Investigation of the Effect of Rising Temperature and Traffic Loading on the Behaviour of Rigid Pavements to Minimise Maintenance Requirements – Case Study of Lebanese Roads

The aim of this project is to study the effects of high temperature on the performance of rigid pavements including that of Lebanese roads and to develop suitable design and maintenance approaches that enable such pavements to sustain high loading of temperature and traffic.
The objectives are to gain a deeper understanding of the condition and performance of existing highway rigid pavements and the need for a durable pavement. More specifically, to fully understand the effect of climate change in terms of temperature changes on rigid pavements and to identify structural layers configuration and material properties that enable the pavement to sustain high temperature and heavy traffic loading, and to develop more effective and sustainable rigid pavement structures to minimise maintenance requirements. The work also includes the design of suitable overlays to maintain and extend the life of the existing rigid pavements.
The methodology used to complete the project is by analysing pavement deflection and the effect of high temperature using specialised highway and structural analysis software, particularly the packages KENPAVE, STREETPAVE12 and ABAQUS.
The main findings are that fatigue and erosion are the two most significant failing scenarios for rigid pavement, but more specifically, as the temperature increases, the cracking index increases which may lead to fatigue failure. Finite element models and analyses were used to determine the distress caused by traffic loading and high temperature. This research has found that the main factors that strengthen the performance and sustainability of the rigid pavements under high temperature and traffic loading are: thicker slab, high modulus concrete, strong and thicker foundation layers and a subgrade with high CBR%, in addition to a strong and thicker overlay to extend the life of the pavement.
The key conclusions are that rising temperatures and high traffic loading have been identified as having a major effect on the performance of rigid pavement, leading to fatigue failure criteria. Erosion is also a common failure criterion which establishes itself at times of high traffic loading. It has been found here that the cracking index of the concrete slab increases when the air temperature changes from 20°C to 60°C. At higher temperatures and with thinner slabs, the cracking index occurrence increases. In conclusion, in Lebanon a minimum of 260 mm rigid pavement would be more suitable to reduce pavement failing under fatigue criteria.