This research survey comprises of concrete regular hexahedrons made with Ordinary Portland Cement and with different constellations of fly ash by replacing cement and all right sum. To accomplish the purpose of this survey, entire 81 concrete regular hexahedrons were cast. Among 81 regular hexahedrons, 9 regular hexahedrons were made with normal concrete, 36 regular hexahedrons were made by replacing 25 % , 50 % , 75 % and 100 % of all right sum with fly ash and 36 regular hexahedrons were made by replacing 10 % , 25 % , 50 % , and 75 % of cement with fly ash. The regular hexahedrons were 6 ” ten 6 ” in cross-section, and the mix design was aimed for 5000 pounds per square inch. After proper hardening of all 81 regular hexahedrons, they were tested at 3, 7 and 28 yearss bring arounding age. The regular hexahedrons were tested in Forney Universal Testing Machine in the Concrete Laboratory of Civil Engineering Department, Mehran University Jamshoro. By analysing the trial consequences of all the concrete regular hexahedron, the following chief findings have been drawn.
The compressive strength of concrete regular hexahedrons made by replacing 100 % all right sum by fly ash was higher than the concrete regular hexahedrons made with Ordinary Portland Cement at all 3, 7 and 28 yearss bring arounding ages. On the other manus, the compressive strength of concrete regular hexahedrons made by replacing 10 % and 25 % cement by fly ash were somewhat lower than the concrete regular hexahedrons made with Ordinary Portland Cement at all bring arounding ages, whereas the compressive strength of concrete regular hexahedrons made by replacing 50 % and 75 % of cement by fly ash were rather lower than the concrete regular hexahedrons made with Ordinary Portland Cement at all bring arounding ages.
Cardinal Wordss: Ordinary Portland Cement, Fine Aggregate, Fly Ash, Compressive strength of Concrete.
*Assistant Professor, **Associate Professor
Department of Civil Engineering, Mehran University of Engineering & A ; Technology, Jamshoro, Pakistan
Introduction
Concrete is a composite stuff which is being used in assortment of constructions. More commonly cement, steel bars every bit good as coarse and all right sums are to be transported from distant topographic points to the site which is rather expensive. Therefore the sums are sooner to be used from whatever is available locally.
Fly ash ( besides known as a Coal Combustion By-Product ) is the finely divided mineral residue ensuing from the burning of powdery coal in electric generating workss. Large measures of industrial byproducts are produced every twelvemonth. These waste byproducts must be efficaciously disposed to extinguish air, dirt, and surface, every bit good as land H2O pollution at added cost to the industry and therefore to the society [ 1- 3 ] .
Fly ash is by and large used as partial replacing of Portland Cement and/or all right sum, an expensive and energy intensive stuff. Therefore usage of fly ash leads to considerable salvaging in cost and energy ingestion. Use of increased volumes of fly ash in concrete will take to preservation of energy and natural resources. Bulk measures of some industrial byproducts such as fly ash, bottom ash and scoria have been used as sums for concrete, route embankment every bit good as sub base building, but such bulk utilizations represents low value applications. On the other manus, their usage as mineral alloies in cement and concrete due to their pozzolanic and cementitious belongingss represents high value applications. [ 4 ]
Addition of finely divided pozzolanic and cementitious stuffs like fly ash, can impact the belongingss of cement mortar/concrete both in fresh and hard-boiled province. In fresh or fictile province, mix proportions, H2O demands for specified consistence, puting features, workability, and heat of hydration are some of the belongingss influenced by mineral alloies. In the hard-boiled province, the rate of strength development and ultimate strength, permeableness, lastingness against frost onslaught, sulfate onslaught, alkali-silica reaction, carbonation, and opposition to thermal checking are significantly affected with the incorporation of mineral alloies in cement concrete. Over the old ages, extended research has been conducted all over the universe to look into the influence of fly ash on the strength of field cement concrete. In this survey the fly ash produced at Lakhra Coal Power Plant is used as a replacing of cement / mulct sum, in order to look into its effects on the strength of concrete.
2. RESEARCH SIGNIFICANCE
Fly ash as Wealth instead than Waste
With the roar in population and industrial growing, the demand for power has increased manifold. It has been observed that the power coevals workss running through coal fuel are bring forthing immense sum of ashes, which is being treated as waste. If this waste is left unutilized, it can foul assorted stages of human environment like air, nutrient, land, shelter and H2O [ 5 ] . However, if this waste is disposed of decently, it can be a new beginning of utile stuff.
Research workers have been trying to change over this waste into the wealth by researching feasible avenues for usage of fly ash. It has been reported that this waste material is being used as all right sum in concrete building and higher strengths are being achieved [ 5 ] . This will necessarily cut down the cement content, which is one of the expensive point in concrete building. Hence the usage of fly ash as a building stuff in those countries where it is cheaply available would be a executable measure in building industry instead than transporting standard hill sand from a far distant beginning.
It is reported that fly ash has cementitious belongingss ; therefore wing ash is an cheap replacing for assorted contents of concrete building. When fly ash is employed with Portland cement, so hydrated lime combines with the fly ash organizing stable cementitious compound which contributes strength. [ 2, 10 ] .
Advantages/ Benefits of Fly ash Concrete
Fly ash refers to the finely divided stuff which is added to obtain specific technology belongingss of cement howitzer and concrete. The other, every bit of import, nonsubjective of utilizing fly ash in cement concrete include economic benefits and environmentally safe recycling of waste by merchandises. Fly ash is by and large finer than Portland Cement. Because of its choiceness, pozzolanic belongingss and self- cementitious nature, it is widely accepted as mineral alloy in howitzer and concrete [ 4 ] .
Fly ash in concrete is used to heighten the public presentation of concrete. The assorted advantages of fly ash in concrete mostly depend on mix proportions, blending process and field conditions. Although fly ash creates environmental jobs, ne’er the less it improves the quality of concrete. It besides lowers the heat of hydration. Fly ash additions strength of concrete, reduces the permeableness and corrosion of reenforcing steel, increases sulphate onslaught opposition and reduces alkali-aggregate reaction [ 10 ] .
2.3 Fly ash of Lakhra Coal Power Plant
Lakhra Power Plant is really close to Jamshoro and Hyderabad and is the lone coal fuel powered works in Pakistan. It is about 35 kilometers form Jamshoro and 55 kilometer from Hyderabad. Lakhra coal field encompasses an country of 250 square kilometres. Fly ash produced through this power works is really all right pulverization recovered from gases created by coal fired electric power coevals. This power works produces about 2 million dozenss of fly ash yearly, which is being dumped like a land fill. It has been reported that dumped wing ash has occupied immense considerable infinite of land in the locality of power works which has created environmental job to the dwellers who are populating in this country. This alarms research workers to devour this land fill wing ash which is bring forthing great environmental impact in the surrounding society.
There may be differences in the fly ash from one works to another, daily fluctuations in the fly ash from a given power works are normally rather predictable, provided works operation and coal beginning remain changeless. The effectual use of fly ash in concrete requires equal cognition of features of fly ash defined by its physical, chemical and mineralogical belongingss.
3. Experimental Plan
3.1 Materials for Concrete Mixture
The assorted stuffs used in concrete mix are given in Table 1.
Table 1. Material used in Concrete mix
No.
Material Description
Material Source
1.
Cement
Dada Bhai Cement Factory
2.
Fine Aggregatge
Bolhari sand
3.
Coarse Aggregatge
Petaro suppression works
4.
Fly ash
Lakhra Power Plant
5.
Water
Concrete research lab, Civil Engineering Department
3.2 Properties of Materials used in Concrete mix
3.2.1 Specific gravitation of Fine sum
Standard trial process as prescribed by ASTM C128-93 was used for this trial. The specific gravitation of all right sum used in this research survey was found to be 2.61.
3.2.2 Specific gravitation of Coarse sum
Standard trial process as prescribed by BS: 812 Part 107: ( Draft ) and ASTM C 127- 93 was used for this trial. The specific gravitation of harsh sum used in this research survey was found to be 2.66.
3.2.3 Specific gravitation of Fly ash
Standard trial process as prescribed by ASTM C128-93 was used for this trial. The specific gravitation of Fly ash was found to be 2.54.
3.2.4 Water soaking up of Fine sum
Standard trial process as described in BS 812: Part 107: ( Draft ) was used for this trial. The H2O soaking up of all right sum was found to be 1.69 % .
3.2.5 Water soaking up of Coarse sum
Standard trial process as described in BS 812: Part 107: ( Draft ) was used for this trial. The H2O soaking up of harsh sum was found to be 1.38 % .
3.2.6 Water soaking up of Fly ash
Standard trial process as described in BS 812: Part 107: ( Draft ) was used for this trial. The H2O soaking up of Fly ash was found to be 16.92 % .
3.2.7 Unit weight of Fine sum
Standard trial process as described in BS 812: Part 2: 1975 and ASTM C 29-91a was used for this trial. The unit weight of all right sum was found to be 103.47 lb/ft3.
3.2.8 Unit weight of Coarse sum
Standard trial process as described in BS 812: Part 2: 1975 and ASTM C 29-91a was used for this trial. The unit weight of harsh sum was found to be 98.48 lb/ft3.
3.2.9 Unit weight of Fly ash
Standard trial process as described in BS 812: Part 2: 1975 and ASTM C 29-91a was used for this trial. The unit weight of Fly ash was found to be 44.52 lb/ft3.
3.3 Design Method:
The British method of concrete mix design, popularly referred to as the “ DoE method ” , was used for design intent. After holding few tests to look into the mix design for the needed strength of 5000 pounds per square inch, the ratio was used as: 1: 1.25: 2.50 @ 0.39 w/c ratio.
3.3.1 Specimen Details and Test set up
In this research survey entire 81 concrete regular hexahedrons were cast. Among 81 regular hexahedrons, 9 regular hexahedrons were made with normal concrete, 36 regular hexahedrons were made by replacing 25 % , 50 % , 75 % and 100 % of all right sum by fly ash and 36 regular hexahedrons were made by replacing 10 % , 25 % , 50 % , and 75 % of cement by fly ash. The regular hexahedrons were 6 ” ten 6 ” in cross-section, and the mix design was aimed for 5000 pounds per square inch. After proper hardening of all 81 regular hexahedrons, they were tested at 3, 7 and 28 yearss bring arounding ages. The regular hexahedrons were tested in Forney Universal Testing Machine in the Concrete Laboratory of Civil Engineering Department Mehran University Jamshoro.
4. Trial RESULTS AND DISCUSSION
After proper hardening of all 81 regular hexahedrons, these were tested at 3, 7 and 28 yearss bring arounding ages. The regular hexahedrons were taken out from the H2O armored combat vehicle and left for surface saturated drying status. The regular hexahedrons were so tested in Forney Universal Testing Machine in the Concrete Laboratory of Civil Engineering Department Mehran University Jamshoro. The trial consequences of all the concrete regular hexahedrons are summarized in Table 2, whereas their graphical presentation is shown in figure 1.
Table 2: Comparison of Compressive Strength of Concrete Cubes
at the Age of 3-Days, 7-Days and 28-Days
S.No.
Description of Cube
Average Compressive Strength ( pounds per square inch )
at the Age of:
3-Days
7-Days
28-Days
01.
Cubes made with Normal cement concrete
3241
4594
5129
02.
Cubes made by replacing 25 % of Fine Aggregate by Fly ash
3033
4287
4896
03.
Cubes made by replacing 50 % of Fine Aggregate Fly ash
3128
4381
4975
04.
Cubes made by replacing 75 % of Fine Aggregate by Fly ash
3377
4561
5041
05.
Cubes made by replacing 100 % of Fine Aggregate by Fly ash
3608
4614
5197
06.
Cubes made by replacing 10 % of Cement by Fly ash
3146
4409
4989
07.
Cubes made by replacing 25 % of Cement by Fly ash
2925
4428
5076
08.
Cubes made by replacing 50 % of Cement by Fly ash
1872
1931
2283
09.
Cubes made by replacing 75 % of Cement by Fly ash
1038
1090
1323
Figure 1: Graphic Presentation of Comparison of Compressive Strength of Concrete Cubes at the Age of 3-Days, 7-Days and 28-Days
The compressive strength of concrete regular hexahedrons made by replacing 100 % Fine sum by Fly ash was higher than the concrete regular hexahedrons made by Ordinary Portland Cement at all 3, 7 and 28 yearss bring arounding ages as shown in Figure 1. The compressive strength of concrete regular hexahedrons made by replacing 75 % of Fine sum by Fly ash was higher at 3 yearss but it was somewhat lower than the O.P.C made normal regular hexahedrons at 7 and 28 yearss as presented in Figure 2.
Figure 2: Graphic Presentation of Compressive Strength of Concrete Cubes
while Replacing Fine Aggregate by Fly ash
Figure 3: Graphic Presentation of Compressive Strength of Concrete Cubes
while Replacing Cement by Fly ash
The compressive strengths of concrete regular hexahedrons made by replacing 10 % and 25 % cement by Fly ash were somewhat lower than the concrete regular hexahedrons made by Ordinary Portland Cement at all bring arounding ages. The compressive strengths of concrete regular hexahedrons made by replacing 50 % and 75 % of cement by Fly ash were rather lower than the concrete regular hexahedrons made by Ordinary Portland Cement at all bring arounding ages as shown in Figure 3.
5. CONCLUSIONS AND RECOMMENDATIONS
By analysing the trial consequences of all the concrete regular hexahedron with Ordinary Portland Cement concrete and with different constellations of fly ash made concrete by replacing all right sum and Ordinary Portland Cement, the undermentioned decisions have been drawn.
As the compressive strength of concrete regular hexahedrons, made by replacing 100 % all right sum with fly ash is more higher than the concrete regular hexahedron, made by utilizing Ordinary Portland Cement and common all right sum, hence the usage of fly ash is recommended in apparent cement concrete as a replacing of all right sum.
As the compressive strength of concrete made by replacing 10 % and 25 % cement with fly ash is comparatively same as made with Ordinary Portland Cement at 7 & A ; 28 yearss, hence the usage of fly ash as a replacing of Ordinary Portland Cement in apparent cement concrete is recommended up to 25 % .
This paper emphasizes on the suitableness of fly ash to replace the all right sum and cement in apparent concrete. Further extended research is required to utilize fly ash for design and building of R.C.C members which may be economical for our building industry.
Recognitions
The first writer is highly grateful to honorable undertaking supervisor Professor Dr. Ghous Bux Khaskheli, Chairman, Department of Civil Engineering, and Director Post Graduate Studies, Mehran University of Engineering & A ; Technology, Jamshoro, Pakistan, for his encouragement and necessary aid at each and every phase of this research work.
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