COALESCENCE OFSILICA FUME, CALCIUM ALUMINATE AND ALUMINUM OXIDEAND ITS EFFECT ON SOME MECHANICAL PROPERTIES OF NORMAL WEIGHT CONCRETEChapter 1: IntroductionAdmixtures have been used in concrete and mortar since at least the Roman Empire. The Romans found that certain materials such as milk, blood and lard, as well as organic materials such as molasses, eggs and rice paste allow greater workability in cementitious mixtures. (Terry Harris and Ara A. Jeknavorian, 2014). Chemical admixtures has five functions. First, the water-reducing admixtures which reduce the water content by 5 to 10 percent of the concrete mixture that attains the required slump using less water. It indicates a lower water-cement ratio that gives a high strength of concrete without adding more cement. The second function is to slow down the pace of setting time due to high temperature that may cause placing and finishing difficult and it is called retarding admixture. Accelerating admixtures tend to improve the concrete performance in an early time. It gives early strength development, reduce hydration, setting and curing time and speeds up the construction cycle. The second to the last function is the superplasticizers which is a bit related to the water-reducing admixture because it also reduce water content on the mixture by 12-30 percent. This admixtures is added on the jobsite that will improve those low to average slump and water-cement ratio. The last function gives us a corrosion-inhibiting admixtures that gives luxury to those water exposed structures such as highway bridges, seaports, sea based airports and structures that will highly exposed to chloride. Silica fume also known as micro silica is a by-product of the smelting process in the silicon and ferrosilicon industry. By-products of the production of silicon metal and the ferrosilicon alloys having silicon contents of 75% or more contain 8595% non-crystalline silica. Silica fume has been recognized as a pozzolanic admixture that is effective in enhancing the mechanical properties to a great extent. By using silica fume, it is easier to obtain compressive strengths of concrete. Addition of silica fume to concrete improves the durability of concrete through reduction in permeability and increase abrasion resistance of concrete. Calcium Aluminate cement also known as High Alumina Cement or (HAC)is a special cement compound that develops strength very quickly. It is also a resistance to mild acids and alkalies; sulfates, sea water, and pure water. They are similar to the more familiar Portland cements in that they both require water for hydration. HAC are rarely used for cast-in-place structural work, except for emergency repairs and foundation construction. HAC are not rapid setting. They are, however, rapid hardening; that is, they will develop as much strength in 24 hours as Portland cement concrete will achieve in 28 days. It should be cured for at least 24 hours, using a water spray or fog, ponding, wet burlap or a curing membrane.Aluminumoxide is a common, naturally occurringcompoundthats employed in various industries, most particularly in the production ofaluminum. There are many differentforms ofaluminumoxide, including both crystalline and non-crystalline forms. Its crystalline form, corundum, its hardness makes it suitable as an abrasive. In the present study, the compressive strength of self-compacting concrete with different amounts of aluminum oxide nanoparticles has been investigated. Aluminum oxide nanoparticles having an average particle size of 15 nm were partially added to cement paste (Portland cement together with super plasticizer) and the compressive strength of the specimens has been measured. The results indicate that aluminum oxide nanoparticles are able to improve compressive strength of concrete and modify the negative effects of adding super plasticizer. Aluminum oxide nanoparticle as a partial replacement of cement up to 4 %wt. could accelerate CSH (calcium silicate hydrate) gel formation as a result of increased amount of crystalline calcium hydroxide at the early age of hydration. The increased aluminum oxide nanoparticles' content of more than 4 % wt., leads to reduced compressive strength because of unsuitable dispersion of nanoparticles in the concrete matrix.1.1. The problem and its background1.1.1. Background of the StudyConcrete plays an important role in the societys infrastructure. It is the most widely used structural material in the construction industry and innovations are continuously being made to provide and perform the structural function of the concrete and its properties. According to The University of California Berkeley, it is estimated that the present consumption of concrete in the world is of the order of 10 billion tonnes (12 billion tons) every year. Concrete is the most construction choice material because of its properties that serve the purposes of the structure.Concrete is a classic material in construction industry, but it is not perfect. There are concrete problems that are categorized in two basic types, the structural strength and appearance. Majority of the structure like buildings, bridges, dams and tunnels used concrete for its strength. Concrete must possess a specified strength to perform its function as a structural material and its mix design is related to its strength. Another concrete problem is abrasion, it occurs due to sliding, rubbing, skidding and scraping on the concrete surface. There are certain number of factors that influenced the concrete abrasion resistance such as concrete strength, aggregate properties, finishing surface and type of hardeners. It is needed to determine the appropriate mix proportions to produce an abrasion resistant concrete. Another is a process called setting time of concrete, it is significant because it denotes when the concrete can be properly placed, consolidated and finished. It is based to the setting of cement paste thus cement properties can greatly affect the setting time of concrete. This are some properties of concrete that made the construction industry to continue innovating a chemical admixtures producing a well-developed concrete performance to maximize the structural function of concrete.

1.1.2. Statement of the ProblemThis study is conducted to determine if the three proportioned admixtures will help improve the mechanical properties of normal concrete weight. In this research the following questions are going to be answered: 1. How much strength it will attain for both flexural and compressive strength compare to the natural concrete weight?CompressiveFlexural

Control4000 psi650 psi

Proportion 16000 psi750 psi

Proportion 26000 psi750 psi

Proportion 36000 psi750 psi

2. How it will affect the workability of concrete?3. Which proportion of admixtures will give the best result?

1.2. Statement of the objectives1.2.1 General Objective/sThe objective of the study is to identify what proportion of admixtures such as Silica Fume, Aluminum Oxide and Calcium Aluminate with a total of 12% by weight of cement will give the best effect on the flexural and compressive strength of concrete.1.2.2 Specific Objective/s1.2.2.1. To study and identify the effects on compressive and flexural strength of concrete using the proportioned admixtures. Compressive and FlexuralStrength

Control4000 psi

With Admixtures6000 psi

1.2.2.2To identify the right admixtures proportion that will sustain a higher concrete properties on the 7th, 14th and 28th day of curing.

1.1. Significance of the studyThe study is significant to the following:1.3.1. To the construction industry:This study will be helpful to the construction industry such as Residential, Light commercial, Industrial, Heavy civil, Superstructure and Substructure. In a way that it will provide better method of producing innovative concrete mixtures and develop sustainable mixtures for future generations to come. High performance materials, mixtures were added to reduce cross sections and the volume of concrete it produced. Our target or aim in the study is to achieve a compressive strength of 6000psi or even higher that can be used or sufficient in certain structural elements like slabs, beams, retaining wall and foundation after achieving its 28th day of curing. As part of the fastest growing industry Concrete must keep evolving to satisfy the increasing demands of all its users. They are also intended to increase the durability of concrete structures to minimize the maintenance needs of concrete especially to the construction industry.1.3.2. To the consumer group:This study will be beneficiary to the owner which their ultimate objective is to get the greatest possible return on investment during the lifetime of the construction. For the contractor because they are capable to determine how much its use would save on the final total cost of the structure and for the concrete producer due to the highest standards of concrete mixtures it has produced.This is to ensure that the structures built will last for years to come, a long term economic benefit solutions to the consumer and it requires less maintenance costs than most other materials used in different construction projects.1.2. Scope and DelimitationsThis study aims to identify the effects of the coalescence of admixtures on some mechanical properties of a normal weight concrete by using combination of admixtures: silica fume, calcium aluminate, and aluminum oxide. In this research it will be observed if the mechanical properties of normal concrete shall be improved based on the particular mix proportions that the researchers will use. This study is limited to the determination of the parameters in a particular mix proportion of 1:1.5:3 and water cement ratio of 0.57 with the target mean strength of 10000 psi. The produced concrete will be tested with different composition, such concrete itself, and concrete with 12% of admixtures by weight of concrete. The admixtures will vary from 3 different percentage of the admixtures. Concrete + admixtures of silica fume with 6%, calcium aluminate with 4%, and aluminum oxide with 2%; and concrete + admixtures of silica fume with 4%, calcium aluminate with 6%, and aluminum oxide with 2%; and concrete + admixtures of silica fume with 4%, calcium aluminate with 4%, and aluminum oxide with 4%. The specimen will be tested on its 7th, 14th and 28th day of curing using Universal Testing Machine (UTM), to be able to know its flexural and compressive strengthincluding slump test and unit weight.The study is delimited to the setting time of concrete, bleeding, segregation, hydration, air entrainment, fire resistance, thermal mass, freeze thawing and chemical properties of a concrete. 1.3. Definition of terms Coalescence - to come together to form one group or mass Abrasion -is the process of scuffing, scratching, wearing down, marring, or rubbing away. It can be intentionally imposed in a controlled process using an abrasive. Abrasion can be an undesirable effect of exposure to normal use or exposure to the elements. Superplasticizers - also known ashigh range water reducers, are chemical admixtures used where well-dispersed particle suspension is required. Alkalies -is abasic,ionicsaltof analkali metaloralkaline earth metalchemical element. Silica fume - is a byproduct of producing silicon metal or ferrosilicon alloys. Calcium Aluminate cement - is a unique class of cement that is different than ordinary Portland cement (OPC), particularly due to the chemical make-up. CAC contains a far greater amount of alumina and a far less amount of silica. Cementitious - having the properties ofcement Pozzolanic Cement admixtures Dispersion - the scattering of the values of a frequency distribution from an average

Chapter 2: Review of Related literature2.1 Related StudiesIn an article entitled The effect of aluminum oxide nanoparticles on the compressive strength and structure of self-compacting concrete published by Magazine of Concrete Research (2011).It was stated in the present study, that the compressive strength with different amounts of aluminum oxide nanoparticles has been investigated. Aluminum oxide nanoparticles having an average particle size of 15 nm were partially added to cement paste (Portland cement together polycarboxylatesuperplasticizer) and the compressive strength of the specimens has been measured. The results indicate that aluminum oxide nanoparticles are able to improve compressive strength of concrete and modify the negative effects of adding polycarboxylatesuperplasticiser. The increased aluminum oxide nanoparticles' content of more than 4 % weight, leads to reduced compressive strength because of unsuitable dispersion of nanoparticles in the concrete matrix.2.1.1 Related StudiesIn 2014, Aysu published an article entitled CALCIUM ALUMINATE CEMENT. The article made a research about the setting time of calcium aluminate cement and it is similar to Portland cement. The test was done by using the Vicat needle method on a paste at standard consistence. According to the research, the British and European Standard requires that the initial setting time shall be not less than 2 hour, and the final setting time not more than 8hour. In comparison made by the research with Portland cement and Calcium Aluminate cement the initial and final setting time is much shorter for the Calcium Aluminate cement; this may be prominent in concretes and mortars. Decreasing lime-to-alumina ratio, the setting time of calcium aluminate phases result to progressively longer. It has been observed that the setting time increases when pastes mixed in small quantities with temperature up to about 27C, further increased in temperature decreases the setting time. However, the effect is less noticeablein concrete mixed in normal quantitiesdue to the range of effects including self-heating and the heating due to the friction during mixing of the aggregates present in the concrete. The setting time can also be adjusted by the use of admixtures and additives.2.1.3. Related StudiesThere are some studies on the effect of adding aluminum oxide nanoparticles to cementing materials. Based on the article of Mohammad Reza, et.al (2012), Aluminum Oxide Nanoparticles in Cement Mortar when adding aluminum oxide nanoparticles up to 3% of weight, each of the compressive, tensile, and flexural strengths increased. When the amount of nanoparticles added was more than 5% of weight, the above strengths decreased to less than the strength of ordinary cement mortar.

2.2 Related StudiesAccording to the study of M. Mazloom, et.al (2004) entitled Effect of Silica fume on Mechanical Properties of High- strength Concrete presents the results of experimental work on short- and long- term mechanical properties of high- strength concrete containing different levels of silica fume. They have investigated the effects of binder systems containing different levels of silica fume on fresh and mechanical properties of concrete. Their work focused more on concrete mixes having a water ratio of 0.35 and a constant total binder content of 500 kg/m3. They used different percentages of silica fume like 0%, 6%, 10% and 15%. In their study it has been observed that the increase of percentages of silica fume will also increase the compressive strength of concrete in 28 days but the workability of concrete decrease.

Chapter 3: Materials and Methods3.1 Materials3.1.1 AdmixturesAdmixtureSource of material

Silica fumeAngono, Rizal

Calcium AluminateAngono, Rizal

Aluminum OxideFairview, Quezon City

3.1.2 AggregatesCoarse AggregatesSizeSource of material

3/4Balintawak, QC

3/8Balintawak, QC

Fine AggregatesSource of material

Bistay SandBalintawak, QC

3.1.3 Binding MaterialBrandSource of material

Lafarge Fortune Type 1Maypulo, Batangas

3.1.4 WaterPotable water 3.2 Mix proportionsMixtureWater/Cementratio*Silica Fume*Calcium Aluminate*AluminumOxide

Control0.57NoneNoneNone

P10.576%4%2%

P20.574%6%2%

P30.574%4%4%

*Percentage of admixtures is by weight of cement.

3.3 Method of testingI. ASTM C 143 03 Standard Test Method for Slump of Hydraulic- Cement ConcretePROCEDURE1. Take a sample from freshly mixed concrete mixture that will represent the entire batch. 2. Dampen the cone mould, base plate and tampering rod. Set the cone over the base plate and place it over a smooth, moist, non-absorbent, level surface large enough to accommodate both the slumped concrete and the slump cone. The cone should be clamped on both sides and stand or foot must be on the base plate to hold the cone firmly.3. Fill the cone in three layers and each layer is approximately 1/3 full of its volume. After filling the 1st layer rod the layer with 25 strokes using 5/8-inch diameter x 24-inch-long hemispherical tip steel tamping rod. Uniformly distribute the rodding in the entire cross section of the layer. Repeat the process for the 2nd and 3rd layer with the same number of strokes. 4. Remove the excess concrete on the tip of the cone using tamping rod as a screed. Clean overflow from base of cone.5. Slowly lift the mould within 5 seconds from the concrete in a vertical direction and avoid lateral motions. Note that the sample must obtain a passing slump of 4 inches.

II. ASTM C 192 06 Standard Practice for Making and Curing Concrete Test Specimens in the LaboratoryPROCEDUREMaking of molds1. Mold specimens as near as practicable to the place where they are to be stored during the first 24 h. If it is not practicable to mold the specimens where they will be stored, move them to the place of storage immediately after being struck off. Place molds on a rigid surface free from vibration and other disturbances. Avoid jarring, striking, tilting, or scarring of the surface of the specimens when moving the specimens to the storage place.2. Place the concrete in the molds using a scoop, blunted trowel, or shovel. Select each scoopful, trowelful, or shovelful of concrete from the mixing pan to ensure that it is representative of the batch.3. Move the scoop or trowel around the top edge of the mold as the concrete is discharged in order to ensure a symmetrical distribution of the concrete and to minimize segregation of coarse aggregate within the mold. Further distribute the concrete by use of a tamping rod prior to the start of consolidation. In placing the final layer the operator shall attempt to add an amount of concrete that will exactly fill the mold after compaction. Do not add non-representative samples of concrete to an underfilledmold.4. Make specimens in layers as indicated in Table 1.

5. Preparation of satisfactory specimens requires different methods of consolidation. The methods of consolidation are rodding, and internal or external vibration (refer to table 1).6. After consolidation strike off the specimen with a trowel or float, then trowel the minimum amount required to form the concrete in the opening concentrically with the rest of the specimen. Use a screed curved to the radius of the specimen to more precisely shape and finish the concrete in the opening.Curing 1. Cure the specimen on the 7th, 14th and 28th day.

III. ASTM C39 / C39M Standard Method of Test for Compressive Strength of Cylindrical Concrete Specimens PROCEDURE1. Compression tests of moist-cured specimens shall be made as soon as practicable after removal from moist storage.2. Test specimens shall be kept moist by any convenient method during the period between removals from moist storage and testing. They shall be tested in the moist condition.3. Zero Verification and Block Seating - Prior to testing the specimen, verify that the load indicator is set to zero. In cases where the indicator is not properly set to zero, adjust the indicator. As the spherically-seated block is brought to bear on the specimen, rotate its movable portion gently by hand so that uniform seating is obtained.4. Apply the load continuously and without shock.5. During application of the first half of the anticipated loading phase, a higher rate of loading shall be permitted. Apply the higher loading rate in a controlled manner so that the specimen is not subjected to shock loading.6. Do not adjust the rate of movement (platen to crosshead) as the ultimate load is being approached and the stress rate decreases due to cracking in the specimen.Apply the compressive load until the load indicator shows that the load is decreasing steadily and the specimen displays a well-defined fracture pattern.

Chapter IVPresentation, Analysis and Interpretation of Data4.1 Physical Properties of AggregatesPhysical Properties

Coarse AggregatesSand

3/43/8

Specific Gravity2.692.852.78

Unit Weight (Rodded)

Trial 11558.57 kg/m31805.36 kg/ m31597.5 kg/ m3

Trial 21564.29 kg/ m31839.64 kg/ m31608.93 kg/ m3

Unit Weight (Loose)

Trial 11411.79 kg/ m31612.5 kg/ m31474.64 kg/ m3

Trial 21360.36 kg/ m31681.07 kg/ m31497.5 kg/ m3

Absorption1.15% 1.0%1.63%

Moisture Content1.22%1.0%7.21%

Fineness Modulus3.041.4%2.75%

4.2 Concrete Mix DesignCylindrical MoldBatch Mix Design

ContentControlP1P2P3

Cement (kg)

Water (kg)

3/4 Gravel (kg)

3/8 Gravel (kg)

Sand (kg)

Admixture

Silica Fume (kg)

Calcium Aluminate (kg)

Aluminum Oxide (kg)

Beam MoldBatch Mix Design

ContentControlP1P2P3

Cement (kg)

Water (kg)

3/4 Gravel (kg)

3/8 Gravel (kg)

Sand (kg)

Admixture

Silica Fume (kg)

Calcium Aluminate (kg)

Aluminum Oxide (kg)

4.3Concrete SlumpAdmixture ProportionsSlump (mm)

Control101.6

P1101.6

P2203.2

P3254

4.4Cost AnalysisContentUnitQuantityCost (php)Total Cost(php)

3/4 Gravelbag2830840

3/8 Gravelbag1230360

Sandbag4123943

Cementbag72201540

Silica Fumekg.1148528

Calcium Aluminatekg.1545675

Aluminum Oxidekg.6120720

TOTAL

5606

4.5Compressive Strength Results

7th Day Compressive Strength Test ResultsCOMPRESSIVE STRENGTH (MPa)

ADMIXTURE PROPORTIONTRIAL 1TRIAL 2TRIAL 3AVERAGE

CONTROL

P1

P2

P3

14th Day Compressive Strength Test ResultsCOMPRESSIVE STRENGTH (MPa)

ADMIXTURE PROPORTIONTRIAL 1TRIAL 2TRIAL 3AVERAGE

CONTROL

P1

P2

P3

28th Day Compressive Strength Test ResultsCOMPRESSIVE STRENGTH (MPa)

ADMIXTURE PROPORTIONTRIAL 1TRIAL 2TRIAL 3AVERAGE

CONTROL

P1

P2

P3

4.6Flexural Strength Results7th Day Flexural Strength Test ResultsFLEXURAL STRENGTH (MPa)

ADMIXTURE PROPORTIONTRIAL 1TRIAL 2TRIAL 3AVERAGE

CONTROL

P1

P2

P3

14th Day Flexural Strength Test ResultsFLEXURAL STRENGTH (MPa)

ADMIXTURE PROPORTIONTRIAL 1TRIAL 2TRIAL 3AVERAGE

CONTROL

P1

P2

P3

28th Day Flexural Strength Test ResultsFLEXURAL STRENGTH (MPa)

ADMIXTURE PROPORTIONTRIAL 1TRIAL 2TRIAL 3AVERAGE

CONTROL

P1

P2

P3

Chapter VSummary, Findings and Conclusion5.1 Summary of Findings1. The proportion that gave the best compressive and flexural strength was the proportion 3 which compose of 4% of Silica Fume, 4% of Calcium Aluminate and 4% of Aluminum Oxide. 2. Concrete with proportioned admixtures highly affects the workability of concrete especially if same water content for the normal weight of concrete is used. 3. Aluminum Oxide is a hard to find additive and a little bit expensive than other admixtures.

Conclusion: The investigation on the effects of coalescence of admixtures on compressive and flexural strength, the researchers concluded the following:

1. The compressive strength of normal weight concrete with admixtures failed to have a higher strength than the conventional. Proportion 3 which has equal percentages of admixtures gave closer results.2. None of the concrete with admixtures attained the 28th day required compressive strength of 28 Mpa set by ACI 318. Proportion 3 delivered the highest result with a compressive strength of ____ Mpa, but still failed to meet minimum required compressive strength. However the control concrete gave a ___ Mpa which passed the ACI compressive strength requirement. Recommendation:Based on the conclusions drawn, the following were recommended:1. The 12% by weight of cementcoalescence of silica fume, calcium aluminate and aluminium oxide is not recommended for concrete as an additive for strength acceleration as it produced a below minimum compressive and flexural strength requirement provided by the ACI. 2. For further studies the higher percentage of the aluminium oxide the higher strength it will produce.3. For further studies, reduced the amount of water per batch mix if these 3 admixtures will be use so that workability will be attained. 4. Explore other mechanical properties of concrete, test for the concrete initial and final setting time. 5. For further research, we recommend to use a new admixture into the mix such as calcium carbonate or fly ash replacing the aluminium oxide since it is a little bit expensive than those two and might give greater results. Also with replacing the aluminium oxide use a total 14% of admixtures by weight of cement.

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