Research in Progress (RIP) https://rip.trb.org/ en-us Copyright © 2024. National Academy of Sciences. All rights reserved. http://blogs.law.harvard.edu/tech/rss tris-trb@nas.edu (Bill McLeod) tris-trb@nas.edu (Bill McLeod) Research in Progress (RIP) https://rip.trb.org/Images/PageHeader-wTitle-RIP.jpg https://rip.trb.org/ Continuous Friction Measurement (SCRIM) to Support Implementation of Improved Pavement Management Systems https://rip.trb.org/View/2062417 Tue, 15 Nov 2022 16:17:39 GMT https://rip.trb.org/View/2062417 Lab Dielectric Measurement System for Asphalt Mixture Bulk Specific Gravity Determination https://rip.trb.org/View/1749087 mb) of compacted asphalt mixtures requires multiple equipment and weight measurements for different conditions which, along with the operator experience, influence the accuracy and variability of Gmb measurements. The use of a laboratory dielectric measurement system (LDMS) was explored in this study as an alternative procedure to the current AASHTO specifications for measuring Gmb. The LDMS measures the dielectric constant of a compacted asphalt concrete specimen using a ground penetrating radar (GPR) system. In Stage 1 of the project, a procedure to measure the laboratory dielectric value of a compacted asphalt concrete specimen was established. Asphalt mixtures with a range of aggregate and mixture properties (geology, nominal maximum aggregate size, binder type, RAP content, etc.) were collected. Compacted asphalt specimens of various specimen surface conditions and sizes were tested using the LDMS. The collected dielectric results were statistically analyzed to study dielectric measurement repeatability and reliability by grouping measurements at various orientations together and comparing them to all measurements of the corresponding asphalt specimen. Sensitivity analysis was also performed to study measurement accuracy and resolution for replicate dielectric measurements. It was determined that taking dielectric measurements at any 3 orientations 120 degrees apart (3 measurements total) yield repeatable dielectric measurements with acceptable accuracy. In Stage 2 of the project, a procedure to determine Gmb based on the laboratory measured dielectric value was developed. A select number of asphalt mixtures from Stage 1 work, along with their component materials (aggregates and RAP) were collected. The Al-Qadi Lahour Leng (ALL) model and the Hashin-Shtrikman (HS) model were investigated and analyzed to establish the relationship between Gmb and dielectric measurements. Based on the gathered data and statistical analyses performed in Stage 2, a procedure using the HS model and laboratory measured dielectric values of component materials was recommended to determine specimen Gmb.  The recommended procedure produces predicted values of Gmb from measured dielectric values that are within the acceptable range of two Gmb results in AASHTO T331 for most specimens evaluated. The final report is available. ]]> Wed, 04 Nov 2020 10:36:53 GMT https://rip.trb.org/View/1749087 Research for AASHTO Standing Committee on Highways. Task 411. Review and Update of AASHTO Standard Practice R 87 https://rip.trb.org/View/1709364 Tue, 02 Jun 2020 10:45:09 GMT https://rip.trb.org/View/1709364 NOI # 2 - Ambient Conditions Corrections for Non-Volatile PM Emissions Measurements https://rip.trb.org/View/1368643 Mon, 14 Sep 2015 11:08:34 GMT https://rip.trb.org/View/1368643