UTILIZATION OF HYPO SLUDGE WASTE FROM PAPER INDUSTRY IN THE PRODUCTION OF CONCRETE A Project Study Presented to the Department of Civil Engineering and Environmental & Sanitary Engineering College of Engineering, Architecture, Fine Arts & Computing Sciences Batangas State University Batangas City In Partial Fulfilment of the Requirements for the Degree of Bachelor of Science in Civil Engineering By: Belegal, Adrian M. Kano, Marikar A. Lising, Jerick A. October 2012 Table of Contents LIST OF TABLESiv LIST OF FIGURESiv CHAPTER I1 INTRODUCTION1
STATEMENT OF THE PROBLEM4 NULL HYPOTHESES5 SCOPE AND LIMITATION OF THE STUDY5 SIGNIFICANCE OF THE STUDY6 CONCEPTUAL FRAMEWORK7 DEFINITION OF TERMS8 CHAPTER II11 CONCEPTUAL LITERATURE11 RELATED LITERATURE31 SYNTHESIS34 CHAPTER III36 RESEARCH DESIGN36 MATERIALS AND EQUIPMENTS38 PREPARATION OF MATERIALS41 TESTING OF MATERIALS43 MIXING AND PREPARATION OF TEST SPECIMEN43 DETERMINATION OF COMPRESSIVE STRENGTH44 DETERMINATION OF FLEXURAL STRENGTH45 STATISTICAL TREATMENT45 FLOW OF THE EXPERIMENTAL STUDY47 LIST OF TABLES TABLE No. | TITLE| 1| Classes of Aggregates| | Composition of Portland cement with chemical composition and weight percentage| 3| A table of admixtures and their functions| 4| Properties of Raw Hypo Sludge| 5| Properties of Hypo Sludge as Cement Ingredient| 6| Comparison of Cement and Hypo Sludge| 7| Number of Specimens Tested for Compression| 8| Number of Test Specimens for Flexural Strength Test At 14 Days Curing Period| LIST OF FIGURES FIGURE No. | TITLE| 1| Conceptual Paradigm of the Study| 2| A flow diagram of Portland cement production| 3| Schematic diagram of rotary kiln| | Schematic illustration of the pores in calcium silicate through different stages of hydration| 5| Rate of heat evolution during the hydration of Portland cement| 6| Schematic drawings to demonstrate the relationship between the water/cement ratio and porosity| 7| A plot of concrete strength as a function of the water to cement ratio| 8| Factory outlet hypo sludge| 9| Flow chart of the experimental study| CHAPTER I THE PROBLEM AND ITS BACKGROUND INTRODUCTION Over 300 million tons of industrial wastes are being produced per annum by chemical and agricultural process in Philippines.
These materials are the major contributor to disposal and health hazards to our environment. The wastes like phosphogypsum, fluorogypsum and red mud contain obnoxious impurities which adversely affect the strength and other properties of building materials based on them. Out of several wastes being produced at present, the use of phosphogypsum, fluorogypsum, lime sludge, hypo sludge, red mud, and mine tailing is of paramount significance to protect the environment (Palanisamy, 2010). Paper making industries generally produces a large amount of solid waste.
Paper fibres can be recycled only a limited number of times before they become too short or weak to make high quality paper. It means that the broken, low – quality paper fibres are separated out to become waste sludge. All the inks, dyes, coatings, pigments, staples and “stickies” (tape, plastic films, etc. ) are also washed off the recycled fibres to join the waste solids. The shiny finish on glossy magazine – type paper is produced using a fine kaolin clay coating, which also becomes solid waste during recycling (Srinivasan and Sathiya, 2010).
This paper mill sludge consumes a large percentage of local landfill space for each and every year. Worse yet, some of the wastes are land spread on cropland as a disposal technique, raising concerns about trace contaminants building up in soil or running off into area lakes and streams. Some companies burn their sludge in incinerators, contributing to our serious air pollution problems. To reduce disposal and pollution problems emanating from these industrial wastes, it is most essential to develop profitable building materials from them.
From the preliminary waste that comes out from the various processes in paper industries, hypo sludge will be taken out for our project to replace the cement utilization in concrete. It has low calcium, maximum calcium chloride and minimum amount of silica. Also the hypo sludge behaves like cement because of silica and magnesium properties present in the waste material which contribute to improve the setting of the concrete. By utilizing the hypo sludge, it will help to minimize the maximum demand for cement and also to provide the most economical concrete from it.
Energy plays a crucial role in growth of developing countries like Philippines. In the context of low availability of non – renewable energy resources coupled with the requirements of large quantities of energy for building materials like cement, the importance of using industrial waste cannot be underestimated. During manufacturing of 1 ton of Ordinary Portland Cement (OPC) we need about 1 – 1? tons of earth resources like limestone, etc. Further during manufacturing of 1 ton of Ordinary Portland Cement an equal amount of carbon di – oxide are released into the atmosphere.
The carbon – di – oxide emissions act as a silent killer in the environment under various forms. In this backdrop, the search for cheaper substitute to OPC is a needful one which the study will provide information. (Online, 2012) Under the Batangas City E-Code, Art. XII, Sec. 84 states that “The City hereby adopts the following regulation on the use of plastic and Styrofoam materials for packaging in all business transactions within the City. The use of plastic bags as packaging materials for dry goods is prohibited.
All business establishments shall pack dry good products in biodegradable materials such as recycled product carton boxes and paper bags. ” (See Appendix A for the whole article) Because of the bill stated above there will be an increase on the demand on paper bags and carton boxes that will also lead to the high production of paper products. It also means that the waste will increase in number too. This will be an advantage of the study to utilize those wastes in producing concrete for construction purposes such as housing projects for the homeless that will be cheaper compared to the conventional concrete.
In other words, this study aims to utilize solid waste material (i. e. hypo sludge) from paper industries which can be a great help for the disposal of the said waste. Also, this will be a source of low in price but high quality cement replacement in making concrete for construction purposes compared to the conventional. STATEMENT OF THE PROBLEM The study aims to utilize hypo sludge waste from paper industry in the production of concrete. Specifically, it aims to provide answer to the following questions: 1. What are the properties of the concrete upon varying the hypo sludge to cement ratio in terms of the following: 1. . Concrete porosity 1. 2. Concrete workability 1. 3. Concrete setting 1. 4. Compressive strength 1. 5. Flexural strength 2. Is there a significant difference upon varying the hypo sludge to cement ratio on the above mentioned properties? 3. Which among the proportion gives the best quality of concrete based from the standard? 4. How do the properties of the concrete using the best proportion as compared to the standard? 5. Is there a significant difference on the properties of concrete using the best proportion compare to the standard? NULL HYPOTHESES
There is no significant difference upon varying the hypo sludge to cement ratio on concrete porosity, concrete workability, concrete setting, compressive and flexural strength of concrete. There is no significant difference on the properties of concrete using the best proportion compare to the conventional. SCOPE AND LIMITATION OF THE STUDY This study will focus on identifying the properties of the concrete upon replacing cement via 30%, 50% and 70% of hypo sludge. Specifically, the properties that the researchers will be considering are concrete porosity, concrete workability, concrete setting, compressive strength and flexural strength.
Moreover, the researchers will conduct compressive and flexural strength tests to determine which among the samples will give the best quality of concrete as compare to the standard. After thorough analysis that will be done to the observations and tests result, the researchers will cite how these hypo sludge affects the strength of concrete and what certain percentage replacement of cement by hypo sludge will be required to obtain its optimum strength. Also, the researchers will cite the properties of these hypo sludge making it suitable as a partial replacement for cement on producing economical and high strength concrete.
SIGNIFICANCE OF THE STUDY The researchers believe that this study will be beneficial to the following: To our environment, because it can replace the cement in attaining concrete that will be very much helpful to minimize the maximum degradation in environment due to cement production and safeguard the ozone layer from greenhouse gases. To the local paper industries, this study will contribute to their pool of knowledge in utilizing such waste that is not known to everybody that has a good effect on the environment.
And also it will help to the disposal of the waste. To the civil engineering students, the results of this study will provide them the knowledge about an economical and environmental friendly cement replacement which promotes green building to minimize the harmful effects of the production of ordinary Portland cement. And to have an idea to save our environment at the same time to minimize the cost of every construction which uses cement as the main ingredient to produce conventional concrete.
To the civil engineering department of Batangas State University, the gathered data will provide the faculty members learning about a new engineering material which can be used in the absence of concrete which has the same properties of it. To the present researchers, this study will serve as a tool of knowledge for them to be more knowledgeable and to improve their skills in studying the merely impact of the new engineering material to the people and its environment and their chosen field to become globally competitive.
Finally to the future researchers, this study can be used as a reference for their future study to further augment their chosen topic. And to motivate every individual that we can utilize such waste to produce something useful. CONCEPTUAL FRAMEWORK This research is intended to investigate and analyse the possibility of using hypo sludge waste from paper industries as a partial replacement to cement to produce an economical and high strength concrete that can be easily adopted in the field. This is also an attempt to reduce the production of cement which causes emissions of greenhouse gases in the atmosphere.
For this, the researchers will gather all the data needed and identify the strength parameters of concrete, perform different strength tests for concrete and compare the strength and cost difference of conventional and partially replaced concrete. To have a better perspective of the study, the conceptual paradigm is presented as shown in Figure 1. PROCESS * Determination of properties * Identifying the best proportion * Comparison to conventional OUTPUT Best proportion of cement and hypo sludge INPUT Varying proportion of cement and hypo sludge Figure 1 Conceptual Paradigm of the Study
DEFINITION OF TERMS The following terms are used in the study to conceptually and operationally define for better and clearer understanding: Cement. Act as a binding substance that sets and hardens independently which is widely used as construction material to do civil works. Concrete Porosity. Voids in concrete can be filled with air or with water. Air voids are an obvious and easily-visible example of pores in concrete. Broadly speaking, the more porous the concrete, the weaker it will be. Probably the most important source of porosity of concrete is the ‘water to cement’ ratio. (Winter, N. 2005. Understanding Concrete) Concrete Setting. The stiffening of the concrete after it has been placed. A concrete can be ‘set’ in that it is no longer fluid, but it may still be very weak that you may not able to walk on it. (Winter, N. , 2005. Understanding Concrete) Compressive Strength. It is the capacity of a material or structure to withstand axially directed pushing forces. (Pytel, A. , 1987. Strength of Materials) Concrete Workability. It is the ability of a fresh concrete mix to fill the form/mould properly with the desired work (vibration) and without reducing the concrete’s quality.
Flexural Strength. The strength of a material in bending expressed as the stress on the outermost fibres of a bent specimen (i. e. concrete), at the instant of failure. (Pytel, A. , 1987. Strength of Materials) Fluorogypsum. This is generated during the production of hydro fluoric acid from fluorspar, a mineral composed of calcium fluoride, and sulphuric acid. Hypo Sludge. This contains low calcium and maximum calcium chloride and minimum amount of silica. Hypo sludge behaves like cement because of silica and magnesium properties. This silica and magnesium improve the setting of the concrete.
Incinerators. A machine which is used in a waste treatment process that involves the combustion of organic substances contained in waste materials Mine Tailing. These are materials left over after extraction of valuable minerals from ore. Ordinary Portland cement (OPC). The most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout. Phosphogypsum. It refers to the gypsum formed as a by-product of processing phosphate ore into fertilizer with sulphuric acid. Red Mud.
A solid waste product of the Bayer process which is the principal industrial means of refining bauxite in order to provide alumina as raw material for the electrolysis of aluminium by the Hall–Heroultn process. Water to Cement Ratio. It is defined as the mass of water divided by the mass of cement in a mix. Consequently, as the water to cement ratio increases, the porosity of the cement paste in the concrete also increases. As the porosity increases, the compressive strength of the concrete will decrease. (Winter, N. , 2005. Understanding Concrete) CHAPTER II REVIEW OF RELATED LITERATURE
This chapter deals with the foreign and local studies which are relevant to the study. It also presents some pertinent concepts from books and magazine that provide discussion about the utilization of industry waste to produce concrete. CONCEPTUAL LITERATURE To begin a discussion on cement, one might logically begin with a definition. According to Merriam-Webster’s Dictionary (2012), cement refers to a powder of alumina, silica, lime, iron oxide, and magnesium oxide burned together in a kiln and finely pulverized and used as a binding element or a substance to make objects adhere to each other.
The importance of concrete in modern society cannot be underestimated. Look around you and you will find concrete structures everywhere such as buildings, roads, bridges, and dams. There is no escaping the impact concrete makes on your everyday life. Concrete is a composite material which is made up of filler and a binder. The binder (cement paste) “glues” the filler together to form a synthetic conglomerate. The constituents used for the binder are cement and water, while the filler can befineor coarse aggregate.
Although there are other cements for special purposes, this module will focus solely on Portland cement and its properties. The production of Portland cement begins with the quarrying of limestone, CaCO3. Huge crushers break the blasted limestone into small pieces. The crushed limestone is then mixed with clay (or shale), sand, and iron ore and ground together to form a homogeneous powder. However, this powder is microscopically heterogeneous. (See flowchart. ) Figure 2 A flow diagram of Portland cement production The mixture is heated in kilns that are long rotating steel cylinders on an incline.
The kilns may be up to 6 meters in diameter and 180 meters in length. The mixture of raw materials enters at the high end of the cylinder and slowly moves along the length of the kiln due to the constant rotation and inclination. At the low end of the kiln, a fuel is injected and burned, thus providing the heat necessary to make the materials react. It can take up to 2 hours for the mixture to pass through the kiln, depending upon the length of the cylinder. Figure 3 Schematic diagram of rotary kiln As the mixture moves down the cylinder, it progresses through four stages of transformation.
Initially, any free water in the powder is lost by evaporation. Next, decomposition occurs from the loss of bound water and carbon dioxide. This is called calcination. The third stage is called clinkering. During this stage, the calcium silicates are formed. The final stage is the cooling stage. The marble-sized pieces produced by the kiln are referred to as clinker. Clinker is actually a mixture of four compounds which will be discussed later. The clinker is cooled, ground, and mixed with a small amount of gypsum (which regulates setting) to produce the general-purpose Portland cement.
Water is the key ingredient, which when mixed with cement, forms a paste that binds the aggregate together. The water causes the hardening of concrete through a process called hydration. Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydrates or hydration products. Details of the hydration process are explored in the next section. The water needs to be pure in order to prevent side reactions from occurring which may weaken the concrete or otherwise interfere with the hydration process.
The role of water is important because the water to cement ratio is the most critical factor in the production of “perfect” concrete. Too much water reduces concrete strength, while too little will make the concrete unworkable. Concrete needs to be workableso that it may be consolidated and shaped into different forms (i. e… walls, domes, etc. ). Because concrete must be both strong and workable, a careful balance of the cement to water ratio is required when making concrete. Aggregates are chemically inert, solid bodies held together by the cement.
Aggregates come in various shapes, sizes, and materials ranging from fine particles of sand to large, coarse rocks. Because cement is the most expensive ingredient in making concrete, it is desirable to minimize the amount of cement used. 70 to 80% of the volume of concrete is aggregate keeping the cost of the concrete low. The selection of an aggregate is determined, in part, by the desired characteristics of the concrete. For example, the density of concrete is determined by the density of the aggregate.
Soft, porous aggregates can result in weak concrete with low wear resistance, while using hard aggregates can make strong concrete with a high resistance to abrasion. Aggregates should be clean, hard, and strong. The aggregate is usually washed to remove any dust, silt, clay, organic matter, or other impurities that would interfere with the bonding reaction with the cement paste. It is then separated into various sizes by passing the material through a series of screens with different size openings. Table 1 Classes of Aggregates CLASS| EXAMPLES OF AGGREGATES USED| USES|
Ultra-lightweight| vermiculite, ceramic spheres, perlite| Lightweight concrete which can be sawed or nailed, also for its insulating properties| Lightweight| expanded clay, shale or slate, crushed brick| Used primarily for making lightweight concrete for structures, also used for its insulating properties. | Normal weight| crushed limestone, sand, river gravel, crushed recycled concrete| Used for normal concrete projects| Heavyweight| steel or iron shot, steel or iron pellets| Used for making high density concrete for shielding against nuclear radiation|
The choice of aggregate is determined by the proposed use of the concrete. Normally sand, gravel, and crushed stone are used as aggregates to make concrete. The aggregate should be well-graded to improve packing efficiency and minimize the amount of cement paste needed. Also, this makes the concrete more workable. PROPERTIES OF CONCRETE Concrete has many properties that make it a popular construction material. The correct proportion of ingredients, placement, and curing are needed in order for these properties to be optimal. Good-quality concrete has many advantages that add to its popularity.
First, it is economical when ingredients are readily available. Concrete’s long life and relatively low maintenance requirements increase its economic benefits. Concrete is not as likely to rot, corrode, or decay as other building materials. Concrete has the ability to be molded or cast into almost any desired shape. Building of the molds and casting can occur on the work-site which reduces costs. Concrete is a non-combustible material which makes it fire-safe and able withstanding high temperatures. It is resistant to wind, water, rodents, and insects. Hence, concrete is often used for storm shelters.
Concrete does have some limitations despite its numerous advantages. Concrete has a relatively low tensile strength (compared to other building materials), low ductility, low strength-to-weight ratio, and is susceptible to cracking. Concrete remains the material of choice for many applications regardless of these limitations. HYDRATION OF PORTLAND CEMENT Concrete is prepared by mixing cement, water, and aggregate together to make a workable paste. It is molded or placed as desired, consolidated, and then left to harden. Concrete does not need to dry out in order to harden as commonly thought.
The concrete (or specifically, the cement in it) needs moisture to hydrate and cure (harden). When concrete dries, it actually stops getting stronger. Concrete with too little water may be dry but is not fully reacted. The properties of such a concrete would be less than that of a wet concrete. The reaction of water with the cement in concrete is extremely important to its properties and reactions may continue for many years. This very important reaction will be discussed in detail in this section. Portland cement consists of five major compounds and a few minor compounds.
The composition of a typical Portland cement is listed by weight percentage in Table 2. Table 2 Composition of Portland cement with chemical composition and weight percentage CEMENT COMPOUND| WEIGHT PERCENTAGE| CHEMICAL FORMULA| Tricalcium silicate| 50 %| Ca3SiO5 or 3CaO. SiO2| Dicalcium silicate| 25 %| Ca2SiO4 or 2CaO. SiO2| Tricalcium aluminate| 10 %| Ca3Al2O6 or 3CaO. Al2O3| Tetracalcium aluminoferrite| 10 %| Ca4Al2Fe2O10 or 4CaO. Al2O3. Fe2O3| Gypsum| 5 %| CaSO4. 2H2O| When water is added to cement, each of the compounds undergoes hydration and contributes to the final concrete product.
Only the calcium silicates contribute to strength. Tricalcium silicate is responsible for most of the early strength (first 7 days). Dicalcium silicate, which reacts more slowly, contributes only to the strength at later times. Tricalcium silicate will be discussed in the greatest detail. The equation for the hydration of tricalcium silicate is given by: Tricalcium silicate + Water —> Calcium silicate hydrate + Calcium hydroxide + heat 2Ca3SiO5 + 7H2O —> 3CaO. 2SiO2. 4H2O + 3 Ca(OH)2 + 173. 6kJ Upon the addition of water, tricalcium silicate rapidly reacts to release calcium ions, hydroxide ions, and a large amount of heat.
The pH quickly raises to over 12 because of the release of alkaline hydroxide (OH-) ions. This initial hydrolysis slows down quickly after it starts resulting in a decrease in heat evolved. The reaction slowly continues producing calcium and hydroxide ions until the system becomes saturated. Once this occurs, the calcium hydroxide starts to crystallize. Simultaneously, calcium silicate hydrate begins to form. Ions precipitate out of solution accelerating the reaction of tricalcium silicate to calcium and hydroxide ions (Le Chatlier’s principle).
The evolution of heat is then dramatically increased. The formation of the calcium hydroxide and calcium silicate hydrate crystals provide “seeds” upon which more calcium silicate hydrate can form. The calcium silicate hydrate crystals grow thicker making it more difficult for water molecules to reach the anhydrate tricalcium silicate. The speed of the reaction is now controlled by the rate at which water molecules diffuse through the calcium silicate hydrate coating. This coating thickens over time causing the production of calcium silicate hydrate to become slower and slower. Figure 4
Schematic illustration of the pores in calcium silicate through different stages of hydration The above diagrams represent the formation of pores as calcium silicate hydrate is formed. Note in diagram (a) that hydration has not yet occurred and the pores (empty spaces between grains) are filled with water. Diagram (b) represents the beginning of hydration. In diagram (c), the hydration continues. Although empty spaces still exist, they are filled with water and calcium hydroxide. Diagram (d) shows nearly hardened cement paste. Note that the majority of space is filled with calcium silicate hydrate.
That which is not filled with the hardened hydrate is primarily calcium hydroxide solution. The hydration will continue as long as water is present and there are still anhydrate compounds in the cement paste. Dicalcium silicate also affects the strength of concrete through its hydration. Dicalcium silicate reacts with water in a similar manner compared to tricalcium silicate, but much more slowly. The heat released is less than that by the hydration of tricalcium silicate because the dicalcium silicate is much less reactive. The products from the hydration of dicalcium silicate are the same as those for tricalcium silicate:
Dicalcium silicate + Water —> Calcium silicate hydrate + Calcium hydroxide + heat2Ca2SiO4 + 5H2O —> 3CaO. 2SiO2. 4H2O + Ca(OH)2 + 58. 6kJ The other major components of Portland cement, tricalcium aluminate and tetracalcium aluminoferrite also react with water. Their hydration chemistry is more complicated as they involve reactions with the gypsum as well. Because these reactions do not contribute significantly to strength, they will be neglected in this discussion. Although we have treated the hydration of each cement compound independently, this is not completely accurate.
The rate of hydration of a compound may be affected by varying the concentration of another. In general, the rates of hydration during the first few days ranked from fastest to slowest are: tricalcium aluminate > tricalcium silicate > tetracalcium aluminoferrite > dicalcium silicate Heat is evolved with cement hydration. This is due to the breaking and making of chemical bonds during hydration. The heat generated is shown below as a function of time. Figure 5 Rate of heat evolution during the hydration of Portland cement The stage I hydrolysis of the cement compounds occurs rapidly with a temperature increase of several degrees.
Stage II is known as the dormancy period. The evolution of heat slows dramatically in this stage. The dormancy period can last from one to three hours. During this period, the concrete is in a plastic state which allows the concrete to be transported and placed without any major difficulty. This is particularly important for the construction trade who must transport concrete to the job site. It is at the end of this stage that initial setting begins. In stages III and IV, the concrete starts to harden and the heat evolution increases due primarily to the hydration of tricalcium silicate.
Stage V is reached after 36 hours. The slow formation of hydrate products occurs and continues as long as water and not hydrated silicates are present. STRENGTH OF CONCRETE The strength of concrete is very much dependent upon the hydration reaction just discussed. Water plays a critical role, particularly the amount used, hence the strength of concrete increases when less water is used to make concrete. The hydration reaction itself consumes a specific amount of water. Concrete is actually mixed with more water than is needed for the hydration reactions. This extra water is added to give concrete sufficient workability.
Flowing concrete is desired to achieve proper filling and composition of the forms. The water not consumed in the hydration reaction will remain in the microstructure pore space. These pores make the concrete weaker due to the lack of strength-forming calcium silicate hydrate bonds. Some pores will remain no matter how well the concrete has been compacted. Figure 6 Schematic drawings to demonstrate the relationship between the water/cement ratio and porosity The empty space (porosity) is determined by the water to cement ratio. The relationship between the water to cement ratio and strength is shown in thegraphthat follows. Figure 7
A plot of concrete strength as a function of the water to cement ratio Low water to cement ratio leads to high strength but low workability. High water to cement ratio leads to low strength, but good workability. The physical characteristics of aggregates are shape, texture, and size. These can indirectly affect strength because they affect the workability of the concrete. If the aggregate makes the concrete unworkable, the contractor is likely to add more water which will weaken the concrete by increasing the water to cement mass ratio. Time is also an important factor in determining concrete strength. Concrete hardens as time passes.
Why? Remember the hydration reactions get slower and slower as the tricalcium silicate hydrate forms. It takes a great deal of time (even years! ) for all of the bonds to form which determine concrete’s strength. It is common to use a 28-day test to determine the relative strength of concrete. Concrete’s strength may also be affected by the addition of admixtures. Admixtures are substances other than the key ingredients or reinforcements which are added during the mixing process. Some admixtures add fluidity to concrete while requiring less water to be used. An example of an admixture which affects strength is super plasticizer.
This makes concrete more workable or fluid without adding excess water. A list of some other admixtures and their functions is given below. Note that not all admixtures increase concrete strength. The selection and use of an admixture are based on the need of the concrete user. SOME ADMIXTURES AND FUNCTIONS Table 3 A table of admixtures and their functions TYPE| FUNCTION| AIR ENTRAINING| Improves durability, workability, reduces bleeding, reduces freezing/thawing problems (e. g. special detergents)| SUPERPLASTICIZERS| Increase strength by decreasing water needed for workable concrete (e. . special polymers)| RETARDING| Delays setting time, more long term strength, offsets adverse high temp. weather (e. g. sugar )| ACCELERATING| Speeds setting time, more early strength, offsets adverse low temp. weather (e. g. calcium chloride)| MINERAL ADMIXTURES| Improves workability, plasticity, strength (e. g. fly ash)| PIGMENT| Adds color (e. g. metal oxides)| Durability is a very important concern in using concrete for a given application. Concrete provides good performance through the service life of the structure when concrete is mixed properly and care is taken in curing it.
Good concrete can have an infinite life span under the right conditions. Water, although important for concrete hydration and hardening, can also play a role in decreased durability once the structure is built. This is because water can transport harmful chemicals to the interior of the concrete leading to various forms of deterioration. Such deterioration ultimately adds costs due to maintenance and repair of the concrete structure. The contractor should be able to account for environmental factors and produce a durable concrete structure if these factors are considered when building concrete structures.
Concrete is everywhere. Take a moment and think about all the concrete encounters you have had in the last 24 hours. All of these concrete structures are created from a mixture of cement and water with added aggregate. It is important to distinguish between cement and concrete as they are not the same. Cement is used to make concrete. (Cement + water) + Aggregate = concrete Cement is made by combining a mixture of limestone and clay in a kiln at 1450? C. The product is an intimate mixture of compounds collectively called clinker. This clinker is finely ground into the powder form.
The raw materials used to make cement are compounds containing some of the earth’s most abundant elements, such as calcium, silicon, aluminum, oxygen, and iron. Water is a key reactant in cement hydration. The incorporation of water into a substance is known as hydration. Water and cement initially form a cement paste that begins to react and harden (set). This paste binds the aggregate particles through the chemical process of hydration. In the hydration of cement, chemical changes occur slowly, eventually creating new crystalline products, heat evolution, and other measurable signs. Cement + water = hardened cement paste
The properties of this hardened cement paste, called binder, control the properties of the concrete. It is the inclusion of water (hydration) into the product that causes concrete to set, stiffen, and become hard. Once set, concrete continues to harden (cure) and become stronger for a long period of time, often up to several years. The strength of the concrete is related to the water to cement mass ratio and the curing conditions. A high water to cement mass ratio yields a low strength concrete. This is due to the increase in porosity (space between particles) that is created with the hydration process.
Most concrete is made with water to cement mass ratio ranging from 0. 35 to 0. 6. Aggregate is the solid particles that are bound together by the cement paste to create the synthetic rock known as concrete. Aggregates can be fine, such as sand, or coarse, such as gravel. The relative amounts of each type and the sizes of each type of aggregate determine the physical properties of the concrete. Sand + cement paste = mortar Mortar + gravel = concrete Sometimes other materials are incorporated into the batch of concrete to create specific characteristics. These additives are called admixtures.
Admixtures are used to: alter the fluidity (plasticity) of the cement paste; increase (accelerate) or decrease (retard) the setting time; increase strength (both bending and compression); or to extend the life of a structure. The making of concrete is a very complex process involving both chemical and physical changes. It is a material of great importance in our lives. Within the literature, Srinivasan gives a definition of concrete which is the most undisputable and indispensable material being used in infrastructure development throughout the world. Although natural fine aggregates (i. e. river sand) are so far and/or will be superior to any other material in making concrete, their availability is continuously being depleted due to the intentional overexploitation throughout the globe. Hence, partial or full replacement of fine aggregates by the other compatible materials like sintered fly ash, crushed rock dust, quarry dust, glass powder, recycled concrete dust, and others are being researched from past two decades, in view of conserving the ecological balance. In this direction, an experimental investigation of strength and durability was undertaken to use hypo sludge for partial replacement of fine aggregate in concrete. Srinivasan, 2010) It was observed and noted that since decade of years that the cost of building materials is currently so high that only corporate organizations, individual, and government can afford to do meaningful construction. Waste can be used as filler material in concrete, admixtures in cement and raw material in cement clinker, or as aggregates in concrete (Olutoge, 2009). Ordinary Portland cement (OPC) is acknowledged as the major construction material throughout the world. The production rate is approximately 2. 1 billion tons per year and is expected to grow to about 3. 5 billion tons per year by 2015 (Coulinho, 2003).
According to Adepegba (1989), the annual cement requirement in Nigeria is about 8. 2 million tones and only 4. 6 million tons of Portland cement is produced locally. The balance of 3. 6 million tonnes or more is imported. If alternative cheap cement can be produced locally, the demand for Portland cement will reduce. The search for suitable local materials to manufacture pozzolana cement was therefore intensified (Adepegba, 1989). Most of the increase in cement demand could be met by the use of supplementary cementing materials, in order to reduce the green gas emission (Bentur, 2002).
Industrial wastes, such as silica fume, blast furnace slag, fly ash are being used as supplementary cement replacement materials and recently, agricultural wastes are also being used as pozzolanic materials in concrete (Sensale, 2006). When pozzolanic materials are incorporated to concrete, the silica present in these materials react with the calcium hydroxide released during the hydration of cement and forms additional calcium silicate hydrate (C – S – H ), which improve durability and the mechanical properties of concrete (Igarashi et al, 2005).
High strength concrete refers to concrete that has a uniaxial compressive strength greater than the normal strength concrete obtained in a particular region. In future, high range water reducing admixtures (Super plasticizer) will open up new possibilities for use of these materials as a part of cementing materials in concrete to produce very high strengths, as some of them are make finer than cement. RELATED LITERATURE In the study of Dunster (2007), he describes the potential use of mill paper sludge and its derivatives as ingredients in Portland cement manufacture and lso in other construction products. Also, in his study the resultant ash after incinerating paper sludge at approximate 800°C contains reactive silica and alumina which contribute chemically to the Portland cement ingredients. Balwaik, et. al. concluded in their study of utilizing paper pulp by partial replacement of cement in concrete that generally, the compressive, split tensile and flexural strength of concrete increased up to 10% addition of waste of paper pulp and there was an increase in water absorption of the concrete mixes as the content of paper pulp increased.
Also, in their study the use of paper pulp in concrete can save the pulp and paper industry disposal costs and produce a “greener” concrete for construction. According to the study of Valls, et. al. , the loss of mechanical strength upon addition of 10% sludge, as well as the longer initial and final setting time in the concrete are impossible. Also, the environmental impact attributable to the addition of sludge is negligible. They concluded that the performance of the concrete containing sludge was acceptable and comparable with the results obtained for the reference concrete not containing sludge.
In this work, they think the possible applications of sludge as additive in construction in low-strength mass concrete and in road bases and sub-bases. Felix F. Udoeyo, Hilary Inyang, David T. Young and Edmund E. Oparadu are the authors of a recent paper in this field of articles “Potential of Wood Waste Ash as an Additive in Concrete” (2006) discusses the enormous amount of wastes produced during wood processing operations in many countries provides challenging opportunities for the use of wood waste as a construction material.
In this research, wood waste (saw dust and wood shaving) ash of pretreated timber of 0, 5, 10, 15, 20, 25 and 30% by weight of cement was added as a supplement to a concrete of a mix proportion 1:2:4:0. 56 (cement: sand: coarse aggregate: water cement ratio), and the strengths and the water absorption of the matrix were evaluated. Also, the metal leach ability of wood waste ash was analyzed. The compressive and the flexural strengths of wood waste ash concrete for the ages investigated ranged from 12. 83 to 28. 66 N/mm2, and 3. 652 to 5. 57 N/mm2 respectively with the lowest values obtained at 30% additive level of ash.
When compared with strength of plain concrete (control), the compressive and the flexural strengths of wood waste ash concrete were between 62 and 91% and 65 and 95%, respectively, of the former. The trend of the water absorption of wood waste ash concrete was a reversal of those of the strengths, that is, the highest water absorption values were recorded for the concrete specimens with the highest additive level of ash. A batch leaching test also performed at an ash leach ant volumetric ratio of 20 produced leachate containing chromium, arsenic, iron, copper and zinc with the following concentrations:410; 6,720; 150; 280 and 1,690 ? /L, respectively, when leached at a pH = 4, and 400; 10; 670; 0; 100; 1,470 ? g/L, respectively, when leached at a pH = 5. These concentration levels exceed the EPA fresh water acute criteria limits. Shi Cong Kou, Chi Sun Poon, Dixon Chan, “Influence of Fly Ash as Cement Replacement on the Properties of Recycled Aggregate Concrete”. (2007) published the results of a research concerning the use of high percentages of recycled aggregates in concrete which would usually worsen the concrete properties. In this study, two series of concrete mixtures were prepared with water-to-binder (W/B) ratios of 0. 5 and 0. 55; the recycled aggregate was used as 0, 20, 50, and 100% by weight replacements of natural aggregate. In addition, fly ash was used as 0, 25, and 35% by weight replacement of the cement. The obtained results showed that the compressive strengths, tensile strength and static modulus of elasticity values of concrete at all ages decreased as the recycled aggregate and the fly ash contents increased. Further, an increase in the recycled aggregate content decreased the resistance to chloride ion penetration and increased the drying shrinkage and creep of concrete.
Nevertheless, the use of fly ash as a substitute for cement improved the resistance to chloride ion penetration and decreasing the drying shrinkage and creep of the recycled aggregate concrete. The results showed also that one of the practical ways to utilize a high percentage of recycled aggregate in structural concrete is by incorporating 25…35% of fly ash as some of the drawbacks induced by the recycled aggregates in concrete could be minimized. The successful utilization of a waste material depends on its use being economically competitive with the alternative natural material.
The stability and durability of products made of concrete using waste material over the expected life span is of utmost importance, particularly in relation to building and structural applications. Rice husk ash has been found suitable for masonry mortar, foundation concrete and mass concrete work (Swamy, 1983). The use of rice husk ash, which is a mineral admixture produced from natural sources, enhances the concrete performance because this material is considered as high activity pozzolanic material containing high content of amorphous silica.
The soundness of rice husk ash permits filling the pores between cement particles and the use of rice husk ash reduces the evolution rate of the hydration heat. Rice husk ash is possible to be used in concrete as a corrosion deterrent material (Al-Heaty, 2000). SYNTHESIS The study of Balwaik, et. al. utilizes paper pulp as partial replacement for cement in producing concrete while in this study the researchers utilizes hypo sludge from paper industries. In the same manner, the present study and the past research study of Balwaik, et. l. aims to produce a ‘greener’ concrete and at the same time can save disposal costs from paper industries. The research of Shi Cong Kou, et. al. entitled “Influence of Fly Ash as Cement Replacement on the Properties of Recycled Aggregate Concrete” focuses on the effects of fly ash the properties of recycled aggregate as a cement replacement for concrete while in the present study; the researchers analyse the effects on the properties of concrete upon partially replacing cement by hypo sludge from paper industry.
Though it seems that none of the previous research studies is really similar to the present study, the previous research still offered a great help to the researchers in giving a wide grasp of ideas regarding the research. It was very useful especially during the conceptualization stage of the researchers regarding the topic in order to visualize the subject matter. It was then the effort of the previous researchers during their research which helped a lot because it served as a guiding inspiration and motivation to the present researchers to finish this study. CHAPTER III MATERIALS AND METHODOLOGY
This chapter presents the research design, experimental design, the raw materials used, preliminary testing of materials, computation of concrete mix per batch, proportioning of concrete, mixing and preparation of test specimens, determination of properties of fresh concrete, determination of compressive and flexure strength of concrete and the flow of the experimental study. RESEARCH DESIGN The study will use a descriptive method of research to evaluate the effectiveness of utilizing hypo sludge waste from paper industry to produce a quality standard concrete which can be used in a construction.
Descriptive research studies deal with collecting data and testing hypotheses or answering questions concerning the current status of the subject of study. It concerns with determining the current practices, status or features of situations. It also enables researchers to organize, summarize, and describe observations. This research method is used to discover the consistency and reliability of the data gathered from the subjected stations. The descriptive method of research deals with the data gathering and testing hypotheses or answering questions based or in line with the study. Also, both qualitative and quantitative methods will be used.
Qualitative methods for providing holistic understanding of complex realities and processes where even the questions and hypotheses emerge cumulatively as the investigation progresses. Quantitative method that main concern is with rigorous objective measurement in order to determine the truth or falsehood of particular pre-determined hypotheses. Furthermore, an experimental investigation on strength of concrete will be conducted by replacing cement via 30%, 50%, and 70% of hypo sludge. In every replacement level, the researchers will make three (3) samples each in concrete cylinders.
The same amount of material (fine and coarse aggregates and water) will be used while replaced with hypo sludge in different levels during casting the cubes and will be subjected to water curing for 7, 14 and 28 days. To figure out the influence of these hypo sludge on the strength of concretes made with different cement replacement levels, several test will be performed like compressive strength and flexural strength test. In an experimental method, one or more variables will be manipulated and controlled. In this experiment, the strength of concrete and its properties will be the ependent variables and the amount of hypo sludge as percentage by weight of cement will be the independent variable. MATERIALS AND EQUIPMENTS This section will discuss about the different material and equipment that will be used in the study to have concrete samples which to be used in the latter part of the study. Cement. The most common cement used is an ordinary Portland cement. The Type 1 is preferred according to IS269-1976, which is used for general concrete structures. Out of the total production, ordinary Portland cement accounts for about 80 to 90%.
Many tests were conducted on cement; some of them are consistency tests, setting tests, soundness tests, etc. Aggregates. It is an important constituent in concrete. They give body to the concrete, reduce shrinkage and effect economy. One of the most important factors for producing workable concrete is good gradation of aggregates. Good grading implies that a sample fractions of aggregates in required proportion such that the sample contains minimum voids. Samples of the well graded aggregate containing minimum voids require minimum paste to fill up the voids in the aggregates.
Minimum paste will mean less quantity of cement and less water, which will further mean increased economy, higher strength, lower shrinkage and greater durability. Aggregate comprises about 55% of the volume of mortar and about 85% volume of mass concrete. Mortar contains a size of 4. 75 mm and concrete contains aggregate up to a maximum size of 150 mm. a) Gravel (Coarse Aggregate). The fractions from 80 mm to 4. 75 mm are termed as coarse aggregate. b) Sand (Fine Aggregate). Those fractions from 4. 75 mm to 150 micron are termed as fine aggregate. Water.
Important ingredient of concrete as it actually participates in the chemical reaction with cement. Since it helps to from the strength giving cement gel, the quantity and quality of water is required to be looked into very carefully. In practice, very often great control on properties of cement and aggregate is exercised but the control on the quality of water is often neglected. So quality of water is checked to its purity. Hypo sludge. This will act as replacement of cement in producing concrete. The following tables 4 – 6 and Fig. 8 show the hypo sludge chemical properties and comparison between cement and hypo sludge.
The hypo sludge waste from paper industry near the province of Batangas will be used in this experimental study. Figure 8 Factory outlet hypo sludge Table 4 Properties of Raw Hypo Sludge SI NO. | Constituent| Present in Hypo Sludge, [%]| 1| Moisture| 56. 8| 2| Magnesium oxide (MgO)| 3. 3| 3| Calcium oxide (CaO)| 46. 2| 4| Loss on ignescent| 27. 00| 5| Acid insoluble| 11. 1| 6| Silica (SiO2)| 9. 0| 7| R2O3| 3. 6| Table 5 Properties of Hypo Sludge as Cement Ingredient SI NO. | Constituent| Present in Hypo Sludge, [%]| 1| Magnesium oxide (MgO)| 3. 3| 2| Calcium oxide (CaO)| 46. 2| 3| Loss on ignescent| 27. 00| | Acid insoluble| 11. 1| 5| Silica (SiO2)| 9. 0| 6| R2O3| 3. 6| Table 6 Comparison of Cement and Hypo Sludge SI NO. | Constituent| Cement, [%]| Hypo Sludge, [%]| 1| Lime(CaO)| 62| 46. 2| 2| Silica(SiO2)| 22| 9| 3| Alumina| 5| 3. 6| 4| Magnesium| 1| 3. 33| 5| Calcium sulphate| 4| 4. 05| PREPARATION OF MATERIALS The experimental study form its preliminary testing of materials, computations, batching, mixing, curing up to testing of experimental specimens will be performed and conducted at the material testing laboratory of the Civil Engineering Laboratory at Batangas State University Main Campus II Alangilan, Batangas City.
Preliminary tests will be conducted to evaluate the physical properties of the constituent materials where the values were required for computations of the individual amounts in the concrete mixture and preparation of concrete cylinders or test specimens. Design of mix proportions will be based on the assumptions that the concrete was of normal weight. Calculation of mix proportion with strength of 21 MPa (3000psi) will be done using weight basis method. Estimates of the required amount will be based on logical computations aided by tables and design mix proportions accepted by ASTM standards.
In the experiment, the amount of gravel, sand and water in each batch of concrete mix will be held constant while the amount of hypo sludge and cement proportion will be varied as to what the amount of each batch of concrete mixtures required. Polyvinyl chloride (PVC) cylinders coated with oil having dimensions of 150 mm diameter by 300 mm high and an assembled mold of 100 mm x 100 mm by 400 mm dimension will be used to cast the concrete specimens. Table 7 shows the number of concrete cylinder specimen that will be tested for compression at different curing periods with varying amount of percentage replacements.
Table 7 Number of Specimens Tested for Compression Percentage of Hypo Sludge| Number of Test Specimen Age of Test| | 7 Days| 14 Days| 28 Days| Total| 0| 3| 3| 3| 9| 30| 3| 3| 3| 9| 50| 3| 3| 3| 9| 70| 3| 3| 3| 9| Total| 12| 12| 12| 36| Table 7 indicates the number of cylindrical specimens tested at the 7th, 14th and 28th day of curing period. A total of three trials were produced per batch in each of the 14th and 28th day curing periods prior to the determination of the compressive strength of these specimens. The total number of the specimens tested for compression was 36.
Table 8 shows the number of concrete specimens that will be tested for flexural strength test at 14 days of concrete age. Table 8 Number of Test Specimens for Flexural Strength Test At 14 Days Curing Period Percentage of Hypo Sludge| Number of Specimen| 0| 3| 30| 3| 50| 3| 70| 3| Total| 12| There will be a total of 12 specimens that will be tested for flexural strength test at 14 days curing period. TESTING OF MATERIALS The tests that will be conducted will be based on procedures and standards of the American Society for Testing of Materials (ASTM). The tests will include the following:
ASTM Designation| Test| C39| Compressive Strength of Concrete| C78| Flexural Strength of Concrete| MIXING AND PREPARATION OF TEST SPECIMEN Mixing and preparation of the test specimen will be done at the Civil Engineering laboratory of Batangas State University Main Campus II in Alangilan. A mixing pan from the laboratory will be used in mixing every batch of concrete. The pan is of sufficient capacity and will allow easy mixing. The mixing of concrete will be done manually by the hand using a shovel. The required amount of the materials will be carefully weighed.
Fine and coarse aggregates, cement and hypo sludge will be dried mixed together to ensure uniform distribution. After all the materials will be blended, a measured amount of water will be added and mixed thoroughly. Mixing of concrete will be done until it looked homogeneous in appearance. Then, a slump test will be done to the fresh concrete. Then, the fresh concrete will be poured and casted to their corresponding molds and will be compacted by 25 strokes of steel rod in each layer. Using a straight edge, the surface will be leveled and finished into a smooth surface.
Concrete placed in the molds will be set aside and will be allowed to harden. After 24 hours, the specimens will be removed from the casting molds and will be transferred in a container filled with water where it will be cured for a period until the time of testing. DETERMINATION OF COMPRESSIVE STRENGTH Determination of the compressive strength of the test specimen will be done in accordance with the procedures and guidelines of ASTM C 39. A total of thirty six (36) specimens will be tested for compressive strength test. For every 7, 14, and 28 days of aging of concrete, three (3) specimens will be tested in each batch.
There will be four (4) batches of concrete corresponding to 0, 30, 50 and 70 percentage replacement of hypo sludge by weight. Compressive load of each specimen will be determined with the use of Universal Testing Machine. Individual compressive strength will be calculated by dividing the determined compressive load by the cross sectional area of the specimen. DETERMINATION OF FLEXURAL STRENGTH The flexural strength of concrete will be determined in accordance with ASTM C 78 guidelines and procedure for flexural strength test. It will be performed to control or check the strength of concrete against bending stresses.
Twelve test specimens of 100 mm x 100 mm x 400 mm dimensions will be used in the test experiment. Three (3) test specimens will be provided in each batch of concrete. The specimens will be tested using UTM and calculations of the flexural strength of concrete will be based on the behavior and location of the fracture or where the failure occurs along the length of the specimen. STATISTICAL TREATMENT Concrete specimens are tested using the ASTM39 Test Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens by using three samples made from the same test at the same age, usually at strength of 28 days old.
Design engineers use the specified strength ?? c to design structural elements. This specified strength is incorporated in the job contract documents. The concrete mixture is designed to produce an average strength (?? cr) higher than the specified strength, such that the risk of not complying with the strength specification is minimized. Cylindrical specimens for acceptance testing should be 6 x 12 inch (150 x 300 mm) size. The Concrete strength is calculated by dividing the maximum load at failure by the average cross sectional area.
Failure Stress = Uniaxial Compressive Strength = Force / Area Concrete compressive strength requirements can vary from 2500 psi (17 MPa) for residential concrete to 4000 psi (28 MPa) and higher in commercial structures. Higher strengths up to and exceeding 10,000 psi (70 MPa) are specified for certain applications. Cylinders are placed in a Compression testing machine and loaded to failure from 20 to 50psi. The type of break should be recorded by a Certified Technician. FLOW OF THE EXPERIMENTAL STUDY Figure 9 Flow chart of the experimental study