350Microsurfacing

2.1 Cationic Polymer -Modified Asphalt Emulsion . Provide CSS -1P in accordance with Section 300.2.4.,

“Emulsified Asphalt.” Specialized emulsions in accordance with Item 300, “Asphalts, Oils, and Emulsions,” are allowed when shown on the plans.

2.2 Aggregate . Furnish crushed aggregate from a single source in accordance with Table 1 and Table 2.

Determine aggregate gradations for mixture design and production testing based on the washed sieve analysis in accordance with Tex -200-F , Part II. Aggregate from sources listed in the Department’s Bituminous Rated Source Quality Catalog (BRSQC) is pre-approved for use. For sources not listed i n the Department’ s BRSQC:  build an individual stockpile for each material;  request that the Department test the stockpile for specification compliance; and  once approved, do not add material to the stockpile unless otherwise approved. Allow 30 calendar days for the Engineer to sample, test, and report results for non- listed sources. Do not combine approved material with unapproved material. Include the amount of mineral filler added to the mix in determining the total minus No. 200 aggregate fraction. Table 1 Master Gradation Limits (% Passing by Weight or Volume) Sieve Size % Passing 3/8" 100.0 #4 86.0–94.0 #8 45.0–65.0 #16 25.0–46.0 #30 15.0–35.0 #50 10.0–25.0 #100 7.0–18.0 #200 5.0–15.0 428 Table 2 Aggregate Quality Requirements Property Test Method Requirement Surface aggregate classification ( SAC) Tex-499-A (AQMP) A1 Magnesium sulfate soundness, five cycles, %, Max Tex-411-A 25 Crushed face count2, %, Min Tex-460-A, Part I 95 Sand equivalent, %, Min Tex-203-F 70 Acid insoluble, %, M in Tex-612-J 55 1. SAC of “A” is required unless otherwise shown on the plans . 2. Only applies to crushed gravel.

2.3 Mineral Filler . Provide a mineral filler that is sufficiently dry, free-flowing, and free of clumps and foreign

matter consisting of non- air entrained cement in accordance with DMS -4600 , “Hydraulic Cement,” or hydrated lime in accordance with DMS -6350 , “Lime and Lime Slurry.”

2.4 Water . Provide water that is potable and free of harmful soluble salts.

2.5 Other Additives. Use approved additives as recommended by the emulsion manufacturer in the emulsion

mix or in any of the component materials when necessary to adjust mix time in the field.

2.6 Tack Coat . Furnish CSS -1H or SS -1H for tack coat binder in accordance with Item 300. Do not dilute

emulsified asphalts at the terminal, in the field, or at any other location before use, unless required dilution rate is shown on the plans. When dilution is required, tack coat dilution must be witnessed by the Engineer.

3.1 Mixing Machine . Furnish a self -propelled microsurfacing mixing machine with:

 self-loading devices to promote continuous laying operations ;  enough storage capacity for mixture of materials ;  individual volume or weight controls that will proportion each material to be added to the mix ;  continuous flow mixing with a revolving multi -blade mixer capable of discharging the mixture on a continuous flow basis ;  opposite side driving stations ;  full hydrostatic control of the forward and reverse speed during operation;  a water pressure system and nozzle- type spray bar immediately ahead of the spreader box and capable of spraying the roadway for the width of the spreader box ;  a mechanical -type spreader box equipped with paddles or other devices capable of agitating and spreading the materials throughout the box ;  a spreader box with devices capable of providing lateral movement or side shift abilities ;  a spreader box with a front seal, adjustable rear strike- off, and adjus table secondary rear strike- off; and  an electronic monitoring system: • consisting of pulse sensors to measure delivery rates, radar gun to monitor distance traveled, programmable micro- controller with operator’s display and input board, and on- board pr inter; • capable of recording, monitoring, and displaying the amount of aggregate, emulsion, mineral filler, water , and additives , in pounds ; • capable of displaying and recording ratios of emulsion to aggregate, mineral filler to aggregate, additive to aggregate, water to aggregate, and application rate in pounds per square yard; • capable of recording the percentages of emulsion, mineral filler, water, and additive; • capable of printing a hard copy report on demand that displays the date and the cumulative weight of aggregate, emulsion, and mineral filler in pounds and the number of gallons of additive and water; the percentages of emulsion, mineral filler, water, and additive; and the ratios of emulsion to 429 aggregate, mineral filler to aggregate, additive to aggregate, water to aggregate, and application rate in pounds per square yard since the last reset; and • accurate to within 0.5% of actual weights and measures. Calibrate at the beginning of each project and properly mark each control device that proportions the individual materials .

3.2 Scales. Scales used for weighing aggregates and emulsion must be in accordance with Item 520, “Weighing

and Measuring Equipment.” The weighing equipment for aggregates may be either a suspended hopper , a belt scale, or the mixing machine electronic system when allowed by the Engineer .

3.3 Asphalt Storage and Handling Equipment . Furnish a thermometer in each tank to indicate the asphalt

temperature when storage tanks are continuously used. Keep equipment clean and free of leaks. Keep asphalt materials free of contamination.

4.1 Certification . Maintain on the project at least one responsible employee certified under the AASHTO

Microsurfacing Certification Program for personnel. The Department representative at the project will also have the AASHTO m icrosurfacing certification.

4.2 Mixture Design . Provide a mixture design meeting the proportions shown in Table 3 and Table 4. Perform

the mixture design using an AASHTO -accredited laboratory experienced in the design of microsurfacing systems. Provide the Engineer with representative samples of all component materials for verification of the mixture design, unless otherwise directed. Identify additives used to control mixture set times and cohesion, as determined by design testing, and provide acceptable limits. The Materials and Tests Division will verify the mixture design to ensure it meets the minimum requirements for wet track abrasion wear value listed in Table 4. Provide the Engineer with approximately 40 lb. of each aggregate stockpile, at least 1 gal. of asphalt emulsion, at least 1 gal. of mineral filler, and sufficient quantities of any additives proposed for use. The Engineer may accept an existing mixture design previously used on a Department project , but the mixture design may be subjected to annual verification using laboratory -produced mixes before starting the paving season. Production may begin at the Contractor’s risk without receiving the results from the Department’s verification if approved by the Engineer. Changes in aggregate source, emulsion source, or mineral filler will require a new mixture design submitted for the Engineer’s approval. The Engineer may require a new test strip if there is a change in aggregate source, emulsion source, or mineral filler. Table 3 Mixture Design Proportions Material Proportion Residual asphalt 6.0–9.0% by wt. of dry aggregate Mineral filler (hydraulic cement or hydrated lime) 0.5–3.0% by wt. of dry aggregate Field control additive As required to provide control of break and cure Water As required to produce proper mixture consistency Table 4 Mixture Design Requirements Property Test Method Requirements Wet track abrasion, g/sq. ft., Max wear value Tex-240-F, Part V 75 Gradation (aggregate and mineral filler) Tex-200-F, Part II ( washed) Table 1 Mix time, controlled to 120 sec. Tex-240-F, Part II Pass Lateral displacement Specific gravity after 1,000 cycles of 125 lb . ISSA TB- 147 5% Max

2.10 Max

Excessive asphalt by LWT Sand adhesion ISSA TB- 109 50 g/ft.2 (538 g/m2) Max

4.3 Reporting, Testing, and Responsibilities . Use Department -provided templates to record and calculate all

test data pert inent to production testing. Obtain the current version of the templates from the Department’s website or from the Engineer. The Engineer will immediately report to the Contractor any test results that fail to meet the specification requirements. Note that mix placed after test results are available to the Contractor may be considered unauthorized work if the results require suspension of operations. Unauthorized work will be accepted or rejected at the discretion of the Engineer in accordance with Article 5.3., “Conformity with Plans, Specifications, and Special Provisions.”

4.4 Temporary Material Storage.

4.4.1 Aggregate Storage . Stoc kpile materials to prevent segregation or contamination. Remix stockpiles using

suitable equipment when necessary to eliminate segregation. Use a scalping screen to remove oversize material while transferring aggregates to the mixing machine.

4.4.2 Mineral Filler Storage . Store the mineral filler in a manner that will keep it dry and free of contamination.

4.4.3 Asphalt Material Storage. Keep asphalt materials free of contamination.

4.5 Weather Limitations. The Contractor may pave any time the roadway has no standing water on the

roadway surface, the roadway surface temperature is at least 60°F , and the ambient temperature is at least 50°F and rising. Place mixtures only when the Engineer determines the roadway surface, weather , and moisture conditions are suitable. The Engineer may restrict the Contractor from paving if the ambient temperature is below 60°F and falling. Cease placement 24 hr. before the weather forecast (National Weather Service) predict s temperatures below 32°F unless otherwise approved.

4.6 Surface Preparation . Prepare the surface by removing raised pavement markers and objectionable material

such as moisture, dirt, sand, leaves, and other loose impediments from the surface before placing mi xture. Provide a water spray immediately ahead of the spreader box when required for existing surface conditions when tack coat is not required. Apply water at a rate that will dampen the entire surface without any free-flowing water ahead of the spreader box.

4.7 Tack Coat . Apply tack coat uniformly at the rate directed by the Engineer when shown on the plans. The

Engineer will set the rate between 0.04 and 0.10 gal. of residual asphalt per square yard of surface area. Apply the tack coat in a uniform manner to avoid streaks and other irregular patterns.

4.8 Material Transfer . Minimize construction joints by providing continuous loading of material during

placement. Remove oversized material before transferring the aggregates to the mixing machine.

4.9 Placing . Make necessary adjustments so that the mixture will have sufficient working life to allow for proper

placement, with considerations for aggregate moisture and at the predicted ambient temperature and humidity . Spread the mixture uniformly to the lines and grades shown on the plans or as directed using a mechanical type spreader box. Shift the spreader box when necessary to maintain proper alignment. Clean the spreader box regularly to prevent buildup from occurring and to minimize clumps. Set and maintain the spreader box skids to prevent chatter in the finished mat. Prevent loss of material from the spreader box by 431 maintaining contact between the front seal and the road surface. Adjust the rear seal to provide the desired spread. Adjust the secondary strike- off to provide the desired surface texture. Clean strike-off regularly to prevent buildup from occurring.

4.10 Curing. Protect the finished mat from traffic until the mixture cures and will not be damaged by traffic. Adjust

mixture properties according to humidity conditions and ambient temperatures to allow traffic on completed travel lanes within 1 hr. after placement with no damage to the surface. Protect locations subject to sharp turning, stopping, and starting traffic for longer periods when necessary.

4.11 Production Testing. Control the production process within the operational tolerances shown in Table 5 and

Table 6 . Provide access to the mixing unit discharge stream for sampling purposes. Suspend production when the Engineer’s test results exceed the operational tolerances. The Engineer will allow production to resume when test results or other information indicate the next mixture produced will be within the operational tolerances shown in Table 5 and Table 6. Take corrective action to address deficiencies. Table 5 Operational Tolerances Property Test Method Requirements Asphalt content, % by wt. Tex-236-F1 or asphalt meter reading s Design target ± 0.5 1. Dried to constant weight at 230 ±10°F . Table 6 Washed Gradation % Passing Operational Tolerances1 Sieve Size1 Requirement2 3/8" ±5 #4 ±5 #8 ±5 #16 ±3 #30 ±3 #50 ±3 #100 ±3 #200 ±2 1. Tex-200-F, Part II, sampled from stockpile or belt. 2. Material passing #200 sieve, including the mineral filler, must conform to the limitations of the master gradation shown in Table 1. 3. Gradations must meet both the master gradation band, shown in Table 1, and the operational tolerance from mixture design. The asphalt content may be reduced below the tolerance when lean mixes are necessary for scratch and rut passes , but not less than the design minimum shown for the wet track abrasion test when approved.

4.12 Workmanship . Immediately take corrective action if microsurfacing material exhibit s evidence of poor

workmanship, delayed opening to traffic, or surface irregularities, including excessive scratch marks, drag marks, tears, streaks, raveling, delamination, and segregation. The Engineer may allow placement to continue for no more than 1 day of production while taking appropriate action. Suspend paving if the problem still exists after 1 day until the problem is corrected to the Engineer’s satisfaction.

4.12.1 Finished Surface . Provide a finished surface with a uniform texture free of excessive scratch marks, tears,

or other surface irregularities. Marks, tears, or irregularities are considered excessive if:  more than one is at least 1/4 in. wide and at least 10 ft. long in any 100 ft. of machine pull,  more than three are at least 1/2 in. wide and more than 6 in. long in any 100 ft. of machine pull, or  any are 1 in. wide or wider and more than 4 in. in length.

4.12.2 Construction Joints . Place mixture so that longitudinal joints on the surface course coincide with lane lines,

or as directed. Provide longitudinal and transverse joints that are uniform and neat in appearance. Provide 432 construction joints that have limited buildup and no gaps between applications. Joints with buildup will be considered acceptable if:  no more than 1/2- in. vertical space exists between the pavement surface and a 4- ft. straig htedge placed perpendicular to the longitudinal joint , and  no more than 1/4- in. vertical space exists between the pavement surface and a 4- ft. straightedge placed perpendicular to the transverse joint.

4.12.3 Edges . Provide an edge along the roadway centerline, l ane lines, shoulder, edge of pavement, or curb line

that is uniform and neat in appearance. The edge is considered acceptable when:  it varies no more than ±3 in. from a 100- ft. straight line on a tangent section, and  it varies no more than ±3 in. from a 100 -ft. arc on a curved section.

4.13 Miscellaneous Areas. Use a single- batch type lay -down machine or other approved method to place

materials on ramps or other short sections. Apply tack coat uniformly at the rate directed by the Engineer when shown on the plans, or lightly dampen the surface with water before placing the mix when tack coat is not required. Provide 100% coverage that is uniform in appearance and comparable to that produced by the spreader box.

4.14 Ruts . Fill ruts, utility cuts, and depressions in the existing surface in a separate pass from the final surface

when shown on the plans. Fill ruts as follows .  Fill irregular or shallow ruts less than 1/2 in. deep with a full -width scratch coat pass. Use a rigid primary strike -off plate unless otherwise approved.  Fill ruts 1/2 in. deep or deeper independently using a rut -filling spreader box that is at least 5 ft. wide. Crown the spreader box to compensate for traffic compaction.  Fill ruts deeper than 1- 1/2 in. in multiple placements unless otherwise approved.  Cure each lift 24 hr . before placement of the next lift when using multiple placements.

4.15 Repairs. Perform full -width repairs unless otherwise directed.

4.16 Test Section . At the beginning of the first day of production, place a test str ip with a minimum length of

500 ft. meeting the mixture design tolerances to demonstrate the mixing and placement procedures. Place the test strip at the same general time of day (night or day) at which the paving is to take place. Inspect t he test strip for variations in surface texture, material ratios, finished surface appearance, and ability to carry normal traffic within 60 min. The Engineer will approve or reject the test strip within 2 hr. of placement. If rejected, the Engineer may require another test strip after the Contractor corrects any deficiency. Paving may proceed after the Engineer approves the test strip.

4.17 Quality Control (QC) . Produce a mixture in conformance with the mixture design and the QC tolerances.

Randomly calculate and report to the Engineer the percent asphalt content of the mixture and the yield of the aggregate from the equipment computer display readings at least three times daily . Maintain quality, and provide to the Engineer a report and log sheet containing the following information:  aggregate used, ton (dry) ;  microsurfacing emulsion used, ton;  bituminous materials for tack coat used, if specified, ton;  mineral filler used, lb.;  water used in mixture, gal.;  additive used in mixture, gal.;  surface area completed, sq. yd.;  surface area application rate, dry lb. aggregate per sq. yd.; and  percentage of emulsified asphalt based on dry aggregate. 433 Test the aggregate for moisture content each day before placement or when aggregate moisture changes because of rainfall events or new material delivery, or as directed. Enter the percent moisture determined in the electronic monitoring system. Report moisture content to the Engineer each day.

5.1 Aggregate . The quantity of aggregate used in the accepted portion of work will be measured by net ticket

weight of each individual load of aggregate based on dry weight of aggregate. Weigh the aggregate at the project stockpile site unless otherwise approved. Use either a suspended hopper scale or a belt scale in accordance with Item 520. The calculated weight of mineral filler based on the accepted portion of work will be used for measurement and included in the total aggregate weight.

5.2 Polymer -Modified Asphalt Emulsion. The quantity of polymer- modified asphalt emulsion in the accepted

portion of work will be measured by the ton of material based on the accepted load tickets issued from the manufacturer. At the completion of the project, any unused emulsion will be weighed back and deducted from the accepted asphalt emulsion quantity delivered.

5.3 Tack Coat . Tack coat will be measured at the applied temperature by strapping the tank before and after

road application and determining the net volume in gallons from the calibrated distributor. The Engineer will witness all strapping operations for volume determination. All tack, including emulsions, will be measured by the gallon applied.