B 122
CAP. 123] Building (Construction) Regulations
[1985 Ed.
[Subsidiary]
L.N. 294/76.
Standard of acceptance for preliminary tests of concrete of designed mixes.
Standard of acceptance for works tests of concrete of designed mixes.
(c) 3 cubes of each set of 6 cubes shall be tested at 7 days and the remaining 3 at 28 days.
(2) (a) The works resistance to crushing of designed mixes shall be determined from a statistical analysis of not less than 40 cube tests at the same age.
(b) A sample of concrete shall be taken on 8 separate occasions during each of the first 5 days of using that mix and thereafter at least 3 samples shall be taken on each day that the mix is used and if more than 120 m3 is used in a day a sample shall be taken from each 40 m3 or part thereof.
(c) 1 cube from each sample taken under sub-paragraph (b) shall be tested at 7 days and 1 additional cube from at least every fourth sample taken under sub-paragraph (b) shall be tested at 28 days.
12. The preliminary test under sub-paragraph 11(1) shall be deemed to be acceptable if the average of the resistances to crushing of the 3 sets of 3 cubes tested at the specified age exceeds the specified resistance to crushing by not less than 2 times the designed standard deviation. If the difference between the greatest and least individual results for any set of 3 cubes is more than 20 per cent of the mean resistance to crushing for which the mix has been designed an additional set of 3 cubes shall be made and tested.
13. (1) The specified resistance to crushing of designed mixes shall be deemed to have been attained if the works test results, when examined individually and in consecutive (but not overlapping) sets of 4 cubes, satisfy each of the following conditions-
(a) no individual result is less than 80 per cent of the specified resistance to crushing:
(b) not more than 2 individual results of any 40 consecutive results fall below the specified resistance to crushing:
(c) the range of any set is not more than 4 times the designed standard deviation:
(d) the average of any set is not less than the specified resistance to crushing plus the designed standard deviation:
(e) the average of not more than 1 set in any 10 consecutive sets is less than the specified resistance to crushing plus 1.1 times the designed standard deviation; and
(f) the overall average of not less than 40 consecutive individual resistances is not less than the specified resistance to crushing plus 2 times the standard deviation of those resistances.
(2) If sub-paragraph (1)(a) is not satisfied the parts of the structure made from the batch of concrete from which the low test result was obtained shall be subjected to individual inspection and testing.
(3) (i) If sub-paragraph (1)(b), (c), (d) or (e) is not satisfied in the first 10 sets the mix shall be modified to increase the resistance to crushing.
(ii) If sub-paragraph (1)(b), (c), (d) or (e) is not satisfied in subsequent sets, the overall average of the previous 40 consecutive results including the non-complying set, shall be calculated and examined for compliance with sub-paragraph (1)(f).
(iii) if sub-paragraph (1)(f) is not satisfied the mix shall be modified to increase the resistance to crushing until it complies therewith.
General considerations.
SECOND SCHEDULE
DESIGN OF CONCRETE MIXES
[reg. 19(7).]
1. (1) The proportions of concretes of special mixes and of design mixes shall be selected within the limits of Table VI so that the designed mean resistance to crushing of the concrete exceeds the specified resistance to crushing (as defined in the First Schedule) by a suitable margin and so that the workability is adequate for the means of compaction available on the site.
(2) In designing a mix to satisfy these requirements attention should be given to the following factors-
B 122
CAP. 123] Building (Construction) Regulations
[1985 Ed.
[Subsidiary]
L.N. 294/76.
Standard of acceptance for preliminary tests of concrete of designed mixes.
Standard of acceptance
for works tests of concrete of designed mixes.
(c) 3 cubes of each set of 6 cubes shall be tested at 7 days and the remaining 3 at
28 days.
(2) (a) The works resistance to crushing of designed mixes shall be determined from a statistical analysis of not less than 40 cube tests at the same age.
(b) A sample of concrete shall be taken on 8 separate occasions during each of the first 5 days of using that mix and thereafter at least 3 samples shall be taken on each day that the mix is used and if more than 120 m3 is used in a day a sample shall be taken from each 40 m3 or part thereof.
(c) 1 cube from each sample taken under sub-paragraph (b) shall be tested at 7 days and I additional gube from at least every fourth sample taken under sub-paragraph (b) shall be tested at 28 days.
12. The preliminary test under sub-paragraph 11(1) shall be deemed to be acceptable if the average of the resistances to crushing of the 3 sets of 3 cubes tested at the specified age exceeds the specified resistance to crushing by not less than 2 times the designed standard deviation. If the difference between the greatest and least individual results for any set of 3 cubes is more than 20 per cent of the mean resistance to crushing for which the mix has been designed an additional set of 3 cubes shall be made and tested.
13. (1) The specified resistance to crushing of designed mixes shall be deemed to have been attained if the works test results, when examined individually and in consecutive (but not overlapping) sets of 4 cubes, satisfy each of the following conditions-
(a) no individual result is less than 80 per cent of the specified resistance to
crushing:
(b) not more than 2 individual results of any 40 consecutive results fall below
the specified resistance to crushing:
(c) the range of any set is not more than 4 times the designed standard
deviation:
(d) the average of any set is not less than the specified resistance to crushing plus
the/designed standard deviation:
(e) the average of not more than 1 set in any 10 consecutive sets is less than the specified resistance to crushing plus 11 times the designed standard devia- tion; and
(/) the overall average of not less than 40 consecutive individual resistances is hot less than the specified resistance to crushing plus 2 times the standard deviation of those resistances.
(2) If sub-paragraph (1)(a) is not satisfied the parts of the structure made from the batch of concrete from which the low test result was obtained shall be subjected to individual inspection and testing.
(3) (i) If sub-paragraph (1)(b), (c), (d) or (e) is not satisfied in the first 10 sets
the mix shall be modified to increase the resistance to crushing.
(ii) If sub-paragraph (1) (b), (c), (d) or (e) is not satisfied in subsequent sets, the overall average of the previous 40 consecutive results including the non-complying set, shall be calculated and examined for compliance with sub-paragraph (1) (/).
(iii) if sub-paragraph (1) (/) is not satisfied the mix shall be modified to increase the resistance to crushing until it complies therewith.
General considerations.
SECOND SCHEDULE
DESIGN OF CONCRETE MIXES
[reg. 19(7).]
1. (1) The proportions of concretes of special mixes and of design mixes shall be selected within the limits of Table VI so that the designed mean resistance to crushing of the concrete exceeds the specified resistance to crushing (as defined in the First Schedule) by a suitable margin and so that the workability is adequate for the means of compaction available on the site.
(2) In designing a mix to satisfy these requirements attention should be given to the following factors-
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