Shad M. Sargand

Evaluation of Warm Mix Asphalt Mixtures Containing RAP Using Accelerated Loading Tests

This paper presents the results of a study that was conducted to evaluate the performance and constructability of warm mix asphalt (WMA) mixtures containing reclaimed asphalt pavement (RAP). Four sections were constructed at the indoor Accelerated Pavement Loading Facility at Ohio University. Aspha-min, Sasobit, and Evotherm WMA mixtures were used in the wearing course layer of the first three sections. In addition, the fourth section had a conventional hot mix asphalt (HMA) mixture, which was used as a control. Temperature was monitored during the production, placement, and compaction of WMA and HMA mixtures. Furthermore, emission tests were conducted at the asphalt plants during the production of each of the evaluated mixtures. Falling weight deflectometer (FWD) and rolling wheel tests were conducted at different temperatures on all evaluated sections. The results of this study showed that emissions were reduced during the production of the Aspha-min and Sasobit WMA mixtures by at least 50 % for volatile organic compounds, 60 % for carbon monoxide, 20 % for nitrogen oxides, and 83 % for sulfur dioxide, when compared to the control HMA mixture. In addition, although WMA mixtures were produced and compacted at much lower temperatures, they achieved better field densities than the control HMA mixture. The FWD test results showed that at 40°F (4°C) test temperature, the control HMA mixture had significantly lower stiffness than that of the WMA mixtures. However, the FWD stiffness measurement of the HMA and the WMA mixtures were statistically indistinguishable at the intermediate and high test temperatures of 70°F (21.1°C) and 104°F (40°C), respectively. Finally, the rolling wheel test results indicated that the three WMA sections, especially the Evotherm section, exhibited more rutting than the control HMA section during the post primary compaction stage. However, the rutting rate of the HMA section was higher than those of the WMA sections in the secondary stage, which suggests that the rutting difference may slowly be mitigated.

Soil Pressure Measured at Various Fill Heights Above Deeply Buried Thermoplastic Pipe

When a flexible pipe is installed in a dense soil fill, stress redistribution takes place around the pipe because of pipe-soil interaction. The degree of this interaction is considered to be influenced by the stiffness ratio between the pipe and its surrounding soil. Classical theory based on elastic solutions shows that in an ideal installation condition, the zone of the pipe-soil interaction may be confined to one to two pipe diameters from the pipe. In 1999 a research team from the Ohio Research Institute for Transportation and Environment installed a total of 18 instrumented thermoplastic pipes at the deep pipe burial project site in Albany, Ohio. These pipes were placed under either a 6.1-m or 12.2-m (20-ft or 40-ft) embankment fill. During the pipe backfilling and subsequent embankment fill placement, soil pressure cells were placed at different fill heights above selected test pipes to measure the vertical extent of the pipe-soil interaction zone. The field-measured vertical soil pressure compared well with the predictions made by the elastic solutions. Summarized here are the information and data related to the vertical soil pressure measurements made in the Ohio University field study.

Soil arching over deeply buried thermoplastic pipe

Soil arching associated with buried thermoplastic pipe is discussed. First, the soil arching phenomenon is described. Then two different approaches are mentioned from the literature to represent the degree of soil arching (or vertical arching factor). The elastic solutions of Burns and Richard are revisited to derive expressions for the vertical soil arching factor for buried pipe. Comparison of the elastic solutions and field soil pressure cell readings reveals the importance of incorporating a bending stiffness parameter. With this finding, the AASHTO method for calculating the load on buried pipe is evaluated against the elastic solutions. The analysis reveals that the AASHTO method is conservative, overestimating the load on thermoplastic pipe by up to 30%. Further evidence to support the finding is found within the strain gauge readings taken on the pipe walls in the field. Therefore, alternative equations derived directly from the elastic solutions are recommended to predict the load on buried thermoplastic pipe instead of the AASHTO method.

Forced vibrations of laterally loaded piles

Abstract An analytical approach for the determination of the response of a single circularcylindrical pile subjected to a lateral dynamic load is presented. The kinetic and the potentialenergies of the pile-foundation system are minimized by variational principle to obtain thegoverning field equations of the pile-foundation system along with the appropriate boundaryconditions. A non-dimensional parameter γ, associated with the characteristics of the pile, thefoundation and the loading is used to represent the elastic medium. This parameter γ can bedetermined by using an iterative procedure. The classical finite difference method is used tosolve the governing field equations of the pile-foundation system. The validation of the proposedmodel is demonstrated by applying to several published field pile load tests. Parametric studieswith regard to the frequency response of the pile head and the resonant frequency of the pile-foundation system are presented.

Viscoelastic FE Modeling and Verification of a U.S. 30 Perpetual Pavement Test Section

ABSTRACT Traditionally, Hot-Mix-Asphalt (HMA) materials in mechanistic analyses for flexible pavements have been treated as pure elastic solids. The research presented herein consists of developing a three-dimensional linear viscoelastic finite element model to simulate the behavior of a perpetual pavement structure subjected to traffic loading at different temperatures and vehicular speeds. The developed model relatively accurately predicted not only the stress and strain responses but also the deflection response concurrently. The results of this research will encourage the pavement community to use viscoelastic analysis of perpetual pavements in practice, which otherwise are extensively being analyzed with the conventional elastic models.

Profile-Wall High-Density Polyethylene Pipes 1050 mm in Diameter Under Deep Soil Cover: Comparisons of Field Performance Data and Analytical Predictions

Although the study of pipe–soil interaction has more than 80 years of history, a lack of long-term field performance data still exists when it comes to the structural performance of large-diameter, profile–wall thermoplastic pipes under deep soil cover. Field-monitored structural performance data were taken for 1050-mm (42-in.) diameter, corrugated high-density polyethylene (HDPE) pipes, which were subjected to 6.1-m (20-ft) and 12.2-m (40-ft) soil fill heights at the ORITE deep burial test site at the Ohio Research Institute for Transportation and the Environment. The field data accumulated over about 2 years indicate that these HDPE pipes are performing satisfactorily. None of the pipes deflected more than −2.5% vertically and 1% horizontally. Closer examinations of the field data obtained at the end of construction and a few months afterward provided insights into the HDPE pipe performance under deep soil cover. Among the analytical methods evaluated in light of the field data, the elastic solutions established by Burns and Richard were most promising in predicting the field performance of the HDPE pipes under deep soil fill.

Interfacial Properties of Ultrahigh-Performance Concrete and High-Strength Concrete Bridge Connections

AbstractRecently, ultra-high performance concrete (UHPC) has been utilized in highway bridge connections, where its superior strength and durability help to reduce joint cracking and enhance transverse load transfer. According to the load and resistance factor design (LRFD) bridge design procedure specified by AASHTO, the strength of the connections is dependent on the adhesion and friction between the connected materials. The objective of the present research is to identify the adhesion value between UHPC and high-strength concrete (HSC) with varying degrees of roughness. To this end, UHPC-HSC specimens were tested in direct tension according to ASTM protocols, and the maximum tensile stress at failure was obtained. Test results show that the average maximum tensile stress for the UHPC-HSC specimens with a smooth interface exceeds that determined from past research for any degree of roughness. Furthermore, the average maximum tensile stress increases with the degree of roughness. The results from the dir...

New Inspection and Risk Assessment Methods for Metal Highway Culverts in Ohio

This paper first describes Ohios new statewide culvert management program, which aimed to reduce the risk of structural failure of culverts that serve major highways. The paper next describes a research project conducted by the Ohio Research Institute for Transportation and the Environment (ORITE) research team at Ohio University to validate the effectiveness of the approaches outlined in the new program. The new culvert program is supported by high-resolution field inspection and rating procedures for concrete, metal, and thermoplastic culverts. This paper focuses on the metal culvert components of the research project. The new field inspection procedure for metal culverts was applied at 25 sites to detect problems common to many metal culvert sites in Ohio. The data produced during the field inspection phase were analyzed statistically to evaluate the effectiveness of the new procedure and to verify the findings made by the previous study about the conditions of the metal culverts that serve Ohios maj...

THERMOPLASTIC PIPE DEEP-BURIAL PROJECT IN OHIO: INITIAL FINDINGS

The paper reviews a project that: monitored the pressure distribution around the perimeter of the thermoplastic pipes subjected to deep burial; detected vertical extent of the soil-pipe interaction zone through readings of pressure calls placed at various heights above the test pipes; monitored the deflection profile around the pipe perimeter and circumferential shortening of the pipes subjected to deep burial; monitored the pipe responses as a function of time; and evaluated reliability of empirical, theoretical, and numerical methods developed for the analysis and design of buried pipe in light of the latest field performance data.

Time-Dependent Deflection of Thermoplastic Pipes Under Deep Burial

Field performance data are presented on the time-dependent deflection of thermoplastic pipes tested at the Ohio Research Institute for Transportation and the Environment (ORITE) at Ohio University in Athens, Ohio. In fall 1999, ORITE began its study of 18 thermoplastic pipe products—12 HDPE (polyethylene) high-density and 6 PVC (polyvinylchloride)—ranging in diameter from 762 to 1524 mm and buried under either 6.1 m or 12.2 m of embankment fill. The installation conditions for these pipes were varied to study the effects of bedding thickness, backfill material type, and relative compaction on their structural performance. The pipes have been extensively monitored using a comprehensive set of sensors. Until this point, insufficient field data have been available for the development of design standards for thermoplastic pipes since previous tests were conducted over a short time period. Long-term tests are more reliable for calculating field performance since the structural response of plastic pipe is time dependent. The focus of the study described was the deflection performance of six of the thermoplastic pipes during burial and over the long term under actual field conditions. The six different thermoplastic pipes were located under 12.2 m of cover using either Ohio Department of Transportation (ODOT) 304 crushed limestone or ODOT 310 river sand materials for backfill. Each pipe was instrumented with displacement potentiometers measuring deflection in the vertical and horizontal directions as well as the circumferential shortening. The results from the study indicate that the deflections stabilized within 2 months from the completion of construction.