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ABSTRACT
Cement concrete is widely being used in construction of structures
throughout the world. Normally concrete constitutes of cement, fine
aggregate, coarse aggregate and water. Following the growth of
infrastructures in developing country, the demands for concreting materials
are also increasing. The strength and behaviour of concrete depends upon the
properties and behavior of its constituents. In concrete, the aggregates occupy
75% to 80% of the total volume of concrete and help to form a rigid skeleton
structure for concrete in addition with space fillers. The aggregates are
generally classified, depending on their size as fine and coarse aggregates. In
India, we generally use river sand as fine aggregate. We are in need to adjust
to the lack of availability of natural sand by using alternative aggregates.
In the present life style, the generation of wastes from various
sources is being increased due to the production of different materials. The
wastes accumulate day to day either directly or indirectly. The generated
wastes are land filled and harm human beings. The disposal or handling of
accumulated waste becomes necessary to safeguard the environment. The
wastes may be classified into hazardous and nonhazardous, natural and
artificial, industrial waste, waste used directly and wastes used after adding
admixtures. The example of wastes which may be used as secondary material
for aggregate in concrete are Pumice, Diatomite, Scoria, Volcanic cinders,
Brick jellies, Rock sawdust, Rice husk, Waste from China clay Industries,
Clinker and Breeze (residue of burnt coal), Foamed slag, Bloated clay,
Sintered fly ash, Vermiculite, Expanded clay aggregates, Glass wastes,
Rubber wastes, Steel slag, Copper slag, etc.
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China clay is a Hydrated Aluminum Silicate Al2O3 2SiO2 2H2O,
one of the purest clay which possesses silica of about 55-58 %. China clay is
formed by alteration of granite due to hydrothermal metamorphism. From the
year 2008-09 to 2010- 11, 2522181 tonnes of china clay had been produced in
India. Out of the total production of china clay, 27% had been mined in the
state of Kerala. China clay is being used in the production of many valuable
products application after undergoing any one of the two direct processes
such as washing and pulverizing. From these processes, nearly 68000 tonnes
of waste had been produced from the china clay processing Industries. The
waste from china clay possesses silica of about 86.10%. In this experimental
study, an attempt was made to incorporate waste material from China clay
washing process Industries, as partial replacement of natural sand in concrete.
The M30 grade concrete mix design was done based on the
experimental test results of concrete ingredient’s properties. To find out the
optimum replacement of natural sand with china clay waste, the specimens
like cubes, cylinders and prisms were cast by adding china clay waste in the
ratio of 0%, 10%, 20%, 30%, 40% and 50%, in place of river sand in
concrete. After 7days, 14days and 28 days water curing, the tests were
conducted for compressive strength, split tensile strength and flexural strength
on cubes, cylinders and prisms respectively. The results of china clay waste
used specimens were compared with conventional specimens based on the IS
code provisions. It was found that 30% china clay waste used specimens
showed higher strengths than that of all other specimens. The 30% china clay
waste used specimens revealed more value of about 19%, 15% and 8% than
the conventional on compressive strength, split tensile strength and flexural
strength respectively.
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The conventional and 30% china clay waste used cube specimens
were cast and tested against acid resistance and heat resistance ability. From
the test results of acid and heat resistance, it was found that 30% china clay
waste used specimen possesses more resistance against acid attack and heat
than the conventional one.
In addition to the preliminary tests, the elements like beams, ‘L’
sections, ‘T’ sections, ‘+’ sections and box frames were cast and tested to
ascertain the suitability of incorporating china clay waste in concrete as a
partial replacement of river sand. The cross section of all elements was 150
mm x 150 mm with 2 nos. of 10mm ø bars each at top and bottom and 8mm ø
bars as stirrups as reinforcement. After 28 days water curing, the elements
were tested in structural loading frame. The test results of both conventional
and china clay waste used specimens were recorded, tabulated, plotted in
graphs and analyzed to examine the elastic properties.
From the test results of beam element, the mean ultimate failure
strength of conventional and china clay waste used elements were determined
as 60 kN and 65 kN respectively. The china clay waste used beam element
attained 8.33% more strength than conventional beam on midpoint loading.
From the test results of ‘L’ sections, the mean ultimate failure
strength of conventional and china clay waste used sections were showed 16
kN and 18 kN respectively. The china clay waste used sections revealed
12.50% more strength than conventional one on free end loading.
The mean ultimate failure strength of conventional and china clay
waste used ‘T’ sections were found as 36 kN and 37 kN respectively. The
china clay waste used ‘T’ sections revealed 2.78% higher value than
conventional one on free end loading.
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From the test results of ‘+’ sections, the mean ultimate failure
strength of conventional and china clay waste used sections were found as 27
kN and 29 kN respectively. The china clay waste used sections attained
7.40% more strength than conventional section on free end loading.
From the test results of box frame, the mean ultimate failure
strength of conventional and china clay waste used frames were determined as
80 kN and 85 kN respectively. The china clay waste used frames showed
6.25% more strength than conventional one on midpoint loading.
ANSYS modelling on both beam elements and ‘L’ sections were
done by incorporating the inputs like properties of the element, engineering
data, geometrical details, reinforcement details and load conditions. From the
results of modelling, it showed that china clay waste used elements withstand
higher normal stress and shows lesser deformation than that of conventional
elements.
From this experimental research it can be concluded that waste
material from china clay washing process Industries can be used as partial
replacement of fine aggregate in concrete for about 30%. On 30% inclusion of
china clay waste in concrete the compressive, split tensile and flexural
strengths got increased. Also the usage of this waste will enhance the cost
effectiveness, environmental sustainability and reclamation of the waste
landfills.
Keywords: China clay waste, Compressive strength, Split tensile strength,
Flexural strength, ANSYS modelling
