The efficiency of microsilica is 35 times that of opc and consequently vastly improved concrete performance can be obtained. Silica fume is the most commonly used mineral admixture in high strength concrete. Fumed silica is being used in various fields such as pharmaceuticals, paints, adhesives and sealants, plastics, rubber and ink except for concrete. Silica fume sf modifies interfacial transition zone between cement paste and aggregate at the micro level. Holland readymixed silicafume concrete is currently used in the united states on a regular basis. Properties of the fumed silica and silica fume have been shown in. Silica fume reduces the permeability of the concrete. It is ultrafine powder with an average particle size of 0. Apr 16, 2016 silica fume is a pozzolanic material that is used with portland cement to produce portland pozzolana cement. Silica fume concrete silica fume is an artificial pozzolona having high pozzolonic activity. Aci 234r96 2000, guide for the use of silica fume in concrete, manual of.
Silica fume sf is the byproduct of the manufacture of silicon for the computer industry. Practical considerations for using silica fume in field concrete terence c. Founded in 1904 and headquartered in farmington hills, michigan, usa, the american concrete institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensusbased standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete. In the united states, silica fume is used predominantly to produce concrete with greater resistance to chloride. Department of civil engineering, north eastern regional. It has become the chosen favorites for high strength concrete and is a good pozzolona and can be used in a big way, adding to the concrete mix will dramatically enhance the workability strength, impermeability of concrete silica fume mixes will. Astm c1240 20 standard specification for silica fume used. Silica fume is not universally available or practical for use, particularly where conventional raw materials used in concrete are more economical, but in some.
Comparative study of the characteristics of nano silica. Founded in 1904 and headquartered in farmington hills, michigan, usa, the american concrete institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensusbased standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design. Specification for sampling, testing and assessing the suitability of water, including water recovered from processes in the concrete industry, as mixing water for concrete. Concrete containing silica fume shows substantial reduced bleeding. This alternative is a fulldepth silica fume concrete bridge deck. One disadvantage is low early strength development than portland ceme. Aci 234r, guide for the use of silica fume in concrete, estimates that for a 15 percent silicafume replacement of cement, there are. In addition to improved durability, the lack of bleeding allows a more efficient finishing process to be used with silica fume concrete. Chemical properties of silica fume concrete compared to conventional sl no ingredients percentage 1 silica 99.
It is a by product from an electric arc furnace used in manufacture of silicon metal or silicon alloy. Fresh and hardened properties of silica fume concrete is superior to conventional concrete. The bulk density uncompacted unit weight of silica fume varies from to 430 kgm3 8 to 27 lbft3. The water demand of concrete containing silica fume increases with increasing amounts of silica fume, see carette and malhotra and scali et al. One in every of the foremost used nano material is nano silica ns. Silica fume concrete silica fume for sale, microsilica. Tests were performed on some 40 mixes made using silica fume as a replacement for. Refer to aci 306r, cold weather concreting,for a discussion of cold weather concreting. One of the most beneficial uses for silica fume is in concrete. In this aspect silicafume concrete is no different from concrete without silica fume. Silica fume is a mineral admixture, a very fine powder of spherical particles that average 0. Silica fume, a byproduct of the ferrosilicon industry, is a highly pozzolanic material that is used to enhance mechanical and durability properties of concrete.
Silica fume concrete is widely used in concrete and fiber cement industries. Silica fume is used in a variety of cementitious concrete, grouts and mortars, refractory, elastomer and polymer applications. Pdf effect of silica fume in concrete researchgate. Comparative study of the characteristics of nano silica, silica fume and fly ashincorporated cement mortars hasan biricika, nihal sarierb adepartment of civil engineering, maltepe university, marmara campus, 34857, maltepe, istanbul, turkey. Properties of the fumed silica and silica fume have been shown in table 1. The use of silica fume concrete for fulldepth bridge deck. These combined properties lead to an extended life expectancy in corrosive environments resistance to chlorides, acids and sulphates and improved strength. Numerous studies have been carried out on use of silica fume as an. These bridge decks were monitored both during construction and after construction to evaluate their. 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. In addition to its pozzolanic properties its is also a very good filler due to its particle size. Silica fume concrete is normally designed for high durability or strength. Rather than working to get that version into the a c i manual of conrete. Silica fume src performs far better than either of them ref fidjestol, 1990 visual damage 1200 days 2 4 6 8 10 visual damage scale 1.
High performance concrete provides enhanced properties in structural precast concrete, including elevated tensile and compressive strength, and a boosted stiffness. Practical considerations for using silica fume in field. 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. The american concrete institute aci defines silica fume as a very fine non. Silica fume in shotcrete pennsylvania state university. Used in the right proportion it can also reduce the overall cost of the concrete. Properties of both fresh and hardened silica fume concrete are affected significantly compared to normal concrete. Verma7 found that silica fume increases the strength of concrete more 25%. Silica fume is an amorphous non crystalline polymorph of silicon oxide.
For normal weight concrete, the flexural strength is usually 15% of its compressive strength. It reacts with lime and water in a similar way to fly ash, also known as pulversided fuel ash pfa, to produce a binder. Use of microsilica as additive to concretestate of art. Silica fume and kim media kryton international inc. The modulus of elasticity is substantially higher than that of ordinary concrete. Because of its chemical and physical properties, it is a very reactive pozzolan. Mechanisms by which silica fume improve concrete strength silica fume increases the compressive strength and durability of concrete grutzeck et. Effect of silica fume on concrete properties and advantages. Because of its extreme fineness and high silica content, silica fume is a very effective pozzolanic material. The silica react rapidly providing high early age strength and durability. 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. These properties indicated silica fume concrete would have a number of advantages when used for the repair of concrete structures. M35 grade of concrete was used for the present investigation. Silica fume is a pozzolanic material that is used with portland cement to produce portland pozzolana cement.
Water measures can be taken to avoid this increase by adjusting aggregate grading and use of super plasticizer. Jan 26, 2017 silica fume concrete silica fume is an artificial pozzolona having high pozzolonic activity. 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. A main hurdle were the needs for official recognition and acceptance of the technology in the form of standards and related specifications. Properties of silica fume the physical and chemical properties of silica fume visavis, opc are presented in table 1. For the silica fume to be effective, there are two issues. Addition of silica fume to concrete has many advantages like high strength, durability and reduction in cement production.
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. During 1986, approximately 350,000 yd3 270,000 m3 of silicafume concrete were placed. Fresh concrete containing silica fume is more cohesive and less prone to segregation than concrete without silica fume. Silica fume concrete with an hrwr is more cohesive and sticky than conventional concrete. 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. Advantages and disadvantages of silica fume in concrete. The use of silica fume in concrete has both engineering potential and economic advantage. Fict, dip m, chartered mcim, dms consultant, united kingdom keywords.
Cement replacement up to 10% with silica fume leads to increase in compressive. Characteristics of silicafume concrete article pdf available in journal of materials in civil engineering 63 august 1994 with 1,516 reads how we measure reads. The durability of this type of concrete is superior to conventional concrete. Under hydrostatic pressure, other forms of waterproofing are required. The optimum silica fume replacement percentage for obtaining maximum 28 days strength of concrete ranged from 10 to 20 % 45. Aci r guide for the use of silica fume in concrete. Additionally, silica fume reduces bleeding by physically blocking the pores in the fresh concrete. Benefits of using silica fume in concrete civil engineer. Silica fume helps to improve concrete by two effects i. The compressive strength of silica fume concrete is higher than ordinary concrete 62 80 mpa, fig. Silica fume is much cheaper than cement therefore it is very important form economical point of view. The influence of silica fume on the compressive strength. Silica fume on the properties of concrete as defined in concrete society report 74, cementitious materials des king hon. Research in the late 1960s showed that the use of silica fume microsilica as a partial.
These bridge decks were monitored both during construction and after construction to evaluate their constructability and performance. The marked increase in the strength of the silica fume. Numerous studies have been carried out on use of silica fume as an additive for concrete, which confirm the improved properties of the concrete. Figure 6 shrinkage of silica fume high strength concrete. The exact addition rate depends upon on the specific performance characteristic to be improved. It is a very finely divided material, many hundreds of times finer than cement.
Investigations on microsilica silica fume as partial cement. When used to produce highperformance concrete, silica fume is typically 415% of the cement weight. Now a days new technology has been introduced in concrete application. Silica fume an admixture for high quality concrete. Silica fume high strength concrete scancem materials. This increase is caused primarily by the high surface area of the silica fume.
Silica fume consists primarily of amorphous noncrystalline. Silica fume concrete is composed of cement, silica fume, fine aggregate, coarse aggregate, and water. Silica fume, cstr74, properties of concrete, effects, cementitious materials, high performance concrete. Pdf since advent of civilization various types of cementitous materials have been used for. The history of silica fume in concrete from novelty to. Astm c1240 20 standard specification for silica fume. Provided silica fume high strength concrete is cured for 24hrs shrinkage is likely to be similar or less than normal concrete. Silica fume is pozzolainc material and is available in different forms. Similarly, the flexural strength is also higher, fig. The effects of utilizing silica fume in portland cement pervious concrete daniel allen mann, candidate for the master of science degree university of missourikansas city, 2014 abstract silica fume has long been used as a supplementary cementing material to provide a high density, high strength, and durable building material. Aci r guide for the use of silica fume in concrete guide for the use of silica fume in concrete aci on free shipping on qualifying. Aci234r 96 guide for the use of silica fume in concrete by aci committee 2347.
The combustion process creates silicon dioxide molecules, which condense to form particles. Six fulldepth silica fume concrete bridge decks were constructed in minnesota between 1997 and 1999. Explore effect of cement replacement by silica fume and fly ash with free download of seminar report and ppt in pdf and doc format. To achieve a maximum improvement in strength and durability, silica fume concrete should contain a high. Pandit3 concluded that addition of micro silica to concrete increases the strength more. Pdf characteristics of silica fume concrete researchgate. The relative density of silica fume is generally in the range of 2. Tests were performed on some 40 mixes made using silica fume as a replacement for cement in quantities of 15, 20, and 30 percent. It may be added directly to concrete as an individual ingredient or in a blend of portland cement and silica fume. Tiwari et al, 2000 presented a research study carried out to improve the early age compressive strength of portland slag cement psc with the help of silica fume.
Silica fume seminar report, ppt, pdf for civil engineering. If concrete without silica fume would require protection, the concrete with silica fume must be protected under the same conditions. Silica fume consists of spherical particles with mean size of about 100 nm which is about 100 times finer than portland cement. Creep of silica fume concrete is lesser than conventional concrete. What are the disadvantages of silica fume in concrete. Fly ash, slag, silica fume, and natural pozzolans, chapter 3. It was observed that there was significant reduction in the chlorideion diffusion with increase in silica fume contents. Investigations on microsilica silica fume as partial. Even though silica fume densifies concrete, it is not a waterproofer. The influence of silica fume on the compressive strength of. It is an excellent for use as a portland cement supplement. 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. In the wetmix process, the silica fume can be introduced as. Latexmodified and silica fume concrete overlays were placed on six bridges on i95 south of emporia, virginia, in the fall of 1994.
Effect of cement replacement by silica fume and fly ash. Use of silica fume does not signi cantly change the unit. It has many advantages and its advantages outweigh its disadvantages. With the proper use of silica fume not only the mechanical properties can be improved, but also the durability of concrete. Advantages and disadvantages of silica fume in concrete silica fume is a byproduct of producing silicon metal or ferrosilicon alloys. After 20 years exposure to ground water containing 4 gl sulfate and 2. Compared to the other ingredients in concrete, the amount of silica fume used is small. Condensed silica fume in concrete pdf fip reports 1988. The increase in water demand of concrete containing silica fume is about 1% for every 1% cement substituted workability is the ease with which a concrete mix can be handled. Adding silica fume to concrete affects the rheological flow properties of the mix.
Whole specimen delaminated opc concrete 20% fa concrete 5% silica fume srpc concrete 10% silica fume. Generally, the rheology of con crete is measured by the familiar slump test astm cl43783, as well as a subjective observation of its ability to flow and consolidate. Silica fume is a very common scm that is frequently used to increase the strength and durability of a concrete structure. Five different watercementitious ratios were used including, 0. This could be attributed to have been caused by addition of silica fume cause. Once silica fume content of about 5% is reached, there will be no bleeding in most concretes. It typically contains 85% or more silica fidjestol and lewis 2003. The high performance concrete usually contains both pozzolanic and chemical admixtures. The efficiency of micro silica is 35 times that of opc and consequently vastly improved concrete performance can be obtained. For instance, it has higher compressive and flexural strength. Guide to using silica fume in precastprestressed concrete. The compressive strengths of silica fume cement paste and mortar were evaluated at various watercementitious ratios. High performance concrete provides enhanced properties in structural precastconcrete, including elevated tensile and compressive strength, and a boosted stiffness. Experiments indicate that concretes become more cohesive and less prone to segregation in the presence of silica fume, moreover, performance of water demand, setting.
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