PDEng Project at the University of Twente entitled: Developing an Asphalt Compaction Simulation Tool

The asphalt construction industry is one perceived to be based on tradition and custom where work methods are largely based on implicit knowledge and experience. The ASPARi research has shown that traditional working methods lead to extensive variability in the asphalt construction process. More importantly, the research shows that the compaction process is a complex activity. Operators have to take into account several factors during compaction including:

Weather conditions (ambient temperature, wind speed)
Asphalt mix properties (mix type, binder type and grade)
Layer thickness being compacted
Temperature of the existing surface
The delivery temperature of the asphalt mix
The location and speed of the asphalt paver and their partner operators’ compaction strategies, patterns and locations

Also, compacting at too high or too low mix temperatures has a negative effect on the mechanical properties of the asphalt mixture leading to problems of early fatigue and permanent deformation. This in turn, leads to costly earlier maintenance than expected of the constructed asphalt layers. In short, roller operators do not know when to start and finishing compacting. The so-called ideal “window of opportunity” for the compaction of various mixes has, as yet, not been developed.

To support roller operators in achieving a more consistent, method-based asphalt compaction process that ensures that they compact within an appropriate “window of opportunity”, there is a need to develop a new tool that simulates the cooling of the asphalt mat behind the asphalt paver under a variety of weather and other conditions. The ASPARi unit has for the past 8 years collected cooling rate data for various mixtures, under various weather conditions and for different asphalt mixtures using its own Cooling Curve Calibration Unit (CCCU). The CCCU uses a combination of thermal imagery, temperature sensors and nuclear density measurements to make explicit the cooling behaviour of the asphalt mix and the related density progression during compaction. This data provides a starting point for developing a simulation tool that predicts asphalt cooling rates based on actual data. This is a departure from previous simulation tool developments that mainly uses theoretical heat transfer models as a means of predicting the “window of opportunity” for compaction.

The aim of this design project is to:
“Develop a compaction simulation tool that will support roller operators achieve a more consistent compaction product”

The main outcomes are:

An integrated software simulation tool capturing the complex asphalt compaction process i.e. it should include factors such as the environmental conditions, existing surface conditions, mix properties and actual cooling rates of the various asphalt mixes.
An improved system/approach for simulating and validating the on-site compaction process in the laboratory.
Machine learning algorithms that can be used to predict and visualise asphalt cooling curves based on large data sets.
Method-based operational strategies that can be simulated, tested and validated before construction commences.

Deadline Application: 13-06-2016

Further details:
PDEng Project at the University of Twente entitled: Developing an Asphalt Compaction Simulation Tool