Page 49 - RoadCem Manual - PCT BV
P. 49

Life span (L)
With respect to lifespan we differentiate between 4 different categories:
• Functional lifespan.
• Structural lifespan.
• Financial lifespan.
• Social lifespan.
The social life span of a pavement is specified by the client. He determines how long a road must be
used for.
The Financial life span of a road construction depends on the period that the client needs to write off the costs for making and maintaining the road.
The financial and social life span determines the structural life span. This ends when cracks and large faults occur in the pavement.
The functional life span is related to keeping the function of the road at an appropriate level. The pavement can fail but not collapse and the traffic can continue. The failure of a road can result due to insufficient stiffness or insufficient noise absorption whereby a road no longer meets the demands other than being able to drive from A to B. The surface layer takes on the most functional properties that a road needs to meet.
3.2.4 Material properties
The physical properties of the different materials used for road construction need to be known in order to determine the layer thickness of each material. This applies also to the physical properties of the sub-base. All of these factors they need to be determined before every project.
The physical properties are:
• Dynamic elasticity module of the future foundation.
• Viscosity of the different materials.
• Pressure strength of the different materials.
• Breaking strength of the bound materials.
• Crushing value of the different materials.
• Stiffness value of the material to be used.
• Fatigue properties of the different materials.
• Water permeability of the different materials.
The value of these properties is used as the starting point when making the design. If the design values above are not known appropriate assumption must be made.
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