Moisture and frost

To prevent problems associated with high moisture of the subgrade, it is recommended to maintain the water table at least 300 mm below the formation level. This can be achieved with the provision of an effective drainage system. 

Additionally, in case the subgrade material is frost susceptible, the total pavement thickness (slab and sub-base) is recommended to be greater than 450 mm, unless the estimated mean annual frost index is less than 50 (see Section 13.5.10). 

2 Thickness determination of siab with continuous reinforcement 

The concrete thickness design value determined assumes the presence of a minimum 1 m edge strip or tied shoulder otherwise, the concrete design thickness should be increased by 30 mm. 

It is also pointed out that, if concrete with a flexural strength 5.5 MPa is to be used, the concrete aggregates should have a coefficient of thermal expansion less than 10 x 10 per degree Celsius. 

---