Hong Kong Regulations

BUILDING (CONSTRUCTION) REGULATIONS - REGULATION 59

Acceptance criteria

(1) The specified grade strength for concrete shall be deemed to have been
attained if the individual test results and the average results of all
overlapping sets of 4 consecutive test results comply with the criteria
specified in Table 8.

(2) When there are more than 4 test results the average of each set of 4
consecutive test results shall be calculated and checked for compliance each
time a new test result is produced, using that test result and the immediately
preceding 3 test results.

(3) Where there are only 2 or 3 test results available, those results shall be
treated for the purposes of this regulation as if they were 4 consecutive test
results.

TABLE 8

COMPRESSIVE STRENGTH COMPLIANCE CRITERIA

Column A Column B

Specified grade strength Average of 4 consecutive test results shall exceed
the specified grade strength by at least Any individual test result shall not
be less than the specified grade strength minus 20 D and above 5 MPa 3 MPa
Below 20 D 2 MPa 2 MPa

(4) If the average strength determined from any group of 4 consecutive test
results does not satisfy Column A of Table 8 then the batches of concrete
represented by the first and last samples in the group and all intervening
batches shall be deemed not to have attained the specified grade strength.

(5) If an individual test result does not satisfy Column B of Table 8 then
only the particular batch of concrete from which the sample was taken shall be
deemed not to have attained the specified grade strength provided that the
averages of all groups of 4 consecutive results in which the individual test
result appears all satisfy Column A of Table 8.

(6) If the requirements in subregulation (1) are not satisfied by any test
result, investigations shall be made to establish whether the concrete
represented by the test result is acceptable or not.

(7) If the difference between the compressive strengths of any pair of cubes
made from the same sample of concrete for specified grade strength 20 D and
above exceeds 15% of the test result for that pair of cubes action shall be
taken to ensure that the sampling and testing procedures as required under
regulation 58 are being followed.

(8) If the difference between the compressive strengths of any pair of cubes
made from the same sample of concrete for specified grade strength 20 D and
above exceeds 20% of the test result for that pair of cubes that test result
shall be disregarded and investigations shall be made to establish whether the
concrete represented by the test result is acceptable or not. (Enacted 1990)