In designing mini-piles, should the strength of grout be neglected during assessment of loading carrying capacity?

In designing min-piles, there are two approaches available:

(i) In the first approach, the axial resistance provided by the grout is neglected and steel bars take up the design loads only. This approach is a conservative one which leads to the use of high strength bars e.g. Dywidag bar. One should note that bending moment is not designed to be taken up by min-piles because of its slender geometry.

(ii) In the second approach, it involves loads to be taken up by both grout and steel bars together. In this way, strain compatibility requirement of grout and steel has to be satisfied.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.