Samenvatting

Pavements are used everywhere, and are of a major importance in the infrastructure. However, conditions for which these pavements are designed for and built in are rapidly changing due to climate change. The trends observed in the Netherlands suggest a maximum temperature increase of 3 degrees Celsius and an increase of the average difference between day and night temperatures of 0,6 degrees Celsius in the coming 60 years.
Rigid (concrete) pavements will be influenced by this change, since temperature gradients, caused by temperature variations, exert a normal force. This normal force can manifest itself through tensile stresses in the pavement construction, due to the pavements shrinking while cooling down and expanding while warming up. These temperature related tensile stresses combined with the tensile stresses exerted by the traffic on the pavement are dealt with in different ways depending on the type of rigid pavement that is used. Jointed concrete pavements give room for pavements to marginally expand and shrink in the joints between the different plates, while reinforced concrete pavements use reinforcement to counteract the tensile stresses. For highways a continuous pavement is often used for highways, since it eliminates joints which improves riding comfort and it almost does not require any maintenance, avoiding construction works over almost the entirety of its designed lifetime. These longer stretches of pavement however do need reinforcement to restrain the tensile stresses, which yields the name Continuously Reinforced Concrete Pavement. During construction, the development of the tensile stresses and tensile strength of the pavement is crucial in forming the cracking pattern that arises when the tensile stresses exceed the tensile strength of the pavement. Lower temperatures can result in a slower development of the tensile strength, resulting in more cracks since the tensile stresses will more often exceed the tensile strength, while higher temperatures could result in the opposite effect. The higher the tensile strength and stiffness of the concrete is when cracking, the bigger the crack width will be. Controlling this crack width is of high importance, because otherwise the pavement could become vulnerable to for example chemicals penetrating into the pavement construction.

Several methods are used to design continuously reinforced concrete pavements. FLOOR 3.0 is an example of a design method that is mostly focused on concrete floors inside buildings, while VENCON 2.0 is an example for the construction of highways. In these methods, all the variables used to calculate the pavement thickness can be categorized in five different categories:
- Traffic loads
- Traffic stresses
- Temperature stresses
- Materials properties
- Foundation

The traffic loads and foundation are used to calculate the expected axle load repetitions that a pavement needs to be designed for. The traffic stresses, temperature stresses, materials used and foundation are used to calculate the allowed axle load repetitions. These are then combined to make sure the pavement meets the requirements.
Temperatures are accounted for in the design using temperature gradients, from the top of the pavement to the bottom and cause a tensile stress. Several temperature gradients, which all occur at different frequencies, are used to represent reality. In other words, small gradients occur more often than large gradients, and both are considered in the design.
The relationship between temperature gradients, caused by daily temperature fluctuations, and pavement thickness is analyzed using a developed model based on VENCON 2.0, which is deemed to be most applicable in this thesis. Both an increase in temperature gradient as an adjustment for the frequency distribution, making bigger gradients occur more often and smaller gradients less, cause the pavement thickness to increase. A direct relationship is not found between daily temperature fluctuations and temperature gradients, but if the established trend of the temperature fluctuations occurs for the used standard temperature gradient as well, the pavement thickness will increase by 1-2 millimeter. However, if the standard temperature gradient, used in the model, is not
representative, then the increase of thickness could be bigger. Additionally, extreme combinations of traffic and temperature stresses could increase the minimum thickness of pavement constructions as well, since extreme conditions are bound by a boundary condition. This condition requires the pavement thickness to be increased if the ratio between the maximum stresses and bending tensile strength gets too large. This minimum thickness primarily occurs for pavements with less than 1*107 axle load repetitions.