1.  Prepared by –
Kapadia Jatin
CIVIL ENGG
3rd SEM.

2.  Batching of Aggregate___
I. Volume batching
II. Weigh batching
 Volume batching
• This method is generally adopted for small jobs .
• Gauge boxes are used for measuring the fine and
coarse aggregate.
• The volume of gauge box is equal to the volume of
one bag of cement.

3.  Gauge bow are also called as FARMAS
 They can be made of timbers or steel.
 They are made generally deep and narrow
 Bottomless gauge boxes are generally avoided.
 While filling the gauge boxes the material should be
filled loosely,no compaction is allowed.

4.  Weigh Batching
• Batching by weight is more preferable
to volume batching ,as it is more accurate and
leads to more uniform proportioning.
• It does not have uncertainities associated with
bulking.
• It’s equipments falls into 3 general catagories:
I. Manual,
II. Semi automatic,
III. Fully automatic.

5. 1) In case of manual batching all weighing and
batching of concrete are done manually.It is used for
small jobs.
2) In case of semi automatic batching the aggregate
bin gates are opened by manually operated
switches.And gates are closed automatically when
the material has been delivered.
This system also contains interlock which prevents
charging and discharging.
3) -----

6. 3) In case of automatic
batching the material are
electrically activates by a
single switch and
complete autographic
record are made of the
weight of each material.
The batching plant
comprises 2,3,4 or 6
compartment bins of
several capacities.Over the
conveyer belt the weigh
batchers discharging are
provided below the bins.

7. Mixing of Aggregate
• The Aim of mixing of concrete is to produce
homogenous,consistent and uniform coloured
concrete.
 Mixing action of CONCRETE involves 2 operation
i. A general blending of different particles size of the
ingredients to be uniformly distributed throughout
the concrete mass.
ii. A vigorous rubbing action of cement paste on to the
surface of aggregate particles.

8.  There are 2 methods
1. Hand mixing,
2. Machine mixing.
 Hand mixing
• For small and unimported jobs concrete is mixed
by Hand using showels.As mixing of concrete is not
eficient throughtly ,it is advisable to add 10 persent
CEMENT.
• For hand mixing a brick platform is prepared by
laying the bricks on the ground.It must be 2 m wide
and 3.5 m long.
Following operations are involved

9. 1. Measured quantity of sand is spread evenly on platform.
2. Spread the measured quantity of cement on this sand
and mix it till the colour of concrete mixture is uniform.
3. Spread the measured quantity of coarse aggregate
on the platform with sand and cement.Now spread the
mixture of cement and sand on the stack of aggregate
and mix it atleast 3 times.
4. Make the hollow of mixed pile.Add 3 quarters of total
quantity of water required and turn thematerial towards
the centre with spades.

10. Machine mixing
• It is adopted for big projects where large quantity of
aggregate is required .It is also Economical.
• Concrete mixers are classified as unders-
 According to the operating conditions-
1. Batch mixers ,
2. Continuous mixers.
 According to the principal of mixing-
1. Gravity type
2. Type with forced mixing

11.  According to the condition of use
1. Stationary concrete mixers,
2. Portable concrete mixers.
 Batch mixers
• The mixers are charged with materials in batches
• Batch mixers are classified in further 3 types
1. Tilting type ,
2. Non-Tilting type ,
3. Reversing type.

12.  As per IS :1971-1985, concrete mixers are designated by
a number representing its nominal mixed batch capacity
in litres.
I. Tilting type-85 T, 100 T,140 T,200 T.
II. Non-Tilting type-200 NT,280 NT,375 NT,500
NT,1000 NT.
III. Reversing type-200 R,280 R,375 R,500 R,1000 R.
T-tilting type
NT-non tilting type
R-reversing type.

13.  Non tilting type mixer
• The mixing drum is cylindrical
in shape and revolves two –
horizontal axis.
• It has opening on both sides.
• The ingredients are charged
in from one opening.
• For discharging concrete chute
is introducedin to other opening
by operating a lever.

14. Tilting type mixer
 It consist a conical drum
which rotates on an
inclinable axis.
 It has only one opening.
 The drum charged
directly and discharged
by tilting and reversing
the drum.

15.  About the half of the quantity of coarse aggregate is
placed in the skip over the which about half of the sand
is poured,on that fully quantity of cement.
 i.e.,-1 bag is poured over which the remaining quantity of
coarse aggregate and sand is placed.
 Before charging the drum abot 25% of water is required
for mixing.
 After discharging the loaded skip into the remaining 75%
is poured water.
 If plastisizer is used 1 litre of water is hold back.

16.  Thank You.