17.10. Case Example: Design of M40 Concrete for Highway Pavement

Try these first

1. 1.

   What is the formula to calculate the target flexural strength?

   Hint

   Think about how we adjust the characteristic strength.

2. 2.

   What is the maximum size of aggregates used for M40 concrete?

   Hint

   Refer back to the design parameters.

3. 3.

   What is the target flexural strength calculated for M40 concrete?

   • 4.5 MPa
   • 5.49 MPa
   • 6 MPa

   Hint

   Remember the formula for calculating target strength.

4. 4.

   True or False: A lower water-cement ratio improves the workability of concrete.

   • True
   • False

   Hint

   Consider the balance required for both workability and strength.

5. 5.

   A new specification requires increasing the target flexural strength to 5.5 MPa due to higher environmental demands. How would you adjust the water-cement ratio to achieve this considering the original ratio was 0.38?

   Hint

   Consider how to maintain the balance between strength and shrinkage.

6. 6.

   If upon testing, your actual flexural strength of a trial mix only reached 3.8 MPa, what remedial actions could you take in future designs?

   Hint

   Reflect on improving the mix design adjustments.