Date post: | 29-Jul-2015 |
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Engineering |
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USE OF MARBLE DUST IN CONCRETE
S.P.SANGEETHAHOD CIVIL
DEPARTMNET OF CIVIL ENGINEERING
SUSTAINABLE DEVELOPMENT
• The sustainable development is achieved when the natural as
well as artificial resources are well managed.
• It is meant to decrease the adverse effects which is caused by
the construction industry on the environment.
• Geo polymer concrete is one of the answer for the sustainable
development.
• It reduces the impact of concrete on the environment.
GEOPOLYMERS
• Geo polymer concrete is obtained from the reaction of the
material which is rich in silica and alumina.
• The beauty of geo polymer is that it does not uses cement.
• Normally fly ash is used as a source material which is rich in
silica and alumina.
• Fly ash is known for its properties as an mineral additive in
concrete.
GEOPOLYMERS
There are many other types of geo polymer concrete which are
based on the material used.
Fly ash based geo polymer concrete is also one of them.
Geo polymer concrete is well-suited to manufacture precast
concrete products that can be used in infrastructure
developments.
SIGNIFICANCE OF GPC
Since it does not uses cement it leads to prevent the application
of cement as a binding material in concrete.
Thereby reducing the emission of CO2 during the production of
cement as well as setting.
It is a fact that 755Kg of CO2 is emitted when one tone of
cement is manufactured.
Hence these can be avoided by adopting the geo polymer
concrete
Constituents of GPC
Source materials: By-product materials such as fly ash, silica fume, slag, rice-
husk ash, red mud. Natural minerals such as kaolinite, clays.
Alkaline solutions: The alkaline liquids are from soluble alkali metals that are
usually sodium or potassium based. The most common alkaline liquid used in geo polymerisation
is a combination of sodium hydroxide (NaOH) or potassium hydroxide (KOH) and sodium silicate or potassium silicate.
FLY ASH USED
Low-calcium (ASTM Class F) fly ash is preferred as
a source material than high-calcium (ASTM Class C)
fly ash.
The presence of calcium in high amounts may
interfere with the polymerization process and alter the
microstructure
Marble dust
During the cutting process about 25% the original marble
mass is lost in the form of dust.
Marble dust is settled by sedimentation and then dumped away
which results in environmental pollution.
Marble dust can be used either to produce new products or as
an admixture so that the natural sources are used more
efficiently and the environment is saved from dumpsites of
marble waste.
Marble dust
Composition of marble dust
compounds percentage
SiO2 43.35
Al2O3 5.17
Fe2O3 9.70
MgO 7.68
CaO 34.10
USE OF MARBLE DUST IN THE PRODUCTION OF BRICKS.
It is resulted that the clay particles up to 50% by its weight
can be replaced by marble dust without affecting its
mechanical properties.
Finally the average strength of 20% marble dust replaced
bricks has higher strength than other % of replacements.
USE OF MARBLE DUST AS A FINE AGGREGATE IN CONCRETE
Compressive strength of concrete has been increased with
increasing % of marble dust at all levels of curing.
The unit weight of concrete is increased when marble dust is
used as a substitute for fine aggregate. This is because the dust
is a good filler material.
MIXTURE PROPORTIONS OF GEO POLYMER CONCRETE
Since alkali solutions were used, the mix cannot be
proportionated as similar to ordinary portland cement
concrete.
A separate mix design procedure is handled.
MIX DESIGN PROCEDURE
• In order to design the good mix, the alkaline liquid-to-fly ash ratio by
mass, water-to-geo polymer solids ratio by mass, the wet-mixing time, the
heat-curing temperature, and the heat-curing time are selected as
parameters.
• With regard to alkaline liquid-to-fly ash ratio by mass, values in the range
of 0.30 and 0.45 are recommended.
• The mass of combined aggregates as 75 to 80% of the mass of concrete.
• The total aggregates consists of 30% of fine aggregate. From this the
quantity of fine as well as coarse aggregate can be determined.
MIX DESIGN PROCEDURE
And the remaining % consists of marble dust, alkaline liquid,
water.
Based on the alkaline liquid to marble dust ratio the quantity of
dust and alkalies is calculated.
Also the ratio between two alkaline solutions is maintained as 2.5.
Note that wet-mixing time of 4 minutes, and steam-curing at 60C
for 24 hours after casting are proposed. Increased wet mixing
time increased the compressive strength by 30%
MIX DESIGNDensity of Geo polymer Concrete = 2400 Kg/m3
Total Aggregate (Fine Aggregate + Coarse Aggregate) = 77% of 2400
= 1848 Kg/m3
Fine Aggregate = 30% of Total Aggregate
= 554 Kg/m3
Coarse Aggregate = (1848-554)
= 1294 Kg/m3
Marble dust + Chemical + Water = 23% of 2400
= (2400-1848)
= 552 Kg/m3
COMPRESSIVE STRENGTH OF CONCRETE AT LIQUID TO DUST RATIO 0.4
TYPE OF CURING
7 DAY STRENGTH
(KN)
AVERAGE STRENGTH
(KN)
28 DAY STRENGTH
(KN)
AVERAGE STRENGTH
(KN)
Ambient curing
49 48.17 275 266.33
42 227
53 297
Hot curing 415 425.33 604 638.67
457 660
404 652
COMPRESSIVE STRENGTH OF CONCRETE AT LIQUID TO DUST RATIO 0.5
TYPE OF CURING
7 DAY STRENGTH
(KN)
AVERAGE STRENGTH
(KN)
28 DAY STRENGTH
(KN)
AVERAGE STRENGTH
(KN)
Ambient curing
49 48.17 275 266.33
42 227
53 297
Hot curing 415 425.33 604 638.67
457 660
404 652
Compressive strength vs type of curing
Compressive strength vs water to solids ratio
COMPRESSIVE STRENGTH VS WATER TO SOLIDS RATIO
DESCRIPTION
The maximum strength is achieved at the lowest water to solids ratio.
As the water to solids ratio increases the strength goes on decreasing.
This is similar to the fly ash based geo polymer concrete.
COMPRESSIVE STRENGTH VS CURING TIME
DESCRIPTION
In hot curing the strength increases as the duration
of curing increases.
From the graph it is seen that the increase in
strength is rapid only up to 24 hours of curing time.
Beyond this the increase in strength is insignificant.
CONCLUSION
The application of marble dust in geo polymer
concrete results in a little decrease in strength when
compared to fly ash based geo polymer concrete.
The mixing of alkali solutions with marble dust
makes the mixing process tedious.
CONCLUSION
Strength obtained in steam curing is relatively higher than
ambient curing. It proves the practical difficulties in curing
because steam curing process is difficult.
But this also exhibits the same features of fly ash based geo
polymer such as
A. decrease in strength when liquid to dust ratio increases and
B. increase in strength with curing time.
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