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Combined
influence of sand and water cement ratio on the compressive
strength of concrete
P.
T. Santhosh Kumar
In
this work, an experimental investigation has been
carried out to study the combined effect of sand and
w/c ratio on the compressive strength of concrete.
Types of sands used were river sand from Bharathapuzha
at Shornur and Kasargod; silted sand from Malampuzha
reservoir; crushed stone sand from Angamali in Ernakulam
District, Kallidukku and from Poovanchira in Thrissur
District, Kerala State. Water-cement (w/c) ratios
were 0.55 to 0.35 in step of 0.05. Compressive strengths
obtained from 150 mm cubes following IS 519 : 1999
were compared with the theoretical compressive strengths
given in SP: 23-1982. It was observed that the average
of the experimental to theoretical compressive strengths
ratios were 1.33,1.22,1.15, 1.24, 1.17 and 1.20 for
mixes with river sand from Bharathapuzha, Kasargod,
Malampuzha and crushed stone sand from Angamali, Kallidukku
and Poovanchira respectively and coefficient of variation
were 9,8,10,10, 11 and 7 % respectively. This indicated
that average compressive strengths of mixes with crushed
stone and river sand were at par. Compressive strengths
of all types of sands - except one - were well above
the values predicted based on SP:23- 1982. Hence,
river sand can be replaced with crushed stone sand
as fine aggregate in concrete provided the tests on
particle size, shape and surface texture, geological
classification, specific gravity and bulk density,
moisture content, water absorption and bulking of
sand, soundness and deleterious contents satisfy IS
2386 (Parts 1 to 6).
An
investigation on the characteristic properties of
high performance SCC with mineral admixtures
Vilas V. Karjinni,
Shrishail B. Anadinni and Dada S. Patil
In
this experimental work, a mix design for Self-Compacting
Concrete (SCC) has been carried out using Nan-Su method.
Flow properties such as passing ability, filling ability,
and segregation resistance were evaluated by varying
the dosage of super plasticiser (HRWRA) and viscosity
modifying admixture (VMA). The mix design incorporated
fly ash, silica fume and metakaolin as mineral admixtures.
Mix proportions for self compacting concrete of strengths
M20, M30, M40 and M50 were developed. Nan-Su method
method is suitable for SCC concrete grades which are
more than M50 but for the normal grades such as M20
to M50, some modifications were needed in the mix
design procedure. Tests revealed that the quantity
of cement was insufficient to get the targeted strengths.
Accordingly, trials were carried out to increase the
cement content by reducing the mineral admixtures.
Comparative evaluations of compressive strength, tensile
strength, flexural strength, young's modulus, Poisson's
ratio and density of concrete on 7 and 28 days cured
specimens are reported Also, SCC's mechanical properties
are compared with those of the conventional concrete.
Acceptability
of shear-wall performance incorporated into constitutive
isotropic damage plasticity modelling
P. Ghatee,
M.S. Jaafar, A. Ibrahim, J. Noorzaei and A.A. Abang
Ali,
Even
though the constitutive damage plasticity model is
suitable for concrete modelling, it is necessary to
provide parameters within a model based on experimental
or mathematical functions. This paper discusses the
sensitivity of a nonlinear analysis of shear walls
considering deviation on the damage parameters. Comparing
the tolerance of numerical predictions with the data
obtained experimentally, evaluated the sensitivity
and reliability of individual material parameters.
The study shows the accuracy of analysis was affected
by variation in certain parameters.
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