358Hot In-Place Recycling of Asphalt Concrete Surfaces

1.1 Recycling . The process in which the existing asphalt pavement is heated, softened, and then milled. A

recycling agent is added, and the material is thoroughly mixed and placed using a standard paving screed.

1.2 Remixing . Similar to recycling , with the addition of virgin aggregate or new hot -mix asphalt (HMA) to the

recycled material. The materials are then thoroughly mixed and placed using a standard paving screed.

1.3 Repaving . Combines either recycling or remixing with an overlay of new HMA placed immediately after the

recycled mixture. The new HMA layer is placed directly on the recycled layer, and both are compacted simultaneously . All typical sections and any grade change requirements; the depth and width of recycling required; core information from the existing roadway , including pavement layers and lift thicknesses; the asphalt content and penetration value of the existing asphalt to be recycled; and any other data collected from the pavement evaluation are as shown on the plans .

2.1 Recycling Agent . Furnish a recycling agent in accordance and Section 300.2. 7., “Recycling Agent.”

2.2 Hot-Mix Asphalt . If the process requires additional HMA, furnish new HMA in accordance with

Section 358.4.2., “Mixture Design.” Use materials in accordance with Article 341.2., “Materials,” to produce the new HMA.

2.3 Aggregate . If the process requires additional aggregate, furnish aggregates in accordance with

Section 358.4.2., “Mixture Design.” Use aggregates in accordance with Articl e 341.2., “Materials.”

3.1 Processing Equipment . Provide equipment that is capable of a continuous single- pass, multi -step

operation, including heating; milling; introducing recycling agent, virgin materials, or HMA (if determined necessary); mixing the reclaimed material; redistributing the recycled material; placing and leveling the mix using an asphalt paver or paving screed; and compacting the mixture, in conformance with the following requirements.

3.1.1 Pavement Pre- Heaters. Supply pavement pre- heaters capable of uniformly heating the existing pavement to

a temperature high enough to remove excess moisture and allow dislodging of the material to the specified depth, while minimizing the fracturing of aggregate particles. Equip heaters with an enclosed or shielded hood to prevent damage to adjacent property or vegetation. Ensure that the heaters overlap the compl eted adjacent lane by at least 6 in. to create a hot bond at the longitudinal joint.

3.1.2 Pavement Milling Heads. Provide milling heads for pavement recycling capable of uniformly loosening the

entire pavement lane width to the depth shown on the plans. Accomplish the recycling using milling heads 443 that have a grade control system for each head. Ensure that the tooth spacing of the milling heads is enough to allow material to pass without excessive retention. Use equipment that can raise and lower the milling heads to recycle the material around manholes and other obstacles. Equip the milling heads such that they can gather the heated and loosened asphalt concrete pavement. Operate the milling heads in such a manner to minimize aggregate degradation. Use milling heads that can creat e a windrow of the milled material ahead of the mixing chamber or subsequent milling units.

3.1.3 Recycling Agent Application System . Provide a system for adding and uniformly applying a recycling

agent at the specified rate to the hot, loosened material. Control the system to within 5.0% of the target application rate. Equip the recycling agent system with positive on- and-off capabilities to prevent any dripping. Add the recycling agent during or after milling to uniform ly apply the recycling agent and adequately mix with the recycled material during the mixing cycle.

3.1.4 Mixing Unit . Provide equipment with an onboard mixing chamber that can thoroughly mix the heated,

reworked material with new materials. Enclose and configure the mixing chamber such that no milled material escapes or bypasses the mixer chamber. Ensure that the rotation of the mixer apparatus does not cause segregation during the mixing process.

3.1.5 Paving Unit . Furnish a paver or paver screed in accordance with Section 320.2.3.1., “Asphalt Paver.”

3.2 Rollers. Provide rollers in accordance with Article 210.2., “Equipment.”

3.3 Broom . Furnish rotary self -propelled power brooms. The broom should have positive control on the

downward pressure applied to the surface.

3.4 Field Laboratory . Unless otherwise shown on the plans, furnish a mobile testing laboratory in accordance

with Tex-237-F and a Level 1A-certified laboratory technician qualified under the Department’s approved program. If fresh HMA is added, perform the tests necessary to control plant production.

4.1 Certification . Personnel certified by a Department -approved hot -mix certification program must conduct all

mixture designs, sampling, and testing. Supply a list of certified personnel and copies of their current certificates before beginning production and when personnel changes are made.

4.2 Mixture Design . Design a mixture to meet the requirements shown in Table 1 using a Superpave Gyratory

Compactor. Compact specimens at the anticipated production temperature between 200°F and 250°F at 50 gyrations in accordance with T ex-241-F . The target number of gyrations may be adjusted when approved. Submit the completed mix design for approval before the start of the project. Perform additional mix designs based on road variability, as directed.

4.2.1 Sampling . Before bidding, the Engineer will provide material and pavement information obtained from

roadway cores, such as layer thicknesses, gradation, asphalt content and recovered asphalt penetration of the pavement to be recycled using the Materials and Tests Division’s protocol and guidelines. Additional cores may be taken by potential Bidders to obtain further information on the material to be recycled when approved. After the project is awarded, obtain an adequate amount of roadway cores throughout the project to perform the mixture design and to determine the existing condition of the roadway to account for any variability within the project limits. Evaluate the material from the roadway cores and document any existing material that could be detrimental to the process ( e.g., rubber seal and fabric underseal). A t least 2 in. of the existing pavement structure must remain in place following milling. Document any base or uncoated material 444 within the layer to be recycled. Provide documentation of any of these conditions before proceeding with the mixture design.

4.2.2 Job-Mix Formula Approval . The job- mix formula (JMF) is the combined aggregate gradation and target

asphalt recycling agent percentage established from the laboratory mixture design.

4.2.3 Hot-Mix Asphalt . If the process requires new HMA, use materials in accordance with Section 341.4.4.,

“Mixture Design,” or as shown on the plans. Document in the JMF the percentage of new HMA used in the laboratory mix design submitted.

4.2.4 Aggregates. If necessary, use aggregates meeting the requirements in Article 341.2., “Materials,” Table 1,

or as shown on the plans.

4.2.5 Additives . Other additives may be allowed to meet the requirements shown in Table 1. When other additives

are used, document the type and percentage in the mixture design submittal. Table 1 Laboratory Mix Design Properties Mixture Property Test Method Requirement Design gyrations (Ndesign) Tex-241-F 50 Laboratory -molded density, % Tex-207-F and Tex-227-F Note1 Indirect tensile strength, psi2 Tex-226-F 75–200 Hamburg wheel Test, minimum number of passes at 12.5 mm rut depth Tex-242-F 10,000 Overlay test, critical fracture energy (CFE), lb. -in./sq. in. Tex-248-F 1.0 Min3 Overlay test, crack progression rate (CPR) 0.55 Max3 Boil Test2 Tex-530-C — Combined Asphalt Property Test Method Requirement Penetration, 77°F, 100 g, 5 sec. T 49 40–80 1. For informational pur poses only. 2. Used to establish a baseline for comparison to production test results. 3. May be adjust ed when approved.

4.3 Pavement Heating . Heat the existing pavement without charring the pavement surface and without

producing undesirable pollutants. Maintain a minimum temperature of 200°F of the material immediately behind the heater. Uniformly heat the pavement surface across its full lane width such that cold milling of the pavement surface does not occur.

4.4 Pavement Milling . Mill the existing pavement to the required depth and width as shown on the plans. Do not

disturb the underlying material in the existing roadway when recycling. Remove grass and other vegetation from the edge of the existing pavement to prevent contamination of the recycled bituminous material during this operation. Use the milling heads to remove at least 3 in. laterally of the completed adjacent pass and make a square vertical cut in the heated material to achieve a hot -bonded longitudinal joint. Ensure all material across the full lane width is processed between consecutive lane passes to assure any wedges (slivers) of unprocessed materials are not left untouched by the milling heads and covered by the recycled material, unless otherwise approved. Ensure the temperature of the milled surface directly behind the milling heads is greater than 160°F so cold milling does not occur. Clean all loosened asphalt material away usi ng the milling heads . A milling tooth pattern must be clearly visible after milling. Remove all material around manholes and utility structures before paving the recycled mixture to allow for the plan depth of the pavement around these structures. 445 Cold mill and sweep clean any areas that cannot be heated and milled by the recycling equipment. Properly tack and pave these areas of cold milling before the recycling process .

4.5 Addition of Recycling Agent . Incorporate the asphalt recycling agent into the hot recycled bituminous

material at the rate determined by the approved mix designs. Sampling and testing during mixture production may result in varying quantities of recycling agent at different portions of the project to meet the requirements shown in Table 1. Change the recycling agent content only as approved.

4.6 Placement of Recycled Material . Spread the material using a paver and screed attached to the mixing and

milling unit or a traditional paver in a separate and continuous operation meeting the requirements of Section 320.2.3.1., “Asphalt Paver.” Spread the recycled material to the established lines and grades. Ensure the temperature of the recycled material behind paver is greater than 200°F .

4.7 Compaction. Uniformly compact the pavement to contain between 3.8% and 8.5% in- place air voids .

Furnish the type, size, and number of rollers required for compaction as approved and meeting the requirements of Article 210.2., “Equipment.” Use a pneumatic -tire roller to seal the surface unless excessive pickup of fines occurs. Use additional rollers as required to remove any roller marks. Use only water or an approved release agent on rollers, tamps, and other compaction equipment unless otherwise directed. On the first day of production, use the control strip method in a ccordance with Tex -207-F , Part IV, to establish the rolling pattern that will produce the desired in- place air voids unless otherwise directed. Operate rollers in vibratory mode only when doing so does not damage the pavement. Establish a new rolling pattern when changes occur in the recycled mix or placement conditions. Adjust or cease compaction when cracking or displacement occurs. Ensure that pavement is fully compacted before allowing rollers to park on the pavement.

4.8 Traffic . Allow the compacted pavement to cool to 160°F or lower before opening to traffic unless otherwise

directed. Maintain the surface of the recycled pavement in a condition suitable for the safe movement of traffic. Power broom the pavement surface to remove all loose particles as directed.

4.9 Irregularities . Identify and correct irregularities, including, but not limited to, segregation, rutting, raveling,

flushing, fat spots, mat slippage, irregular color, irregular texture, roller marks, tears, gouges, streaks, uncoated aggregate particles, or broken aggregate particles. The Engineer may also identify irregularities, and in such cases will promptly notify the Contractor. If the Engineer determines that the irregularity will adversely affect pavement performance, the Engineer may require the Contractor to remove and replace (at the Contractor’s expense) areas of the pavement that contain irregularities and areas where the mixture does not bond to the existing pavement. If irregularities are detected, the Engineer may require the Contractor to immediately suspend operations or may allow the Contractor to continue operations for no more than 1 day while the Contractor tak es appropriate corrective action.

4.10 Curing. A surface treatment may be allowed as the final riding surface when shown on the plans. Cure the

hot in- place recycled bituminous material for at least 7 days, or as directed when HMA or another applicable surface treatment is placed as a surface course.

4.11 Weather Conditions . Unless otherwise approved, perform hot in- place recycling operations when the

existing pavement surface temperature is 60° F or higher and when weather conditions and moisture conditions of the roadway surface are suitable, in the opinion of the Engineer. Measure the roadway surface temperature using a handheld infrared thermometer. The Engineer may allow mixture placement to begin before the roadway surface reaching the required temperature requirements, if conditions are such that the roadway surface will reach the required temperature within 2 hr. of beginning placement operations. 446 5. PRODUCTION ACCEPTANCE

5.1 Production Lot . Each day of production is defined as a production lot. Lots will be sequentially numbered

and will correspond to each new day of production. Note that lots are not subdivided into sublots for this Specification.

5.2 Production Sampling.

5.2.1 Mixture Sampling . The Engineer may obtain mixture samples in accordance with Tex -222-F at any time

during production.

5.2.2 Recycling Agent Sampling . The Engineer may obtain or require the Contractor to obtain 1-qt. samples of

the recycling agent at any time during production in accordance with Tex -500-C , Part III. The Engineer may test any of the samples to verify compliance with Item 300, “Asphalts, Oils, and Emulsions.”

5.3 Production Testing. The Engineer will test at the frequency shown in Table 2. The Engineer may suspend

production if production tests do not meet specifications or are not within operational tolerances shown in Table 2. The Engineer may suspend operations if the Contractor’s corrective actions do not produce acceptable results. The Engineer will allow production to resume when the proposed corrective action is likely to yield acceptable results. Table 2 Operational Tolerance and Minimum Testing Frequency Description Test Method Allowable Difference from JMF Target Minimu m Testing Frequency Contractor Engineer Asphalt binder content, % Tex-236-F ±0.5 1 per lot 1 per lot Theoretical max spec. (Rice) gravity Tex-227-F N/A 1 per lot 1 per 5 lots Laboratory -molded density, % Tex-207-F ±1.0 1 per lot 1 per 5 lots Hamburg Wheel -Tracking Test, 50°C, mm Tex-242-F N/A1 1 per 5 lots 1 per project Overlay Test, CFE and CPR Tex-248-F N/A2 N/A 1 per project Boil Test Tex-530-C N/A3 1 per lot 1 per project Air voids Tex-207-F N/A4 1 per lot 1 per lot 1. Hamburg values must not exceed 12.5 mm in 10,000 passes, unless otherwise directed. 2. Overlay values must not exceed the requirements for CFE and CPR in Table 1. 3. Compare with sample from mix design to determine amount of stripping. 4. In-place air voids should be between 3.8% and 8.5%.

5.4 Total Asphalt Binder Content . Adjust the asphalt recycling content based on mix design recommendations

for varying roadway conditions to meet the requirements shown in Table 2.

6.1 Placement Lot . A placement lot is defined as the area placed during a production lot ( 1 day’s production).

Placement lot numbers will correspond with production lot numbers.

6.2 Placement Sampling . Provide the equipment and means to obtain and trim roadway cores onsite. Onsite is

defined as in close proximity to w here the cores are taken. Obtain the cores within 1 working day of the time the placement lot is completed unless otherwise approved. Unless otherwise shown on the plans, obtain two 6-in. diameter cores side- by-side at each location selected by the Engineer for in-place air void determination. Mark the cores for identification, measure and record the untrimmed core height, and provide the information to the Engineer. The Engineer will witness the coring operation and measurement of the core thickness. Visually inspect each core and verify that the current paving layer is bonded to the underlying layer. If an adequate bond does not exist between the current and underlying layer, take corrective action to ensure that an adequate bond will be achieved during subsequent placement operations. 447 Trim the cores after obtaining the cores from the roadway in accordance with Tex -207-F if the core heights meet the minimum untrimmed shown on the plans. Trim the cores onsite in the Engineer’s presence. Use a permanent marker or paint pen to record the date and lot number on each core as well as the designation as Core A or Core B. The Engineer may require additional information to be marked on the core and may choose to sign or initial the core. The Engineer will take custody of the cores immediately after they are trimmed and will retain custody of the cores until the Department’s testing is completed. Before turning the trimmed cores over to the Engineer, the Contractor may elect to wrap the trimmed cores or secure them in a manner that will reduce the risk of possible damage occurring during transport by the Engineer. After testing, the Engineer will return the cores to the Contractor. The Engineer may elect to have the cores transported back to the Department’s laboratory at the HMA plant via the Contractor’s haul truck or other designated vehicle. In such cases where the cores will be out of the Engineer’s possession during transport, the Engineer will use Department -provided security bags and the Roadway Core Custody protocol located on the Department’s website to provide a secure means and process that protects the integrity of the cores during transport. Instead of the Contractor trimming the cores onsite immediately after coring, the Engineer and the Contractor may mutually agree to have the trimming operations performed at an alternate location, such as a field laboratory or other similar location. In such cases, the Engineer will take possession of the cores immediately after they are obtained from the roadway and will retain custody of the cores until testing is completed. Either the Department or Contractor representative may perform trimming of the cores. The Engineer will witness all trimming operations in cases where the Contractor representative performs the trimming operation. Dry the core holes and tack the sides and bottom immediately after obtaining the cores. Fill the hole with the same type of mixture, and properly compact the mixture. Repair core holes by other methods when approved.

6.3 Placement Testing . The Engineer may measure in- place air voids at any time during the project to verify

specification compliance.

6.3.1 In-Place Air Voids. The Engineer will measure in- place air voids in accordance with Tex -207-F

and Tex-227-F . Before drying to a constant weight, cores may be pre-dried using a Corelok or similar vacuum device to remove excess moisture. The Engineer will use the corresponding theoretical maximum specific gravity to determine the air void content of each core. The Engineer will use the average air void content of the two cores to determine the in- place air voids at the selected location. The Engineer will use the vacuum method to seal the core if required in accordance with Tex-207-F . The Engineer will use the test results from the unsealed core if the sealed core yields a higher specific gravity than the unsealed core. When the in- place air voids exceed the range of 3.8– 8.5%, take immediate corrective action to bring the operation within these tolerances. The Engineer may suspend operations or require removal and replacement if the in- place air voids are less than 2.7% or greater than 9.9%. The Engineer will allow paving to resume when the proposed corrective action is likely to yield between 3.8% and 8.5% in- place air voids.

6.3.2 New Hot -Mix Asphalt . If applicable, control the quantity of new HMA added to the recycled mix from haul

tickets to within 5.0% of the target JMF.

6.3.3 Depth of Recycled Material . Maintain the required nominal depth on both outside vertical faces and in the

center of the recycled area. Manually measure and report recorded depths each 1/4 mi . approximately each hour of production. Measure from the bottom of the mill pass to the top of the surface placed.

6.4 Ride Quality. Use Surface Test Type A to evaluate ride quality in accordance with Item 585, “Ride Quality

for Pavement Surfaces,” unless otherwise shown on the plans. 448 7. MEASUREMENT Hot in -place recycling of asphalt concrete surface will be measured by the square yard. The dimensions for determining the surface areas are established by the depths and widths shown on the plans and the lengths measured at placement. Recycling agent will be measured at the applied temperature by the gallon from strap depths measured from the calibrated strap stick for each load or other approved automated means. New HMA will be measured by the ton of composite mix, which includes asphalt, aggregate, and additives. Measure the new HMA on scales in accordance with Item 520, “Weighing and Measuring E quipment.”