Page 53 - RoadCem Manual - PCT BV
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 4.Design criteria Weakest, Weaker, Weak, High, Higher, Highest
4.1 Introduction
To carry the traffic load and the weight of the pavement structure the sub-base must have a certain bearing strength. Traditionally, soil was not considered to be a valuable material for the construction of roads and aside from using it as a sub-base it was usually avoided in road construction. Instead what was considered to be an appropriate material was imported.
However we know that soil can also be used as a structural material, for example earth dams have been constructed for centuries throughout the world, houses have been constructed using soil as a main building block and different soils have been used in the manufacture of bricks and other structural materials for centuries. Why than is it that soil has not been considered as good road building material?
The answer to the above question partially lies in our tendency to follow the common practice and past solutions and partially in our failure to ask a question:
“How can we use any type of soil in road construction”??
This question has now been asked and some answers have been provided. RoadCem is one of such answers as it allows us not only to improve soil as a sub-base but also to use soil for the construction of pavements proper. How this can be done will be discussed in the next chapter. In this chapter we focus on soil and its characteristics of importance to us from the road construction point of view. The main purpose of this chapter is therefore:
“Understanding important properties of soils as a road building material”
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