Volume-IF - JantERmantER

DCPL-K9AOI
slreng1h of the concrete cubes falls below 1he requirement, 1he method
described IIbove shall be repeated till acoepIabIe msults are obtained. The
method may haVe 10 be repeated whenever there is a significant change In the
quality of any of 1he ingredients for concrete, at the discretion of1he Engineer.
3.1.2 Batchlng of Concrete
For !=Ofltrolled collCl8te, only weigh balchlng shall be allowed. All concre1e
ingredients, except water, shall be balched by weight, using an approved'.
rnakil of weigh betcher. Batchlng shall be accurate to 112 Kg. The batcher \
shall be tested for 8CCU11IeY of calibration, fU'Sl before commencement of
work and at least once a fortnight or as directed by 1he Engineer 1hereafter.
Water shall be batchad by weight or by volume measures. as approved by
the Engineer.. •
3.1.3 Mixing of Concrete
Materials for concre1e shall be empt1ed in rotation into the mixer. When all
1he ingredients are In tha drum. 1he drum ~II rot8te for one, minute for dry
mixing. Af1er 1hat "'(aIer shall be edded In measured quantities in the manner
specified. The mixer shaH 1hen rotate for at least two minutes. or at least
forty revolutions or unUl,1here Is apparent uniform distribution of the materials
and tiU 1he masil is unilOrm In colour. The entire content of the drum shall be
discharged before 1he Ingredients for 1he'succeeding batch are fed Into 1he
drum. The mixer shall be 1horoughly cleaned to the satisfaction of 1he
Engineer, before a different quality of concrete is put through the mixer and
also at the end of day's wolk.
3.1.4 Workability of Concrete
The' degree of workability necessary to allow the concrete to be well
consolidated and to be wolked Into 1he comers of formwolk and around 1he '
reinforcement and embedments. and to give 1he required surface finish shall
depend on 1he type and nature of &tructure and shall be based on experience
and tests. 15 mm. to 40 mm. slump In chimney works shall be adopted
~ to Engineer's ap,proval unless stated o1herwise (vide serial 1 (d) of·
~use np. 3.3.6). The usuat ~miIs' of consistency for various types of
structure are given below ; " . .
".