Issam Khoury

INSTRUMENTING OHIO TEST PAVEMENT

The Ohio Department of Transportation (ODOT) constructed a test pavement on US-23 in Delaware County, Ohio. Of the nine Specific Pavement Studies (SPS) formulated by the Strategic Highway Research Program (SHRP), four (SPS-1, SPS-2, SPS-8, and SPS-9) were included at the OH-SHRP DEL-23 site. Sensors were carefully selected and installed to monitor structural response and seasonal parameters on the basis of prior field experiences accumulated in the United States and Canada. Criteria used to select the sensors were cost, accuracy, sensitivity, longevity, and level of success in previous pavement research projects, especially projects in Ohio. Described here is the development of the Ohio test pavement in terms of objectives, overall instrumentation plan, and selection of sensors as well as typical instrumentation plans for asphalt concrete and portland cement concrete sections.

Contribution of Transverse Tie Bars to Load Transfer in Adjacent Prestressed Box-Girder Bridges with Partial Depth Shear Key

AbstractAdjacent box-girder bridges have become a popular choice as they can be constructed quickly, easily, and economically. In spite of their good performance during many years of service, one major problem has been recurrent longitudinal cracking of the grout material in the shear key. A combination of shear keys and transverse posttensioning (TPT) ties in such kind of bridges is typically used to connect the bridge girders together so that they would behave as a single integrated unit. However, information regarding the contribution of the TPT tie bars on load transfer between adjacent box girders is limited. In this study, a single-span precast prestressed concrete adjacent box-girder bridge was instrumented and monitored to study the effect of TPT tie bars on load transfer mechanism and overall bridge behavior under static and dynamic truck loads. Two sets of instruments were installed in the girders and tie bars during and after the construction of the bridge. A good correlation was achieved betwe...

Structural Study of Perpetual Pavement Performance in Ohio

Three perpetual pavement test sections were constructed on U.S. Route 23 in Delaware, Ohio (DEL-23) with AC thicknesses 28, 33, 38 cm and instrumented to detect strains in Fatigue Resistant Layer (FRL) and base layers. The 28 and 33 cm sections were constructed on lime stabilized subgrade, while the 38 cm section was constructed on compacted subgrade. Four additional test pavements were built in the Accelerated Pavement Load Facility (APLF) and instrumented similarly to DEL-23. The sections were thinner, but included Highly Modified Asphalt (HiMA) with Kraton polymer binder in sections of depth 20, 23, and 25 cm. An 28 cm section used conventional asphalt in the base as a control with HiMA in surface and intermediate layers. There was no FRL. All sections were placed on 46 cm of cement stabilized subgrade. Strains at bottom of FRL during Controlled Vehicle Load (CVL) testing on DEL-23 in summer indicated the 33 cm section on stabilized subgrade and 38 cm section on compacted subgrade met the perpetual pavement criteria of NCHRP Project 9-44A, while 28 cm section on stabilized subgrade did not. Testing at the APLF included thoroughly heating the pavement to 37.8 °C and subjecting each section to 10,000 passes of a 40 kN wheel load. Pavement strains at the bottom of the base and intermediate layers in the longitudinal and transverse directions were measured after 1000, 3000, and 10,000 wheel passes using test loads of 27, 40, and 53 kN. The serviceability of the pavements was determined by comparing the longitudinal strains within the base layer of each pavement to fatigue endurance limits (FEL) calculated by using flexural stiffness standards from NCHRP 9-44A and a method recommended by Kansas researchers. At the APLF, the thinnest section produced maximum average strains higher than the calculated FEL at 37.8 °C using the NCHRP 9-44A equation, while the 25 and 28 cm sections met the perpetual pavement criteria. Using the Kansas researchers approach, all four test sections were found to have lower longitudinal strains than the calculated FEL.

Rutting resistance of asphalt mixes containing highly modified asphalt (HIMA) binders at the Accelerated Pavement Load Facility in Ohio

Highly modified asphalt (HiMA) mixes have been proposed as a stronger alternative to standard asphalt concrete mixes that will enable thinner perpetual pavements in Ohio. HiMA uses a polymer-enhanced binder has a higher unit cost, but has the potential to reduce the thickness of perpetual pavements, resulting in savings compared to conventional HMA perpetual pavement projects. Test sections containing HiMA in the surface, intermediate, and base layers were constructed with total thicknesses of 20, 23, and 25 cm, created by varying the depth of the AC treated base, in the Accelerated Pavement Load Facility (APLF) at Ohio University in Lancaster, Ohio. An additional 28 cm section was installed as a control with a non-HiMA base layer and HiMA surface and intermediate layers to compare with the experimental sections. Each pavement was subjected to 10,000 passes with a single axle load of 40 kN while the pavement was held at each of two pavement temperatures of 21.1 and 37.8 °C. Rutting on the surface of the pavement was measured using a rolling wheel profilometer after 100, 300, 1000, 3000, and 10,000 wheel passes at each temperature. The four sections showed no significant rutting damage after being subjected to a total of over 20,000 passes, and remained well below ODOT’s “low rutting” threshold of 3.2 mm. Extrapolating the rutting data indicated the worst-performing section would reach the low rutting threshold after more than a million passes of the load. The rutting data were compared to those obtained in a previous perpetual pavement study in the APLF that had surface courses including Aspha-min warm mix asphalt and a conventional hot mix asphalt, which crossed the low rutting threshold well before 10,000 passes at the high temperature.

Environment-Induced Behavior of Transverse Tie Bars in Adjacent Prestressed Box-Girder Bridges with Partial Depth Shear Keys

AbstractAdjacent box-girder bridges are commonly built in United States because of their fast, easy, and economical construction. They have shown good performance and service life except for freque...

Field Inspection of Corrugated HDPE Pipeline Network under Heap Piles at a Copper Mine Site in Chile

AbstractIn-service conditions of a corrugated high density polyethylene (HDPE) pipeline network embedded within a bioleaching pad in the Atacama Desert in Chile were assessed. The pipes provided air for the copper extraction process and were subjected to large overburden stresses generated by the ore heap pile. A pipe crawling device was developed for the study. The field data collected revealed that the pipes were suffering from excessive deflections, circumferential shortening, and flexural bending. Wall buckling was observed in some sections. The flexural bending affected the pipe joint integrity. Field data also revealed localized punctures at some locations because of ore rocks pressing against the pipes. A few sections showed reversed curvature and joint failure. These conditions can generate a loss of functionality for the pipeline system. After a review of the construction record, it was determined the distresses were a result of using inappropriate backfill material and a poor installation procedure.

Forensic Study on a Collapsed Structural Plate-Arch Culvert in Ohio

In April 2014, a large structural plate arch culvert collapsed in Licking County, Ohio. The structure’s demise appeared to be related to a slope failure experienced by the roadway embankment fill above the inlet section. Shortly after the incident, a team of researchers from Ohio University conducted a forensic investigation of the structure. The team collected forensic data by visiting the site, testing soil samples taken near the culvert, and reviewing any past relevant documents. The team then employed the traditional slope stability analysis method, the AASHTO LRFD method, an empirical method found during a literature search, and computer simulation methods to gain further understanding of the culvert failure. The results of these analyses pointed the cause of the culvert failure toward what was speculated based on the field observations.