605Surface Recycled Asphalt Construction

- SURFACE RECYCLED ASPHALT CONSTRUCTION SURFACE RECYCLED ASPHALT CONSTRUCTION

605.1DESCRIPTION

Construct the hot-in-place recycling of the existing asphalt surface as specified in the Contract Documents. The activities associated with this work include heating the existing pavement, scarifying and/or hot milling the existing surface, adding a rejuvenating agent, mixing, spr eading, leveling and compacti ng the recycled material. This process is referred to as Hot In-Place Recycled As phalt Pavement (HIR). The term surface recycling and HIR are synonymous in the specification. BID ITEMS UNITS Surface Recycling (*) Station Asphalt Rejuvenating Agent Ton *Thickness

605.2MATERIALS

submit a mix design complying with TABLE 605-1. In the mix design, analyze the mixture at a minimum of 3 different ARA contents starting with 0.5% at the low end. Run the indirect tensile strength test (KT-60) at the lowest ARA content. Run the Asphalt Pavement Analyzer (AASHTO T 340) at the highest ARA content. TABLE 605-1: SURFACE RECYCLE MIX DESIGN REQUIREMENTS Property Test Method Limits Air Voids at 30 gyrations, (%) KT-58, KT-15, & KT-39 Report Tensile Strength, (psi min) KT-56 75 Retained Strength based on cured stability, (% min) KT-56 80 Rut Resistance, (mm max) AASHTO T 340 8 Thermal Cracking, (oC max) KT-60 -22 Testing procedures: • Core the pavement to obtain Reclaimed Asphalt Pavement (RAP) for the mix design. • Break down the RAP (representing the depth of the HIR) to a maximum particle size of 1 inch. • The compaction temperature range for KT-58 is 200ºF to 250ºF. • Perform all tests on plugs that are compacted to 30 gyrations, thus the air void criteria stated in KT-56, KT-60 and AASHTO T 340 are waived. • Use procedure III when performing KT-15.

605.3CONSTRUCTION REQUIREMENTS

the pavement which would be detrimental to the HIR or would not comply with the design criteria of subsection 605.2b.

uniformly heat and recycle the existing pavement to the specified depth. Flames on the pavement can be prevented by heating the roadway more slowly us ing additional heaters. Intermittent or occasional flaming on the roadway or in the windrow that extinguishes on its own within 10 seconds is permissible, but if in the opinion of the Engineer it is detrimental to the final product, production will cease. In addition, production will cease when smoke is being produced continuously. (Smoke caused when the heaters pass over a maintenance patch is excluded from this - SURFACE RECYCLED ASPHALT CONSTRUCTION clause.) The Contractor and Engineer will agree to a course of action to prevent this overheating before production is resumed. If flames or excessive smoke persists, th en production is ceased until th e Contractor modifies the operation and can demonstrate acceptable results without ex cessive smoke or flames on the pavement or in the windrows. When the depth of the HIR is more than 1 inch, heat the material in lifts not more than ¾ inches. When heating in multiple lifts, remove each lift at a uniform dept h across the full width of the recycled pavement. This material may be windrowed when heating the next lift. Use equipment complying with SECTION 155. Provide adequate provisions for equipment calibration. Remove from the roadway milled or scarified material that can not be placed with a paving unit due to equipment breakdown or malfunction. Bring these removed areas to grade using a HMA approved by the Engineer.

tests shall equal or exceed the contract depth. If the 3-poi nt moving average is less th an the contract depth, KDOT will assess a Surface Recycling Pay Adjustment using Equation 1. The pa y adjustment will correspond to those segments within the 3-point moving average that were deficient in depth. Equation 1:

-= T M1)S(400P Where: P is the Surface Recycling Pay Adjustment, ($0.00) S is the number of stations (single lane) in penalty, (0.00) M is the Measured Depth 3-point moving average, (0.000 feet or 0.00 inches) T is the Plan Depth, (0.000 feet or 0.00 inches). T and M shall be the same unit of measure. If 4 consecutive 3-point moving average values are less than the contract depth, stop production and evaluate the process with the Engineer. Change the process to the satisfaction of the Engineer before production is resumed. If the next 2 tests are deficient in thickness, E quation 2 will be used for the remainder of the project. The Engineer reserves the option to term inate production until a satisfactory agr eement is reached anytime the 3-point moving average value is less than the contract depth for more than 2 consecutive tests. Equation 2:

-= T M1)S(900P If both KDOT and the Contractor agree that recycling to the contract depth would be detrimental to the project, the unit price will be negotiated for the reduced de pth before proceeding with th e project, and the Engineer would create a change order (SECTION 104) for the item at the new unit price.

prior to scarifying and/or hot milling. Maintain the temp erature of the HIR, directly behind the paver, between 190ºF and 300ºF. HIR temperatures take n within 2 feet of each other, transverse to the roadway, shall not vary by more than 30ºF. HIR temperatures taken within 10 feet of each other, transverse to the roadway, shall not vary by more than 50ºF. If these temperature requirements are not satisfied within 1 hour after a discrepancy is discovered, the HIR train will be stopped and the Engineer and Contr actor will determine a course of action to correct the deficiency before the HIR train proceeds.

the ARA and thoroughly mix the HIR. Include all of the pr eviously scarified and/or hot milled material into the mixing operation.

mixing operations, begin work to fulfill the requirements of one of the following operations:

Smooth-Faced Steel Rollers complying with SECTION 151 . The Engineer will determine the initial approved rolling procedure from densities obtained with various roller combinations. - SURFACE RECYCLED ASPHALT CONSTRUCTION Density will be determined by using a nuclear gauge. Use the approved rolling procedure. Achieve the maximum density before the temperature of the HIR falls below 160°F. Do not crush the aggregate. When the mat temperature falls below 160°F, roller marks may be removed from the mat with a self-propelled Smooth-Faced Steel Roller operated in the static mode. If there is a significant change in factors affecting density, such as weather or compaction equipment, the Engineer will reevaluate and modify the rolling pr ocedure as required. Stop the HIR operation whenever rolling is not being performed according to the approved rolling procedure.

Documents is completed. When required, apply a tack coat before placing the surface treatment. If a seal coat, asphalt seal, micro-surfacing or u ltra-thin bonded asphalt su rface is included in the Contract Documents, allow the HIR surface to cure 1 week before sealing.

the amount specified of the new asphalt surface material. SECTIONS 601 and 602 apply. If a HMA overlay is included in the contract, place the HM A and surface recycle concurrently, or the 2 materials may be blended and laid as 1 lift.

weather is not foggy or rainy. Only construct surface recycling between May 1 and September 30, when either the minimum ambient air temperature or the road surface temperature shown in TABLE 605-2 is met. TABLE 605-2: MINIMUM HIR TEMPERATURE REQUIREMENTS Existing Surface Type Ambient Air Temperature (oF) Road Surface Temperature (oF) On HMA Surface 50 55 On Asphalt Seal Surface 55 60

605.4MEASUREMENT AND PAYMENT

The Engineer will measure surface recycling by the Station, along the centerline. On divided highways, the Engineer will measure surface recycling by the Station, along the centerline of each divided direction. This includes all widened and irregular areas and irregular variations in depth. The Engineer will measure asphalt rejuvenating agent by the ton. Payment for "Surface Recycling" and "Asphalt Rejuvenating Agent" at the contract unit prices is full compensation for the specified work. The bid item Surface Recycling Pay Adjustment will be an item added to the contract.