12.4.3. Indirect Tensile Stiffness Modulus (ITSM)

Try these first

1. 1.

   What does ITSM stand for?

   Hint

   Think about the stiffness and tensile properties of bituminous mixes.

2. 2.

   What is the formula to calculate ITSM?

   Hint

   Remember the components in the formula.

3. 3.

   What does ITSM measure?

   • Tensile strength
   • Stiffness under indirect tensile loading
   • Viscosity

   Hint

   Focus on the concepts of stiffness and load.

4. 4.

   True or False: Increasing sample thickness always raises the ITSM value.

   • True
   • False

   Hint

   Think logically about the relationship.

5. 5.

   A pavement core is subjected to a peak load of 5000 N with a thickness of 75 mm, a horizontal deformation of 2 mm, and a diameter of 150 mm. Calculate its ITSM and assess whether it meets the required stiffness level of 10 N/mm².

   Hint

   Use the formula and ensure your units are consistent.

6. 6.

   Discuss the implications of consistently obtaining low ITSM values in project mixes and the recommended course of action to rectify potential pavement issues.

   Hint

   Consider how mix design impacts performance.