Difference between class c and class f fly ash

Class c fly ash has selfcementing properties as well as pozzolanic properties. Differences between portland cement concrete and fly ash. The inclusion of class f fly ash minimised the sorptivity of concrete in both initial 28 stage of curing and later stages of curing at 180 d. Class c and class f fly ash minnesota concrete council. Jul 17, 2017 fly ash is a type of residue recovered from the exhaust of coal mills, where the ash is a contaminant in the smoke. How to practically differentiate between class c fly ash.

Class f vs class c flyash concretemasonry structural 16 oct 12 15. C 618 to the classes of coal from which class f and class c fly ashes are derived, there was no requirement that a given class of fly ash must come from a specific type of coal. Requirement for class f fly ash for resistance to alkali silica reaction asr design professionals often specify prescriptive requirements such as quantities of class f. Chemical comparision of fly ash and portland cement. Cost and use fly ash is easy to use and is recycled from a process already at work, making it less expensive than portland cement. Charah solutions supplies both class c and class f fly ash from locations around the country. Class f fly ash increases resistance to sulfate attack.

The content of this activator was evaluated by the proportion of na 2 o to class c fly ash cfa. A glance at the table reveals that the same compounds exist in fly ash and portland cement. Astm c618 defines two classes of fly ash for use in concrete. Biggest single difference between class f and class c ash. Compressive strength and microstructural characteristics. Coal fly ash user guideline portland cement concrete. Coal fly ash material description user guidelines for. Comparison of class c versus class f fly ash for concrete pavement wisconsin highway research program results the two class c ash sources had a very low loi 0. Comparative analysis on aac, clc and flyash concrete blocks. Fly ash is a type of residue recovered from the exhaust of coal mills, where the ash is a contaminant in the smoke.

Additional chemical properties are listed in table 1. The specific gravity of fly ash is ranging between 2. Additional chemical requirements are listed in table 2. The biggest difference between class c and class f fly ash is their recommended dosage rate and their result on the concrete mixture. The chief difference the chief difference between these classes is the amount of calcium, silica, alumina, and iron content in the ash. Effect of class f fly ash on the durability properties of. The primary difference between class c and class f fly ash is the chemical composition of the ash itself. Coal fly ash user guideline portland cement concrete fhwa. Comparison study of class f and class c fly ashes as cement. Oct 06, 2010 hawaiian cements class f fly ash is the next generation for concrete products. The higher specific surface area of fly ash limits the transition zone between the aggregates.

Slag cement will provide lighter concrete with higher reflectivity than plain portland cement concrete. Type f fly ash is produced from the combustion of bituminous or an anthracite coal contains cao below 10 percent and possesses pozzolanic properties. Class f and class c ashes most available information, until re c e n t l y, has dealt with class f ash. The chief difference between these classes is the amount of calcium, silica, alumina, and iron content in. Class f fly ash sources were eliminated from wisdot specifications in the 1990s due to high values of loss on ignition loi, which led to difficulties in establishing. Slag cement and class f fly ash will both provide protection against sulfate attack and asr. Comparisons, applications, and performance larry sutter michigan technological university. Types of fly ash astm c618 defines two classes of fly ash. Class f fly ash is often used at dosages of 15% to 25% by mass of cementitious material and class c fly. The chemical properties of the fly ash are largely influenced by the chemical content of the coal burned i.

How to practically differentiate between class c fly ash and classf. The concrete supplier is the end user and vaules a steady. Some fly ashes meet both class f and class c classifications. The chief difference between these classes is the amount of calcium. What is the difference between class c fly ash and class f fly ash. Mar 20, 2018 most of the fly ash produced is class f. Unlike class f, selfcementing class c fly ash does not require an activator.

It has a higher percentage of calcium oxide than class f and is more commonly used for structural concrete. The use of fly ash in concrete products offers benefits in both the hardened and plastic state of concrete. In addition to economic and ecological benefits, the use of fly ash in concrete improves its workability, reduces segregation, bleeding, heat evolution and permeability, inhibits alkali. Class c fly ash generally contains more than 20% lime cao. Use of high volumes of class c and class f fly ash in concrete. Currently, more than 50% of the concrete placed in the u. What is the difference between type c fly ash and type f fly. The properties of fly ash can greatly affect the properties for both fresh concrete and hardened concrete.

However, the effect of fly ash varies considerably as the composition of the ash varies. The primary difference between class f and class c fly ashes is the calcium. Jul 23, 2006 class f is fly ash normally produced from burning anthracite or bituminous coal, and class c is normally produced from the burning of subbituminous coal and lignite as are found in some of the western states of the united states halstead 1986. The two designations for fly ash used in concrete are class c and f and are described in astm c618. According to the us department of transportation, highway pavement or structural concrete mixes should use between 15 to 25 percent by weight of class f fly ash while class c fly ash should range from 20 to 35.

Class f vs class c flyash structural engineering general. Evaluate several locally available class f fly ash sources in comparison with class c fly ash for impact on. Class c and f fly ashes were used in this research project. The chief difference between class f and class c fly ash is in the amount of calcium and the silica, alumina, and iron content in the ash. What is the difference between class c and class f fly ash. Class c and f fly ash having intermediate lime class f fly ash having low lime use of fly ash according to is. Class f fly ash is designated in astm c 618 and originates from anthracite and bituminous coals. Compressive strength and microstructural characteristics of. Most supplies of fly ash are under long term supply contracts with major distributors and cement companies. What is the difference between type c fly ash and type f. Fly ash concrete block are lighter in weight because of partial replacement of fine aggregate and. M is the modulus of the mixed alkali activator viz. The effectiveness of class f fly ash in controlling expansion due to asr is well established.

With the potential for shortages in fly ash supply in parts of texas, contractors and concrete suppliers should prepare to transport fly ash from farther distances and txdot should expect a resulting increase in the price of concrete. It consists mainly of alumina and silica and has a higher loi than class c fly ash. Loss of ignition loi may 12, 2017 the fly ash is finely divided residue resulting from the combustion of ground or powdered coal. The replacement level of class f fly ash is often at 1525% by mass of cemetitious materials, and it is between 1540% by mass of cementitious materials for class c fly ash. Comparison of class c versus class f fly ash for concrete. Hawaiian cements class f fly ash is the next generation for concrete products. Alkali and sulfate so4 contents are generally higher in class c fly ashes. Moisture content, max for fly ash class n, f and c is 3%.

Fly ash, slag, silica fume, and natural pozzolans, chapter 3. Class c mortar was cured at ambient temperature, while class f was cured in ambient and 60c temperatures. Suppliers are the entities that have responsibility for the final properties of the material. Class c or f fly ash are accepted for use on arkansas department of transportation projects based on certification by the supplier. Those of fly ash are amorphous glassy due to rapid cooling. These flyashes were classified as a class f pozzolanic ash and a class. Class c fly ash is typically composed of highcalcium fly ashes with a carbon content of less than 2 percent. Dosage rates vary depending on the type of fly ash and its reactivity level. 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. This can be sourced from most of the ntpc power plants across india and also other thermal power plants having the electrostatic precipitation system required to extract fly ash from flue gasses. Fly ash concrete block are lighter in weight because of partial replacement of fine aggregate and fully replacement coarse aggregate. The chief difference between these classes is the amount of calcium, silica, alumina, and iron content in the ash.

Acknowledgements nchrp report 749 methods for evaluating fly ash for use in highway concrete. Blending, fly ash, durability, permeability created date. Ft performance strength maturity provide mixture design guidance based on statistical analysis of over 40 different mixture designs. How do you include fly ash in a concrete mix design. Energy savings and life cycle impacts of fly ash use. Class c and class f fly ash will produce, respectively, a buff or darker gray concrete.

Class f fly ash also has a lower calcium content than class c fly ash. Apr 26, 2017 the primary difference between class c and class f fly ash is the chemical composition of the ash itself. What are the effects of fly ash on air entrainment. This paper reports the results of research performed in the development and use of high volumes of class c and class f fly ash in concrete mixes for roadway paving projects. Pca 5 edition pgs 6869 assume that the equal amounts of class c and class f flay ash are used in concrete mix tures a and b listed below. Fly ash, especially class f fly ash, is an important component of durable concrete. Class f is fly ash normally produced from burning anthracite or bituminous coal, and class c is normally produced from the burning of subbituminous coal and lignite as are found in some of the western states of the united states halstead 1986. Mix proportions were developed for paving roadway concrete with 20 and 50% class c fly ash and 40% class f fly ash replacements for portland cement. Uses, benefits, and drawbacks of fly ash in construction. Evaluation of the physical and chemical properties of fly ash. Flyash disposal and utilization linkedin slideshare. Fly ash is generally captured from the chimneys of coalfired power plants. Typically, class f fly ash is used at dosages of 15% to 25% by mass of cementitious material and class c fly ash at 15% to 40%.

Fly ash is used in about 50% of ready mixed concrete pca 2000. Class c fly ash is also resistant to expansion from chemical attack. Class f vs class c flyash class f vs class c flyash wwteng structural op. This is ash produced from bituminous coals commonly available in the central and eastern p a r ts of the country, somewhat less commonly in the west. The fly ash is finely divided residue resulting from the combustion of ground or powdered coal. Influences of class f and c fly ash blending author. Class c fly ash is designated in astm c 618 and originates from subbituminous and lignite coals. Compressive strength of the class c fly ash geopolymer cfag cured at room an elevated temperature of 75 c for 4, 8, and 24 h.