Microsilica in concrete types, properties, and practical. Once again, this cohesiveness is due to its fine particle content. Explore silica fume with free download of seminar report and ppt in pdf and doc format. Silica fume concrete silica fume is an artificial pozzolona having high pozzolonic activity. Silica fume seminar report, ppt, pdf for civil engineering. Properties of the fumed silica and silica fume have been shown in table 1. Benefits of using silica fume in concrete civil engineer. It is an excellent for use as a portland cement supplement.
These bridge decks were monitored both during construction and after construction to evaluate their. The efficacy of local exhaust ventilation for controlling dust exposures during concrete surface grinding. Silica fume and microsilica are very important materials in building construction. Tests were performed on some 40 mixes made using silica fume as a replacement for.
Use of silica fume does not signi cantly change the unit. The effect of condensed silica fume on the strength development in concrete was studied by replacement of 0, 5, 10, and 20% cement by silica fume. Most civil engineering students will be benefited after seeing this. Silica fume created during silicon alloy production has a higher silica content, while silica fume produced as a result of manufacturing ferrosilicon alloys has a significantly lower silica content. Study of concrete containing silica fume and activated. Different chapters of the manual may be of interest to concrete specifiers, concrete producers, concrete contractors, or concrete inspectors.
Properties of the fumed silica and silica fume have been shown in. For instance, it has higher compressive and flexural strength. Fumed silica is being used in various fields such as pharmaceuticals, paints, adhesives and sealants, plastics, rubber and ink except for concrete. The waste materials which can be used as additional cementitious material like fly ash, silica fume, blast furnace, steel slag etc. To achieve a maximum improvement in strength and durability, silica fume concrete should contain a high. The physical properties of concrete with additions of silica fume and activated natural amorphous silica were investigated. Silica fumes behavior in concrete is predictable, but still dictated by the materials composition. To produce hpc with normal ingredients one use mineral admixtures like silica fume, fly ash and metakoline.
Pdf effect of silica fume on workability and compressive. Silica fume will protect concrete against deicing salts, seawater, road traffic and freezethaw cycles. Six fulldepth silica fume concrete bridge decks were constructed in minnesota between 1997 and 1999. Legally binding document step out from the old to the newjawaharlal nehru invent a new india using knowledge. This document, derived from the occupational health and safety administrations osha small entity compliance guide for the respirable crystalline silica standard for general industry and maritime, is designed to provide. The bulk density uncompacted unit weight of silica fume varies from to 430 kgm3 8 to 27 lbft3. Developments in the formulation and reinforcement of concrete second edition, 2019. Most microsilica particles are less than 1 micron 0. The construction was funded with 20% virginia department of transportation maintenance funds and 80% special istea section 6005 federal funds specifically allocated to demonstrate overlay technologies. Silica fume, a byproduct of the ferrosilicon industry, is a highly pozzolanic material that is used to enhance mechanical and durability properties of concrete. How microsilica improves concrete concrete construction. At 7 days of curing, stc index of control concrete 0% silica fume was 16.
Astm c1240 20 standard specification for silica fume used. The national ready mixed concrete associations guide for. The silicafume concrete was stable with no clumping during batching and mixing. Silica fume is a byproduct in the carbothermic reduction of highpurity quartz with carbonaceous materials like coal, coke, woodchips, in electric arc furnaces in the production of silicon and ferrosilicon alloys. Cement and concrete ced 2 designator of legally binding document.
The effects of silica fume sf on compressive strength of concrete have been analyzed. The ability of high c3a cement to complex with chlorides results in the formation of insoluble compound, able to reduce the mobility of free chloride ion to the reinforcement concrete surface. Silica fume is a pozzolanic material that is used with portland cement to produce portland pozzolana cement. Fly ash comes from coalfired power plants, and silica fume and slag comes from some steel refineries. It may be added directly to concrete as an individual ingredient or in a blend of portland cement and silica fume. Silica fume reduces the permeability of the concrete. Also explore the seminar topics paper on silica fume with abstract or synopsis, documentation on advantages and disadvantages, base paper presentation slides for ieee final year civil engineering ce or ieee civil construction btech, be, mtech students for the year 2017 2018. It is a by product from an electric arc furnace used in manufacture of silicon metal or silicon alloy. Figure 6 shrinkage of silica fume high strength concrete. Silica fume concrete is composed of cement, silica fume, fine aggregate, coarse aggregate, and water. Astm c1240 20 standard specification for silica fume.
Silica fume, a byproduct in the manufacture of ferrosilicon and also of silicon metal, is a very efficient pozzolanic material, though there are some problems associated with its use in concrete. Because of its extreme fineness and high silica content, silica fume is a very effective pozzolanic material. Pdf effect of silica fume on high performance concrete. The water demand of concrete containing silica fume increases with increasing amounts of silica fume, see carette and malhotra and scali et al. Panesar, in developments in the formulation and reinforcement of concrete second edition, 2019. Calcium silicate hydrate csh, which is the strength producing crystallization, and calcium hydroxide ch, a byproduct also called free lime which is responsible for nothing much. The effect of silica fume only on concrete was give 61% increment in compressive strength, but with polymers together give about 72% increment, flexural strength increased from 3. The exact addition rate depends upon on the specific performance characteristic to be improved. Its small particle size which is 100 times finer than ordinary portland cement complements the finess modulus of concrete and provides a ballbearing effect, which improves thixotropic behavior, in effect modifying concrete viscosity. As the molten metal is produced, a silicabased gas is emitted. High performance concrete hpc is now a days used widely in the construction industry worldwide. The use of pozzolans in concrete concrete countertop institute. It has many advantages and its advantages outweigh its disadvantages. Most civil engineering students will be benefited after seeing this wonderful presentation november 1, 2014 at 1.
In the wetmix process, the silica fume can be introduced as. Provided silica fume high strength concrete is cured for 24hrs shrinkage is likely to be similar or less than normal concrete. Microsilica in concrete microsilica is a byproduct from silicon metal or ferrosilicon industries, where these metals are produced in submerged electric arc furnaces. The relative density of silica fume is generally in the range of 2. These properties indicated silica fume concrete would have a number of advantages when used for the repair of concrete structures. The silica exposure control plan applies to all purdue university employees who are expected to be exposed to respirable crystalline silica as outlined in section 4. Silica fume is the finest with most particles averaging 0. Latexmodified and silica fume concrete overlays were placed on six bridges on i95 south of emporia, virginia, in the fall of 1994. The use of silica fume concrete for fulldepth bridge deck. Chapters 1 and 2 provide basic information explaining what silica fume is and how it is used in concrete. Microsilica is a mineral admixture composed of very fine solid glassy spheres of silicon dioxide. This alternative is a fulldepth silica fume concrete bridge deck. Jan 26, 2017 silica fume concrete silica fume is an artificial pozzolona having high pozzolonic activity. Many pozzolans are waste products from industrial processes.
Guide to using silica fume in precastprestressed concrete. Effect of silica fume on concrete properties and advantages. Silica fume and metakaolin admixtures are formulated to produce extremely strong and durable concrete. Once portland cement and water in the mix start reacting with each other hydrating, primary chemical reactions produce two chemical compounds. What are the disadvantages of silica fume in concrete. Silica fume in shotcrete pennsylvania state university. If the silica fume concrete contains superplasticizers, both the shear resistance and the cohesiveness of the concrete will be reduced, and improved flow will result. Specification for silica fume number of amendments. Properties, advantages, and applications silica fume concrete is composed of cement, silica fume, fine aggregate, coarse aggregate, and water. This increase is caused primarily by the high surface area of the silica fume. Petrographic examination of the silicafume concrete was conducted for the silicafume supplier, and the odot lab. The combustion process creates silicon dioxide molecules, which condense to form particles. Frequently called condensed silica fume, microsilica is a byproduct of the industrial. The silica fume association 38860 sierra lane, lovettsville,va 20180 tel.
Fresh and hardened properties of silica fume concrete is superior to conventional concrete. The silica fume was added by pumping directly into the mobile mixing chamber from the transport truck 1. Much research has been carried out to this point regarding the effects of silica fume on concrete, and it has been made clear that silica fume additions are effective in improving strength characteristics, resistance to. This gaseous fume, as it rises, cools rapidly and forms extremely minute, amorphous, spherical particles. The use of pozzolans in concrete concrete countertop. Silica fume high strength concrete scancem materials. When silica fume is added to concrete, initially it remains inert.
One disadvantage is low early strength development than portland ceme. From all these waste material the most successful cementitious material is silica fume because it improves the. The results of the experiments showed that when the polymerbinder materials ratio increases, the compressive strength of concrete decreases. The use of silica fume in concrete should be limited to specialized applications that can take full advantage of its unique properties. When used to produce highperformance concrete, silica fume is typically 415% of the cement weight. Tests were performed on some 40 mixes made using silica fume as a replacement for cement in quantities of 15, 20, and 30 percent. Control of silica exposure from hand tools in construction. Fly ash, slag, silica fume, and natural pozzolans, chapter 3. Concrete containing silica fume shows substantial reduced bleeding. The ability of high c3a cement to complex with chlorides results in the formation of insoluble compound, able to reduce the mobility of free chloride ion to the reinforcementconcrete surface. For the silica fume to be effective, there are two issues. For more information, contact the construction divisions rigid pavements and concrete materials branch at 512 5065858.
Burnett csr days drying time microstrain 0 10203040 50607080 90 0 200 400 600 800 90 mpa 80 mpa 60 mpa figure 7 teamwork for silica fume high strength. Compared to the other ingredients in concrete, the amount of silica fume used is small. Besides, highstrength concrete enhanced with silica fume provides architects and engineers with greater design flexibility. Cdc silica, engineering controls for silica in construction. Pdf effect of silica fume on strength parameters of. Silica fume is a byproduct from the production of elemental silicon or alloys containing silicon in electric arc furnaces.