Upload
dinhkhanh
View
219
Download
2
Embed Size (px)
Citation preview
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.II/ Issue I/January-March 2011/299-305
Research Article
STUDY CRUSHING SND FLEXURAL STRENGTH OF
FIBER REINFORCED CONCRETE CONTAINING HIGH
VOLUME FLY ASH Indrajit Patel
1, C D Modhera
2
Address for Correspondence 1Research Scholar, Applied Mech. Department, SVNIT, Surat, Gujarat
2Professor and Supervisor, Applied Mech. Department, SVNIT, Surat, Gujarat
E Mail: [email protected]
ABSTRACT.
Concrete is the most consumed material after water on the earth for infrastructure & construction
industries, a commendable contribution can be made by optimizing the use of cement and natural
resources in concrete manufacturing. High volume Fly Ash concrete is one of the major developments
since last three decades leading to utilization of Fly Ash in a bulk quantity and thereby reducing cement
consumption and ultimately reducing emulsion of CO2 in order of one ton per a ton of Cement. The past
research has been given due consideration for application of HVFA in different sectors like mass
concrete, foundation, transportation etc. But the limitations of HVFA like early slower strength
development, ductility, poor performance towards expansion and contraction, flexural property,
impact and abrasion resistance have made its use limited. Introduction of structural/non structural
fiber with HVFA concrete application can overcome these problems and use of HVFA can be
increased in developing nation like India for sustainability.
KEY WORDS: Fly Ash, Polyester fibre, Compressive Strength, Flexural Strength.
INTRODUCTION
With aim to improve engineering and
durability properties of conventional High
Volume Fly Ash (HVFA) concrete
experimental work has been carried out as
part of PhD study. Though HVFA
concrete has development history of more
than four decades the use has not been
significant and notable due to many reason
including slower early strength
development, resistance to bending,
impact and abrasion for its application on
wide base. The replacement of Portland
cement in context of Indian Standard is of
order 35% by mass of cementing material.
Even the blended cement contains 25% of
fly ash. This will not address the issue of
green concrete and sustainability of
concrete technology to the desired extent.
Inclusion of 50% or more fly ash to
normal concrete forms HVFA concrete for
low to high strength and high performance
concrete with or without adding micro
sized material like silica fume or micro
quartz.
The present work includes mix design for
M25, M30, M35 and M40 grade HVFA
concrete with different percentage of class
F fly ash 50%, 55% and 60%. To improve
the engineering properties viz.
compressive, flexural, impact strength and
abrasion resistance 12mm triangular
shaped polyester fibre is use at rate of
0.25% by the mass of cementitious
material. The test results for compressive
strength at 3,7,28 and 56 days for plain
HVFA concrete for all grade with and
without meets codal requirement. The use
of polyester fibres has increased the
compressive strength to order of 12 to 15
%. Flexural strength using center point
loading also meets the required parameters
and fibre reinforced HVFA shows 16 to
23% increase compared to plain HVFA
concrete at 28 and 56 days. There is
notable increase in ductility of HVFA
concrete which is the need of days for
design & construction of earthquake
resistant structures.
MATERIALS
Cement & Fly Ash: 53 grade Ordinary
Portland cement conforming to BIS
12269-1999 was used. Class F fly ash
from Wanakbori Thermal Power station,
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.II/ Issue I/January-March 2011/299-305
Gujarat conforming to BIS 3812-2003 was
used in the present study. Test results are
shown in Table [1] & Scanning Electron
Microscopic view for fly ash is shown fig.
[1]
Admixtures: High range water reducing
admixtures for fibre reinforced HVFA
samples Poly carboxylate based super
plasticizer was used.
Aggregates: Crushed stones of 20mm
down and 10mm down were used as
coarse aggregate. Local river sand was
used as fine aggregate in the concrete
mixtures. Samples ere tested as per BIS-
2386 and results were confirmed with IS-
383
Fiber: 12mm size triangular-Trilobal
shaped polyester fibre confirming to type
III fibres under ASTM C: 1116 were used
as a supplementary reinforcing material to
enhance the mechanical properties of
hardened concrete. The test results and
microscopic view is presented in Table [2]
& fig. [2] respectively.
TABLE 1: CHMICAL AND PHYSICAL PROPERTIES OF FLY ASH
Sr.
No Properties
Result
obtained
in %
Requirement as IS 3812-Part-1-
2003
Siliceous
Pulverize
Fuel Ash
Calcareous
Pulverized
Fuel Ash
1 Silicon dioxide (Sio2) plus aluminium oxide
( Al2O3), plus Iron Oxide ( Fe2O3), Percent by
mass min.
95 70 50
2 Silicon dioxide ( SiO2), Percent by mass, min 62 35 25
3 *Reactive silica in percent by mass, min -- 20 20
4 Magnesium oxide ( MgO), percent by mass, max 0.50 5.0 5.0
5 Total Sulphur as sulphur trioxide (SO3). Percent
by mass, max 0.30 3.0 3.0
6 Available alkalis as sodium oxide (Na2O) in
percent by mass, Max 0.90 1.5 1.5
7 Total chlorides in percent by mass Max 00.035 0.05 0.05
8 Loss on ignition, in percent by mass ,Max 1.20 5.0 5.0
9 Calcium Oxide 22.15 -- --
10 Moisture content 01.30 -- --
Sr. No. Properties Test Results
1 Fineness - Specific Surface in m2/kg 395
2 Lime Reactivity, N/mm2 2.50
3 Compressive Strength, N/mm2 79.00
4 Drying Shrinkage 0.21
5 Soundness, 0.33
Figure 1 : SEM VIEW OF FLY ASH
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.II/ Issue I/January-March 2011/299-305
TABLE 2: POLYESTER FIBRE
Figure 2: SEM VIEW OF POLYSTER FIBRE
EXPERIMENTAL SET UP
Final design mix was prepared for all the
designated mix as shown table [3]. Latter in
second stage with the same proportion 0.25%
of polyester fibre was added. For each
batching of the sample and design mix the
slump values were measured after 60 min
retention period using standard slump cone
and results were confirmed as per BIS: 456-
2000. For compression strength standard
150mm cube were casted to measure strength
at 3, 7, 28 and 56 days. Sample were casted
and tested as per BIS 516 Comparative study
was made for strength development for
different dose of flyash as well as with
inclusion of 12mm triangular shaped polyester
fibre content i.e. 0.25 . Flexural strength was
measured at the age of 14, 28 and 56 days for
all samples using central point load over span
of 400mm, for specimen size
100x100x500mm and span 400mm. Test
procedure was carried out as per BIS-516.On
the basis of test results obtained from the trial
mixes, final concrete mixes were cast with
minimum cement content fulfilling the
strength requirements.
Particular Test Result/Observation
Application Concrete
Indian Roads Congress Accredited
Material Polypropylene
Denier (Approximate) 11.7
Shape(Cross-section) Triangular –Trilobal
Cut Length 12.1 mm
Diameter 30-35u
Specific Gravity 0.91
Packing Type Pouch
Dispersion Excellent
Melt Point 160-165 0
Elastic Modulus, psi (ACI) 500-700
pH 7.3 ± 0.5 @ 10%
Colour Colourless & White
Solubility in Water Not Soluble in Water
Water Absorption (% by Wt.) Nil
Alkaline Resistance Conforms to Test Procedure laid by ICBO AC 32
UV Stability Higher UV Resistance
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.II/ Issue I/January-March 2011/299-305
Table 3: HVFA DESIGN MIX
M25 GRADE SAMLE C FA C=FA W SP W/C+
FA
S CA
<20MM
CA
<10M
SLUMP
MM
DENSITY
KG/M3
A10 195 195 390 120 2.40 0.30 642 761 441 90 2394.4
A20 202 248 450 125 3.6 0.28 600 853 379 75 2410.6
A30 180 270 450 140 3.6 0.31 591 839 373 110 2396.6
M30 GRADE SAMPLE C FA C=FA W SP W/C+
FA
S CA
<20MM
CA
<10M
SLUMP
MM
DENSITY
KG/M3
B10 225 225 450 130 3.4 0.29 554 757 432 95 2326.4
B20* 225 275 500 130 4.0 0.26 585 850 351 90 2417.0
B30 200 300 500 145 4.00 0.30 568 825 341 100 2383.0
M35 GRADE
SAMPLE C FA C=FA W SP W/C+
FA
S CA
<20MM
CA
<10M
SLUMP
MM
DENSITY
KG/M3
C10 250 250 500 140.0 4.0 0.28 554 757 432 100 2387.0
C20 247 303 550 138.0 3.8 0.26 526 848 336 95 2370.0
C30 220 330 550 137.5 3.8 0.25 514 826 327 110 2358.3
M40 GRADE SAMPLE C FA C=FA W SP W/C+
FA
S CA
<20MM
CA
<10M
SLUMP
MM
DENSITY
KG/M3
D10 280 280 560 150 4.0 0.27 501 761 415 110 2392.6
D20 270 330 600 160.0 4.0 0.27 486 800 367 95 2437.0
D30 240 360 600 144.0 4.20 0.35 471 839 319 110 2377.2 A: M25, B=M30,C=M35,D=M40 1= 50 2=55 3=60 % flyash 0= no fibre 1=0.25 % fibre
Action of Fly Ash Incorporating Matrix and Chain Mechanism
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.II/ Issue I/January-March 2011/299-305
RESULTS AND DISCUSSION
The batching for all the designed mix and
inclusion of varied flyash as well as polyester
fibres have made as per the standard
procedure. Slump for all the batches were
measured after 60 min. retention period and
comparative study for different mix meets
desired value ranging from 85 mm to 115 mm
as desired for RMC standards. W/C ratio is of
order 0.25% to 0.40% within limits specified
under guide lines of HVFA and BIS. Slump
measurement and comparative study is
presented in Table [4] & Fig [3].Compressive
strength measurement for all the mix with 0.0
and 0.25% fibre dose was measured 3, 7, 28,
56 days as shown in Table [5]. Comparison of
compressive strength according to variation in
fibre content 0.0 and 0.25% at end of 28 days
for all mix is shown graphically in figure [4]
28 days flexural strength comparative study is
shown study in fig. [5]
Table 4: SLUMP MESUREMENT
MIX
Fly Ash 50% 55 % 60%
Fibre 0.00% 0.25% 0.50% 0.00% 0.25% 0.50% 0.00% 0.25% 0.50%
w/c S w/c S w/c S w/c S w/c S w/c S w/c S w/c S w/c S
M25 .30 90 .40 95 .44 110 .28 90 .32 90 .32 95 .31 90 .42 110 .35 115
M30 .29 95 .34 90 .44 115 .28 100 .30 85 .32 90 .30 100 .36 90 .32 105
M35 .28 100 .34 90 .34 95 .26 100 .28 80 .28 85 .25 110 .30 85 .32 100
M40 .27 110 .30 85 .39 100 .26 110 .28 80 .28 85 .35 110 .28 80 .30 95
Fig 3: SLUMP COMPARRISION
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.II/ Issue I/January-March 2011/299-305
Table 5: COMPRESSIVE STRENGTH N/MM2
Mix Days/
Fiber
50% flyash 55% flyash 60%flyash
0.0 0.25 0.0 0.25 0.0 0.25
25
3 15.30 16.05 16.20 17.29 18.56 19.48
7 19.40 20.66 24.81 26.80 29.96 32.13
28 35.33 39.74 37.48 42.35 35.61 39.52
56 40.625 46.100 41.800 46.805 38.99 44.16
30
3 16.65 17.73 19.67 20.75 19.91 21.20
7 23.30 25.16 25.42 27.45 30.28 32.47
28 36.45 43.74 37.72 41.86 39.16 43.27
56 40.64 46.33 42.055 47.735 43.66 49.23
35
3 21.18 22.35 22.94 24.31 24.44 25.87
7 25.37 27.27 28.84 31.09 28.65 31.08
28 40.22 46.25 41.10 44.59 42.90 47.83
56 44.443 50.310 45.825 51.55 47.51 53.45
40
3 21.93 23.24 29.39 31.08 29.39 31.37
7 29.06 32.50 33.65 36.45 31.83 34.61
28 48.23 55.93 49.16 55.30 49.48 55.66
56 53.775 59.425 53.830 60.695 53.20 61.30
Table 6: FLEXURAL STRENGTH IN N/MM2
Mix Days/
Fiber
50% flyash 55% flyash 60%flyash
0.00 0.25 0.0 0.25 0.0 0.25
25
14 3.96 4.93 4.05 4.91 3.92 4.67
28 4.76 6.14 5.21 6.43 4.85 5.77
56 5.84 6.70 6.12 7.05 5.61 6.35
30
14 4.20 5.57 4.33 5.94 4.42 5.22
28 5.63 7.01 6.25 8.01 5.56 6.44
56 6.62 7.77 7.20 8.14 6.40 7.17
35
14 4.53 5.60 4.71 5.87 4.46 5.45
28 6.16 7.43 6.27 7.50 5.86 6.57
56 6.65 8.04 7.90 8.17 6.33 7.30
40
14 4.76 5.88 4.83 6.24 4.72 5.80
28 6.25 7.47 6.63 7.90 6.02 7.01
56 7.10 7.44 8.40 7.05 7.53
Figure 4: 28 DAYS COMPRESSIVE STRENGTH
International Journal of Advanced Engineering Technology E-ISSN 0976-3945
IJAET/Vol.II/ Issue I/January-March 2011/299-305
Figure 5: 28 DAYS FLEXURAL STRENGTH
CONCLUSION
• Inclusion of fibre at the rate of 0.25% by
mass of the cementitious material does not
have much effect on the w/c ratio and 60
min. slump values as well.
• For higher proportion of cementing
material in higher concrete grade the
dosage of plasticizer was increased to
1.00% to achieve desired slump and
workability.
• Increase in compressive strength at 7 days
age for all mix with fibre varies between
7.00 to 9.50%,this will address to slower
strength gaining problem in case of plain
HVFA concrete.
• Increase in 28 days compressive strength
as compared to plain HVFA concrete is of
the order 9.75 to 15 %
• All sample shows required flexural
strength at 14, 28 and 56 days age.
Increase in strength between 14 to 28 days
is of order 22 to 30% and 28 to 56 days is
7.50 to 13.5%.
• 55% cement replacement shows optimum
gain of compressive and flexural strength
for all grade of plain and fibre reinforced
HVFA concrete.
REFERENCES 1. Bouzoubaa,N.,Fournier,B.,Malhotra,V.M.,
and D.M.Golden,”Mechanical Properties
and Durability of Concrete Made with
HVFA Blended Cements Produced in a
Cement Plant”;CANMET Report MTL
2001-23 (J) ,October 2001, Natural
Resources Canada , Ottawa, Canada.
2. Desai, J.P., “Construction and
Performance of High Volume Fly Ash
Concrete Roads in India, ACI SP-221,
V.M.Malhotra, ed, 2004,pp.589-603.
3. Malhotra, V.M., “Making Concrete
Greener with Fly Ash”; Concrete
International, V.21, No.5, May 1999,
pp.61-66.
4. Malhotra, V.M., “CANMET
Investigations Dealing with High-Volume
Fly Ash Concrete”; CANMET
Publication: Advance in Concrete
Technology, MSL 92-6, 1992, pp. 433-
470.
5. Mehta P.K.and V.M.Malhotra, “High
Performance, High Volume Fly Ash
Concrete “, February 2002, pp.15-32,
pp.34-36, pp. 37-42 , pp.43-49, pp.66-69.
6. Mehta, P.K.,”Concrete Technology for
Sustainable Development”, Concrete
International, V.21, No.11, Nov.1999.
7. M.S.Shetty, “Concrete Technology
Theory and Practice “ , Pub. S. Chand ,
2006, Pp.27-296, pp. 421-428.
8. Naik, Tarun et al, “Mechanical Properties
and Durability of Concrete Pavements
Containing High Volumes of Fly Ash;
ACI SP-212, June 2003, V.M.Malhotra
ed., pp.319-340.