:
The laboratory that performed the tests and designed the mixture shall sign the laboratory report. The report shall show the results of the tests on individual materials and shall compare their values to those required by these special provisions. The report shall clearly show the proportions of aggregate, filler (minimum and maximum), water (minimum and maximum), set control additive, and MSE solids content (minimum and maximum) based on the dry mass of aggregate. The laboratory shall report the quantitative effects of moisture content on the unit mass of the aggregate (bulking effect) in conformance with the requirements of ASTM Designation C 29M. Previous laboratory reports covering the same materials may be accepted provided the material test reports were completed within the previous 12 months. The mix design shall further show the recommended changes in mineral filler, water, and additive proportions for high temperature weather conditions by reporting proportions of materials required for 60 seconds of mix time with materials heated to 100 °F (38°C). This 100 °F (38°C) mixing report will not be required for projects requiring nighttime application. The component materials used in the mix design shall be representative of the microsurfacing materials proposed by the Contractor for use on the project. Once the mix design is approved by the Engineer, no substitution of other material will be permitted unless the materials proposed for substitution are first tested and a laboratory report is submitted for the substituted design in conformance with the provisions of these special provisions. Substituted materials shall not be used until the mix design for those materials has been approved by the Engineer. The completed mixture, after addition of water and set control agent, if used, shall be such that the microsurfacing mixture has proper workability. At the expiration of the road closure hours, in conformance with the provisions in "Maintaining Traffic" of these special provisions, the microsurfacing mixture shall be sufficiently cured to support unrestricted traffic. PROPORTIONING Aggregate, mineral filler, MSE, water, and additives, including the set-control agent, if used, shall be proportioned by volume utilizing the mix design approved by the Engineer. If more than one kind of aggregate is used, the correct amount of each kind of aggregate to produce the required grading shall be proportioned separately, prior to adding the other materials of the mixture, in a manner that will result in a uniform and homogeneous blend. The aggregate shall be proportioned using a belt feeder operated with an adjustable cutoff gate. The height of the gate opening shall be determinable. The MSE shall be proportioned by a positive displacement pump. Variable rate emulsion pumps, if used, shall be calibrated and sealed in the pump's calibrated condition in conformance with California Test 109 prior to usage. The delivery rate of aggregate and MSE per revolution of the aggregate feeder shall be calibrated at the appropriate gate settings for each mixer-spreader truck used on the project in conformance with California Test 109 and in conformance with the provisions 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 3 runs of at least three tons (3 tonnes) each. The emulsion pump shall deliver MSE 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 3 runs of at least 300 gallons (1135 L) each. 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 3 runs of at least 300 gallons (1135 L) each. The MSE storage tank shall be located immediately before the emulsion pump and shall be equipped with a device which will automatically shut down the power to the emulsion pump and aggregate belt feeder when the MSE level is lowered to a point where the pump suction line is exposed. A temperature-indicating device shall be installed in the emulsion storage tank at the pump suction level. The device shall indicate the temperature of the MSE and shall be accurate to within 10°F (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. The device for monitoring the 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 the device will monitor the movement of the aggregate belt by detecting revolutions of the belt feeder. The devices for monitoring no flow or belt movement shall automatically shut down the power to the aggregate belt when the aggregate belt movement is interrupted. The device to detect revolutions of the belt feeder will not be required where the aggregate delivery belt is an integral part of the drive chain. To avoid erroneous shutdown by normal fluctuation, a delay of 3 seconds will be permitted between sensing and shutdown of the operation. MIXING AND SPREADING EQUIPMENT The microsurfacing shall be mixed in continuous pugmill mixers of adequate size and power for the type of microsurfacing to be placed. All indicators shall be in conformance with the provisions of these special provisions and shall be in working order prior to commencing mixing and spreading operations. Mixer-spreader trucks shall be equipped to proportion the MSE, water, aggregate, mineral filler, and set-control additives by volume. Rotating and reciprocating equipment on mixer-spreader trucks shall be covered with metal guards. The mixer-spreader truck shall not be operated unless low-flow and no-flow devices and revolution counters are in good working condition and functioning and metal guards are in place. 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 three inches (75 mm) 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 microsurfacing mixture, to be spread in areas inaccessible to the controlled spreader box, may be spread by other methods upon approval of the Engineer. PREPARATION FOR MICROSURFACING Before placing the microsurfacing, the pavement surface shall be cleaned by sweeping, flushing or by other means necessary to remove loose particles of paving, dirt, and other extraneous material. When required, the roadway surface may be fogged with water ahead of the spreader box. The application of the fog spray may be adjusted to suit temperatures, surface texture, humidity and dryness of pavement. A paint binder (tack coat) of asphaltic emulsion shall be applied to all Portland cement concrete surfaces when there is a contract item for the work or when the work is required in these special provisions. The asphaltic emulsion for paint binder (tack coat) shall be grade SS1, SS1h, CSS1 or CSS1h and shall conform to the provisions in Section 94, "Asphaltic Emulsions," of the Standard Specifications. The asphaltic emulsion shall be mixed in the proportion of one part of emulsion (which contains up to 43 percent water) to 3 parts water. The mixture shall be applied at the approximate rate of 0.04 – 0.08 gpsy (0.16 - to 0.32-L/m2). When asphaltic emulsion is used as a paint binder (tack coat), microsurfacing shall not be placed until the asphaltic emulsion has cured. PLACING The microsurfacing mixture shall be uniformly spread on the existing surfacing within the rate specified without spotting, rehandling or otherwise shifting of the mixture. The microsurfacing mixture shall not be placed when the ambient temperature is below 50 °F (10°C) or during unsuitable weather. Microsurfacing shall not be placed if rain is imminent or if there is the possibility that there will be freezing temperatures within 24 hours. When wheel path depressions have a cross section that is deformed ½ inch (12.5 mm) or more, the individual wheel paths shall first be filled utilizing a wheel path depression (rut) box in conformance with the provisions of the special provisions. The depth of the wheel path depression shall be determined after the adjacent ridges have been removed, when applicable. The maximum single application for wheel path depressions shall be one inch (25 mm). Wheel path depressions of depths greater than one inch (25 mm) shall require multiple applications in each depression. Wheel path depression repair shall be constructed with a slight crown to allow for initial compaction by traffic on the microsurfacing. Freshly filled wheel path depressions shall be compacted by traffic for a minimum of 12 hours before additional lifts of microsurfacing material are placed for rut filling purposes or as surface courses. Microsurfacing shall be spread at a rate within the following ranges of pound of dry aggregate per square yard (kilograms of dry aggregate per square meter).
Longitudinal joints shall correspond with the edges of the traffic lanes. The Engineer may permit other patterns of longitudinal joints if the patterns will not adversely affect the quality of the finished product. Through traffic lanes shall be spread in full lane widths only. Longitudinal joints common to 2 traffic lanes shall be butt joints with overlaps not to exceed 3 inches (76 mm). Building paper shall be placed at the transverse joints to avoid double placement of the microsurfacing. Other suitable methods to avoid double placement of the microsurfacing will be allowed. Hand tools shall be available to remove spillage. The mixture shall be uniform and homogeneous after placing on the surfacing and shall not show separation of the MSE and aggregate after setting. The completed surface shall be of uniform texture and free from ruts, humps, depressions, or irregularities. 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 or be picked up by the tires of vehicles. Placement of the microsurfacing shall cease a minimum of one hour before the expiration of the road closure hours as specified in "Maintaining Traffic" of these special provisions, unless the Contractor proves to the satisfaction of the Engineer that the surface will be ready for unrestricted traffic at the expiration of the road closure hours. TEST STRIP The Contractor shall construct a test strip for evaluation by the Engineer. The test strip shall be 300 feet (100 m) to 500 feet (150 m) long and shall consist of the application courses specified. The test strip shall be constructed at the same time of day or night that the full production of microsurfacing will be placed and may be constructed in 2 days or nights when multiple course applications are specified. The Engineer will evaluate the completed test strip after 12 hours of traffic on the completed test strip to determine if the mix design and placement procedure are acceptable. If the mix design or the placement procedure is determined by the Engineer to be unacceptable, the test strip will be rejected, the Contractor shall make modifications, and a new test strip shall be constructed and evaluated by the Engineer. The cost of materials and placement of the test strips, which have been rejected, shall be borne by the Contractor and will not be considered as part of the contract work. If ordered by the Engineer, rejected test strips shall be removed at the Contractors expense. REPAIR OF EARLY DISTRESS If bleeding, raveling, delamination, rutting, or washboarding occurs within 60 days after placing the microsurfacing, the Contractor shall diligently pursue repairs by any method approved by the Engineer. The Contractor shall not be relieved from maintenance until repairs have been completed. MEASUREMENT Microsurfacing will be measured by the Square Yard. The quantity of microsurfacing to be paid for will be the square yards of actual area covered by the microsurfacing. Quantities of asphaltic emulsion for paint binder (tack coat), to be paid for as contract items of work, will be determined in accordance with the methods provided in Section 94, “Asphaltic Emulsions,” of the Standard Specifications. PAYMENT The contract price paid per square yard for microsurfacing shall include full compensation for furnishing all labor, materials, tools, equipment, and incidentals, and for doing all the work involved in placing microsurfacing, complete in place, including testing for and furnishing mix design, cleaning the surface, furnishing added water and set-control additives, and protecting the microsurfacing until it has set, as shown on the plans, as specified in these special provisions, and as directed by the Engineer. When there is a contract item for asphaltic emulsion (paint binder),
the quantity of asphaltic emulsion used as paint binder (tack coat)
will be paid for at the contract price per ton for asphaltic emulsion
(paint binder). When there is no contract item for asphaltic emulsion
(paint binder), full compensation for furnishing and applying paint
binder (tack coat) shall be paid for by Extra Work Force Account. |
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