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The rapidly developing Northern Metropolis (NM) is situated in a geologically complex region in Hong Kong where clastic sedimentary rocks being affected by metamorphism are present. Due to extensive folding, faulting and weathering, meta-sedimentary (MS) rocks in the NM are found to be highly variable in nature. However, there is a general lack of geotechnical information for those MS rocks mainly because of minimal urban development in the region so far. As there will be a surge of development works within the region in the coming few decades, the Geotechnical Engineering Office (GEO) recently initiated a large-scale pile loading test programme with a view to collecting extensive field data on end-bearing capacity and rock socket shaft resistance of various types of MS rocks in the region. The key objective is to explore room for enhancing the prevailing foundation design guidelines for MS rocks, thereby facilitating material and cost saving of the associated foundation works. As part of the study, some trial piles are strategically designed to investigate the constructability and performance of using eco-friendly Ground Granulated Blastfurnace Slag (GGBS) and high-strength S690 steel section in piling works. The study outcome would facilitate the wider application of these new and green materials for the benefit of advancing sustainable and cost-effective geotechnical solutions. While the pile loading tests are actively on-going, this paper reports the preliminary findings of the trial piling works, including bi-directional loading tests on instrumented piles, the applications of high-percentage GGBS concrete and grout as well as S690 steel section in pile foundations.