1. AIB 011
Manufacturing Sand and Aggregates for
Concrete in India
Historically, a large percentage of sand has been
produced from alluvial deposits. However we are now
experiencing a global shortage of natural sand, and
environmental pressures, costs and a shortage of this
type of deposit has necessitated the manufacture of sand
from quarried material.
One of the problems often experienced with natural
sand is the presence of contaminants, which can be very
difficult to remove.
These contaminants may be silt, organic matters and
sometimes, harmful chemicals, such as sulphates and
chlorides, all of which can have significant detrimental
effects on the performance of structural concrete.
Manufactured sand, on the other hand, comes directly
from good quality virgin rock, and thus very few, if
any contaminants are present.
Case Study
An Indian company was designing a dry crushing plant
to produce concrete aggregate and manufactured sand
from basalt rock.
Their major concern was to find a crushing technology
which would enable them to manufacture sand that was
of a high enough quality for use in concrete.
Proposal
Metso Minerals proposed the installation of a Barmac
VSI crusher as a tertiary stage crusher, to process the
product from the primary and secondary jaw crushers.
Solution
The Barmac crusher was installed in closed circuit with
a screen to crush minus 25mm material, giving two
products; 12 - 4.75mm and 4.75 - 0 mm.
The plant has a capacity of 30-35 tph of sand and 15-20
tph of minus 12mm aggregate.
Conclusion
The final sand product from this plant is of a
consistent high quality, has good equidimensional
shape, and falls well within specification. In fact,
following test work, the producer has confirmed that:
• Concrete made using Barmac sand is more
cohesive, has an increased density (making it more
resistant to chemical attack) and performs better
generally than an equivalent concrete made with
natural sand.
• The sand has been successfully tested for structural
concrete, plaster first coat, mortar and concrete
blocks.
• Water demand to get the equivalent workability to
a natural sand concrete is lower.
• Cement consumption is reduced by 10-15%.
• Barmac sand is, in fact, 17-18.5% less expensive to
produce than the local natural sand.
Further Business
This installation has created considerable interest in
the Barmac for manufacturing sand. In fact, it has
paved the way for some very significant Barmac sales
into the industry.
Major Benefits To The Concrete Industry
Natural sand is a product of many thousands of years of erosion. However, the Barmac VSI crusher
simulates the particle size reduction and shaping that occurs in nature, using a unique rock-on-rock
crushing action. The Barmac grinds and mills the feed material to produce a fine product with no
contamination from wear parts. As the material fed into the Barmac grinds and impacts against itself,
the typical wear cost per tonne of material processed is very low.
Manufactured, or Barmac Sand is being successfully used in the production of high quality concrete
and asphalt around the world. Its superior shape puts it well within specifications imposed on sand for
use in concrete production.
Barmac Model Selected
• B6000 Barmac VSI
• 110kW [150 hp]
• Throughput: 93 tph
• Material: Basalt
• Work Index: 22
• Feed: –25mm
• Products: –12 +4.75mm and –4.75mm
• Rotor tip speed: 62 m/s
• Circulating load: 50 tph

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0.01 0.1 1 10 100
Sieve Size (mm.)
Cum%Passing
Barmac Prod
Screen U/S
Barmac VSI crushers are also used in the industrial minerals, mining, recycling and general quarrying industries. A wide range
of materials are processed through Barmac crushers worldwide. For more information on this or any other Barmac application,
please contact your nearest Barmac representative.
AIB 011 – 1 – 4/99
MetsoMinerals(Matamata)Limited
Mangawhero Road, Private Bag 4071,
Matamata, New Zealand
Tel. +64 7 881 9060, fax +64 7 888 5244
minerals.info@metso.com
Primary Jaw
Crusher
Scalps
Secondary Jaw
Crusher
2-Deck Screen
Cut 1 = 12mm
Cut = 4.75mm
Barmac B6000
110kW [150 hp]
Rotor tip
speed = 62 m/s
33 tph
–4.75mm
17 tph
12mm + 4.754.75mm
50 tph