Routine concrete-strength tests have raised concerns about structural components in Blocks 3, 4 and 5 of a public-housing project in Tung Chung Area 42. The Housing Authority said the components might not have met required safety standards, and ordered the contractor to repeat the tests.
The authority’s engineering team found the issue during concrete cube tests carried out between late August and early September. The matter was confirmed publicly on the Saturday before 14 September, about a month after it was discovered, according to Housing Authority member Scott Leung, who urged officials to complete the re-examination quickly.
A failed test cube does not by itself establish that the concrete in the buildings is too weak. Engineering-sector lawmaker Aaron Bok said engineers would need further checks, including on-site testing or more intrusive sampling, to measure the strength of the structural concrete itself.
Bok said the result could be linked to the concrete or to the way the test cubes were prepared and compacted. Air trapped in a poorly compacted cube could weaken it, while excessive moisture was another possible factor he mentioned. These possibilities remain subject to the further examination.
As a precaution and to minimise delays, a different concrete supplier is now providing material for the project, Leung said. The Housing Authority said no similar problem had been found at other sites. Leung nevertheless suggested extra sample testing across other development projects to check concrete quality more widely.
If repeat testing confirms inadequate strength, the response would depend on how serious the problem is. Bok said the design’s safety margin could affect whether remedial work was needed; possible measures could include thickening structural elements or drilling holes to install reinforcement.
The effect on the project schedule and public-housing supply, along with responsibility for the problem, will depend on the re-examination. Its key task is to establish whether the result came from spot-check procedures or whether the concrete in the three blocks requires remedial work.