Major elements found in fly ash and the composition required by astm c618 for class f fly ash, and composition of the cem iias 42. Conservative attitudes are among the factors that limited the use of fly ash in concrete to generally a maximum of 25% replacement of portland cement. Fly ash reacts with caoh 2 released from the hydration of cement in the concrete and produces cementing materials. Abstract in present study, concrete has been partially replaced with microsilica which acts as a byproduct in electric furnace and fly ash which is a byproduct in thermal power plants. For concrete production, the reduction of cement content in concrete can be achieved by utilization of supplementary cementitious materials such as fly ash, blastfurnace slag, natural pozzolans, and biomass ash. In this research work the silica fume and fly ash both are mixed in concrete with the some partial replacement that is the cement and fine aggregate, the some amount of cement is replaced by the silica fume and the some amount of fine aggregate is replaced by the fly ash so what will be their effect it is find. Before coal is consumed in a power plant, it is first ground into a fine powder. Effect of parameters on the compressive strength of fly. Fly ash fly ash is a byproduct from the burning of coal in power plants. In order to enhance the reaction of fly ash, extra gypsum was added. The optimization of the effect of silica fume and fly ash with partial replacement of cement and fine aggregates. In this study, cement has been replaced by fly ash accordingly in the range of 0% without fly ash, 10%, 20%, 30%, 40%. Effect of calcium formate on hydration mechanism of cement.
Two categories of fly ash and rise husk ash with four distinct content of 5%, 10%, 15%, 20%, 30% in terms of weight was perform for the substitution of cement and addition of a persistent 5%egg shell. Pdf effect of fly ash on compressive strength of portland. From the results obtained it can be clearly seen that for 10% to 20% replacement of fly ash with weight of cement compressive strength is increases and then if we further increases percentage of fly ash, compressive strength decreases. Effect of curing temperature on pozzolanic reaction of fly. This, however, improves significantly when the fly ash has reacted. Fly ash from thermal plant is used as partial substitute for cement. Effect on compressive strength of concrete by partial.
This report summarizes the effect of the partial replacement of cement with fly ash on the temperature rise in concrete. It can be concluded that the replacement of cement by fly ash and slag will prolong the overall setting time and retard the early strength gain of the cam mixture. Chapter 3 fly ash in portland cement concrete fly ash facts for. In concretes having similar cement contents and equal quantities of reactive sand, the concrete with 20% fly ash addition suffered no damage, while the concrete without fly ash experienced considerable expansion and cracking. The fly ash concrete samples showed less drying shrinkage than the control concrete samples when designed for the same 28day compressive strength of the control concrete.
Effects of various fly ashes on compressive strength, resistance to. Table 2 details of proportions of cement and fly ash symbols % of cement % of fly ash c100 100 0 f10 90 10 f20 80 20 f30 70 30 f40 60 40 4. The effect of ggbs and fly ash as partial cement replacement was examined on concrete cubes, cylinder and beams. Sarker1b 1department of civil engineering, curtin university, australia. Effects of fly ash on earlyage properties and cracking of. Various research works have already been conducted to study the effect of fly ash on different grades of concrete. Amount of cement utilized in concrete and water to cement ratio are considered major factors specify or control the strength of concrete. Uses, benefits, and drawbacks of fly ash in construction. Pdf effect the local fly ash on cement mortar properties. American concrete institute aci manual of concrete practice, section 211. Use of fly ash in concrete imparts several environmental benefits and thus it is ecofriendly.
Using a fly ash with a high total alkali content, nixon. Fly ash use in concrete improves the workability of plastic concrete, and the strength and durability of hardened concrete. The effect of fly ash on shrinkage depends on its fineness and water requirements. Investigate the effect of silica fume and fly ash on mechanical property of concrete. Effect of fly ash on the durability properties of high. Ash that falls to the bottom of the boilers combustion chamber commonly called a firebox is called bottom ash. The aim of the investigation was to evaluate the feasibility of mixing fly ash in cement to make mortar specimens for getting an agreeable compressive strength of the mortar. Fly ash provides a dramatic lubricating effect which greatly reduces water demand 2% to 10%. Fly ash reacts with the hydrating hydraulic cement to form a. It is more difficult to control the color of concrete containing fly ash than mixtures with portland cement only.
A supplementary cementitious material, when used in conjunction with portland cement, contributes to the properties of the hardened concrete through hydraulic or. 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. The results also show that the thermal gradient is not linear through the depth of a concrete member from middepth to the expc8ed conrete surface. Fly ash is proven to be substantially influential in decreasing the detrimental effect of alkali aggregate reactions aars. Cement with fly ash reduces the permeability of concrete and dense calcium silicate hydrate csh. The development of the strength, heat, porosity, bound water, and calcium hydroxide content was measured. Experimental analysis of partial replacement of cement by. Effects of fly ash on development of concrete strength.
Workability, concrete is easier to place with less effort. Fly ash is used in concrete as an admixture as well as in cement. When mixed with lime and water, fly ash forms a compound similar to portland cement. The structural effects of fly ash may be more critical, but cosmetic concerns also affect its use in concrete. Presented to the faculty of the graduate school of the. This paper investigates the effect of fineness and replacement levels of fly ash on the fluidity of cement paste, mortar, and concrete. Concrete mixtures were produced, tested and compared in terms of compressive strength. The evolution of properties of cement fly ash blends are greatly influenced by the degree of hydration of both fly ash and cement. The effect of these fly ash on durability of concrete is discussed in this article. Hassaballah abstract this study was directed toward studying performance of astm class c and f fly ashes in mortars under varying water to cementitious materials ratio. However, due to the pozzolanic activity of fly ash, the compressive strength increased in later stages of curing 4, 5. This water reduction reduces internal voids and bleed channels and keeps harmful compounds out of the concrete. Further research is needed to determine the quan tity of alkalies added to fly ash by these agents and their effect on asr.
Effect of fly ash on alkalisilica reactivity in concrete. The effect of fly ash on the temperature rise in concrete. In addition, in january 1983, the environmental protection agency published federal comprehensive procurement guidelines for cement and concrete containing fly ash to encourage the utilization of fly ash and establish compliance deadlines. The use of fly ash in portland cement concrete pcc has many benefits and improves concrete performance in both the fresh and hardened state. Research shows that adding fly ash to concrete, as a partial replacement of cement less than 35 percent, will benefit both the fresh and hardened states. Optimizing the use of fly ash in concrete concrete introduction fly ash is used as a supplementary cementitious material scm in the production of portland cement concrete. The present study involves replacing of cement with fly ash in the range of 30, 40 and 50% by mass of cement for m30 grade concrete mix with 0. Partial replacement of cement with fly ash in concrete and its effect authors. The addition of ultrafine fly ash ufa to cement paste, mortar and concrete can improve their fluidity, but some coarse fly ash cant reduce water. Figure 4 shows the distribution in terms of calcium. Fly ash use in concrete improves the workability of plastic concrete, and the strength. Herein, cement is totally replaced by mineral admixtures rich in aluminosilicates such as fly ash and is formed by the alkali activation using alkaline activator solutions, such as sodium hydroxide naoh and sodium silicate na 2 sio 3.
Using fly ash in concrete is environmentally beneficial because it reduces the portland cement a major contributor of co2 required in concrete. Effect of lignosulphonate plasticizer on rheological. The ash is collected from the combustion gases and the particles form glass spheres 0 1 mm in diameter. Characterization of fly ash and it effects on the compressive. When 10% of the cement content was replaced by fly ash and slag, there was a critical drop in the strength of the cam mixture with a ucs value of 0. While in the fresh state, the fly ash improves workability.
So, in this study a byproduct fly ash of al aslaah bricks factories in the south iraq is used to evaluate the effects for physical properties of the. Pdf effect of fly ash on selfhealing of cracks in concrete. Inclusion of fly ash reduced sorptivity and chloride ion permeation. Fly ash is commonly used in concrete in replacement ranging from 0% to 30% by weight of the total cementitious material. Fly ash is used to lower the cost and to improve the performance of pcc. In addition, this study shows that concrete containing fly ash is less permeable to chloride ion intrusion than concrete without fly ash. This same effect also improves concrete pumpability by reducing frictional. Effect of fly ash fineness on the performance of cement. Using a fly ash pozzolan consumes calcium hydroxide ch. The design of water retaining structures is mainly based on the serviceability limit state crack control. The present study aims to study the effect of fly ash on concrete by partial replacement of cement with 0%, 10%, 20% and 30% of fly ash. The use of fly ash in limited amounts as a replacement for cement or as an addition to cement requires a little more water for the same slump because of fineness of the fly ash.
Effect of fly ash on compressive strength of portland. Fly ash is a byproduct from the combustion of pulverized coal, and is widely used as an ingredient in hydraulic cement concrete. Explore effect of cement replacement by silica fume and fly ash with free download of seminar report and ppt in pdf and doc format. Carbonation is a process in which carbon dioxide in air reacts with calcium hydroxide and sometimes calcium silicates and aluminates in hydrates cement and produce calcium carbonate. Effect of fly ash on properties of concrete semantic scholar. Effect of microsilica and fly ash on the strength of concrete. Strength fly ash can increase strength strength gain happens slower with a pozzolanic class f vs. Fly ash carbon effects on concrete air entrainment. Most published work on the effects of fly ash on the rate of heat development and temperature rise in concrete have focussed on lowcalcium class f fly ashes. The use of concrete in aggressive and potentially aggressive environmental condition has been increased substantially.
Concrete cubes, cylinders and prisms are cast, tested and compared in terms of strength at different ages of curing. In partial fulfillment of the requirements for the degree. Ease of pumping, pumping requires less energy and longer pumping distances are possible. Large quantities of fly ash and lime are available around the world at low cost and the use of high volume fly ash and lime seems to offer the best solution to rising cement demands.
This coal powder is blown into the power plants boiler, the carbon is consumed leaving molten particles rich in silica, alumina. At what percentage of partial replacement we will achieve the optimum result, increase in the strength of concrete. Figure 2 influence of available alkali of cement and fly ash on expansion. The allowable crack width depends on the selfhealing ability of concrete and the use of supplementary cementitious material like fly ash in concrete mixes might affect it. Work by the bureau of reclamation dunstan 1984 indicated that the rate of heat development generally increases with the calcium content of the ash. 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. Fly ash is another materials that has been used in partial replacement of cements in concrete and cement mortars, jo et al. Pdf effect of fly ash on the properties of cement esat. The effect of fly ash, betacyclodextrin and fly ashbeta. The fly ash in concrete makes efficient use of product of hydration of cement such as calcium hydroxide ch which is otherwise a source of weakness in normal cement concrete converts it into denser and stronger csh ompounds by pozzolanic reaction. Effect of fly ash additive on concrete properties semantic scholar.
The effect of fly ash on cement hydration in aqueous suspensions ceramics. The fly ash used in this investigation have d90 52,2 m. Class f fly ash is often used at dosages of 15% to 25% by mass of cementitious material and class c fly ash is used at dosages of 15% to 40% by mass of cementitious material. In this study, cement has been replaced by fly ash accordingly in the range of 0% without fly ash, 10%, 20%, 30%, 40%, 50% and 60% by weight of cement for m25 mix with 0. Typically, 15 percent to 30 percent of the portland cement is replaced with fly ash, with even higher percentages used for mass concrete placements. Atis pointed out the application of high volume fly ash in concrete, particularly 50% replacement of cement by fly ash led to the shrinkage reduction by 30% compared to the conventional concrete.
Effect of fly ash on the microstructure of cement mortar. This paper presents an effect of fly ash on properties of concrete. Creep and shrinkage properties in concrete containing fly ash by mohand l. Concrete property can be maintained with advance mineral admixtures such as flyash as partial replacement of cement 0 to 30%. Study the strength property of concrete using fly ash fa.
Oct 26, 2019 the present study involves replacing of cement with fly ash in the range of 30, 40 and 50% by mass of cement for m30 grade concrete mix with 0. It saves the cement requirement for the same strength thus saving of raw materials such as limestone, coal etc required for manufacture of cement. This research concludes the study of the effect of fly ash on the properties of concrete. Summary of effects of fly ash on concrete properties, 6. Effect of cement replacement by silica fume and fly ash. Fly ash, slag, silica fume, and natural pozzolans, chapter 3.
Fineness of fly ash has a positive effect on the compressive strength of cement fly ash mixtures and many studies have shown that compressive strength increases with the increase of fineness 21. Jul 17, 2017 fly ash is a byproduct from coalfired power plants that is frequently used as an admixture in concrete to replace a portion of the portland cement. Effect of fly ash on alkali aggregate reactions in concrete. These issues are addressed in sections effect of fly ash on the. Fly ash, a waste material from industry, can be incorporated in the manufacture of geopolymer concrete. Effect of fly ash on the durability properties of high strength concrete p. Due to the complexity in the reaction mechanism of fly ash in cement, despite the broadbased research carried out in the past few decades, hydration mechanisms of cement fly ash is not well established yet. Abstract utilization of fly ash as a supplementary cementitious material adds sustainability to concrete by reducing the co 2 emission of cement production.
Abstract this paper describes the results of an investigation desig ned to gain further insight into interactions between fa carbon and air entraining surfactants, and the way in which. Creep and shrinkage properties in concrete containing fly ash. Optimizing the use of fly ash in concrete portland cement. Different proportions of cement and fly ash were tried at laboratoryscale. Effects of fly ash on properties of hardened concrete. Partial replacement of cement with fly ash in concrete and. Material properties such as compressive strength, indirect tensile strength, and elastic modulus were measured with different percentage replacements of opc with fly ash. Pdf fly ash or pulverised fuel ash is a byproduct of the combustion of pulverised coal in thermal power plants. Microscopic photographs of fly ash left and portland cement right fly ash improves workability for pavement concrete typical strength gain of fly ash concrete permeability of fly ash concrete fly ash concrete is used in severe exposure applications such as the decks and piers of tampa bays sunshine skyway bridge fly ash concrete finishing. Following are the effects of using fly ash on hardened concrete properties. Effect of fly ash on strength of concrete springerlink. Thus, compressive strength is reduced with the increment of fly ash content in concrete.
Effects of water to cementitious ratio on compressive strength of cement mortar containing fly ash by tarun r. Fly ash is used in about 50% of ready mixed concrete pca 2000. Results and discussions various parameters which significantly affect the properties of hardened concrete with the inclusion of fly ash are discussed below. Also explore the seminar topics paper on effect of cement replacement by silica fume and fly ash with abstract or synopsis, documentation on advantages and disadvantages, base paper presentation slides for ieee final year civil engineering ce or ieee civil. Effects of fly ash on concrete properties civilblog. Compressive strength of concrete with different dosage of fly ash was studied as partial replacemnet of cement. Effect of fly ash on selfhealing of cracks in concrete. This conservatism can be understood in the context of concrete where the ash is mixed raw, and the effects. The material composition is dependent on the noncombustible matter in the coal, and will also contain a. Other reports in this series will address the topics of sealing resistance, abrasion resistance, freezethaw durability, creep and shrinkage at early ages, and fly ash characterization.
In this research paper we have kept percentage of fly ash for every trial constant except for conventional trial and ggbs was used to replace cement partially from 40% up to 70% while keeping fly ash 25% as constant throughout. This paper investigates the effect of fineness of fly ash on the performance of cement mortar. The ball bearing effect of fly ash creates a lubricating effect when concrete is in its plastic state. Because it improves many desirable properties of concrete, it is introduced either as a separately batched material or as a component of blended cement. Oct 31, 2016 introduction fly ash concrete is an ecofriendly construction material in which fly ash replaces a part of portland cement. Initially, the replacement of cement by fly ash weakens the pasteaggregate interfacial zone due to reduction of contact points, and increases the local waterto cement ratio. Effect of fly ash on mortar mixes with quarry dust as fine. It is aimed at materials which can fulfil the expectations of the construction industry in different areas.
This paper presents the results of an experimental investigation carried out to evaluate the compressive strength and transverse strength of 1. High volume fly ash concrete is a concrete where a replacement of about 35% or more of cement is made with the usage. In order to study the effect of fly ash as partial cement replacement on the strength of concrete, 63 cubes for a mix have been cast in the laboratory. Fly ash also may cause visual inconsistencies in the finished surface, such as dark streaks from carbon particles. The fly ash samples were supplied from different thermal power. Effect of palm oil fuel ash pofa on strength properties of. An equivalent or greater weight of fly ash is substituted for the cement removed. However, only grade i is recommended for manufacture of portland pozzolana cement. Pdf effect of fly ash properties on concrete strength researchgate.
Fly ash is a pozzolan, a substance containing aluminous and siliceous material that forms cement in the presence of water. The heat generated during hydration initiates the pozzolanic reaction of fly ash. This advantageous effect of fly ash is reduced or limited to reactions in which siliceous aggregates is involved. This makes fly ash suitable as a prime material in blended cement, mosaic tiles, and hollow blocks, among other building materials. Also, mastersizerx technique and their effects on the compressive strength properties of ordinary portland cement opc were investigated. Fly ash has a positive impact on shrinkage mitigation. Technical bulletin 6 4 fly ash increases resistance to sulfate attack, u. The effect on shrinkageinduced cracking of replacing some ordinary portland cement opc with fly ash has not been studied previously. Introduction fly ash concrete is an ecofriendly construction material in which fly ash replaces a part of portland cement. Properties experimental codal requirement is 1489 pt11991. A typical lowcalcium fly ash was used as additive in mortar, replacing part of the volume either of portland cement or aggregate. Fly ash concrete is basically the same as regular concrete except some of the cement has been replaced with a material called fly ash. Slump loss of concrete increases with increase in wc ratio of concrete. The utilization of fly ash in concrete as partial replacement of cement is gaining immense importance today, mainly on account of the improvement in the long term.726 904 1211 54 329 1240 391 422 707 1353 801 998 174 995 180 1298 1083 1314 196 190 1441 1354 299 899 272 1381 664 859 206 751 558 1410 1477 761 1277 459 1372 877 190