Reclaimed Asphalt Pavement (RAP)

Transcription

1 Reclaimed Asphalt Pavement (RAP) 1

2 What is RAP An asphalt material removed from the road that is intended to be reused on the roadway. RAP could be used as base course material, shouldering material, and reused in the new asphalt pavement. 2

3 Why would we use RAP? RAP can be used if it is cost effective and it performs well. It is likely that if we see performance in mixes that contains RAP as well as mixes without, and we see a cost savings, then we will be more interested in using mixes with RAP. These are typically the two main ingredients that we are all interested in. 3

4 Is RAP Successful? RAP has been used in our Region for years with little performance concerns. We have pushed for test sections that contain 30% RAP to determine how much we could be using. We also feel strongly about allowing the contractors to use RAP from our roads back on our roads. 4

5 How do contractors assure that RAP is performing well and When RAP is used on a CDOT project, we use our current procedures and specifications to verify that the RAP material is acceptable: CP 52-Contractor Asphalt Mix Design Approval Procedures Standard Special Provision 401-Reclaimed Asphalt Pavement The Quality Control Plan per SSP 401-RAP being cost effective? 5

6 Colorado Procedure 52- Contractor Asphalt Mix Design CP 52 Explains what is needed to get a mix design approved. It will list the tests and the number of tests needed to verify the mix design. Approval Procedures 6

7 CP 52-Asphalt Mix Approval 3.1-CP 52 states that a complete mix design is required for all mixes placed on the project. 3.2-The mix design shall be submitted on a CDOT Form #429 a minimum of 4 weeks prior to the anticipated paving start date. All mix designs shall be stamped by a Colorado License PE. The RME must approve the mix design before paving may proceed. The mix design shall include an electronic version of the Form # To verify the mix design, the aggregates used shall be sampled by the contractor in accordance with CP 30 & CP 32. The aggregates shall be tested for gradation, Specific Gravity, Absorption, & PI by CDOT and the Contractor. 7

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9 CP 52-Asphalt Mix Approval RAP to be used on the project shall be sampled by the contractor in the presence of the Project Engineer and tested by CDOT Central Lab. The RAP shall be tested for Asphalt Binder Content, Gradation and Specific Gravity The mix design data cannot be accepted with results that are more than 1 year old. If the Form #429 is more than 3 months old, the RME may request new gradation and coarse and fine aggregate bulk specific gravities. If the average gradation for any material varies by more than 5% for the design, or 2% on the #200 sieve, a one-point verification may be required. The one-point shall meet the design specifications. If not, the RME may request a new mix design. If the Form #429 is from a mix design developed more than 2 months prior, the RME may request additional aggregate data per Section 4.2(1) B &C. 9

10 CP 52-Asphalt Mix Approval If the average gradation for any material on any individual sieve varies by more than 5% from the design or 2% from the minus 200 sieve, or the combined gradation based on averages varies by more than 3% on any sieve or 1% on the minus 200 sieve, a one-point verification, perform at optimum AC may be required using current production aggregates. The result of the one-point shall meet the project design specifications. In addition, the results for air voids in mineral aggregate shall be within 1% of the design target. If the one-point does not meet these criteria a new mix design may be required by the RME. 10

11 CP 52-Asphalt Mix Approval 3.4-If all tests meet the specs, a CDOT Form #43 will be executed by the RME. 3.5-All properties must satisfy the 403 Spec. 3.6-Once the mix is approved the binder change shall be handled as followed: Same supplier but different binder-one Point A new mix design would be required for a new supplier. 4. Mix Design Requirements 4.1-Anyone performing the testing shall be properly certified. 11

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13 CP 52-Asphalt Mix Approval 4.2-It is recommended that a complete mix design consisting of results from the trial blends be conducted when material sources have not been verified. The design must contain: (1) Aggregate Data (2) RAP used shall include the source and the following data from at least 10 samples tested within the last two months of the submittal: A. Percent Binder from extractions or burnoffs if correction factor is performed per 401. B. Gradations C. Effective Specific Gravity D. Uniformity Calculations for the 401 Spec. 13

14 CP 52-Asphalt Mix Approval Note 2.-If the materials used in the mix design was crushed/stockpiled more than two months prior to submitting the design, the 10 most recent samples shall be used for gradation. (3) RAS-Not used (4) Combined Aggregate Properties (5) Source and grade of AC from supplier (6) Name and percentage of additive (7) AC Tests (8) Graphs of stability, Voids, VMA, VFA or virgin effective AC content for RAP vs total AC Content. (9) Lottmans and wet/dry tensile strength at optimum AC. 14

15 Will there be any changes to 1. Are we testing 10 samples? CP 52? 2. Are the results given to CDOT? 3. Do the results include the correction factor, uniformity values and all associated calculations? 4. Are we getting it early enough so we are able to verify the results? 15

16 Questions about CP 52? 16

17 Standard Special Provision of 401-Reclaimed Asphalt Pavement (b) RAP is allowed in the HMA up to the maximum binder replacement of 23%. Fine aggregate angularity requirements shall apply only to the virgin fraction of the fine aggregate. The RAP shall not contain clay balls, vegetable matter, deleterious substances, and must meet the uniformity requirements. Verification Testing for AC and gradations will be performed with a burnoff. The %AC shall be the average %AC in accordance with 1B or 1C. 17

18 Total Binder Replaced Standard Special Provision of 401-Reclaimed Asphalt Pavement Total Binder Replaced=(RAP %AC)x(%RAP)/(Effective Binder Content) So, for the calculation above here is an example: (5.8%)x(20%)/(5.6%)=21% The binder replaced shall not exceed 23% either in the mix design or during production. We will be verifying this prior to and during production. 18

19 Standard Special Provision of 401-Reclaimed Asphalt Pavement QC Plan RAP shall be controlled in accordance with and The Contractor shall have an approved QC Plan that details how the RAP will be processed and controlled including: A. RAP Processing Techniques. This requires a diagram and narrative that explains the processing(crushing, screening, and rejecting) and stockpile operation for this project. B. Control of RAP %AC. This may be done with burnoffs if you have a correction factor using AASHTO T-164 A or B. The correction factor shall be determined by performing correlation testing on the first five samples, then 1 /5 AC Contents thereafter. Frequency is 1/1000 tons of processed RAP(Minimum 5 tests). 19

20 Standard Special Provision of 401-Reclaimed Asphalt Pavement C(Alternate). The Contractor may propose a RAP AC correction factor to be used. The correction factor shall be used in the mix design and QC Testing. The methodology shall be outlined in detail in the approved QC Plan. At a minimum, the proposed CPL 5120 correction factor shall identity the principal source locations of the RAP, gradation, and ignition oven identification used on all RAP testing. The RAP source location, gradations, equipment shall substantiate CPL 5120 AC Content correction factor used for testing. The substantiation must be from data gathered from historic information or specific asphalt correction data obtained from tests performed on similar virgin aggregate sources, virgin material gradations, and equipment. D. Control of RAP Gradation(CP 31 or AASHTO T-30):Frequency 1/1000 tons with a minimum of 3 tests. 20

21 Standard Special Provision of 401-RAP E. Process Control Charts shall be maintained for binder content and each screen listed in this spec, during the addition of any RAP material to the stockpile. The Contractor shall maintain separate control charts for each RAP stockpile. The control charts shall be displayed and made available, along with RAP AC extraction testing reports upon request. 2. The RAP must be 100% passing the 1-1/4 inch sieve. The aggregate in the RAP shall be 100% passing the 1 inch sieve. The RAP shall satisfy: UNIFORMITY* Parameter Standard Deviation Binder Content 0.5 Percent Passing 19 mm (¾ ) 4.0 Percent Passing 12.5 mm (½ ) 4.0 Percent Passing 9.5 mm (⅜ ) 4.0 Percent Passing 4.75 mm (#4) 4.0 Percent Passing 2.36 mm (#8) 4.0 Percent Passing 600 m (#30) 3.0 Percent Passing 75 m (#200) 1.5 *Uniformity is the Maximum allowable Standard Deviation of test results of processed RAP. 21

22 Standard Special Provision of 401-RAP 3. If RAP millings generated are incorporated into the project, in accordance to CPL The Contractor shall pave with virgin mix until sufficient amount or processed RAP has been stockpiled and tested to allow full production. CPL 5145-Asphalt Mix Approval with RAP Millings from the project. 1. Determine the %AC and plan amount of RAP on the project. 2. Samples may be taken by milling or coring on the project prior to the start of the project. 3. Create a mix design using the RAP sampled from the project prior to the anticipated paving start date. 4. If sampling can t be accomplished before construction, then virgin mix shall be used until enough millings are produced. 22

23 Will there be any changes to 401 or QC Plan Requirements? 1. Are you verifying that the RAP does not contain clay balls, deleterious material, vegetable matter, and that it can satisfy the uniformity requirements prior to creating a mix design or submitting the QC Plan? 2. Does the QC Plan list the RAP source, crushing and stockpiling practices? 3. Is the QC Plan verified by you and us? 4. Are we verifying that we satisfy the Uniformity Requirements? 23

24 RAP Best Practices? 1. A consistent and uniform RAP generates a more consistent mix and allows for better problem solving if necessary. 2. RAP stockpiles should be separated as much as possible. 3. Some of the best aggregates available are already on our roads. We would like to keep the material from our roads on our roads. 4. The QC Plan should be accurate and it should be verified by us. If the RAP contains clay balls, sticks, large rocks, or is not RAP, we will reject the RAP. 24

25 Questions about 401 or the QC Plan? 25

26 Where do we go from here? 1. Can we improve our processing techniques? 2. What can CDOT due to better verify the RAP? 3. Do we have a RAP Problem? 4. Do we have a spec problem? 26

27 What s Next? 1. Are there any changes that you feel I should discuss with the MAC? 2. What other production issues can we work on? Thank You! 27