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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Behavior of the Expanded Polystyrene (EPS) Elastic Inclusion at Integral Abutments</title>
      <link>https://rip.trb.org/View/1872849</link>
      <description><![CDATA[The Virginia Department of Transportation (VDOT) Structure and Bridge Division
has promoted and developed guidelines for the use of integral or jointless bridges. The
lateral movement of integral abutments due to the repetitive expansion/contraction cycles sometimes causes excessive settlement at the bridge approaches (bump at the end of the bridge). To minimize this problem, VDOT implemented the use of elasticized Expanded Polystyrene (EPS) inclusion. However, the properties of different EPS materials that are available on the market vary widely and there are no standardized tests and reliable data available to assess their suitability for the integral bridge applications. This research will focus on developing specific testing procedures that are relevant to this problem. Long-term mechanical properties of different EPS materials under cyclic load applications will be investigated in detail. Based on the results obtained from these tests, elastic inclusion design recommendations for integral bridges will be proposed.
]]></description>
      <pubDate>Mon, 16 Aug 2021 07:57:19 GMT</pubDate>
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      <title>Implementation Using Geofoam for Bridge Approach Slabs and Roadway Embankments</title>
      <link>https://rip.trb.org/View/1359586</link>
      <description><![CDATA[Texas Department of Transportation's (TxDOT's) Fort Worth District installed a novel lightweight fill material, Expanded Polystyrene (EPS) geofoam, as part of a rehabilitation of the US 67 bridge over SH 174 in Johnson County. The bridge embankment constructed in 1995. is approximately 40 ft. high. Readily available moderate plasticity clay soil has been adopted as the fill material. For the past 16 years, the approach slabs at each end of this bridge had experienced more than 17 in. of settlement. The District funded a rehabilitation project to remove the modular block walls underneath, construct 3:1 slopes, repair bridge beams, and remove and replace 150 ft. of approach slab and pavement on each end. EPS geofoam was selected due to its lightweight and high compressibility attribute. The weight of EPS geofoam utilized is only a small fraction of soil that was excavated. Geofoam was designed to replace 6 feet of the embankment from the bottom of the bridge abutment upward. The additional 2 ft. remaining at the top of pavement was constructed with a 10 in. layer of item 247 flexible base, 4 in. of item 3224 Type. B hot mix, and 10 in. of CRCP concrete pavement. This rehabilitation work started in January 2012 and was completed in the following month (February 2012). This area was instrumented with four (4) horizontal inclinometers and four (4) pressure cells to monitor the settlement behavior and pressure response of the embankment in relation to the dead load of the overlying pavement structure, live traffic loading, embankment settlement, and pressure against the abutment and wingwalls. After the completion of installation in February 2012, University of Texas, Arlington (UTA) research team conducted field performance monitoring at regular interval. It can be observed from the horizontal inclinometer data that during the three years after opening to traffic, less than 1.5 in. (38 mm) of post-construction vertical displacement [settlement] has occurred. No visible deformation or bump is observed in the concrete pavement surface. However, soil erosion at shoulder and a 3 in. (76mm) differential settlement at the pavement has been observed and documented on the south side slope of the embankment. it appears that the slope soil is creeping laterally away from the roadway thereby leading to this differential settlement at the pavement and wing wall edge. Continual wet soil exists at the end of a drain line installed at the end of the wing wall during construction and draining down the slope. The origin of this water is still unknown. Due to the continual soil movement and water draining from under the approach slab, the influencing factors contributing to settlement of geofoam installation are not yet identified. Additional data collection is desired in order to evaluate the longer-term performance of the EPS geofoam in this embankment. Hence, continued site visits for data collection need to be conducted for at least 5 to 6 years. Long-term performance data will also help in the formulation of design charts for future use of EPS geofoam in other projects.]]></description>
      <pubDate>Wed, 01 Jul 2015 02:45:46 GMT</pubDate>
      <guid>https://rip.trb.org/View/1359586</guid>
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      <title>Investigation of the Carrs Creek Geofoam Project</title>
      <link>https://rip.trb.org/View/1261345</link>
      <description><![CDATA[The I88 crossing of Carrs Creek in Delaware County, NY was washed out during record flooding in 2006. Two persons were killed and the roadway was closed for traffic. A new pre-cast concrete culvert was rapidly constructed using geofoam and compacted soil backfill. Shortly after construction, excessive settlements developed in the geofoam and all of the backfill was sub-excavated and replaced with lightweight expanded shale. A large number of unconfined compression tests were performed on exhumed geofoam samples at different laboratories in a follow up investigation. The test results indicated the geofoam initial modulus was lower than indicated in ASTM D 6817 for the specified grade of geofoam. The study identified the noted inferior geofoam quality to be the likely cause for the excessive settlements. The relatively rigid culvert, compressible geofoam and compacted soil constitute conditions of soil structure interaction. This proposal is for detailed study of the geofoam failure through selected laboratory tests, computer modeling and simulation to provide a better understanding of the main causes and mechanisms that contributed to the failure. The investigation will feature selected laboratory tests on geofoam of the same grade and also on exhumed samples that have acquired a stress history. Stress induced anisotropy and confining stress effects on geofoam strength and modulus will be examined. A geofoam inclusion within the backfill can offer significant advantages. Because of its low density, the weight of the backfill on the culvert will become less. The relatively high compressibility of geofoam would facilitate differential movement and arching effects. Depending on the type of arching and extent of induced trench conditions that develop, loadings on culverts can be significantly reduced. This can lead to use of standard culvert sections under high fills to enable cost savings and rapid construction. The research will investigate these effects in the geofoam failure considering the construction sequence and installation details. As part of the deliverables, the geofoam failure will be re-designed optimizing the amount and location of the geofoam within the backfill and considering extreme flood levels and potential for uplift due to buoyancy. The adequacy of the specification and alternative uses for the exhumed geofoam stockpile will be considered.]]></description>
      <pubDate>Thu, 05 Sep 2013 01:00:19 GMT</pubDate>
      <guid>https://rip.trb.org/View/1261345</guid>
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