Page 122 - RoadCem Manual - PCT BV

Ultimately, the challenge of good pavement design is to provide a pavement that fulfills its function at minimum life-cycle cost at an optimal level of service.
However, positive action in the form of timely and appropriate maintenance will be necessary, to ensure that the assumptions of the design phase hold true over the design life.
5.2.2 Environmental Effects
Environmentally induced distress through climatic influences, including temperature and rainfall, play a particularly important role in the performance of road pavements. For example, high temperature can accelerate hardening of binders in road surfacings through loss of volatiles and oxidation, resulting in their loss of flexibility and consequent ravelling of the aggregate and brittle fracture of the layer.
High rainfall can also result in a change in the moisture content of the pavement and subgrade materials. Poor drainage conditions and moisture sensitive materials adversely affect the pavement structure and its performance under traffic. It should be noted that when RoadCem is used the pavement structure is highly unlikely to be vulnerable to a high moisture content and this mode of failure is largely eliminated.
Carbonation of traditional materials stabilised with lime and cement can also occur. This is a reaction between the traditional stabilising agents and carbon dioxide in the air or under road pavements and leads to a weakened material. It is noted that when RoadCem is used the mechanism of interaction between pavement structure and carbon dioxide in the atmosphere is very different than in the case of traditional material and as a result carbonation problem is significantley. The pavement structure may actually be sequestering carbon dioxide which in these days of climate change is a positive effect.
Damage can also occur to road surfacings as result of salt crystallisation. This effect is especially prevalent in dry climates and/or in circumstances where pavements have been constructed with traditional materials or water with a relatively high salt content (e.g. mine waste).When RoadCem is used the problem with salts is reduced. Even during the binding process salt water can be used because salts have no influences on the binding and hardening process of RoadCem treated layers.
A traditional view of what causes the failure of a pavement is shown in table 5.5.
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