PACKAGE : I Bid Document VOLUME : II - Public Health Engineering

(III) Coarse aggregate:
a) Coarse aggregate for concrete, except as noted above, shall conform to
IS: 383. This shall consist of crushed stone and shall be hard, strong,
durable clean and free from elongated, flaky or laminated pieces,
adhering coatings, clay lumps, coal residue, clinkers, slag, alkali,
mica, organic matter or other deleterious matter.
b) Screening and washing: Crushed rock shall be screened and or
washed for the removal of dirt or dust coating, if so requested by the
Engineer.
c) Grading: Coarse aggregate shall be either in single size or graded, in
both cases the grading shall be within the following limits.
Percentage passing for single sized Percentage passing for graded
IS Sieve aggregate of normal size aggregate of normal size
Desig- nation 40 20 16 12.5 10 40 20 16 12.5
mm mm mm mm mm mm mm mm mm
63 mm 100 -- -- -- -- 100 -- -- --
40 mm 85 100 -- -- -- 95 -- -- --
100
100
20 mm 0 85 100 -- -- 30 95 100 --
20 100
70 100
16 mm -- -- 85 100 -- -- -- 90 --
100
100
12.5 mm -- -- -- 85 100 -- -- -- 90
100
100
10 mm 0 0 0 0 85 10 25 30 40
5 20 30 45 100 35 35 70 85
d. Water: Water for mixing concrete, mortar or grout shall conform to
IS:456-2000. If required to do so by the Engineer, the Contractor shall
take samples of the water and test them for quality.
7.3 Transporting and depositing concrete.
Mixing plant shall be located as close as possible to the point of placement.
Concrete shall be placed within 30 minutes after mixing and shall be transported
from the mixer to its final placement as rapidly as practicable, taking care to see that
no segregation or loss of ingredients take place. It shall also be ensured that the
concrete is of the required workability at the point and time of placing.
GTS : General Technical Specification. Page 52