Better Roads

September 2013

Better Roads Digital Magazine

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/3PG RoadScience continuously determining the stiffness of the hot-mix asphalt material being compacted," says Michael M. Arasteh, FHWA pavement and materials engineer. "Then, by marrying these two data groups together, it is possible to obtain a map of stiffness or the number of roller passes for the entire pavement surface." Temperature variation in mat surfaces can be recorded during breakdown rolling, and this also can become part of the project database. On-board color-coded displays for GPS-enabled intelligent compaction give roller operators a "heads up" as to the number of passes made over a section and the degree of stiffness attained, including "soft spots." Ultimately, IC systems will be able to measure and record internal mat temperatures, as well as surface temperatures. These data will be stored in an on-board computer and then downloaded onto a thumb drive to be taken to the trailer for loading in a construction management, QA program, laptop or handheld device. Or, the data may be sent in real-time via a dedicated cellular line both to the trailer and to corporate headquarters. It's Dangerous Out There ALWAYS BE SAFE Whether you work off the road or over the road, Bridgestone wants you to make safety your first concern. Maintaining a safe workplace and reinforcing safety rules contributes to a more productive operation and reduces costs. If you need a better reason, it saves lives. Correlating Stiffness, Density LESSONS IN SAFETY There is simply nothing more important than starting your shift safely and getting your people home without harm. That's why we've produced a series of short videos that you can use in safety meetings or at shift start. Access them at bridgestoneminingsolutions .com/safety and select from a range of topics. Bridgestone Commercial Solutions For your nearest Bridgestone Authorized Dealer, visit our website ©2013 Bridgestone Americas Tire Operations, LLC. All Rights Reserved. Text INFO to 205-289-3789 or visit BAN120164_Equip World Fractional Ad 1 1 8 September 2013 Better Roads Bridgestone_BR0413pg12.indd 1 JOB # BAN120164 CLIENT Bandag RoadScience_BR0913.indd 8 While nuclear and non-nuclear density meters can measure density of compacted asphalt pavements, IC-equipped rollers can't measure density on the fly. But, it may be possible to extrapolate density based on stiffness measurements, which are an integral part of asphalt IC. In 2012 and 2013, FHWA's IC study team attempted to correlate on-board IC readings with actual density. Current IC roller measurement values (IC-MV) are accelerometer-based technology, the values of which vary from manufacturer to manufacturer. But IC-MVs do relate to the stiffness of materials. To help manage these data, as part of an Intelligent Compaction Pooled Fund project, the Veda software program was developed. "This software is a great first step in addressing one of the biggest barriers to IC implementation, which is a myriad of issues related to handling the massive amount of data produced during the compaction process," say Robert D. Horan, P.E., The Asphalt Institute; George K. Chang, P.E., Qinwu Xu, The Transtec Group; and Victor L. Gallivan, P.E., FHWA, in their 2012 TRB paper, Improving Quality Control of Hot Mix Asphalt Paving Using Intelligent Compaction Technology. (Veda software is available to the public. For more information, visit "Using IC can benefit both the owner/agency and HMA contractor as IC addresses some of the major shortcomings in conventional equipment and processes," they write in the paper. "These new IC tools include on-board, color-coded displays, capability to measure underlying materials support prior to paving and capability to collect data for statistical analysis of the effectiveness of compaction operations." A case study of the Wisconsin ICPF research underscored how IC can improve quality control of HMA paving, they say. The project consisted of a two-lift HMA overlay on rubblized concrete pavements. IC could have improved QC in three ways if used effectively for the entire project, they conclude. IC could have: • Provided a tool to evaluate the concrete pavement rubblization process while it was underway. By measuring IC-MV with the IC roller after rubblization and analyzing the collected data, the contractor could make decisions about the optimum degree of rubblization that needed to be performed. • Decreased variability in pavement density by improving the consistency of roller patterns during the HMA compaction operation by training the roller operator to use the on-board color-coded display. • Provided an independent analysis (separate from agency requirements) of quality by using Veda software to perform a statistical analysis of IC data. v 12/19/12 2:19 PM 3/28/13 12:26 PM DATE 12.19.12 INITIALS CD Rob P. DATE 8/30/13 8:21 AM

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