Form ProjStat
(Rev. 5/2013)
(RTI)
Research Project Statement 17-39
FY 2017 Annual Program
Title:
Revised Allowable Maximum Recycled Binder Ratio (RBR) Specification
The Problem:
Several newly constructed asphalt pavements are experiencing premature failures such as
potholes and stripping. This is observed mainly for mixes utilizing recycled materials, and which
may also include substitute binders. There is a concern that the amount of recycled materials
(RAP and RAS) allowed in the mix per the current TxDOT allowable maximum recycled binder
ratio (RBR) specification is being detrimental, especially for mixes produced at lower
temperatures; i.e., warm-mix asphalt, and that better performance tests are needed to capture
potentially problematic mixes. In addition, substitute binders typically do not have elastic
recovery requirements and may not be polymer modified; whereas, the binders they are
replacing typically are. A research study to quantify the effect of the RAP, RAS, substitute
binders, recycling agents, and warm-mix additives on the blended asphalt binder properties, as
well as on the performance of the mixes, will help understand and identify procedures to
eliminate this problem.
Technical
Objectives:
The research will be divided in the following components:
A. Laboratory evaluation of binder blends with various RBRs (combinations of virgin binder,
recycled binder, recycling agents, and warm-mix additives), and corresponding mixes.
1. Establish a procedure for determining the optimum recycling agent dosage.
2. Evaluate the compatibility and rheological properties of unaged and RTFO/PAV
aged binder blends.
3. Perform comparative analyses of specified binder vs. substitute binder in blends,
using the most common grades and substitute grades from Standard
Specification Item 341, Table 5.
4. Evaluate the performance (rutting, moisture susceptibility, and cracking)
properties of unaged and aged mixes, per AASHTO R30.
5. Recommend binder and mixture tests and thresholds to identify problematic
material combinations.
B. Field evaluation of binder blends at average and high RBRs and corresponding mixes.
1. Extract and evaluate the rheological properties of binder from the RAP and RAS
stockpiles.
2. Extract and evaluate the rheological properties of the blended binder from mix
sampled during production.
3. Evaluate the performance properties of mixes prepared in the laboratory with
mix sampled during production.
4. Extract and evaluate the rheological properties of the blended binder from cores
obtained soon after construction.
5. Extract and evaluate the rheological properties of the blended binder from cores
obtained 6-12 months after construction.
6. Perform Steps 1-4 for a virgin mix; i.e., without recycled materials.
C. Investigate methods to enhance blending of binder, recycled materials, and additives at
the asphalt plant during mix production.
Project Statement 17-39
Form ProjStat
(Rev. 5/2013)
(RTI)
Desired
Deliverables:
1. Value of Research (VoR) that includes both qualitative and economic benefits.
2. Final research report documenting all the work performed in this project, and recommended
changes to the current specifications.
3. Training materials, including the framework and tools developed, and a PowerPoint
presentation that will be used for training purposes to disseminate the research results to
various audiences.
Proposal
Requirements:
1. Utilize the deliverable based templates (see the University Handbook).
2. Proposals will be considered non-responsive and will not be accepted for technical
evaluation if they are not received by the deadline or do not meet the requirements stated in
RTI’s University Handbook.
3. Proposals should be submitted in PDF format, 1 PDF file per proposal. File name should
include project name and university abbreviation.
Pre-Proposal
Meeting
Information:
Wednesday, April 20, 2016
1:30 – 2:30 PM
Austin Riverside Campus
118 E. Riverside Dr.
RTI Conference Room, 1st Floor
Webex Information:
1. Go to https://txdot.webex.com/txdot/j.php?MTID=mfc14ab977fe5e9b0f08bd6c460e4a647
2. Meeting Number: 738 720 136
3. If requested, enter your name and email address.
4. If a password is required, enter the meeting password: 1234
5. Click "Join".
Teleconference Information:
Provide your phone number when you join the meeting to receive a call back. Alternatively, you
can call:
Call-in toll-free number: 1-866-637-1408 (US)
Conference Code: 199 125 9183
Notifying RTI of
Intent to
Propose:
Notify your University Liaison of your intent to submit a proposal. Your Liaison will provide
information regarding the RFP.
Proposal
Deadline:
Proposals are due to RTI by 4:00 P.M. Central Daylight Time, June 2, 2016. Email submissions
should be sent to rtimain@txdot.gov.
Project Statement 17-39