Presumed Allowable Bond or Friction Between Rock and Concrete or Grout for Piles

Category of rock	Presumed allowable bond or friction between rock and concrete or grout for piles (kPa)
as defined in Table 2.1	Under compression or transient tension	Under permanent tension
1(c) or better 1(d) or 2	700 300	350 150

Notes:

• Concrete or grout should have a minimum characteristic compressive strength of 30 MPa.

• The presumed value of transient tension is for design for transient load such as wind load.