CHAPTER ONE 1.0 INTROD INTRODUCT UCTION ION 1.1 1.1 Backg Backgro round und Infor Informa mati tion on
Due to current levels of major construction in Kenya, there is an ever-increasing demand for concrete materials such as fine aggregates. Fine aggregates constitute the bulk of a concrete mixture mixture hence they they are an integral integral part part of concrete. concrete. Power plants plants which produce more more than than half of the the elec electri tricity city consum consumed ed in the the Unit United ed Stat States es today today are fueled fueled by coal. coal. In additio addition n to electricity, these plants produce a material that is fast becoming a vital ingredient for improving improving the performa performance nce of a wide range range of concrete concrete products products.. That material material is is fly ash ash (Halstead (Halstead & Crumpton, 1986). Fly ash is comprised comprised of the non-combustible mineral portion of coal. When coal is consumed in a power plant, it is first ground to the fineness fineness of powder. Blown into the power plant’s boiler, the carbon consumed consumed leaves molten molten particles particles rich in silica, silica, alumina and calcium. calcium. These particles solidify as microscopic, glassy spheres that are collected from the power plant’s exhaust before they can “fly” away — hence the the product’s product’s name: Fly Ash Ash (Gianoncelli (Gianoncelli et al., 2013). Chemically, fly ash is a pozzolan. When mixed with lime (calcium hydroxide), pozzolans combine to form cementitious compounds. Concrete containing fly ash becomes stronger, stronger, more durable, and more resistant to chemical attack. Mechanically, fly ash also pays dividends for concrete production. Because fly ash ash particles are small, they effectively fill voids. Because fly ash particles are hard and round, they have a “ball bearing” effect that allows concrete to be produced using less water. Both characteristics characteristics contribute to enhanced concrete workability and durabi durabilit lity y (Halst (Halstead ead & Crumpto Crumpton, n, 1986). 1986).
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Furthermore, fly ash use creates significant benefits for our environment. Fly ash use conserves natural resources and avoids landfill landfill disposal of ash ash products. By making concrete more durable, life cycle costs of roads and structures structures are reduced. Furthermore, fly fly ash use partially displaces production production of other concrete ingredients, resulting in in significant energy savings savings and reductions reductions in greenhouse gas emissions emissions (Gianoncell (Gianoncellii et al., 2013). During During iron iron and steel steel production, production, slag is generated generated as a byproduct. byproduct. It is is a non-metal non-metallic lic product, consisting essentially of calcium silicates and ferrites combined with fused oxides of iron, aluminum, manganese, calcium, and magnesium that are developed simultaneously with steel in basic oxygen, electric arc, or open-hearth furnaces. The main constituents of iron iron and steel slags are silica, alumina, calcium, and magnesia, which to gether make about 95% of the total composition composition.. Minor elements included included are manganese, iron, iron, Sulphur Sulphur compounds, compounds, and traces of several other elements. elements. The addition of slag reduces reduces the rate of heat evolution and and increases the resistance to chemical attack. It is made use of in hot regions due to less effect on early ea rly strength of concrete. The percentage of slag used also depends upon the aggregate. If the aggregate were highly reactive, it would require more of the slag to mitigate ASR or alkalisilica silicate te reaction reaction (Tripa (Tripathi thi & Chaudhar Chaudhary, y, 2016). 2016). The rapid increase in the annual consumption of natural aggregates due to the expansion of the construction industry worldwide means that aggregate reserves are being depleted rapidly, particularly in Kenya where the construction construction industry is at an all-time high. It has been reported that, if alternative aggregates are not utilized in the near future, the concrete industry will globally consume 8-12 billion tons of natural aggregates annu ally. Such large consumption of natural aggregates will cause destruction of the environment. Therefore, it is imperative that alternative substitutes for natural aggregates be found. One possibility is the utilization of
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industrial by-products and waste materials in making concrete, which will lead to a sustainable concre concrete te design design and a greene greenerr environm environment ent (Monosi (Monosi,, Girett Giretti, i, Morico Moriconi, ni, Favoni Favoni & Collepar Collepardi, di, 2001). Concrete's potential contribution to a more sustainable world includes the possibility of using by-products from other industries that would otherwise pose awkward disposal problems. A new opportunity comes from the possible use of slags and other by-products from non-ferrous metal product production ion in concrete. concrete. This could could eventually eventually mean mean an impress impressive ive double double win that is is by saving saving tax for the metal metal and constructio construction n industries industries,, while helping helping the environme environment nt (Monosi (Monosi et al., 2001). Producers of such metals as zinc and aluminium currently pay millions to stockpile or send slag and unwanted by-products b y-products to landfill. If these were to prove viable as an a ggregate, concrete manufacturers would then have a source of recycled material, exempt from the pay of aggregates tax, while metal producers would no longer need to dump the material and pay landfill landfill taxes and charges charges (Tripathi (Tripathi & Chaudhary, Chaudhary, 2016). 1.2 Problem Statement
The damping damping of industri industrial al wastes wastes such as ISF ISF slag and and fly ash ash at waste manageme management nt dumpsites causes a major problem to our environment by destroying destroying soils and release of toxic fumes to to the atmosphere. atmosphere. Hence, the the utilization utilization of ISF slag slag and fly ash, which which constitute constitute industrial industrial wastes, wastes, can provide provide solutions solutions to the environment environmental al degradation degradation challenge challenge posed by dumping of industrial wastes such as ISF slag and fly ash since these wastes are non biodegradabl biodegradable. e. In order order to curb curb this, this, there is need to to provide provide an alternat alternative ive use of ISF slag and and fly ash by substit substituting uting them them as partial partial replacem replacements ents to natural natural fine aggregates. aggregates.
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1.3 1.3 Obje Object ctiv ives es of the the Stud Study y 1.3. 1.3.1 1
Main ain Obje Object ctiv ivee
The projec projectt focuse focusess on investi investigat gating ing the possib possibili ility ty of using using imperi imperial al smeltin smelting g furnace furnace slag slag as a partial partial replacement replacement of fine fine aggregates aggregates in concret concretee containing containing fly ash. 1.3. 1.3.2 2
Spec Sp ecif ific ic Obje Object ctiv ives es
1. Design Design a concre concrete te mix mix contai containin ning g fly ash with with vary varying ing ratio ratioss of ISF ISF slag. slag. 2. Determ Determine ine the the compre compressi ssive ve stren strength gth of of concret concretee mixed mixed with with ISF ISF Slag. Slag. 3. Determ Determine ine the leachi leaching ng rate rate of Heavy Heavy Meta Metals ls from from concr concrete ete contai containing ning ISF slag slag at different ages. 1.4 1.4 Just Justif ifiicati cation on
Disposal Disposal of ISF slag slag and fly ash is causing an alarm alarm to the environment environment due to pollution. pollution. The more wastes are being dumped away in landfills, the more the the environment pays the price. The release of toxins to the environment has led t o a series of complications to human life. Therefore, Therefore, we need to to find a way to solve the problem problem caused caused by the disposal disposal of ISF slag and and fly ash. Also, with the rapid rapid increase in construction projects in Kenya and the growth of the constructi construction on industry industry in the country, there is need for more more greener concrete. concrete. Hence, the use of industrial by-products such as fly ash and Imperial Imperial Smelting Furnace (ISF) (ISF) slag will provide a substitute to natural aggregates, reduce the construction cost by some significant margin, improve durability, and increase the efficiency of the design p rocess. 1.5 1.5 Sign Signif ific icanc ancee of the Stud Study y
Slag and fly ash ash are industrial industrial wastes wastes that that lie idle in dumpsites dumpsites causing causing hazardous hazardous effects effects to the environment environment.. The lack of a way of of putting putting them to any use makes makes them them readily readily available available
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and they they are low low cost cost materia materials. ls. There Therefor fore, e, they can be used used in economi economizin zing g the cost cost of a projec project. t. Apart from from economy, it also saves saves the environmental environmental cost cost of cement since the use of cement cement leads to a production of high amount of carbon dioxide that causes greenhouse effect. effect. Hence, this study will provide a new approach of reducing the costs associated with the construction process as well as saving the environment.
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CHAPTER TWO 2.0 LITERATURE LITERATURE REVIEW 2.1 Introduc Introductio tion n
Cement is the core constituent constituent material in concrete, mortars mortars and renders whose properties are crucial for the construction of good structures. For any co nstruction, the ease with which Portland Portland cement concrete concrete is mixed, transporte transported, d, placed, placed, and compacte compacted d is extremely extremely important important in executing successful concrete construction. In order to achieve achieve this, an analysis of the concrete workability in the Kenyan market is important. American Concrete Institute (ACI) Standard 116R-90 (ACI 1990b) defines workability as “that property of freshly mixed concrete which determines the ease ea se and homogeneity with which it can be mixed, placed, consolidated, and finished.” For this study, workability is considered to increase or improve as the ease of placement, consolidation, and finishing finishing of concrete increases. In this this study, study, workability workability of the concrete concrete is consider considered ed to increase increase with with the addition addition of ISF slag in replacing replacing sand sand as fine aggrega aggregates tes by enhancing enhancing the the properti properties es of concrete concrete mixed with fly fly ash ash (Pepe, 2016). 2.2 Previous Research on the Topic
A variety of of reports reports for use of ISF ISF Slag in concrete concrete as a replacement replacement of of sand have been written and reported in literature. A brief survey of the research work d one in this area is discussed below. Shashidhara and Vyas (2010) reported the results of replacing sand in cement concrete using imperial smelting furnace Zinc slag in Indian Concrete Journal. The fine aggregate fraction so produced conformed to the grading requirements of both fine aggregate and all in aggregate. The workability of concrete improved as the replacement level increased, though the packing
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density of the dry all-in aggregate reduced. Replacing sand with zinc slag did not affect the compressive strength, but in a leaching test, complete replacement resulted in Lead (Pb) setting leached above the permissible level. Hooper, R. et al. (2002) focused on setting characteristics characteristics of ISF Slag, the effect of fly ash in minimizing retardation of set as well as the European policies for reuse of secondary materials. According to them, the UK Ten Year T ransport Plan, including the development of the highway infrastructure, offers opportunities to demonstrate successfully the consumption of small volume streams of secondary materials, materials, including ISF slag, slag, within the local area. Pavement construction offers several opportunities for consumption, the most credible of these being the replacement of the sand fractions by the slag in bound mixtures, cement and bituminous. The paper focused upon cementitious mixtures alone. The p resence of zinc and lead ions in the ISF slag were proven to have an impact impact on the setting characteristics of concrete mixtures, although there is little difference in the compressive strengths strengths after 28 days. The leaching, characteristics of the slag suggested that the retardation is not linearly related to the quantities of zinc or lead leached. Additionally, leaching tests in combination with pulverized fuel ash (fly ash) and ground granulated blast furnace slag indicated that it might be possible to minimize retardation of set in by including these materials in the concrete mixture. Tripathi, B. et al. (2012) (2012) assessed the strength strength and abrasion characteristics of ISF Slag Concrete. In their report, they assessed the potential of ISFS (Imperial (Imperial Smelting Furnace Furnace Slag) as sand in concrete, considering the presence of tox ic elements (lead and zinc) and their detrimental effects on the early hydration of cement. Equivalent volume of sand was replaced by b y ISFS in different percentages. Concrete specimens were prepared at different water to cement ratios. Compressive, flexural, and pull off strength, along with abrasion resistance, resistance, were examined.
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Leaching potentials of toxic lead, zinc, and cadmium from ISFS ISFS concrete mixtures were were also analyzed to evaluate environmental viability. Their Results were encouraging be cause sign of delay in setting was not observed. Improvement in compressive compressive and pull off strength; strength; comparable flexural strength and abrasion resistance; and, leaching of toxic elements within safe limits assured the potential of future use of the ISFS as sand in concrete. Morrison Morrison and Richardson Richardson (2004) (2004) stated stated in their study of Re-use of zinc zinc smelting smelting furnace furnace slag in concrete, studied environmental concerns associated associated with the reuse of ISF Slag concrete due to the presence of heavy metals like Zinc and Lead. They concluded that that the ISF slag is physically suitable for for use as an aggregate, although there are several barriers that must be overcome overcome before it can can be used in concrete. concrete. The study also reported reported that that the glassy nature of the the – silica slag initially raised concerns regarding the potential for alkali – silica reaction (ASR) to occur in concrete. However, after a comprehensive series of accelerated ASR tests indicated that the material was not susceptible to this type of deleterious reaction. 2.3 Properties Properties Of Materia Materials ls 2.3.1 Aggregates
Aggregates is a general term applied to those inert (chemically inactive) material, which when bounded bounded together by cement, cement, form concrete. concrete. Most aggregate aggregatess used in Kenya are naturally naturally occurring aggregates such as sand, crushed rock and gravel. Aggregates for concrete are divided into three categories: •
Fine Aggregates: Most of which passes passes through 4.75 mm sieve and retained on
150micron •
Coarse Aggregates: Most of which which passes passes through through 63 mm sieve and retained retained on
4.75micron
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•
All in Aggregate: Mixed aggregat aggregate, e, as it comes from from the pit or riverbed riverbed.. It is sometimes sometimes
used for unimportant unimportant work without separating into different sizes. Properties of Natural Aggregates
The properties properties should should comply with with the norms laid laid down in BS EN 12620:2002+A1 12620:2002+A1:2008 :2008 specification for C.A. and F.A. from natural sources for concrete. Aggregates Aggregates should be chemically inert, strong, hard, durable, of limited limited porosity (water absorption when immersed in water for 24 hours should not be more than 10%.), 10%.), free from adherent coating, clay lumps, coal and coal residues and should contain contain no organic or other admixture that may cause corrosion of the reinforcement or impair the strength or durability of the concrete. The s hape (rounded, irregular, angular and flaky) and sizes of the aggregates should conform to the strength and workability requirements (Chaudhary & Tripathi, 2013). Functions of the Aggregates in a Mix
Aggregates serve the following purposes: •
They reduce the cost of the concrete. Natural aggregates require only extraction, washing and grading prior to transportation to the site. site.
•
Correctly graded aggregates produce workable, yet cohesive concrete.
•
They reduce the heat of the hydration of the concrete since they are normally chemically inert and act as heat sink for h ydrating cement
Uses of the the Aggregate Aggregatess •
Naturally occurring crushed stone aggregates can be used for producing any type of good go od concrete concrete or R.C.C. for construction construction purpose purpose
•
Broken brick aggregates is used to produce plain concrete but not suitable for R.C.C. which is lighter lighter than broken stone aggregate aggregate
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•
Air- cooled blast blast furnace slag, slag, which is a by- product product in the process of pig iron, iron, forms a stronger and durable concrete when mixed with sand, and has a high fire resistance
•
Lightweight aggregate produce low density concrete, which can be used for interior parts of the building where high strength are not desired
2.3.2 Fly Ash
It is a Pozzolanic Pozzolanic material which itself does not have any cementitious property property but in finely divided form and in the presence of moisture ch emically react with lime to form compounds having cementitious properties. It is a residue resulting from the combustion of powder powdered ed coal coal (Halst (Halstead ead & Crumpt Crumpton, on, 1986). 1986). Properties •
They gain strength slowly and require curing ove r a longer period of time
•
The long term strength is high
•
Used for economizing the use of cement
•
Classification by ASTM: Class F (having less than 5% CaO) and Class C (CaO content in excess of 10%)
•
Use of good quality fly ash reduces the water demand
•
With water reduction, bleeding and shrinkage will reduce
2.3.3 Slag Why Use Fly Ash and Slag Slag Repl Replace acemen ment? t? •
Fly Ash and Slag are artificial artificial Pozzolanic Pozzolanic materials materials that improve improve the properties properties of concrete in both fresh and hardened state
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•
The calcium hydroxide formed after hydration h ydration of tri-calcium and di-calcium silicate reacts reacts with finely divided divided siliceous siliceous or aluminous aluminous compounds compounds in fly ash to form highly highly stable stable cementitio cementitious us substances substances
•
Pozzola Pozzolan n + Ca(OH) Ca(OH)2 + wate waterr--- C-S-H gel
•
Economize the use of cement as cement production causes production of carbon dioxide into the atmosphere which is harmful for the environment
Properties Properties of GGBS (Ground Granulated Granulated Blast Furnace Slag) •
Surface hydration of slag is slightly slower
•
Reduces heat of hydration, therefore, good fo r use in mass structures
•
Refinement of pore structures
•
Reduces permeability
•
Increased resistance to chemical attack
•
Possesses cementitious properties
2.4 Chemical Chemical Composition Composition of Sand and ISF slag slag
The elemental composition of sand was determined at the IIC, IIT Roorkee, by energy dispersive X-Ray analysis (EDAX). The Oxide composition of elements present in ISF slag determined by X-Ray fluorescence (XRF) was supplied. The chemical composition of sand and ISF slag are as shown in Table 1 and Table 2.
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Table 1 Composition Composition of ISF ISF Slag
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Table 2: Chemical composition of Sand and
XRF of ISF slag
ISF slag (EDAX (EDAX of Sand) Element
% by weight 11.91
C
Constituent detected SiO 2
02.53
Al2O3
Na
06.91
CaO
Al
29.92
Si
03.19
K
01.16
Ca
01.85
PbO
Na2O
17.91 1.93
0.68
K 2O Mn2O3 9.21 1.22
6.28 (+)5.68
Insoluble residue
Loss on ignition (LOI)
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34.28 8.17
MgO
1.41 Sulphide Sulphur
18.08
Fe2O3
42.53
O
ZnO
% content
0.71
1.33
CHAPTER THREE 3.0 METHOD METHODOLO OLOGY GY 3.1 3.1 Intr Introd oduc ucti tion on
The properties of material used, that is, fineness modulus and specific gravity using pycnometer, of sand, slag as well as the sieve analysis of fine and coarse aggregates will will be carried out, and the results determined in the laboratory. Grading curves as well as the underlying underlying zones for the the fine aggregate aggregate and slag will will also be determined determined in the laboratory laboratory accord according ing to BSI codes codes of practi practice. ce. The compr compress essive ive stren strength gth tests tests will will have have to be carrie carried d out using the the standard standard procedure procedure as prescr prescribed ibed in the code code BS EN 12390-3:200 12390-3:2009. 9. The Metal Metal Leaching Test will also conducted for different different mixes. 3.2 Preparation Preparation of Aggregat Aggregates es
The term aggregates is used to describe the gravel, crushed crushed stones and other materials, which are mixed with with cement to make concrete. concrete. 3.2.1 Essential Requirements Requir ements of Aggregates
a) Durability - Aggregate should be hard and should not contain materials that are likely to decompose or change in volume when exposed to weather or to affect the reinforcement. b) Cleanliness Cleanliness - Aggregates Aggregates should should be clean clean and and free free from from any organic organic impuriti impurities. es. The The particles should be free from coatings of dust or clay, as they prevent proper bonding of the particles. Gravel and sand should therefore be washed to remove clay, silt and other impurities which if present in excessive amounts, results into poor quality concrete. 3.2.2 Size of the Aggregates Aggregat es
In reinforced and pre-stressed concrete construction, nominal maximum sizes of the coarse aggregates are usually 40, 20, 14, and 10. Aggregates should be small enough enough to allow
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concrete concrete to flow around around reinforced reinforced bars so that it can be adequately compacted. compacted. On the other hand, it is advantageous to use the higher maximum sizes because in general, as the maximum size of aggregate increases, a lower water/cement ratio can be used for a given workability to obtain a higher strength. However, above 40mm, the gain of strength due to the reduced water/cement ratio is offset by the adverse effects of the lower bond area between the cement paste and the aggregate and by the the discontinuity caused by the large particles (Chaudhary & Tripathi, 2013). 3.2.3 Grading of the Aggregates
For concrete concrete to be durable, durable, it has to be dense and when fresh, it should should be sufficient sufficiently ly workable for it to be properly compacted. The mortar should be sufficiently sufficiently more to fill fill the void in the coarse aggregates. In turn, the cement paste should be slightly more than sufficient sufficient to fill the void in the fine aggregates. In essence, the voids in the aggregates depend on its particle particle size distribution. The grading grading of the aggregates affects the strength of the concrete mainly indirectly, though it has an important important effect on water/cement ratio ratio required for specified specified workability. Badly graded aggregates require a higher water/cement ratio and hence results in the weaker concrete (Chaudhary & Tripathi, 2013). 3.2.4 Sampling of Aggregates Riffling
It involved involved the splitting splitting of the samples samples into halves halves using a riffle riffle box. The sample will will be discarded into the riffler over its full length and the two halves collected into two boxes on each side. One-half One-half discarded, discarded, and riffling riffling of the other other half will be be repeated repeated until the sample sample is reduced to the desired quantity for testing and ex periments to follow.
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3.3 Material Material Testing and Specificati Specification on 3.3.1 Sieve Analysis
Aggregate is said to be graded when it contains different sizes of particles in suitable proportions. The main advantage of the graded aggregate is that it provides minimum voids created by the larger particles. It also improves workability considerably. Sieve analysis therefore enables us to determine the proportion of different particle in an aggregate sample. The results of sieve analysis are given in terms of percentage (%) of the total aggregate passing through each of the sieve size. To have a visual grasp of the grading, the results can be plotted on a graph, whose ordinates indicate percentage (%) passing and abscissa indicates sieve sizes on the logarithm scale. The finer the grading, the greater is the water requirement resulting into poor concrete. And the coarse grading, the greater the tendency of segregation. The most suitable grading is that which gives minimum number of fines sufficient to give the mix necessary cohesiveness. The procedure procedure involved involved,, bringing bringing the sample sample to an air-dry air-dry condition condition before before weighing weighing and sieving sieving by dying to a temperature temperature of 105-110C, and the dried dried sample weighed. weighed. The weighed weighed sample sample will then be placed on on the sieve sieve and and sieved sieved successively successively on the appropri appropriate ate sieves sieves starti starting ng with the largest. largest. The sieve sieve sizes used according according to according according to BS EN 12620:2002+A1: 12620:2002+A1:2008 2008 and arranged as: •
Coarse aggregates; 20, 15, 10, 5
•
Fine aggregates; 2.38, 1.20, 0.6, 0.3, 0.15, 0.074,
Each sieve was shaken separately over a clean tray until not more than a trace passes. On completion completion of sieving, sieving, the material material cleaned cleaned from from the mesh, mesh, will be be weighed. weighed.
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3.3.2 Batching Of Materials Material s and Mixing
In every project, it is a pre-requisite that the material for use is p repared in advance to allow the project to run as scheduled. The initial material material preparation under this project will involve involve the acquisit acquisition ion of the sample sample from from the yard. yard. Batching Batching will then be done using using the the weight weight method. method. A control mix ratio ratio of 1:2:4 will be used of designated designated grade grade of M15. Various Various mixes will be developed using varying fly ash and ISF slag percentages. 3.3.2.1 Mix design Factors to be considered for f or mix design •
The grade designation giving the the characteristic strength requirement of concrete.
•
The type of cement influences the rate of development of compressive strength of concrete.
•
Maximum nominal size of aggregates to be used i n concrete may be as large as possible within within the limits limits prescribe prescribed d by BS EN 12620:2002+A1 12620:2002+A1:2008. :2008.
•
The cement content is to be limited from shrinkage, cracking and creep.
•
The workability of concrete for satisfactory placing and compaction is related to the size and shape of section, section, quantity, quantity, and spacing spacing of reinforcement reinforcement and technique technique used for transporta transportation, tion, placing, placing, and compaction. compaction.
Mix Design Procedure Step 1: The volume volume of of mix, which needs to to make nine cubes of size size 150 mm mm will be calculated. calculated.
The volume of mix is sufficient sufficient to produce 9 numbers of cube and to carry out the concrete slump test. Step 2: The volume of mix will be multiplied multiplied with with the constituent constituent contents contents obtained obtained from the
concrete mix design process to get the batch weights for the trial mix.
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Step 3: The mixing of concrete is according to the procedures given in laboratory guidelines. Step 4: Firstly, Firstly, cement, cement, fine and course aggregat aggregatee will be mixed in a mixer for 1 minute. minute. Step 5: Then, water will be added and and the cement, cement, fine and course course aggrega aggregates tes and water water will be
mixed approximate approximately ly for another 1 minute. Step 6: When the mix is ready, the tests on mix are proceeding. Mix Design Tests
1.
The The slu slump mp test testss will will be cond conduc ucte ted d to to det deter ermi mine ne the the wor worka kabi bili lity ty of fres fresh h conc concre rete te..
2.
Conc Concre rete te will will be plac placed ed and and com compa pact cted ed in thre threee lay layer erss by a tam tampi ping ng rod rod wit with h 25 25 times, in a firmly held slump cone. On the removal of the cone, the difference in height between the uppermost part of the slumped co ncrete and the upturned cone will be recorded recorded in mm as the slump. slump.
3.
Nine Nine cube cubess are are prep prepar ared ed in 150 150 mm mm x 150 150 mm each each.. The The cube cubess are are cure cured d befo before re testing. The procedures for making and curing are as given in laboratory guidelines. Thinly coat the interior surfaces of the assembled mould with mould oil to prevent adhesion of concrete. Each mould filled with two layers of concrete, each layer tamped 25 times with a 25 mm square steel rod. The top surface finished with a trowel trowel and the date of manufacturi manufacturing ng will be recorded recorded in the surface of the concrete. concrete. The cubes will be stored undistur undisturbed bed for 24 hours at a temperat temperature ure of 18 to 220C and a relative relative humidity humidity of not less than than 90 %. The concrete concrete all will be covered covered with wet gunny sacks. sacks. After After 24 hours, the mould mould will be striped striped and and the cubes will will be cured further by immersing them in water at temperature 19 to 210C until the testing date.
4.
Comp Compre ress ssiv ivee str streng ength th test testss will will be condu conduct cted ed on the the cub cubes es at the the age age of 7 day days. s. Then, Then, the mean mean compress compressive ive streng strengths ths after 28 days will be calculated. calculated.
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3.3.3 Tests on Concrete
Various tests will be conducted on the concrete bl ocks molded out of the different mixes according to the mix design used. The tests will be used to prove the validity of the hypothesis on the grounds that the tested stimuli will be measured in respect respect to the alternative result expected. expected. The results results obtained obtained will be recorded, recorded, documented, documented, and analyzed later later on in the development of the study. Some of the tests that will be conducted on the concrete molds will be: •
Slump Test
•
Compaction Factor Test
•
Compre Compressi ssive ve Streng Strength th Test
•
Metal leaching tests
3.3.3.1 Slump Test
This is a suitable test for normal cohesive mixes of medium to high workab ility and is the workability test that is most commonly used. A workable concrete is defined as a concrete suitable for placing and compacting under the site conditions. The slump test will be carried on the designed mixes. The standard slump cone with a base plate was used. A change in the value of slump indicated changes in material water content or in the proportion of the mix, so was useful useful in controlling controlling the the quality of of the concrete concrete produced. produced. The apparatus apparatus will consist consist of a truncated conical mould 100mm diameter at the top, 200mm at the bottom and 300mm high with a steel tamping rod 16mm diameter and 600mm 600 mm long with both ends hemispherical. The inside of the mould mould will be cleaned cleaned and oiled oiled before the the test and and the mould mould will be made to stand stand on a smooth smooth hard surface. surface. The mould will be held down using using the feet feet rested on the foot foot rests, rests, will be filled in three layers of approximately equal depth. Each layer will be tamped with 25 strokes of
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tamping rod and the strokes being un iformly distributed over the cross-section of the layer. The top surface surface will will then be smoothened smoothened using using the rod as the the straight straight edge, edge, and the surfac surfacee of the cone and and base plate plate will be wiped clean. clean. The The cone will will then be lifted lifted vertically vertically upright upright and the the slump measured. 3.3.3.2 Compaction Factor Test
The compaction factor test measures the degree of compaction resulting from the application of a standard amount of work. The apparatus consist of a rigid frame frame that supports two conical hoppers vertically aligned above each other and mounted above a cylinder. The top hopper is slightly larger than the bottom hopper, while the c ylinder is smaller in volume than both hoppers. To perform the test, test, the top hopper will be filled with concrete but not compacted. The door door on the bottom bottom of of the top hopper hopper will then be opened and and the concrete concrete allowed allowed dropping dropping into the lower lower hopper. hopper. Once all of the concrete concrete had fallen fallen from from the top hopper, hopper, the door on the lower hopper will be opened to allow the concrete to fall fall to the bottom cylinder. A tamping rod will be used to force especially cohesive cohesive concretes through the hoppers. The excess concrete will be carefully carefully struck struck off the top of the cylinder and the mass of the concrete concrete in the cylinder cylinder recorded. This mass will will be compared to the mass of fully compacted concrete in the same cylinder achieved with vibration. The compaction factor is de fined as the ratio of the mass of the concrete compacted in the compaction factor apparatus to the mass of the fully compacted concrete. The compacting factor = mass of free-fall concrete / mass of compacted concrete. 3.3.3.3 Compressive Strength Stren gth Test
The compressi compressive ve strength strength test will be done in accordan accordance ce with BS EN 12390-3:20 12390-3:2009. 09. By the mix design I will obtain the total amount of cement, sand, aggregate required along with a specified specified percentage percentage (%) of slag and Fly-ash Fly-ash per cubic cubic metre. metre. I will then then calculate calculate the total total
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quantity of material required for 9 cubes per mix design. (3 cubes for 7 day testing, 3 for 28 days testing and 1 for Metal Leaching Test and 2 for long-term tests). Moulds of 150mm by 150mm by150mm by150mm cubes will be used, thus the total volume of the material material will be calculated. calculated. The moulds will be assembled, placed on a rigid rigid horizontal surface and filled filled with concrete and then compacted compacted to remove the entrapped entrapped air, with no segregat segregation. ion. The The concrete concrete will will then be placed placed in layers layers of 50mm and then vibrated. vibrated. Concrete paste, paste, mixed with additional additional cement cement will then be used as capping material. The idea is to increase the strength of the cap to reduce weak point hence allowing distribution of the load. The surface will will be smoothened and left for 24hrs before dismantling the moulds and then cured by immersing in water according to BS EN 123902:2009. The specimens will then be removed from water, weighed, measured to determine the area of the cylinder and the density of the concrete. Tests will be carried out on the concrete at ages 7 and 28 days to determine determine the rate of strength strength gain of the concrete. concrete. Metal Leaching Leaching Test will be done after after 28 Days. Days. Before Before testing testing the concrete, concrete, all cylinder cylinderss will be inspected inspected for defects defects in the concrete to ensure consistent results and the n loaded in the testing apparatus at the concrete concrete laboratory laboratory.. At each each age, two specimens specimens will be tested tested to ensure ensure accurate accurate result resultss will will be obtained. The compressive strength of the concrete is determined from the following formula; Fc = P/Ac Where: Fc - Is the compres compressive sive streng strength th of the concrete concrete;; P - Is the maximum maximum force measured measured during during testing; testing; Ac is the area of the cylinder or cube being tested. The results will then be noted and graphs will be plotted showing the strength variation.
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3.3.3.4 Metal Leaching Tests
The metal leaching leaching test was carried carried out to find the leaching leaching of metals especially especially zinc after after 28 days of curing the cube. The test aims at understanding the durability aspect of the cube and its strength strength as a heavy amount of leaching leaching reduces the durabilit durability y of the cube in adverse environmental situation. The steps for testing are as follows: 1. Concr Concret etee cube cube will will firs firstt be crus crushe hed d in in the the comp compre ress ssio ionn-te test stin ing g mach machin ine. e. 2. To crush crush the concr concrete ete furthe further, r, aggreg aggregate ate impactimpact-tes testin ting g machi machine ne will will be used. used. 3. The residu residuee from from the the impact impact-te -testi sting ng machin machinee will will then then be passed passed through through a sieve sieve of 250 250 micron. 4. The mate materia riall passin passing g throug through h 250 micro micron n sieve sieve will will be weighe weighed d to 0.6 0.6 grams grams in a sensitive balance. 5. The The mate materi rial al will will then then be put put into into the the fla flask sk of of the the extra extract ctin ing g unit unit and and is is heat heated ed to to 60-70 60-70 degree Celsius. 6. 7.5 ml of HCl HCl and and 7.5 7.5 ml ml of H2SO4 will will then then be added added to the flas flask k result resulting ing in white white fumes and then allowed to react for 15-20 15 -20 min until black fumes emerge out. ou t. 7. Then Then I wi will add add H2O2 drop by drop until brown fumes emerge out of the mix. mix. I will will keep keep adding peroxide for 3-4 times. 8. The mixtur mixturee will will be allowe allowed d to digest digest and and then then allowed allowed to cool cool after after whic which h a yellow yellow colour will be obtained obtained which shows shows the completion completion of digesti digestion. on. 9. I will will dilut dilutee the mix to to 100 ml and and filte filterr it with with Whatma Whatman n filter filter paper paper no. 42.
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10. I will obtain the filtrate for further further test of metal leaching on AAS (Atomic Absorption Spectrophotometer). This will enable me to to determine the metal concentration in in the filtrate. 3.4 DATA DATA ANALYSIS ANALYSIS
This is the stage where the data collected and recorded in the laboratory after various tests have have been conducted conducted on the concrete molds, the data data will be analyzed, analyzed, tabulated, tabulated, and presented in form form of graphs, flow-charts, pie charts or any other means of visual presentation. In order to derive a conclusion from the research, dat a interpretation shall be conducted. Statistical tools such as charts as well as graphs may be used to give a true true representation of the parameters being studied. studied. According According to the interprete interpreted d data, we will go back to our research research objectives objectives and assess if they were answered and hypothesis proven or not.
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APPENDICES APPENDIX 1 TIME SCHEDULE MONTHS SN
ACTIVITIES
1
Literature review
2
Invent Inventory ory Equipm Equipment ent Acquis Acquisiti ition on
3
Laboratory Experiments
4
Data analysis
5
Desk study
6
Conclusion
7
Report Report writin writing g and presen presentat tation ion
8
Corre Correct ctio ion n and and pres presen enta tati tion on
1
Key 1. January 2. February 3. March 4. April 5. May 6. June 7. July 8. August 9. September 10. October 11. November 12. December
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2
3
4
5
6
7
8
9
10
11
12
APPENDIX 2 BUDGET ESTIMATE SN
Activity
Estimated Cost (Ksh)
1
Equipment Cost
5,000
2
Travelling Cost
2,000
3
Research Expenses
5,000
4
Publications
1,000
5
Subsistence Allowance
2,000
6
Others
1,000
7
Total
16,000
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REFERENCES
1. Chaudhary, S., Misra, A., & Tripathi, B. (November (November 01, 2013). Strength and Abrasion Characteristics of ISF Slag Concrete. Journal of Materials in Civil Engineering, 25, 11, 1611-1618. 2. Gianoncelli Gianoncelli,, A., Zacco, A., Struis, Struis, R. P. W. J., Borgese, Borgese, L., Depero, L. E., & Bontempi, E. (January 01, 2013). Fly Ash Pollutants, Treatment and Recycling. 3. Halstead, Halstead, W. J., J., & Crumpton, Crumpton, C. F., F., American American Associati Association on of State State Highway Highway and Transportation Officials., United States., & National R esearch Council (U.S.). (1986). Use of fly ash in concrete. Washington, D.C: Transportation Research Board, National
Research Council. 4. Hooper, Hooper, R. (2002). (2002). Ferro-silicate slag from ISF zinc production as a sand replacement: A review. (Innovations in design with emphasis on seismic, wind, and environmental
loading; quality control and innovations in materials/hot weather concreting, 811-837). 5. Monosi, S., Giretti, Giretti, P., Moriconi, G., Favoni, O., & Collepardi, M. (January 01, 2001). Nonferrous slag as cementitious material and fine aggregate for con crete. 33-43. 6. Morrison, C., & Richardson, D. (December 01, 2004). Re-use of zinc smelting furnace slag in in concrete. Engineering Sustainability, 157, 4, 213-218. 7. Pepe, M. (2016). (2016). A conceptual model for designing recycled aggregate concrete for structural applications.
8. Shashidhara, S. M. S., & Vyas, A. K. (January 01, 2010). Properties of cement concrete with imperial smelting furnace slag as replacement of sand. Indian Concrete Journal, 84, 11, 41-49.
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9. Tripathi, B., & Chaudhary, S. (January (January 20, 2016). Performance based evaluation of ISF slag as a substitute of natural sand in concrete. Journal of Cleaner Production, 112, 672-683.
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