The exact addition rate depends upon on the specific performance characteristic to be improved. 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 concrete is composed of cement, silica fume, fine aggregate, coarse aggregate, and water. Silica fume in shotcrete pennsylvania state university. For additional information, please contact your silica fume supplier or the silica fume association. Six fulldepth silica fume concrete bridge decks were constructed in minnesota between 1997 and 1999.
Latexmodified and silica fume concrete overlays were placed on six bridges on i95 south of emporia, virginia, in the fall of 1994. The results of the experiments showed that when the polymerbinder materials ratio increases, the compressive strength of concrete decreases. It has many advantages and its advantages outweigh its disadvantages. Silica fume high strength concrete scancem materials. High performance concrete hpc is now a days used widely in the construction industry worldwide. Explore silica fume with free download of seminar report and ppt in pdf and doc format. 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. Specification for silica fume number of amendments. 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. The effects of silica fume sf on compressive strength of concrete have been analyzed. Fly ash comes from coalfired power plants, and silica fume and slag comes from some steel refineries. Provided silica fume high strength concrete is cured for 24hrs shrinkage is likely to be similar or less than normal concrete. The waste materials which can be used as additional cementitious material like fly ash, silica fume, blast furnace, steel slag etc.
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. Besides, highstrength concrete enhanced with silica fume provides architects and engineers with greater design flexibility. Silica fume, a byproduct of the ferrosilicon industry, is a highly pozzolanic material that is used to enhance mechanical and durability properties of concrete. Control of silica exposure from hand tools in construction. Astm c1240 20 standard specification for silica fume. The use of silica fume in concrete should be limited to specialized applications that can take full advantage of its unique properties. Study of concrete containing silica fume and activated. The use of pozzolans in concrete concrete countertop institute.
At 7 days of curing, stc index of control concrete 0% silica fume was 16. Four silica fume concrete mixes with silica fume contents of 5%, 10%, 15%, and 20% of the total cementitious material content were prepared along with one plain portland cement concrete mix and. As the molten metal is produced, a silicabased gas is emitted. Compared to the other ingredients in concrete, the amount of silica fume used is small. How microsilica improves concrete concrete construction. The efficacy of local exhaust ventilation for controlling dust exposures during concrete surface grinding. Panesar, in developments in the formulation and reinforcement of concrete second edition, 2019. 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. When silica fume is added to concrete, initially it remains inert. These bridge decks were monitored both during construction and after construction to evaluate their.
Figure 6 shrinkage of silica fume high strength concrete. From all these waste material the most successful cementitious material is silica fume because it improves the. Chapters 1 and 2 provide basic information explaining what silica fume is and how it is used in concrete. Petrographic examination of the silicafume concrete was conducted for the silicafume supplier, and the odot lab. Microsilica in concrete types, properties, and practical. Tests were performed on some 40 mixes made using silica fume as a replacement for. Properties, advantages, and applications silica fume concrete is composed of cement, silica fume, fine aggregate, coarse aggregate, and water. To achieve a maximum improvement in strength and durability, silica fume concrete should contain a high. Fly ash, slag, silica fume, and natural pozzolans, chapter 3. 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. Fresh concrete containing silica fume is more cohesive and less prone to segregation than concrete without silica fume. Once portland cement and water in the mix start reacting with each other hydrating, primary chemical reactions produce two chemical compounds. Cdc silica, engineering controls for silica in construction. 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.
It may be added directly to concrete as an individual ingredient or in a blend of portland cement and silica fume. Microsilica is a mineral admixture composed of very fine solid glassy spheres of silicon dioxide. Jan 26, 2017 silica fume concrete silica fume is an artificial pozzolona having high pozzolonic activity. Astm c1240 20 standard specification for silica fume used. Guide to using silica fume in precastprestressed concrete. Silica fume will protect concrete against deicing salts, seawater, road traffic and freezethaw cycles. Silica fume and microsilica are very important materials in building construction. The combustion process creates silicon dioxide molecules, which condense to form particles. The compressive strength results of concrete mixed over different waterbinder ratios as well as different replacing percentages of sf were analyzed. Microsilica in concrete silica fume for sale, microsilica. 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 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. The bulk density uncompacted unit weight of silica fume varies from to 430 kgm3 8 to 27 lbft3.
The use of silica fume concrete for fulldepth bridge deck. Pdf effect of silica fume on workability and compressive. This increase is caused primarily by the high surface area of the silica fume. Use of silica fume does not signi cantly change the unit. Blending of plain concrete with 1020% silica fume significantly improved the corrosion resistance. Legally binding document step out from the old to the newjawaharlal nehru invent a new india using knowledge. Silica fume is a pozzolanic material that is used with portland cement to produce portland pozzolana cement. What are the disadvantages of silica fume in concrete. Silica fume is the finest with most particles averaging 0. It is a by product from an electric arc furnace used in manufacture of silicon metal or silicon alloy. The silica fume was added by pumping directly into the mobile mixing chamber from the transport truck 1. In the united states, silica fume is used predominantly to produce concrete with greater resistance to chloride. Silica fume and metakaolin admixtures are formulated to produce extremely strong and durable concrete. Different chapters of the manual may be of interest to concrete specifiers, concrete producers, concrete contractors, or concrete inspectors.
Most civil engineering students will be benefited after seeing this. Properties of the fumed silica and silica fume have been shown in. Frequently called condensed silica fume, microsilica is a byproduct of the industrial. Fresh and hardened properties of silica fume concrete is superior to conventional concrete.
The silicafume concrete was stable with no clumping during batching and mixing. As the molten metal is produced, a silica based gas is emitted. The physical properties of concrete with additions of silica fume and activated natural amorphous silica were investigated. Most microsilica particles are less than 1 micron 0. One disadvantage is low early strength development than portland ceme. 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. Silica fume concrete silica fume is an artificial pozzolona having high pozzolonic activity.
For instance, it has higher compressive and flexural strength. To produce hpc with normal ingredients one use mineral admixtures like silica fume, fly ash and metakoline. Silica fume concrete with an hrwr is more cohesive and sticky than conventional concrete. It is an excellent for use as a portland cement supplement. Silica fume seminar report, ppt, pdf for civil engineering.
The national ready mixed concrete associations guide for. This alternative is a fulldepth silica fume concrete bridge deck. Properties of the fumed silica and silica fume have been shown in table 1. Cement and concrete ced 2 designator of legally binding document. Fumed silica is being used in various fields such as pharmaceuticals, paints, adhesives and sealants, plastics, rubber and ink except for concrete. Silica fumes benefits are already evident in the fresh concrete state before it begins to harden. The relative density of silica fume is generally in the range of 2. Microsilica in concrete microsilica is a byproduct from silicon metal or ferrosilicon industries, where these metals are produced in submerged electric arc furnaces. Silica fume is a byproduct from the production of elemental silicon or alloys containing silicon in electric arc furnaces. Once again, this cohesiveness is due to its fine particle content.
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. 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. Silica fume reduces the permeability of the concrete. These properties indicated silica fume concrete would have a number of advantages when used for the repair of concrete structures. The use of pozzolans in concrete concrete countertop. Benefits of using silica fume in concrete civil engineer. For more information, contact the construction divisions rigid pavements and concrete materials branch at 512 5065858. Adds cohesiveness and reduced bleeding improves strength and durability. Additionally, silica fume reduces bleeding by physically blocking the pores in the fresh concrete. 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. Many pozzolans are waste products from industrial processes. 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.
Effect of silica fume on concrete properties and advantages. In the wetmix process, the silica fume can be introduced as. For the silica fume to be effective, there are two issues. 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. Concrete containing silica fume shows substantial reduced bleeding. Silica fumes behavior in concrete is predictable, but still dictated by the materials composition. Most civil engineering students will be benefited after seeing this wonderful presentation november 1, 2014 at 1. Pdf effect of silica fume on strength parameters of.
When used to produce highperformance concrete, silica fume is typically 415% of the cement weight. 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. The water demand of concrete containing silica fume increases with increasing amounts of silica fume, see carette and malhotra and scali et al. Developments in the formulation and reinforcement of concrete second edition, 2019. Effects of silica fume on concrete compressive strength. The silica fume association 38860 sierra lane, lovettsville,va 20180 tel. 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. Tests were performed on some 40 mixes made using silica fume as a replacement for cement in quantities of 15, 20, and 30 percent.
1513 588 403 1581 1557 1328 335 804 1027 531 1053 313 1187 259 631 521 1358 1201 1271 974 588 1552 1268 1146 1097 1510 1445 160 125 291 1226 597 607 474 111 702 1404 1421 495 1239 584