Anowai and job 12 confirmed that partially replacing cement with fly ash reduced the alkalinity of banana fibre reinforced concrete. Fly ash normally produced from burning anthracite or bituminous coal f that meets the applicable requirements for this class as given herein. Physical, chemical, and geotechnical properties of coal. The chemical composition of fly ash is shown in table 3, and its main physicalmechanical properties in table 4. Physical properties help in classifying the coal ashes for engineering purposes and some are related to. Geotechnical properties of fly ashsoil mixtures fly ashsoil mixtures were prepared at several fly ashsoil ratios i. The permeability of concrete reduces on addition of fly ash to cement. Fly ash, rice husk ash, expansive soil, industrial waste26 etc. Evaluation of the physical and chemical properties of fly ash. Effects of fly ash on development of concrete strength.
Chemical composition of fly ash from power plant gacko component sio2 al2o3 fe2o3 cao mgo so3 lost of. Many countries have their own national standards and specifications regulating the use of fly ash in concrete. Fly ash consists of inorganic, incombustible matter. Modern coalquality data and geologic field observations are interpreted in terms of the coal geology in a small area near pocahontas, va. Effects of fly ash on properties of hardened concrete. The four most relevant characteristics of fly ash for use in concrete are loss on ignition loi, fineness, chemical composition and uniformity. Pdf study on physical and chemical properties of fly ash from. Fly ash has a much lower density than cement, therefore samples with a higher percentage of fly ash had lower densities and subsequently lower thermal conductivities. In view of these superior properties, generating geopolymers by using alkaliactivated fly ash to improve the bearing capacity of foundation soil has been reported recently 27, 28. Chemical analyses and physical properties of 12 coal. The coal properties including calorific values differ depending upon the colliery.
Elmrabet and others published study of properties of fly ash cements find, read and cite all the research you need. Fly ash consists of inorganic, incombustible matter present in the coal that has been fused during combustion into a glassy, amorphous structure. Updating physical and chemical characteristics of fly ash for use. Detailed chemical analyses and physicalproperty determinations of 12 channelcoal samples reported on wholecoal and laboratory ash basis indicate that the coals are mostly of high coking quality, low.
Nearly 30% of the coal is converted into ash on burning out of which 75% is in fine fly ash form and rest 25% in the form of coarse bottom ash. Effect of moisture content of wet fly ash on basic properties of mortar and concrete is studied. We have covered significant area in our work, and developed the knowhow to manufacture lowcalcium fly ashbased geopolymer concrete. Fly ash is a byproduct from the combustion of pulverized coal, and is widely used as an ingredient in hydrauliccement concrete. The data generated on properties of fly ash have been compared with other filler or reinforcement materials, such as glass microspheres, al 2o 3, sio 2, and sic particles. The choice and effectiveness of an additive depends on the type of soil and its. Pdf dielectric properties of epoxy resin fly ash composite. Interpretation of geotechnical properties of cement. The effect of fly ash chemical composition on the degradation of pvc composites was studied by comparing the thermal properties of composites containing two different classes of fly ash, classf. Fly ash is the finely divided mineral residue resulting from the combustion of coal in electric generating plants. Thermal properties of highvolume fly ash mortars and. Fresh propertiesthat is, slump, water demand, and set timeand hardened propertiesthat is, shrinkage and compressive strength of concrete containing sf. Wet fly ashes prepared in the laboratory are used in the investigation.
Physical and chemical properties of fly ash from coalfired power plants with reference to environmental impacts. When incorporated in concrete mixtures, fly ashes are known to influence both its fresh and hardened properties. Fly ash or flue ash, also known as pulverised fuel ash in the united kingdom, is a coal combustion product that is composed of the particulates fine particles of burned fuel that are driven out of coalfired boilers together with the flue gases. Type f fly ash is produced from the combustion of bituminous or an anthracite coal contains cao below 10 percent and possesses pozzolanic properties. Apart from it, fly ash uses gives the economic substitute of portland cement and make concrete economical and it provides the. Density and thermal conductivity are often positively correlated.
Effects of fly ash on concrete properties civilblog. A pozzolan is a siliceousaluminous material that, when mixed with lime and water, forms a cementitious compound. Fly ash fly ash from power plant gacko is used as mineral filler for mixtures of bituminous aggregate. Mechanical properties of tunnel muck with flyash geopolymer. Finally, the use of fly ash in concrete can modify the properties of concrete in fresh state as well as in hardened state. The chemical composition of fly ash depends upon the type of coal used and the methods used for combustion of coal. This book draws together a large quantity of research that has been carried out on pulverised fuel ash pfa over the past 30 years. View the table of contents for this issue, or go to the journal homepage for more. Fly ash slightly improves the resistance of concrete to sulphate attack. Fly ash closely resembles volcanic ashes used in production of the earliest known hydraulic cements about 2,300 years ago.
Fly ash particles are generally spherical in shape and range in size from 2. The second report summari zes the effect of fly ash on concrete used for highway applications. Comparison of compressive strength using different wt. Study of properties of fly ash cements request pdf. Following are the effects of using fly ash on hardened concrete properties. Currently, fly ash is used in more than 50% of all ready mixed concrete placed in the united states, yet many design professionals continue to remain overly restrictive. Fly ash reacts with caoh 2 released from the hydration of cement in the concrete and produces cementing materials. Optimizing the use of fly ash in concrete portland cement. They consist mostly of silicon dioxide sio 2, aluminium oxide al 2 o 3. Fly ash is considered as one of the most important and advantageous waste material in construction industry.
Fly ash reacts with the hydrating hydraulic cement to form a cementing medium. Properties of concrete containing ultrafine fly ash. Fly ash mostly consists of silicon dioxide sio2, aluminium oxide al2o3 and iron oxide fe2o3. Fly ash consists primarily of oxides of silicon, aluminum iron and calcium. The chemical properties of fly ash are influenced to a great extent by those of the coal burned and the techniques used for handling and storage. The third report of the series summarizes the effects of fly ash on the durability of concrete containing fly ash. Fly ash is produced by coalfired electric and steam generating plants. As only limited details on manufacture and parameters influencing properties of sintered fly ash aggregates have been reported in the literature, a systematic study was undertaken.
Mechanical properties of epoxy resin fly ash composite. Dielectric properties of epoxy resin fly ash composite. Pozzolans that are commonly used in concrete include fly ash, silica fume and a variety of natural pozzolans such as calcined clay and shale, and. Mechanical properties of high volume fly ash concrete. Fly ash substitution to cement is a wellrecognized approach to reduce co 2 emissions. Opc of 53 grade replaced with class f fly ash with 5 25 % in the increments of 5 %. In general, the specific gravity of coal ashes lies around 2. It is residue produced during the combustion of coal or any other form of coal. High volume fly ash concrete is a concrete where a replacement of about 35% or more of cement is made with the usage of fly ash. Although fly ash concrete is prone to brittle behavior, researchers have shown that addition of fibers could reduce brittle behavior. Effect of moisture content of wet fly ash on basic. Physical and chemical properties of fly ash from coal.
Fly ash consists of fine, powdery particles predominantly spherical in shape, either solid or hollow, and mostly amorphous in nature. Those cements were made near the small italian town of pozzuoli which later gave its name to the term pozzolan. Strength properties of fly ash mortars were evaluated through laboratory investigations. Geotechnical properties of fly ash and soil mixtures for. The properties of fly ash can greatly affect the properties for both fresh concrete and hardened concrete.
Moreover, geopolymers combined with loess and fully weathered granite were developed as useful building materials 29 31. Fly ash booklet for pdf federal highway administration. These mortars contained 50 % fly ash by mass replacement for cement except for the control mixture without fly ash, a watertocementitious materials ratio wcm. Fly ash, slag, silica fume, and natural pozzolans, chapter 3. There are basically four types, or ranks, of coal, each of which varies in terms of its heating value, its chemical composition, ash content, and geological origin. Fly ash properties, types, mechanism and uses the constructor. Over 61 million metric tons 68 million tons of fly ash were produced in 2001. The results shown that at early age at all fly ash replacements the strength decreased with respect to normal mortar.
Fly ash, slag, silica fume, and natural pozzolans fly ash, ground granulated blastfurnace slag, silica fume, and natural pozzolans, such as calcined shale, calcined clay or metakaolin, are materials that, when used in conjunction with portland or blended cement, contribute to the properties of the hardened concrete through hydraulic or. The chemical and physical properties of a particular uffa are reported herein. Amount of cement utilized in concrete and water to cement ratio are considered major factors specify or control the strength of concrete. The properties studied included sphericity of fly ash particles, wall thickness, the ratio of wall thickness to diameter, and modulus. Coal fly ash is a coal combustion product that has numerous applications in highway construction. Fly ash concrete is an ecofriendly construction material in which fly ash replaces a part of portland cement. Fuel ash and fly ash are produced as waste from burining coal or waste materials and have many uses within the construction industry such as in concrete land reclamation, treating oil and sewage wastes, bricks and blocks and grouting voids in the. Chemical and toxicological properties of coal fly ash. Properties and use of coal fly ash ice virtual library.
Because it improves many desirable properties of concrete, it is introduced either as a separately batched material or as a component of blended cement. Fly ash is the finely divided residue that results from the combustion of pulverized coal and is transported from the combustion chamber by exhaust gases. In the united states, astm c 6181, standard specification for coal fly ash and. Fly ash properties and uses monolithic dome institute.
Fuel ash and fly ash are produced as waste from burining coal or waste materials and have many uses within the construction industry such as in concrete land. The properties of mortar and concrete made with the wet fly ash are investigated and compared with those made with dry fly ash. The results indicate a significant increase in strength and index properties with 15% blend of fly ash, rice husk ash and soil. Ash that falls to the bottom of the boilers combustion chamber commonly called a firebox is called bottom ash. Material designation % fly ash by weight compressive strength nmm2 c1 30 84. Type c fly ash is produced from the combustion of lignite or sub bituminous coals, contains cao higher than 10 percent and possesses cementitious properties in addition to pozzolanic properties. Influence of binders on properties of sintered fly ash. Determining the thermal properties of fly ash concrete.
Properties of fly ashextended asphalt concrete mixes abdulrahman s. As the need for power increases, the volume of fly ash would increase. In this paper, the relative performance of three binders, viz. Properties of fly ashextended asphalt concrete mixes.
388 379 1429 1591 587 1334 216 857 721 446 565 602 103 496 233 1576 1212 762 1005 1169 1324 653 967 1279 1381 1426 861 385 272 119 437 1165 42 1330