DOI

10.5703/1288284313160

Report Number

FHWA/IN/JTRP-2001/06

Abstract

Ultra-thin Whitetopping (UTW) involves placing a very thin concrete overlay 50 mm to 100 mm thick (2”-4”) on the milled surface of a distressed asphalt pavement. To investigate the performance of UTW placed over a flexible pavement subjected to slow and heavy moving wheel loads, whitetopping mixes were placed over a milled pavement surface in the Accelerated Pavement Testing (APT) facility of the Indiana Department of Transportation (INDOT) Research Division in West Lafayette Indiana in the fall of 1999. The UTW installation experiment consisted of four test ‘lanes’ of two different thicknesses; each utilizing plain and fiber reinforced concrete. The test ‘lanes’ were instrumented using strain gages, Variable Differential Transducers (LVDTs) and thermocouples to measure the strains, deflections, and to monitor the pavement temperatures respectively. The test ‘lanes’ were subjected to both static and dynamic tandem wheel loads of varying magnitudes. In addition, one of the test ‘lanes’ was also exposed to thermal load by applying a temperature gradient to the pavement. A mix design for the UTW was developed based on literature survey of previous UTW projects. The mechanical properties of concrete were evaluated in the laboratory before the UTW pavements were constructed at the APT facility. The pavements were monitored continuously during the testing period and the dynamic-load strains during the motion of the wheel, as well as the static strains due to the stationary wheel load were recorded. This data was analyzed to determine the maximum strains and their location, the degree of bonding between the UTW overlay and the underlying asphalt and the pavement performance under repeated loading. In addition, non-destructive test method was utilized to evaluate the pavement condition after the accelerated pavement testing was completed. In addition, cores obtained from the pavement were subjected to shear force to determine the quality of the bond. A three-dimensional finite element model was developed using a general finite element code, ABAQUS, to conduct an analysis of the response of the composite pavement to the wheel loads. The principal goal was to develop a simple and reliable model using reasonable geometry, boundary conditions and material properties, to verify the pavement response observed experimentally. No significant differences were found between the predicted and the experimental pavement response.

Keywords

ultra-thin white topping, plain concrete, fiber reinforced concrete, strain, deflection, stress, repeated wheel loading, pavement, temperature gradient, finite element model, SPR-2340

SPR Number

2340

Project Number

C-36-46Q

File Number

6-14-25

Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, IN

Date of this Version

2002