ABSTRACT
This paper presents the findings of the study on the expected useful life of the building
structures of the Hong Kong Housing Authority (HA) public housing blocks completed
after 1992. A total of eight sample blocks, aged from eight to sixteen years, was selected
from HA current stock of 515 post-1992 blocks. In the study, a dual approach was used
comprising both the traditional coring (destructive) method for the determination of compressive
strength, carbonation depth and chloride content, and non-destructive methods for
the determination of depth of concrete cover to re-bars and corrosion rate of re-bars. The
estimation was based on two hypotheses, namely (i) re-bar corrosion is the single most significant
cause of deterioration of the reinforced concrete in the selected HA buildings, and
(ii) carbonation and chloride ingress are the two principal means causing corrosion of rebars.
From the above findings, a coarse estimate of the total service life of the post-1992 HA
buildings is about 100 years. It is expected that substantial maintenance or improvement of
the buildings will not be required over this service life period. The aforementioned findings
also confirm significant enhancement of the quality of HA rental blocks since the late 1980s,
which focused in particular on the structural materials and workmanship in our building
construction.
Keywords: Expected useful life, Public housing, Carbonation depth, Chloride content, Concrete cover.
