The International Society for Concrete Pavements (ISCP) will be featuring a
Student Highlight for our news feed.
The new feature will be called “STUDENT RESEARCH SPOTLIGHT”!
Each month, or every other month, a student will provide a 1-page illustrated abstract of the research they are currently conducting. This is a wonderful opportunity for the student, our ISCP Members, and technology/research transfer to our concrete paving industry.
Our inaugural post for December 2021 is Katelyn Kosar, a Phd student from the Department of Civil and Environmental Engineering-University of Pittsburgh (Pitt).
Bio:
Katelyn Kosar is a Ph.D. student studying Pavement Engineering in the Department of Civil and Environmental Engineering at the University of Pittsburgh. She obtained her Bachelor’s degree in Civil and Environmental Engineering from West Virginia University.
Katelyn’s research field deals primarily with
early age properties of concrete pavements and
non-destructive testing. The topic of her thesis project is
“the early opening of concrete pavements to traffic”.
Early Opening of Concrete Pavements
Research by:
Katelyn Kosar, Ph.D. Student-Pavement Engineering-Department of Civil and Environmental Engineering-Pitt
Katelyn Kosar casting cylinder
and beam specimens.
Click to enlarge.
A major question in pavement construction is how to shorten it as much as possible. This led to the introduction of many advances that allow construction time to shorten from days to hours, including the use of high early strength concrete. However, these advances often come at a financial cost to the project and even then, additional time can be saved by allowing traffic earlier than the current criteria. Every Department of Transportation has its own guidelines for when to open to traffic, each varying significantly. Current criteria are often simple and generalized so they are applicable for the entire state. These requirements are also conservative to account for all the different roadway needs.
MnROAD pavement section
where data was collected
to determine the effect of
opening a pavement to
traffic early. Click to enlarge.
In theory, a pavement can be opened to traffic once it reaches the minimum concrete strength needed to carry the expected traffic loads without long term damages. This can be accomplished by better calculating and predicting the early age concrete strength and long-term effects by accounting for time of construction, pavement design, traffic loading, climate, and edge support conditions or having separate traffic loading criteria. The calculation and field measurement of concrete strength can be improved using non-destructive testing. The methods being utilized in this thesis include maturity and ultrasonic tomography. A damage analysis model that accounts for factors effecting early age concrete can be used to predict the effect of traffic on pavement performance based on the concrete maturity, shear wave velocity, or p-wave velocity at which it is to be opened.
The ability to specify opening criteria to individual projects has many benefits. Lightweight passenger vehicles do not cause the same stresses in the pavement as heavy trucks. Providing a separate earlier strength criterion will allow for reduced congestion without damaging the pavement. The primary benefit is of course the decrease in construction time. This lowers the risk to the construction workers and lowers the effect on the surrounding community including lowered congestion and faster access to roadways for businesses. This method also has a low impact on the current construction practices. It is simply a retiming of a current pavement procedure using strength prediction methods already in use. Finally, there is a potential decrease in cost. The user cost is accounted for in the life cycle cost analysis which includes the effect of congestion and detours on the drivers. Allowing traffic earlier will reduce these costs and allow for a more optimized pavement schedule.
ISCP would like to feature a “STUDENT RESEARCH SPOTLIGHT” every month, or every other month. If you would like to nominate a student, or if you are a student and would like to nominate yourself or a colleague, please send ISCP an email to: newsletter@concretepavements.org