Measuring the smoothness of wet concrete pavement
Ames Engineering Real Time Profiler
GOMACO Smoothness Indicator
Any driver enjoys a smooth ride. In fact, it is known that highway user satisfaction largely depends on pavement smoothness. This has led highway engineers to measure smoothness of both operating and new highways. However, equipment used for measurements does not provide the same values.
In an attempt to correct this inconsistency, several lightweight profilers are currently being designed. Iowa State University researcher Jim Cable evaluated two such systems: GOMACO Smoothness Indicator (GSI) and Ames Engineering Real Time Profiler (RTP).
Lightweight profiler systems
The GSI is a noncontact pavement profiler that can be used to measure the pavement profile of either wet or hardened concrete. The RTP is a laser-based profiler systemthat can be used to measure and record the pavement profile during construction. Both the GSI and the RTP provide the data in a variety of useful formats.
What profilers can do
The profilers evaluated in this study were found to be able to do the following:
- Detect roughness in the final profile, including localized roughness and roughness at joints.
- Detect dowel basket ripple, which is a significant source of pavement surface roughness, with enough clarity to warn the paving crew.
- Detect some stringline disturbances, which degrade smoothness, during paving
operations.
Additionally, the RTP produced profile values with a clear relationship to those produced by an inertial profiler after paving was completed.
What profilers can’t do
The profilers evaluated in this study are not currently able to produce the same absolute IRI values on the plastic concrete that can be measured by inertial profilers on the hardened concrete.
Benefits of these profilers
The profilers evaluated in this study
- are able to provide real-time warnings for most surface roughness problems
- can be used to take corrective action prior to set of concrete
For more information
Construction guidelines are provided in the project report Measuring Pavement Profile at the Slip-Form Paver (1.9 mb pdf) on CTRE’s website, www.ctre.iastate.edu. For specific questions, contact James K. Cable, associate professor of civil, construction, and environmental engineering, Iowa State University, 515-294-2862, jkcable@iastate.edu.
