Hong Kong Regulations

BUILDING (CONSTRUCTION) REGULATIONS - REGULATION 58

Concrete cubes

(1) The compressive strength of concrete shall be determined by testing
standard 150 mm cubes 28 days after mixing.

(2) A representative sample shall be taken from the fresh concrete to make
test cubes and each sample shall be taken from a single batch.

(3) The rate of sampling fresh concrete shall be at least that specified in
Table 7 and at least one sample shall be taken from each grade of concrete
produced on any one day.

(4) From each sample of concrete taken 2 cubes shall be made by a suitable
method.

(5) Each concrete cube shall be given a number in serial sequence and no
serial number shall be duplicated or omitted.

(6) All cubes shall be adequately cured on site or in the laboratory until
ready for testing.

(7) 28 days after mixing, all cubes shall be tested for compressive strength
by a recognized method and the average compressive strength of each pair of
cubes made from the same sample shall be taken as the test result.

TABLE 7

SAMPLING RATES

Type or part of building, building works or street Quantity of concrete to be
represented by each sample Masts, cantilevers more than 3 m in length,
columns, shear walls, prestressed and other critical elements 10 m3 or 10
batches whichever is the smaller volumn Solid rafts, pile caps, caisson caps
and mass concrete retaining walls 100 m3 or 100 batches whichever is the
smaller volumn All other types or parts 25 m3 or 25 batches whichever is the
smaller volumn (Enacted 1990)