Estimation of stiffness modulus

The laboratory determination of the stiffness modulus within a range of temperatures and times of loading is a time-consuming process and requires the existence of relatively expensive equipment. If not available, the stiffness modulus of conventional bitumen can be predicted using the Van der Poel nomograph (Van der Poel 1954). 

Using the Van der Poel nomograph, the stiffness modulus of a bitumen can be predicted at any conditions of temperature and loading time by using only penetration and softening point data. 

It is noted that Van der Poel s nomograph cannot be used for determining the stiffness modulus of modified bitumen or of waxy bitumen. 

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