Institute for Transportation

About the research

The VKelly test was developed to provide agencies and contractors a tool that reports how a slipform paving mixture responds to vibration. In the past, the slump test was useful but did not provide a complete picture of the workability of a mixture.

Initial evaluation showed that the test provided useful, numerical, and repeatable data on how a mixture will perform in a paving machine and that it could distinguish between the workability of mixtures with similar slumps. It was used to develop mixture proportions that were reported to be successful in the field. So, a number of rigs were sent to agencies around the country for them to evaluate. Feedback indicated that while seemingly technically sound, the test was still challenging to operate.

The aim of this project is threefold:

• Make the test more user-friendly
• Understand the science behind the method to guide mixture proportioning and field operations based on test results
• Broaden the applicability to include structural mixtures

The long–term vision of this work is to develop an understanding of how mixtures can be proportionated that are relatively insensitive to vibration abuse or are ideal for the vibration
system planned to be used on a given site. In addition, it is desirable that a real-time test be available on a site so that as a mixture is delivered, it can be tested for workability variances due to batching or transport, thus providing the operator with guidance on how to tune the placing equipment for that particular truckload.