High RAP proposed NSSP in California

High RAP Proposed NSSPin California

Ontario– CalAPA

ALON

ALON USA

Alon Asphalt Company

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CalTrans PG-Grades

As of 2013: PG-M allow 10% crumb rubber

ALON USA


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On July 2015, industry received the following proposal:

Section 39-2.02B Mix Design:If RAP greater than 15 percent is used, determine the actual performance grade of the virgin binder in accordance with AASHTO T315 If RAP greater than 15 percent is used, the HMA mixture asphalt binder calculated PG grading must meet the requirements for the asphalt binder specified in section 39-2.02C.

Section 92-1.02B:Delete footnote d ( + 3 degree bump) RAP/RAS NSSP:Replace "Reserved" in section 39-2.02C of the RSS for section 39:If RAS is used, the virgin asphalt binder must meet the requirements of AASHTO M320If RAS is used, the recovered asphalt binder must meet the requirements for the asphalt binder specified in section 39-2.02C, with the following modifications:If the original binder DSR fails at the specified test temperature, test the sample at 3 °C higher or lower.If the RTFO DSR fails at the specified test temperature, test the sample at 3 °C higher or lower.If the RTFO + PAV DSR fails at the specified test temperature, test the sample at 1.5 °C higher or lower.If the BBR fails at the specified test temperature, test the sample at 3 °C higher or lower.

ALON USA


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On January 2016, binder suppliers make the following recommendations to Caltrans regarding the true grading of binders for use with RAP:

1)To minimize the amount of true grading for RAP, consider following the simpler AASHTO M323 recommendations:

a) no change in binder grade for less than 15% RAP; b) one grade softer binder for 15-25% RAP; and c) use of blending charts for RAP percentages over 25%. This approach has been endorsed by FHWA, NCAT, and by the Asphalt Institute in its MS-2 Mix Design Manual (7th edition). This approach seems reasonable because it is with the high percentages of RAP (greater than 25%) where most of the cracking problems have been encountered.

Although MS-2 cites the use of blending charts as the most robust approach, it also concurs with the simpler approach of M323 (with some additional guidelines), and notes the additional time and expense of using the blending charts.

ALON USA


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2) As described in the Caltrans draft Construction Procedure Directive (CPD) on Hot Mix Asphalt with Reclaimed Asphalt Pavement (January 13, 2016), continue to place the responsibility for determining the virgin binder true grade upon the contractor who uses RAP, rather than upon the binder supplier, whether the use of true grades and blending charts begins at 16% or 26%.

In closing, the binder suppliers are committed to supplying virgin asphalt binders according to Caltrans Standard Specifications, Section 92, Asphalt Binders.

Interpretation:

No changes for the COC binder suppliers requirements

ALON USA


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By March of 2016 the NSSP was presented as follow:

Replace the paragraphs in section 39-2.01C(2) of the RSS for section 39 with:The JMF must be based on the Superpave HMA mix design system as described in the MS-2 Asphalt Mix Design Methods by the Asphalt Institute.

For a Type A HMA mixture using RAP substitution greater than 15 percent of the aggregate blend. The HMA mixture binder grade must not be stiffer than the PG binder grade specified and must be determined by blending charts for high, intermediate, and low critical temperatures.

Original binder requirements, ductility requirements, & note d in the table of section 92-1.02B do not apply in the determination of binder grade using blending charts.

Interpretation:

Orig DSR 1-2 doesn’t apply

RTFO Ductility min of 75cm doesn’t apply

+3C tolerance on PAV DSR doesn’t apply

No Elastic Recovery exemption was given for modified binder or maybe overlooked i.e. expected to meet 75% ER with 30% RAP?

ALON USA


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Replace the row for moisture susceptibility, dry strength, in the table in item 3 in the list of the paragraph of section 39-2.02A(4)(e) with:

Moisture susceptibility (psi, dry strength) AASHTO T 283 100–300

Interpretation:To prevent brittle mixes that can lead to early cracking

ALON USA


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Add to section 39-2.01C(3) of the RSS for section 39:For RAP substitution greater than 15 percent of the aggregate blend, submit blending calculation sheets and blending charts for high, intermediate, and low critical temperatures. The blending calculation sheets and blending charts must be based on the MS-2 Asphalt Mix Design Methods by the Asphalt Institute.

You may use critical temperatures of virgin binder or the maximum theoretical critical temperature of the PG grade of the virgin binder.

Critical temperatures must be in whole degree.

The calculation sheets must be sealed and signed by an engineer who is registered as a civil engineer in the State or by the AMRL-AASHTO-accredited laboratory manager responsible for the calculations and blending charts.

Interpretation:RAP binder will need to be graded at 110C and 100C PAVSince PG64-10, PG64-16 are at 100 PAV and PG70-10 is at 110 PAV

ALON USA


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Add to the list of the paragraph of section 39-2.01D(5) of the RSS for section 39 with:For RAP substitution greater than 15 percent of the aggregate blend, the asphalt binder grade must comply with the specified binder grade. A tolerance of +2 degrees C may be applied to the critical high and low temperatures of the blended binder. Original binder requirements, ductility requirements, and footnote d in the table in the 1st paragraph in section 92-1.02B do not apply in the determination of the PG binder grade using blending charts.

Interpretation:

If Target binder is PG70-10 and using blended chart which give a true grade of PG75-10.

Then with +2C Tolerance the binder can be accepted if tested as PG77-8. Per the PG grading system it will be a PG76-0

ALON USA


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Add to section 39-2.02A(4)(b)(iii):39-2.02A(4)(b)(iii)(iii) Virgin and Recovered Reclaimed Asphalt Pavement BinderPerform solvent extraction of RAP binder under AASHTO T 164, Method A, and recovery under AASHTO R 59 or ASTM D1856. Test the quality characteristics of the recovered RAP binder under the test methods and frequencies shown in the following table:

Quality characteristic Test method Minimum testing frequencyCritical temperatures of RAP binder

AASHTO T 315and

AASHTO T 313

1 per project if RAP is not augmented or 1 per 500 tons of augmented RAP

If you use critical temperature of virgin binder in blending charts, test the quality characteristics of the virgin binder under the test methods and frequencies shown in the following table:

Quality characteristic Test method Minimum testing frequency

Critical temperatures of virgin binder

AASHTO T 315and

AASHTO T 313

1 per 5 paving days or 1 per project, whichever is greater

ALON USA


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High RAP proposed NSSP in California

Engineering

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