ITEM 421 MICROSURFACING
421.01 Description. This work consists of constructing a cold laid polymer modified emulsified
asphalt pavement course to fill ruts or provide a leveling and/or surface course for existing pavements. Warrant the microsurfacing for two years.
421.02 Materials. Furnish materials conforming to:
Emulsified Asphalt (Binder) ....................... ........................................ 702.16, Type C Aggregate ............................ 703.01, 703.05 Water ................................................ 499.02 Mineral Filler (Portland Cement) ........ 701.04 or 701.05 Tack Coat ......................................... 421.09 Use a quick-traffic polymer modified emulsified asphalt binder (Binder) conforming to 702.16, type
C.Use only Binder certified according to Supplement 1032. Provide to the Engineer certified test data and a statement from the Binder supplier with each load of Binder that the Binder is the same base asphalt binder, polymer, polymer percentage as formulated and used in the mix design. Include the percent residue on the Bill of Lading. Conform to 703.01 and 703.05 for aggregate, except as follows: TABLE 421.02-1 Percent by weight of fractured pieces 100 Sand Equivalence (AASHTO T176) 55 minimum Do not use aggregates designated with “SR” or “SRH.” Provide an aggregate blend of 50 percent crushed carbonate stone (CCS) and 50 percent igneous diabase (ex. Ontario Trap Rock) for Surface Course (FR). Provide CCS aggregates for all other microsurfacing courses. Provide a final blend of aggregates that conform to Table 421.02-2 Gradation A for the aggregate for surface courses, Gradation B for the aggregate for rut fill courses, and Gradation A or B for the aggregate for leveling courses. Stockpile tolerance will be based on target gradation stated in the mix design but will not exceed design gradation band for No. 200 sieve. TABLE 421.02-2 Sieve Size Total Percent Passing A B Stockpile Tolerance 3/8 inch (9.50 mm) 100 100 No. 4 (4.75 mm) 85 to 100 70 to 90 ± 5.0% No. 8 (2.36 mm) 50 to 80 45 to 70 ± 5.0% No. 16 (1.18 mm) 40 to 65 28 to 50 ± 5.0% No. 30 (600 µm) 25 to 45 19 to 34 ± 5.0% No. 50 (300 µm) 13 to 25 12 to 25 ± 4.0% No. 100 (150 µm) – 7 to 18 ± 3.0% No. 200 (75 µm) 5 to 15 5 to 18 ± 2.0% Screen the aggregate for oversize material prior to use using a 3/8 inch (9.5 mm) screen size. When a blend of aggregates is to be used to meet gradation A or B, proportion the aggregates in a separate stockpile and blend to a uniform consistency prior to screening. Screen the aggregate to complete the blending process and to remove any oversize material prior to use. If oversize material becomes present in the mixture, screen the aggregate directly into material support units. For mineral filler, use Supplement 1028 Certified Portland cement conforming to 701.04 ASTM C 150, Type I or 701.15 ASTM C 595, Type IL. Do not interchange Type I and Type IL and specify which is being used in the mix design. Adjustments in the quantity of mineral filler added to the mixture are permitted to improve mixture consistency, mix time, or set time. Do not exceed ± 0.5% from the mix design during placement. Use water conforming to 499.02. Add water to the mixture to control mixture consistency only and not to control mix time. Use mix set additives as stated in the mix design to control the mixture’s mix and set time. If mix set additives are used during production of mixture, include as part of the mix design. Ensure additives are compatible with the other components of the mix.
421.03 Proportioning. Develop a mix design to comply with the mix design criteria and submit
to OMM on approved forms, at least two weeks prior to the start of calibration, for preliminary JMF approval. OMM may require additional time prior for preliminary approval to perform tests on lab materials to ensure mix compliance. OMM will notify the Contractor if additional time for testing is required. Final JMF approval will be granted upon successful placement in the field. OMM may require the Contractor to design and submit for a new JMF for lack of mix compliance or lack of field performance. Submit the mix design and proposed materials to OMM. Include a minimum of 11 pounds (5,000 g) of each aggregate, one quart (1 L) sample of Binder, 3.5 ounces (100 g) of mineral filler, and one pint (0.5 L) of additive, if used, and a complete mix design packet prepared by an AASHTO-accredited laboratory in Pavement Preservation. Prepare the mix design for gradations A or B and present all test data for all tests specified in Table 421.03-1. Determine the residual binder content and present related proportioning of total water (includes moisture in aggregate), mineral filler, and additive with tolerances for each in the final designed mixture. Verify during the mix design the compatibility of the aggregate, Binder, mineral filler, and other additives. Produce the mix design using the same materials that will be used on the project. Approved JMF’s expire on December 31st.
A.Ensure that the mix design:
1.Has aggregate meeting the gradation specified.
2.Has residual asphalt by dry weight of aggregate of 7.5 to 8.5 percent for leveling and surface courses or 6.5 to 8.0 percent for rut fill courses.
3.Has a mineral filler content of 0.3 to 2.5 percent by dry weight of aggregate and a tolerance of not greater than ± 0.5 percent of the mix design within the required minimum and maximum.
4.Has mix times and wet cohesion requirements based on specific minimum and maximum percent mineral filler, total water, and additive.
5.Has a total water content with a tolerance not greater than ± 1.5 percent.
6.Has a total non-diluted additive content with a tolerance not greater than ± 0.2 percent. Verify that the additive dilution rate with water specified in the mix design is consistent with the paving machine being used.
7.Meets the specified properties of the following International Slurry Seal Association (ISSA) tests: TABLE 421.03-1 ISSA Test No. Description Specification TB-139 Wet Cohesion 30 minutes min. (set time) 12 kg-cm min. 60 minutes min. (traffic) 20 kg-cm min or near spin TB-114 Wet Stripping 90 percent min. TB-100 Wet Track Abrasion Loss 1-hour soak 6 day soak 450 g/m² max. 650 g/m² max. TB-144 Saturated Abrasion Compatibility 2 g loss max. TB-113 Mix Time @ 25 C Controllable to 120 seconds Mix Time @ 40 C Controllable to 45 seconds TB-147 Lateral Displacement (For Leveling and Rut Fill courses only) 5%, max. TB-109 Excess Asphalt by LWT Sand Adhesion 538 g/m² max. Check the ISSA TB-139 (set time) and ISSA TB-113 (mix time) tests at the highest and lowest temperatures expected during construction.
B.Report the following in the mix design (all percentages are based on the dry weight of the aggregate):
1.Source and location of each individual material. Provide percentage of each aggregate source if multiple aggregate sources are used.
2.Aggregate gradation, washed and dry (dry for field QC). Provide aggregate gradation of each source and final combined if multiple sources are used.
3.Sand equivalence of the aggregate.
4.Percentage of mineral filler and tolerance.
5.Percentage of total water and tolerance and acceptable pH range.
6.Percentage and Type of mix set additives (if required) and tolerance.
7.Percentage of Binder and residual asphalt content in the mixture.
8.Quantitative effects of moisture content on the unit weight of the aggregate per AASHTO T 19 from 0.0 to 10.0% moisture content.
421.04 Quality Control Program (QCP). Create and implement a Quality Control Program
(QCP) for each construction season. The QCP will cover processes conducted to provide a microsurface mixture at the project site that is uniform in composition, conforms to the specification requirements and project mix design, and that when placed is free of any defects (lack of mixing, inconsistent texture, inconsistent profile, excessive overlap at joints, streaking, drag marks, roughness, raveling, rutting, holes, and debris, etc.) within the Contractor’s control at project completion. Submit a hard copy of the proposed QCP to OMM for review and acceptance. Submit by February 28 or a minimum of five (5) weeks before calibration. Include a revision date on the cover sheet and revision sheet listing the date(s), what section(s) and page(s) a revision was made, and a short description of what was revised, added, or removed. Submit a hard copy and a digital copy (if available) of the QCP acceptance letter and accepted QCP to District Testing a minimum of two weeks prior to calibration. Keep copies of the letter and the QCP with each Contractor’s Quality Control Manager and provide a copy of both to the Engineer . Digital copies of the QCP and letter in pdf format are allowed with the following requirements: The file icon must be appropriately labeled and be on the computer desktop. The QCP must contain page numbering and a Table of Contents inside the front cover locating all sections by page number and out of date QCPs must be removed from the computer desktop. Failure to comply with the approved QCP may result in work stoppage and adversely affect the Contractor’s Prequalification rating. The QCP is a reflection of a Contractor ’s sincerity and ability in producing a quality product. Development of this program beyond the minimum requirements specified below is encouraged. Include in the program:
A.The assignment of quality control responsibilities. Quality control includes all efforts required to achieve a product meeting specifications. List individuals as required below and note their designated responsibilities to meet QCP requirements. Provide a Quality Control Manager who is a company employee who is routinely and usually at the paving site during placement of any microsurfacing. Provide a list designating technician responsibilities and expected actions. Ensure only trained personnel handle and test samples at all times. Define who is responsible at the project site and specific methods for ensuring mixing equipment, haul vehicles, etc. meet requirements.
B.Means for annual training of company and consultant technicians and their supervisors in ethical conduct according to company expectations. Document how and when training is given, what the expectations are, how expectations are communicated, and list all personnel trained. Describe the QC Manager’s and technician supervisor’s responsibilities and methods in ensuring ethical conduct is maintained throughout the year.
C.Provisions to meet the Department mix specifications including warning bands and action plans for aggregate, Binder, and tack coat materials to ensure they meet Department testing.
D.Procedures for extra testing (e.g., job start, responses to poor test results or field mix problems, aggregate stock testing, moistures) and any other testing necessary to control materials not already defined in these Specifications.
E.Methods to maintain all worksheets, including all handwritten records, and other test and sample records from the project for the duration of the contract or eight years, whichever is longer. Define the test record process. Define company records retention requirements. Provide copies of all test reports and forms used in the quality control process.
F.Procedures for calibration and documentation for all testing equipment. Procedures for calibration record storage. Procedure to supply documentation records of testing equipment calibration at the request of the engineer.
G.Method of performing mixing equipment calibrations including scales to be used, yield checks, and documentation for each project.
H.Procedure for random sampling to be used at the project and documentation method. Procedures for sample taking, tracking, handling, and documentation method for all samples taken at the project paving site.
I.Procedure for ensuring that every Contractor employee involved in the testing of aggregates and microsurfacing mix and operation of the mixing equipment has read the QCP and has on site access to all applicable Department specifications, proposals, policies, and the current approved JMF.
J.Procedure for ensuring binder Bills of Lading with BOL load number, binder source and grade, and binder percent residue are reviewed against running mix designs and record of review listing the above information be kept with the QC Manager for the duration of the project. Means to meet the handling and storage requirements of the Binder and tack coat suppliers.
K.Means to meet placed mixture uniformity and hauling/trucking requirements.
L.Define the roles and responsibilities of the QC Manager.
M.Signature of the Quality Control Manager and, if different, the person in authority to enforce all operations covered by the QCP as outlined in this subsection.
421.05 Weather Limitations. Apply the mixture only when it is not raining, pavement has no
standing water, and the existing pavement surface and atmospheric temperature is a minimum of 45 F (7 C) and rising and there is no forecast of an atmospheric temperature below 32 F (0 C) within 24 hours from the time the mixture is applied. Between September 30 and May 1, do not apply the mixture if the existing pavement surface temperature is less than 50 F (10 C).
421.06 Mixing Equipment . Produce the mixture in a self -propelled, front feed, continuous
loading mixing machine equipped with a conveyer belt aggregate delivery system and an interconnected positive displacement, water jacketed asphalt emulsion gear pump to accurately proportion aggregate and asphalt emulsion or a variable displacement computerized rate control to accurately proportion aggregate and asphalt emulsion. Locate the mineral filler feed so the proper amount of mineral filler is dropped on the aggregate before discharge into the pugmill. Provide a spray bar to completely prewet the aggregate dropping into the pugmill with additive and water before introduction of asphalt emulsion. Ensure that the twin -shaft, multi-blade pugmill is a continuous flow type and minimum of 49 inches (1.25 m) long. Ensure that the blade size and side clearances meet the equipment manufacturer’s recommendations. Introduce the emulsion within the first one -third of the mixer length to ensure proper mixing of all materials before exit from the pugmill. Equip the machine with opposite side driving stations to allow full control of the machine from either side. Equip the mixer with a remote forward speed control at the back mixing platform so the operator controlling the mixture placement can control forward speed and level of mixture in the spreader or rut box. Provide material control devices that are readily accessible and positioned so the amount of each material used can be determined at any time. Equip the mixing machine with a water pressure system and nozzle type spray bar to provide a water spray ahead of and outside the spreader box when required. Apply water at a rate that will dampen the surface, but will not create free flowing water ahead of the spreader box. The Contractor may use truck -mounted batch machines with a conveyer belt aggregate delivery system and without the front feed, continuous loading feature on projects of less than 15,500 square yards (13,000 m 2), on spot repairs, on projects with multiple routes where every route is less than 15,500 square yards (13,000 m2), or where specified in the plans.
421.07 Equipment Calibration. Before mix production, calibrate the mixing equipment to the
approved JMF in the presence of the Engineer according to Supplement 1040. Verify that the project calibration is not affected by any previous calibrations and scale factors by removing or resetting prior to starting a new calibration. Generate documentation for the Engineer, including individual calibrations of each material at various settings. Perform a calibration for each JMF used on the project. Following calibration, do not make any further calibration adjustments to the mixing equipment without the Engineer’s approval. The Engineer may require additional calibrations following any equipment break down related to the aggregate delivery belt, asphalt emulsion gear pump, or mixture performance issues. Submit the approved mix design information and JMF(s) to the Engineer and District Testing at least 48 hours prior to start of calibration.
421.08 Spreading Equipment. If a leveling or surface course is specified, apply the mixture by
means of a conventional spreader box attached to the mixer. If a rut fill course is specified, apply the mixture with a 5 to 6 foot (1.5 m to 1.8 m) width V-shaped rut filling spreader box attached to the mixer. Equip the rut filling spreader box with a steel strike-off. If a leveling course is specified, apply the mixture with a spreader box equipped with a steel or rubber strike-off that is designed to fill wheel path ruts. A secondary strike -off may be used to reduce roughness of the leveling course but will not remove mixture in wheel path ruts or affect desired cross section. Equip the spreader box with paddles or augers mounted on an adjustable shaft to continually agitate and distribute the materials throughout the box. Ensure that the equipment provides sufficient turbulence to prevent the mix from setting in the rut fill or spreader box or causing excessive side build- up or lumps. To prevent loss of the mixture from the spreader box, attach flexible seals, front and rear, in contact with the road. Operate the spreading equipment in such a manner as to prevent the loss of the mixture on superelevated curves. For surface courses, attach a secondary strike-off to the spreader and adjust as required to provide a uniform mixture texture. The Contractor may use burlap drags or other drags, if necessary, to obtain the desired finish. Replace drags having excessive build-up.
421.09 Surface Preparation. Before applying the mixture, thoroughly clean the surface.
Remove raised pavement markers according to 621.08, when specified. Remove all existing pavement markings so that less than 5% of the line remains visible. Repair damage to the pavement that results in the removal of more than 1/8 inch of pavement thickness. When a grinder drum is mounted to a skid steer loader, the drum m ust be able to accommodate a minimum of 150 teeth. Seal visible joints and cracks longer than 2 feet (600 mm) in length and any joint or crack greater than 1/4 inch (6 mm) in width no matter the length using Item 423 Type II only. Apply crack sealant material at a width of 2 to 4 inches (50 to 100 mm) and at a thickness of not less than 1/16 inch (2 mm) and not greater than 3/16 inch (5 mm). Apply a tack coat to the existing pavement surface conforming to 702.16, Type C CSS -1hM, consisting of a minimum of 15% asphalt residue achieved by diluting with water. Apply the tack coat at a rate of 0.06 to 0.12 gallons per square yard (0.25 to 0.45 L/m²) that provides uniform coverage without excess run -off and allow tack to break before releasing to construction traffic. Adjust application rate of tack coat based on surface texture and porosity. Apply the tack coat only to areas that will be covered by the microsurface during the same day. Do not apply tack coat on top of a leveling course prior to placing the surface course. Protect drainage structures, monument boxes, water valve, etc. during material application.
421.10 Test Strip. Construct a continuous 1000 foot (300 m) long by lane width test strip for
each approved JMF(s) for the project. The test strip will demonstrate the mix and set time of the material and ability to perform under full traffic. If handwork will be performed on the project, include handwork in the test strip. Construct the test strip at the same time of day or night the full production will be applied. Perform a yield check to ensure the proper spread rate, surface quality requirements and compliance with JMF components are met. Submit results to the Engineer. The Engineer will evaluate the completed test strip and yield check report after a minimum of 12 hours under traffic, to determine if the mix design and application is acceptable. The Contractor may begin full production after the Engineer accepts the test strip. If the microsurfacing is being applied between May 1 and October 15, the Department may waive the test strip if the Contractor has constructed a Department accepted test strip during the same time frame with the same materials and JMF(s) and with no documented project performance issues. Provide documentation (Project Number, District, Route, Test Strip Date, Engineer , etc.) and history from the previous test strip(s) and calibration(s) to the Engineer.
421.11 Application. Apply the microsurface mixture to the prepared surface in a manner to fill
cracks, shallow potholes, and minor surface irregularities and achieve a uniform textured surface without causing streaking, drag marks, skips, lumps or tears. Carry a sufficient am ount of material at all times in all parts of the spreader box to ensure complete and uniform coverage. Avoid overloading of the spreader box. Do not allow lumping, balling, or unmixed aggregate in the spreader box. When specified, place leveling courses to cover the entire pavement area as specified. Place the leveling course in a manner to maintain or improve the ride quality of the existing pavement. Provide a completed leveling course with no drag marks or tears greater than 1/2 inch (13 mm) wide, 1/4 inch (6 mm) deep, or 12 inches (25 mm) in length. Provide a completed leveling course free of flushing, bleeding, or added roughness. The completed leveling course may exhibit minor raveling upon opening to traffic but will not exhibit any continued raveling after the first four hours of traffic. When specified, apply rut fill courses in widths from 5 to 6 feet (1.5 to 1.8 m) for each wheel path. Apply enough material to fill the wheel paths without excess crowning (overfilling). An excess crown is defined as 1/8 inch (3 mm) after 24 hours of traf fic compaction. If rut depth exceeds 1.0 inches (25 mm), apply rut fill course in multiple courses. Provide a smooth, neat seam where two rut fill passes meet. Take care to restore the designed profile of the pavement cross -section. After compaction by traffic, ensure the completed rut fill does not result in deviations in excess of 1/4 inch (6 mm) as measured across each wheel path using a 6 foot (1.8 m) straight edge. Do not place microsurfacing surface course material until wheel path deviations in exces s of 1/4 inch (6 mm) are corrected. Place the rut fill course in a manner to maintain or improve the ride quality of the existing pavement. Provide a completed rut fill course with no drag marks or tears greater than 1/2 inch (13 mm) wide, 1/4 inch (6 mm) deep, or 12 inches (25 mm) in length. Provide a completed rut fill course free of flushing, bleeding, or added roughness. The completed rut fill course may exhibit minor raveling upon opening to traffic but will not exhibit any continued raveling after the first four hours of traffic. If a leveling course and a surface course are specified, apply the microsurface mixture at a minimum of 14 pounds per square yard (7.6 kg/m 2) of dry aggregate weight for the leveling course and 18 ± 1 pounds per square yard (9.8 ± 0.5 kg/m2) of dry aggregate weight for the surface course. Apply the two courses at a minimum combined rate of 32 pounds per square yard (17.4 kg/m 2) of dry aggregate weight. If a surface course is specified and it is not placed on a microsurfacing leveling course, apply the microsurface mixture at a rate of 22 ± 0.5 pounds per square yard (11.9 ± 0.3 kg/m 2) of dry aggregate weight. Apply the mixture in a manner to produce a uniform surface texture across the entire paving pass. For leveling and surface courses, provide a smooth, feathered, neat seam of 1 to 3 inches (25 to 75 mm) where two passes meet at the pavement centerline and at edge of shoulder. In variable width pavement sections minimize overlap and feather overlapping p ass on to the completed surface. Construct overlaps such that cross slope drainage is maintained. Immediately remove excess material from the ends of each run. Construct surface courses at a width to cover the outside edges of rut fill and leveling courses. Construct seams at or near edge of lane but do not construct seams in wheel paths. Maintain straight edge lines along curbs and shoulders. Do not allow runoff in these areas. Ensure that lines at intersections are straight. Use squeegees and lutes using similar material as the secondary strike -off to spread the mixture in areas inaccessible to the spreader box and areas requiring hand spreading. The Contractor may adjust the mix set additive to provide a slower setting time if hand spreading is needed. Do not adjust the water content to adjust the setting time. If hand spreading, pour the mixture in a small windrow along one edge of the surface to be covered an d spread it uniformly by a hand squeegee or lute. Provide uniform appearance of the entire surface area regardless of the means used to spread material. Ensure that the microsurfacing cures at a rate that will permit traffic on the pavement within one hour after application without damaging the pavement surface. However, should the Contractor experience a curing condition that does not allow the opening to traffic within one hour, work out an arrangement agreeable to the Engineer before releasing traffic on the pavement. If the final surface course is not uniform in texture, free of streaks, drag marks, lumps or tears, stop applying the mixture and take steps to correct the problem. Do not resume work until the Engineer is satisfied the problem has been corrected.
421.12 Quality Control. Use the methods described in this section to control the quality of the
mixture and application, and to measure compliance. If any test results or measures of compliance exceed any of the identified quality control tolerances or specification requiremen ts, stop placement and immediately notify the Engineer and District Testing. Identify the cause of exceeding any of the identified quality control tolerances and document in detail the corrective action necessary to bring the deficiency into compliance. Implement the corrective action and resume work and imm ediately perform a test or measure to confirm corrective action has resolved the deficiency. If upon resuming work the tolerances are exceeded, stop the work. Present a revised corrective action plan and obtain the Engineer’s approval before resuming work. Upon resuming work, immediately perform a test or measure to confirm corrective action has resolved the deficiency. The Department can obtain samples of materials at any time. Aggregate samples can be taken from sources, on-hand stockpiles, or from the mixing equipment. Work can be stopped and materials and JMF can be rejected on the basis of poor Department test results. If the Department reports non - compliance on any material test, th e Department will compare results with the Contractors Quality Control Manager. The Engineer will determine if the tests or compliance measurement has been satisfactory corrected. Prior to starting placement, verify the pH of the water to be used is within the acceptable range on the JMF. Verify again if source of water changes. Perform a minimum of four yield checks daily with one occurring within the first 1000 linear feet (300 linear meter) of continuous placement and the last occurring in the last 1000 linear feet (300 linear meter). Perform at least one yield check for each c ourse applied. For cross-overs, driveways, and any other irregular areas, determine yield checks by a means acceptable to the Engineer . Ensure yield checks are a minimum of 500 linear feet (150 linear meter) for continuous loading mixing machines or one full -loaded truck -mounted machine. Ensure yield checks meet and include documentation of compliance for sections 421.03, 421.05, 421.09, 421.11, and 421.13.
A.Binder. Obtain and label a Binder sample from supply tanker and diluted tack coat sample from the distributor truck at the direction of the Engineer and give the samples to the Engineer the same day. Provide and sample the Binder and diluted tack coat in one -quart (1 L) plastic containers with plastic screw tops. Label and retain one sample per each additional day for the Department. Take more samples when requested by the Engineer. Visually inspect Binder in supply tanker(s) to ensure uniform material with no separation or contamination. Verify temperature of binder and tack coat. Monitor and verify proportioning of asphalt emulsion and water into distributor and proper mixing before use or sampling. Perform a minimum of one Binder and tack coat cook-off each production day to determine the residue content of the Binder and tack coat and verify compliance. If residue content is in warning band or out of compliance provide the Engineer with corrective actions prior to using. Ensure mixing equipment is set at design asphalt emulsion percentage during production. Do not exceed a tolerance of ± 0.3% residual content from the design residual content or the minimum and maximum content in the microsurface mix due to fluctuation in r esidual content in the Binder. If tolerance is exceeded, stop production. Correct the issue by correcting the Binder residual content by methods allowed by Supplement 1032 certified supplier or adjust the asphalt emulsion percent, if approved by the Engineer . Recalibrate the mixing equipment to the new adjusted asphalt emulsion percent to meet the design residual content of the microsurfacing mix for positive displacement mixing equipment.
B.Aggregate. Ensure the aggregate stockpile or final blended aggregate stockpile if two aggregates are used gradation does not vary by more than the stockpile tolerance in Table 421.02-2 compared to the approved JMF and does not exceed the design gradation band for No. 200 (75 µm) sieve. Ensure the percent passing does not change from the high end to the low end of the range for any two consecutive sieves. Verify the blending and screening of aggregates at the stockpile site and sample the blended and screened aggregate for QC testing. When two aggregates are used, ensure that the 50/50 blend is within 5 percent based on each stockpile gradation and theoretical blend. Stockpile a minimum of 10 percent of the project aggregate or 200 tons (180 metric tons) of aggregate whichever is less at a staging area. Obtain three (3) aggregate samples from the stockpile prior to any production starting and perform gradation testing on each sample according to AASHTO R 90, AASHTO R 76, Supplement 1004 (AASHTO T 11 where required), and moisture content per AASHTO T 255. Use dry gradations for determining the No. 200 (75 µm) sieve. Determine the percent passing for each sieve size listed in Table 421.02-2. Calculate the average of each sieve for all three tests. Ensure the average value for each sieve is within the requirements of Table 421.02-2. Do not begin production if not in compliance with gradation band and stockpile tolerance. Prior to production, the Contractor may request a JMF adjustment to the JMF gradation in writing to the Engineer within the below limits without a redesign of the mixture based on the results from the three stockpile samples. Limit the adjustment from the original JMF gradation to conform to actual production to ±3 percent passing each of the No. 4 (4.75 mm) and No. 8 (2.36 mm) sieves and ±1.0 percent passing the No. 200 (75 µm). The Department will not approve adjustments that exceed the design ranges in Table 421.02- 2. At a minimum test one sample taken from the stockpile randomly during each production day. When two aggregates are used, sample a minimum of one sample from each stockpile and final blended stockpile randomly. Include additional testing when directed to sa mple and test by the Engineer. The Contractor may perform an additional aggregate test to verify results if first test is not in compliance with stockpile tolerance. Report and track all test results and monitor trends of the aggregate gradation within the stockpile. Reject aggregate that does not meet the stockpile tolerance in Table 421.02-2 compared to the approved JMF or JMF adjustment. Do not exceed the design gradation band for No. 200 sieve. For data collection by the Department, if requested by the Engineer, obtain a mix sample randomly during the day by dragging a tube sampler across material under the mixer but before the spreader box as it moves forward. Obtain a 10 pound (4535 gram) minimum mix sample, put in a suitable plastic container, and provide to the Engineer.
C.Mixture Application. Ensure the Quality Control Manager and trained technicians perform and use the methods described in this section to control quality and measure compliance.
1.Supervise the mixing machine calibration, test strip application, and verify compliance before production begins.
2.Establish with the mix operator restrictive operating limits for use of total mixture water, additive, and mineral filler subject to weather conditions and course applied.
3.Maintain all calibration records and compare calibration results for each project through construction season.
4.Direct all material input settings required to produce mix design compliance.
5.Verify mixture meets required mix time, set time and mix consistency.
6.Perform an aggregate moisture test at the start of each production day.
7.Communicate and direct any desired adjustments with the Binder supplier (asphalt emulsion) for mix and set time properties.
8.Evaluate roadway for determination of planned application rates and maintain direct communication with Department personnel, application personnel, and Engineer on all compliance issues.
9.Verify and document that all cracks greater than 1/4 inch (6 mm) in width and all cracks longer than two feet (50 mm) have been filled and that the crack sealant is in compliance with thickness requirements.
10.Monitor roadway during application for proper surface cleaning.
11.Monitor application of tack coat for proper coverage and document application rate.
12.Monitor mixture placement for consistency, uniformity of thickness across paving pass, and use of water spray bars.
13.Monitor mixture application rate and finishing methods to ensure uniform surface.
14.Monitor cross section compliance subject to course type specified.
15.Monitor set properties for opening to traffic and durability under traffic.
16.Monitor daily production reports for compliance with mix design tolerances.
17.Maintain each material usage by ticket weight and verify consistency to mixing machine calibrated use.
18.Direct adjustments of material settings and mixture subject to material test results and field performance.
19.Monitor haul trucks, mixing machine, and allied equipment for oil drippings, aggregate spillage and other factors that may affect the adherence or performance of the applied mixture.
D.Documentation. Provide the Engineer a daily report no later than the next calendar day (excluding Sundays) with the following:
1.A printout from the mixing machine showing the total pounds of aggregate, emulsion, and cement as well any other materials capable of being printed used for the day as part of the daily production report.
2.Project number, county, and route.
3.Date, air temperature, pavement temperature, and humidity.
4.Binder temperature, percent residue, and pounds per gallon (grams per liter)
5.Production report with course(s) applied, lane(s) completed, location of work, daily summary of each material used, application rate for each course and lane and total area per course.
6.Yield checks on application rate and compliance with application placement requirements (four per day, minimum).
7.Gradation and moisture content (one random sample during the day and any other samples when directed by the Engineer).
8.Total gallons (L) of tack coat used and residual asphalt content.
9.Quality Control Tests and Reports.
10.Contractor representative’s signature. Provide a Bill of Lading for Binder and aggregate as requested or at project completion..
421.13 Acceptance. Maintain continuous control of the Binder to dry aggregate proportioning to
conform to the approved JMF(s) within a tolerance of ± 1.5 gallons per ton (±6.3 L/metric ton). Control the spread rate to not less than the specified quantity of aggregate per sq uare yard (square meter) on a dry weight basis. The Engineer will base acceptance of the binder-to-dry aggregate proportion and spread rate on the Engineer’s summary of quantities used each day. The Engineer will approve and accept a day’s application of microsurfacing provided:
A.The Engineer ’s summary indicates conformance with the above control requirements for proportioning and spread rate.
B.The course(s) applied are in compliance with the application requirements of this specification.
C.The pavement cracks are sealed prior to placement of the microsurface.
D.The Quality Control requirements are met.
E.The pavement is uniform in composition and texture, free from excessive scratch marks, tears, rippling and other surface irregularities (segregation, raveling, rutting, holes, debris, etc.), longitudinal joints and lane edges coincide with any lane lines and edge lines and transverse joints are uniform, neat and provide a smooth transition. The spread rate requirement does not apply to rut fill courses if the Contractor filled the wheel paths according to this specification..
421.14 Performance Review. Perform remedial actions for any defect exceeding the threshold
levels in Table 421.14-1 for a period of two years from the date of substantial work complete as documented on the Department’s Form C-85. Contact the Department to schedule a final performance review at least 60 days prior to the end performance review period. The Department will review the pavement before the end of the two-year performance review period to determine if remedial action is required. The Department will issue the results in writing to the Contractor upon completion of the performance review. Remedial Actions. Perform Remedial Actions by October 15th of the same year as the review. If the Department determines that immediate repairs are necessary, due to a potential hazard to the traveling public, the Department will notify the Contractor and establish a date that all repairs are to be finished. Provide construction traffic control when performing any work required or allowed by this specification in accordance with current Department policy and the Ohio Manual of Uniform Traffic Control Devices. Obtain Department approval for the time the work will be performed. Provide approved materials, equipment, and labor to perform Remedial Actions at no additional cost to the Department. Prior to performing a Remedial Action, submit a Remedial Action plan to the DCE for approval. State in the plan when and how the Remedial Action will be performed; what material will be used; and how traffic will be controlled. Warrant Remedial Action work for the remainder of the warranty period. Use only microsurfacing for permanent repair and resurfacing areas. Perform temporary repairs using material approved by the DCE. Replace temporary repairs with a permanent repair as soon as weather permits. Replace pavement markings or raised pavement markers (RPM) removed, obliterated, or damaged while performing a Remedial Action with equivalent approved pavement markings or RPM products at no cost to the Department. The Contractor is not responsible for pavement damage beyond the Contractor’s control (i.e., car fire, oil spill, structural issues etc.). TABLE 421.14-1 Defect Type Threshold Level (6) (allowable distress levels) Non-uniform texture (1) 300 square feet (28 m2) Surface Loss (2) 20 square feet (1.8 m2) Raveling (3) 300 square feet (28 m2) Rutting (4) (5) 0.25 inch (6.5 mm) continuous in any Segment. Notes:
1.Texture inconsistencies in either the transverse and or longitudinal direction.
2.Loss of surface by traffic wear, debonding, or delamination.
3.“Moderate” level raveling as defined in the Strategic Highway Research Program (SHRP) “Distress Identification Manual for the Long -Term Pavement Performance Project” (SHRP-P-338).
4.Measure the wheel path with a 4 foot (1.2 m) straight edge.
5.Only applies during the first 120 days of Warranty or after any Warranty work.
6.Based on 1000 foot (300 m) lane Segment. The beginning of a Segment is the beginning of any distress type. If any 1000 foot (300 meter) lane segment has repairs or defects greater than 5 percent of the area, resurface with a full lane width of microsurfacing meeting the requirements of this specification.
421.15 Method of Measurement. The Department will measure Microsurfacing, Surface
Course and Microsurfacing, Leveling Course by the number of square yards (square meters), complete and accepted in place. The Department will base the width of the pavement course on the width shown on the plans, specified in this specification, or directed by the Engineer. The Department will measure the length along the centerline of each roadway or ramp. The Department will measure the number of raised pavement markers removed. The Department will measure Microsurfacing, Rut Fill Course by the number of tons (metric tons) of dry aggregate used, complete and accepted in place. The Department will base the weight of the dry aggregate used on the calibrated unit weight as reported from the aggregate delivery belt.
421.16 Basis of Payment. The cost of tack coat and Item 423 Crack Sealing is incidental to
microsurfacing. The Department will pay for removal of existing pavement markings according to 421.08 under Items 642, 643, 644, 645, 646, 647, and 648 as specified. The Department will pay for removal of existing raised pavement markers according to Item 621 Raised Pavement Markers Removed. The Department will pay for the construction of accepted test strips at the individual bid prices for the courses constructed. The Department will pay for accepted quantities at the contract prices as follows: Item Unit Description 421 Square Yard Microsurfacing, Surface Course (Square Meter) 421 Square Yard Microsurfacing, Surface Course (FR) (Square Meter) 421 Square Yard Microsurfacing, Leveling Course (Square Meter) 421 Ton Microsurfacing, Rut Fill Course (Metric Ton)
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Microsurfacing in other states
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Source: Construction and Material Specifications, 2023 (rev. 7/17/2026) Edition. Pages 201–215 of 892. View official source ↗