Pavement structural behaviour during spring thaw: interpretation of FWD measurements by monitoring environmental data from county road 126 at Torpsbruk

Download
Farhad Salour

The present research project has been carried out based on the environmental data and Falling Weight Deflectometer (FWD) measurements from the county road 126 in southern Sweden during the year 2010. The county road 126 has a relatively thin flexible pavement structure with unbound aggregate base and subbase layers. The major intention of this study was to investigate the behaviour of the pavement structure during spring thaw. Temperature and moisture content of the pavement structure profile were continuously monitored throughout the year 2010. Layer moduli backcalculation as well as deflection basin analyses were performed using the FWD measurement data. A comprehensive study on the effect of environmental factor variations and pavement structural capacity were carried out during the spring thaw and the recovery period. The result showed a considerable decrease in the bearing capacity of the pavement structure during the spring thaw period when the highest annual moisture content was also registered. Both deflection basin indices and backcalculated layer modulus indicated that the pavement was weakest during the subgrade thawing phase. Backcalculation on the FWD measurements showed a 67% loss in stiffness of the subgrade soil and 43% in the granular base and subbase course during the spring thaw compared to the summer values. In addition, the compatibility of the analysis with a predictive moduli-moisture content model for unbound materials was studied. The measured field data from the test road pavement in Torpsbruk showed promising agreement with the resilient modulus predictive model, both for the granular layer and subgrade material. Similar models could be developed or calibrated for other soils and granular materials if sufficient data become available in the future.

MEET US


19-20
Oct

ERPUG 2017

The five year anniversary of  European Road Profile Users' Group (ERPUG) Forum will take place at Ramboll head quarter, Copenhagen, Denmark October 19-20, 2017. 

LATEST NEWS


2017-07-05

Vehicle Driver Monitoring: sleepiness and cognitive load

To prevent road crashes it is important to understand driver related contributing factors, which have been suggested to be the critical reason in 94 per cent of crashes. The overall aim of the project Vehicle Driver Monitoring has been to advance the...


2017-06-29

Tomas Svensson new director-general

Tomas Svensson was today appointed Director-General of VTI. Tomas has been acting Director-General since January 2017. 


2017-05-30

Crash testing bicycles at VTI

For the first time single bicycle crashes have been simulated at the VTI crash safety laboratory.


2017-05-15

A case study exploring firefighters’ and municipal officials’ preparedness for electrical vehicles

A VTI-study presents a social perspective on new vehicle technology. It explores the self-reported preparedness of the fire departments (i.e., rescue services) in Sweden’s three largest cities regarding rescue operations involving electrical vehicles (EVs).


2017-05-02

Pioneering research on and about bicycles at VTI

Under what circumstances might cyclists lose tyre grip? What actions could then be taken to prevent a crash? VTI is currently developing a theoretical model of the behaviour of bicycle tyres during braking and steering in different situations and on different...


2017-05-02

Virtual pedestrians create efficient stations

If more people are to choose sustainable travel, then the public transport stations of the future must be designed so that pedestrians can get where they are going quickly, without congestion or queues. The Swedish Road and Transport Research Institute (VTI)...