The Buildings Department today said it has completed examining the test results of five residential towers of Pavilia Farm, where the concrete strength of some reinforced concrete structures was found not to have met the requirements.

The concrete strength of some reinforced concrete structures in Phase III of Pavilia Farm, a private development project on top of Tai Wai Station, was lower than the specified grade strength as shown on the building plans approved by the department.

The department earlier requested people responsible for the development project to conduct additional testing and submit a report on the remaining five residential towers of the same development where superstructure works had been completed.

The five residential towers are Tower 2 and 3 of Phase I, as well as Tower 5, 6 and 7 of Phase II.

Additional testing was conducted on the reinforced concrete columns and walls of these towers, including the collection of extra concrete core samples at specified locations for compressive strength tests.

The department said that all test results of the samples collected at the Phase II towers fully met the required standards.

While for the Phase I towers, the test results showed that the concrete strength of approximately 5% of samples was lower than the specified grade strength as shown on the approved building plans.

Noting that the two Phase I towers do not show obvious structural danger, the department said it had required the registered building professionals and contractors responsible for the development project to propose follow-up works for that phase.

It had also today approved the relevant strengthening works and granted consent for the start of the works, which are expected to be completed in a few months' time.

All building works should be carried out in accordance with the approved plans and the Buildings Ordinance, and an occupation permit for the development project would be issued only upon satisfactory completion of all works, the department stressed.

Meanwhile, it has requested the registered building professionals and contractors to submit reports on the incidents where the concrete used in some structural elements in Phase I and Phase III of the development project was lower than the Government's requirements.

It has also initiated an investigation into the incidents to identify if anyone had contravened the ordinance.

The department said it is not in a position to comment on the matter at this stage, adding that it will take appropriate follow-up action pursuant to the ordinance based on the investigation result.

However, it will impose additional requirements when granting new consents to the commencement of building works in order to allay public concerns and further strengthen the quality monitoring of works involving reinforced concrete structures.

The requirements will include conducting additional regular rebound hammer tests (RHT) during the construction of structural works for private buildings.

The department is drafting a practice note on the implementation details of the new measure and targets to roll it out in the first quarter of next year.

Moreover, it is also actively considering the introduction of embedded sensors, which can be used as an alternative for complying with the additional RHT requirement by the industry. This technology is being put on trial in some private and public works projects.

The department plans to further explore such technology with the industry and provide detailed guidelines early next year.