VTRC Reports
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The Virginia Transportation Research Council (VTRC) has released two new reports on two recent studies.
Interlaboratory Study for the Indirect Tensile at High Temperature Test and Ideal Rutting Test
Abstract
The Indirect Tensile at High Temperature (IDT-HT) test and Ideal Rutting (IR) test were recommended for screening rut-susceptible asphalt mixtures in the Balanced Mix Design (BMD) process, based on a research study by the Virginia Transportation Research Council (VTRC). The Virginia Department of Transportation (VDOT) is in the initial stages of implementing the IDT-HT test as part of the BMD initiative for dense-graded surface asphalt mixtures with unmodified asphalt binders. However, for full implementation, additional considerations such as fine-tuning the test procedure and determining precision estimates of the test method are necessary, and this study specifically addressed these aspects for the IDT-HT and IR tests. The work included three tasks: a sensitivity assessment, an interlaboratory study (ILS), and a proficiency study. All tasks were based on evaluation of specimens from four mixtures with varying rutting potentials.
Abstract
Due to the increasing interest in the use of recycled concrete as a base coarse aggregate, the Virginia Department of Transportation (VDOT) identified the need for in-depth research investigate the clogging potential of the geotextile used in highway edge drains if crushed hydraulic cement concrete (CHCC) is placed adjacent to the drainage fabric geotextile. To answer the research needs of the VDOT and address the discrepancies in the existing literature, George Mason University conducted a laboratory-based study and published their findings (VTRC 21-R12). The study identified two major mechanisms through which CHCC reduces the flowability of the geotextile used in underdrains: physical (fine particles migrating onto the voids in between the filaments of the geotextile) and chemical (precipitation of chemicals within geotextile filaments) phenomena. The findings showed that although the drainage fabric geotextile experienced some level of reduction in its flow capacity, as was expected, the reduction was not significant enough to impact and impede the overall flow of the geotextile/CHCC system. However, the laboratory study had some limitations, e.g., while simulating the physical and chemical phenomena simultaneously, temperature, rain, and humidity variations during seasonal changes were not accounted for, the potential effects of the pavement over the top of CHCC were not included, and drainage pipes were not considered.
