The research project will evaluate the moisture susceptibility and low temperature cracking properties of RAP mixtures produced with WMA technologies. Plant mixtures produced with varying RAP contents and warm mix technologies will be sampled. Laboratory testing will include an evaluation of mixtures susceptibility to moisture damage using one or more of the following tests: (1) AASHTO T324 “Hamburg Wheel-Track Testing of Compacted Hot Mix Asphalt (HMA)”, (2) AASHTO T-283 “Resistance of Compacted Hot Mix Asphalt (HMA) to Moisture-Induced Damage”, and (3) ratio of wet to dry dynamic modulus measured at 20ºC. The test(s) selection will be based on the literature review conducted under Task 1. Also, the low temperature cracking susceptibility will be evaluated using the following two tests: (1) AASHTO TP10-93 “Standard Test Method for Thermal Stress Restrained Specimen Tensile Strength (TSRST)” and (2) AASHTO T322 “Standard Method of Test for Determining the Creep Compliance and Strength of Hot Mix Asphalt (HMA) Using the Indirect Tensile Test Device.” Additional testing will include evaluating the effect of the different WMA technologies on the workability of the mixtures and evaluating the degree of blending between the RAP binder and the virgin binder using a procedure developed by Bonaquist.
PROGRESS/ACCOMPLISHMENTS THROUGH MARCH 31, 2015:
- UMass Dartmouth hosted the project Kick-Off Meeting on February 7th, 2014. UMass Dartmouth conducted two phone meetings with two contractors (Palmer Paving – MA, & Tilcon – CT) who will produce mixtures for this study. Due to plant limitations, the batch plant mixtures may not be produced in 2014, but may be produced in 2015. The remaining mixtures are scheduled to be produced in late April or early May 2014. UMass Dartmouth will be on site during production for sampling and specimen production. A production information sheet was developed to be utilized to quantify the critical production parameters related to the mixtures. UMass Dartmouth updated the internet survey based on the comments obtained during the Kick-Off Meeting. Subsequently, UMass Dartmouth began the process of loading the surveys onto the internet system for solicitation of responses.
- UMass Dartmouth conducted additional meetings with the two contractors, (Palmer Paving – MA, & Tilcon – CT). Based on the additional meetings, the production matrix was updated. UMass Dartmouth updated a list of state agencies and contractors that will be targeted to complete the surveys.
- UMass Dartmouth conducted additional meetings with the two contractors, (Palmer Paving – MA, & Tilcon – CT) to determine when the mixtures will be produced. Each responded they will be produced in the fall of 2014. In September 2014, UMass Dartmouth formally requested a no additional cost time extension for this project of twelve month (new end date 9/15/2016). The basis of the request is that the contractors have not produced or provided the mixtures required for this study. Recently, the contractors informed the PI that the mixtures should be produced very soon in the fall of 2014. Therefore, an extension is needed as the testing will require sixteen months for completion (as listed in the proposal). UMass Dartmouth is waiting for a response on this time extension request. UMass Dartmouth continued work on Task 1: Literature Review and Task 2: Determine Critical Information (Survey).
- Tilcon CT produced 12.5mm mixtures required for this study on 10/11/14. UMass Dartmouth was on-site during production to sample each mixture and document production parameters (RAP moisture content, etc.). UMass Dartmouth began verifying the volumetric properties of each produced mixture. The mixtures verified did not meet the volumetric properties. The contractor assured UMass Dartmouth that these mixtures will be reproduced again during spring 2015.
- UMass Dartmouth contacted Tilcon CT about reproducing the mixtures produced in October 2014 that did not meet the required volumetric properties.
- UMass Dartmouth contacted the other contractor (Palmer Paving) who agreed to produce mixture for this study. This contractor stated that they will produce the mixtures in April or May 2015.
- An additional contractor was contacted (PJ Keating) to determine if they would help with producing the mixtures for this study in the event one of the selected contractors cannot supply the mixtures.
Technical Committee Members
- Denis M. Boisvert (Chairperson), New Hampshire Department of Transportation
- Michael Byrne, Rhode Island Department of Transportation
- Bryan Engstrom, Massachusetts Department of Transportation
- David J. Kilpatrick, Connecticut Department of Transportation