International Journal of Research and Scientific Innovation (IJRSI) | Volume V, Issue VIII, August 2018 | ISSN 2321–2705
1.2.2. 920SH Concrete cylinders of 100 × 200 mm were prepared by
replacing the cement with fly ash in the range of 40-60%
920 SH is a chloride free, super plasticizing admixture based
by weight. These concrete specimens, after 28 days
on selected sulphonated naphthalene polymers. It is supplied
curing, were exposed to varying peak temperatures
as a brown solution which instantly disperses in water. 920SH
ranging from 100 to 900oC to investigate the influence of
disperses the fine particles in the concrete mix, enabling the
temperature on the behavior of fly ash concrete. The
water content of the concrete perform more effectively. The
compressive and split tensile strength of concrete
very high levels of water reduction is possible by allowing
increased initially with an increase in the temperature up
major increase in strength to be obtained.
to 300oC, however, further increase in the exposure
temperature caused reduction in both strengths. The loss
II. LITERATURE REVIEW
of weight of the concrete increased with increase in the
The following literature gives an idea on various design codes temperature as well as the fly ash content.
used for design mix proportioning of high strength concrete iv. Muhammad Masood Rafi et al (2017) Conducted
and the advantages for the use high strength concrete.
experimental testing programme on cylindrical specimens
i. Mohamed bhai (1986) [1] carried out tests on 100 mm of 100 × 200 mm size. They were heated at temperatures
concrete cubes heated to temperatures in the range of 200- which were varied from 100°C to 900°C in increment
800oC, to determine the effect of varying time of exposure of 100°C. Similar specimens were tested at ambient
and rates of heating and cooling on the residual temperature as control specimens. The compressive and
compressive strength of concrete. These variables were tensile properties of heat treated specimens were
found to have a significant effect on concrete heated to the determined. The colour of concrete started to change
lower range of temperatures, but their effect became less at 300°C and hairline cracks appeared at 400°C. Explosive
pronounced at high temperatures. It was reported that spalling was observed in few specimens in the temperature
almost all the loss of compressive strength occurred within range of 400°C-650°C which could be attributed to the
two hours of exposure to the maximum temperature. It pore pressure generated by steam. Significant loss of
was observed that the exposure time beyond one hour had concrete compressive strength occurred on heating
a significant effect on the residual strength of concrete, but temperatures larger than 600°C, and the residual
the effect diminished as the level of exposure temperature compressive strength was found to be 15 per cent
increased, where as the loss of strength in bulk occurred at 900°C. Residual tensile strength of concrete became
within first two hours of exposure. It was also observed less than 10 per cent at 900°C. The loss of concrete
that the effect of exposure time on coral-sand concrete is stiffness reached 85 per cent at 600°C. Residual Poisson’s
similar to that on basalt-sand concrete. It was also noticed ratio of concrete increased at high temperatures and
that the rates of heating and cooling had no effect on the became nearly six times larger at 900°C as compared to
residual compressive strength of concrete heated to lower that at ambient temperature.
temperature.
III. MIX DESIGN PROCEDURE
ii. Srinivasa Rao et al (2006) studied the effect of elevated
temperatures on compressive strength of concrete. In this The ACI Standard 211.4 code “Guide for selecting
study, M60 grade of concrete was generated with water proportions for High-Strength Concrete with Portland cement
cement ratio 0.25 using Ordinary Portland Cement of 53 and Flyash” is used for mix design
grade. Part of the cement is replaced with flyash. At
3.1.1 Design Stipulations
different ages of 1, 3, 7, 28, 56 and 91 days of curing, the
compressive strength of concrete is obtained after exposed Grade of concrete : M150
to temperatures 50-250oC for 3 hours duration. The size of
Size of aggregate : 10 mm
the concrete specimen is 100 mm. The rate of heating is
maintained as 1oC/min and the specimens are tested in hot Degree of workability : 0.76 (compaction factor)
condition. From the test results it is concluded that
Degree of quality control : good
retention of residual compressive strength is more in PPC
than OPC. The residual strengths decreased as the Type of exposure : moderate
temperature increased at different ages. For earlier ages
the decrease in strength is 10 to 30% for OPC and PPC Cement : Portland Pozzolana Cement
concrete with exposure duration, 3 hours. At 250oC, the (PPC)
maximum decrease in strength for OPC concrete is 40% 3.1.2 Test Data for Materials
and for PPC, it is 18%. As age of concrete increased,
residual compressive strength increased. Specific gravity of cement : 3.15
iii. Khan and Abbas (2015) studied the behavior of high Specific gravity of fine aggregate : 2.68
volume fly ash concrete at varying peak temperatures. Specific gravity of coarse aggregate : 2.72
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Electronic copy available at: https://ssrn.com/abstract=4328411
International Journal of Research and Scientific Innovation (IJRSI) | Volume V, Issue VIII, August 2018 | ISSN 2321–2705
Water absorption of fine aggregate : 1.2% Step-6 Estimation of coarse aggregate content
Water absorption of coarse aggregate : 0.8% From the Table 4.3.3 of ACI 211.4R, the volume of
3 oven dry rodded coarse aggregate per unit of volume of
Bulk Density of coarse aggregate : 1720 kg/m
concrete = 0.65 for 10 mm aggregate with fineness modulus
Aggregate Impact value : 8.4% (Exceptionally Strong) of fine aggregate as 2.68.
3.1.3 Sieve Analysis Bulk Density of Coarse aggregate = 1720 kg/m3
Fine aggregate : Sand zone II according to IS: 383 -1970 Per 1m3 of Concrete, the Volume of C.A = 0.65 m3
Coarse aggregate : Confirming to IS: 383 -1970 The quantity of C.A = 1720*0.65 = 1118 kg
Trial strength Step-7 Estimation of Fine Aggregate Content
fcr = Trial Mix Strength Volume based calculation
fck= Specified Compressive Characteristic Strength = Volume of water = 183/1000 = 0.183 m3
150 N/mm2 Volume of Cement = 732 / (3.15*1000) = 0.232 m3
S = Standard deviation (from ACI 211.4) =10 Volume of Coarse aggregate
1) fcr= fck+1.34*S = 150 + 1.34*10=163.4 N/mm2 = 1118 / (2.72*1000) = 0.411 m3
Or
Volume of entrapped air = 0.05 m3
2) fcr= 0.9*fck+2.33*S=0.9*150+ 2.33*10=158.3
N/mm2 Volume of Fine aggregate
Larger Value out of these two is taken as fcr = 1 - 0.183 - 0.232 - 0.411 - 0.05
2
Therefore, the Value of fcr = 163.4 N/mm = 0.124 m3
Step-1 Choice of slump Fine Aggregate Content = 0.124x2.68x1000
The value of slump height is taken from the table = 332.32 kg
4.3.1 of ACI 211.4R based on the type of work. Slump Height
Step-8 Adjustments for Aggregate Moisture
is considered as 50 mm.
Aggregate quantities actually to be weighed out for
Step-2 Choice of maximum size of aggregate
the concrete must allow for moisture in the aggregates.
The ACI method is based on the principle that the Usually the air-dry condition for the coarse aggregate is close
Maximum size of aggregate should be the largest available so enough for use in laboratory, but the fine aggregate is often
long it is consistent with the dimensions of the structure. 2% or 3% above or below SSD.
When high strength concrete is desired, best results may be This means that a correction must be made before a
obtained with reduced maximum sizes of aggregate as they laboratory batch of concrete is made.
produce higher strengths at a given w/c ratio. The maximum
Step-9 Trial Batch Adjustments
size of Coarse aggregate is taken as 10 mm from the Table
4.3.2 of ACI 211.4R code. The ACI method is written on the basis that a trial batch of
concrete will be prepared in the laboratory, and adjusted to
Step-3 Estimation of mixing water and air content
give the desired slump, freedom from segregation,
From the Table 4.3.4 of ACI 211.4R, the quantity of finishability, unit weight, air content and strength.
water required (for 50 mm Slump and 10 mm aggregates) = Table 1: Mix Proportion of M150 Grade Concrete
183 kg/m3
Coarse
Cement Fine Aggregate Water
Step-4 Selection of water/cement ratio Aggregate
732 kg 332.32 kg 1118 kg 183 kg
Let the water/cement ratio = 0.25
1 0.454 1.527 0.25
Step-5 Calculation of cement content
Water / Cement ratio = 0.25
Water/cement ratio = 0.25 & Water content = 183 kg/m3 &
Specific gravity = 3.15 IV. EXPERIMENTAL TEST RESULTS
=> Cement content = 183 / 0.25 By conducting the workability slump test, it is found that the
= 732 kg amount of 920SH required for getting the slump height 50
mm = 2% (total weight)
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