1964_BUILDING_(CONSTRUCTION)_REGULATIONS — Page 15

1985 Ed.] Building Construction; Regulations

[CAP. 123

B 15

(c) remain undisturbed after consolidation until hardened sufficiently to withstand safely any stresses to which it may be subjected; and

(d) be adequately protected from the weather, from premature

drying, or other causes of damage until it has hardened.

(7) Notwithstanding the provisions of paragraph (3) but subject to the provisions of regulations 157 to 165 and the First and Second Schedules, concrete mixes may be designed to possess a resistance to crushing within the ranges specified in Table VI subject to the mix limitations in that Table being complied with and such mixes shall be known as special mixes or designed mixes.

(8) In the application of Tables IV and V-

(a)

(b)

(i) cement shall be measured by weight:

(ii) aggregate may be measured by weight:

(i) the weight required shall be determined from the volume given in the Tables and the mass per cubic metre of the aggregate; and

(iv) the proportions given in the tables are for dry aggregates and where the aggregates are moist due allowance must be made for bulking; and

(i) concrete shall satisfy the requirement for resistance to crushing at 28 days after mixing:

(ii) the resistance to crushing at 7 days after mixing may be used as a control but a sufficient number of tests at 28 days after mixing shall be made to confirm that the gain in strength between 7 and 28 days is satisfactory: and

(iii) the respective ratio of resistances to crushing at 7 and 28 days shown in the Tables are appropriate for ordinary Portland cement and where rapid hardening Portland cement alters the ratio it is to be adjusted accordingly.

(9) In the application of Table VI -----

(a) the weights of aggregate given in the Table are based on the density of crushed granite, and should be adjusted accordingly for aggregate with a density different from crushed granite; and

(b) the ratio of the resistance to crushing within 7 days after mixing to the resistance to crushing within 28 days after mixing shall be taken as 1:1.3 for intermediate resistances within the limits specified in Table VI.

(10) High alumina cement concrete shall not be used in general building works except with the written approval of the Building Authority.

[Subsidiary]

First Schedule and Second Schedule.

IN 294776

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