Cause and control of transverse cracking in conc rete bridge decks. Transverse cracking in concrete bridge ieft, and steel girder bridge right. Silica fume, cstr74, properties of concrete, effects, cementitious materials, high performance concrete. Transverse cracking of high performance concrete bridge decks. Silicafume concrete acts much like conventional concrete duri n g t ra n s p o r t, placement, and consolidation. Pdf effect of transverse reinforcement on bond strength. Influence of silica fume replacement of cement on expansion. Aci member joann browning is an associate professor of civil. A decrease in crack density is observed for 5% silica fume overlay decks, which appears to be the result of increased efforts to limit evaporation prior to the initiation of wet curing.
From the data, it appears that cracking is caused by several factors. Tests were performed on some 40 mixes made using silica fume as a replacement for. His aci duties include secretary of the silicafume concrete subcommittee, and chapter author to the highstrength concrete, parking structures, and concrete proportioning committees. Transverse cracking in concrete bridge decks information services.
The objective of this program was to study the effect of different factors such as. Transverse cracking of high performance concrete bridge. Fict, dip m, chartered mcim, dms consultant, united kingdom keywords. The final study summarizes the results of two experimental bridge deck overlays containing silica fume.
Silica fume is much cheaper than cement therefore it is very important form economical point of view. In this study, it was determined that the addition of 8% silica fume to recycled concrete recycled concrete with silica fume improved this behaviour. The class s deck showed only hairline cracking after 1 year, but transverse cracking occurred in the hpc decks. Permeability of silica fume concretes with higher dosage of silica fume could not be measured. A fasttrack implementation study volume 2 materials. Concretes containing silica fume had higher shrinkages at early ages than other concretes.
Transverse cracking in concrete bridge ieft, and steel girder bridge. Transverse cracks predominately over transverse bars gpr width of transverse cracks were typically 15 to 25 mils plastic shrinkage cracking noted on some decks, most severe on florenceeast mp 10. Fly ash increases workability when compared with conventional concrete with same water content. The use of silica fume in concrete should be limited to specialized applications that can take full advantage of its unique properties. Cracking in concrete bridge decks the national academies press. Pandit3 concluded that addition of micro silica to concrete increases the strength more. Chapter six cracking in concrete bridge decks concrete. Flexural behaviour and ductility of high strength concrete. The combustion process creates silicon dioxide molecules, which condense to form particles. Because of its extreme fineness and high silica content, silica fume is a very effective pozzolanic material. Cracking and chloride contents in reinforced concrete. The durability of this type of concrete is superior to conventional concrete. Effect of fly ash and silica fume on concrete properties.
Factors that influence the rate of evaporation of bleed water either separately or collectively include. Pdf accelerated curing of silicafume concrete researchgate. In denser silica fume, concrete the amount of cracking over a period of time is often greater. Once again, this cohesiveness is due to its fine particle content. Cracking tendency and drying shrinkage of silica fume concrete for bridge deck applications authors. The objective of this program was to establish a mix for the production of superior quality concrete using silica fume and type 10 cement at lower quantities.
Apart from crack width, the crack depths, cracking frequency and healing of. Concrete, deck, cracking, cracks, transverse, bridges, causes of cracking, control of cracking unclassified unclassified 204 fhwanj2002019 m. Silica fume concrete is very susceptible to plastic shrinkage cracking owing to its lack of bleeding. Silica fume on the properties of concrete as defined in concrete society report 74, cementitious materials des king hon. The trend in cracking for decks with silica fume overlays cast in the 1990s containing 5% silica fume, however, is quite the opposite. These decks tend to develop full depth, transverse cracks and. However, wide variety of results on the effect of crack widths on corrosion of steel in concrete are reported in many studies. Pdf effect of transverse reinforcement on bond strength of. Effect of transverse reinforcement on bond strength of reinforcing bars in silica fume concrete article pdf available in materials and structures 326. Silica fume concrete with an hrwr is more cohesive and sticky than conventional concrete. Plastic shrinkage cracks appear in the surface of fresh concrete soon after it is placed and while it is still plastic. Effect of wc and silica fume on tensile stress produced by autogenous shrinkage of concrete paillere et al. As such, the terms diagonal, longitudinal, transverse, vertical and horizontal are often. Using the ringtest method to detect the plastic shrinkage cracking of sf paste.
Cracking tendency and drying shrinkage of silica fume. A number of states allow the use of sfc as an option to low slump or latex modified concrete. Latexmodified and silica fume concrete overlays were placed on six bridges on i95 south of emporia, virginia, in the fall of 1994. Cause and control of transverse cracking in concrete bridge decks. This was accomplished in two parts, the laboratory part. Some states specify combinations of silica fume and fly ash or slag to obtain the desired end result. Silica fume was used as a partial replacement by weight of cement from 0% to.
According to idot,2 the average snowfall in this part of the state is. The use of good quality fly ash with a high fineness and low carbon content reduces the water demand of concrete. Instruments were placed in the decks to monitor strains. Chapter two types and causes of concrete cracking in bridges. 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. Free from the presence of salts that absorbs the moisture from the atmosphere and lead to efflorescence. An inspection of the bridge three months after the placement of the silica fume concrete overlay re vealed four short transverse cracks and. Many recent concrete bridge decks have been built with high performance concrete with low performance results showing significant cracking between very low permeability silica fume ternary mixes with hrwr concrete. They are usually parallel to each other on the order of 1 to 3 feet apart, relatively shallow, and. Silicafume concrete sfc has been used in bridges outside the united states. Concrete containing silica fume shows substantial reduced bleeding. Silica fume concrete is composed of cement, silica fume, fine aggregate, coarse aggregate, and water.
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. Apart from crack width, the crack depths, cracking frequency and healing of cracks. Trbs national cooperative highway research program nchrp synthesis 500. Concrete mixture proportions cracking in bridge decks is a function of.
Howe ve r, depending on the amount of silica fume, the fre s h c o n c r ete can be more cohesive and less prone to segregation than conventional concre t e. Moreover, the use of this material in recycled concrete produced changes in its structural behaviour similar to those induced in conventional concrete conventional concrete with silica fume. Silica fume is extremely fine material with mean particle sizes that are 0 times less than that of cement. The causes and prevention of cracking in concrete basf. The use of silica fume concrete for fulldepth bridge deck. Concrete resurfacing is a method of rehabilitation of tone or damaged concrete floor or pavement surfaces to make it available for use without the reconstruction of the whole structure before undergoing any kind of method as a part of resurfacing of concrete, it is necessary to conduct an evaluation of the existing surface. The total length of the three gorges dam is about 2308m, the dam height is 185m, and the normal water storage level is 175 meters, and the investment is rmb 5 billion 200 million yuan. Curing methods to mitigate early age bridge deck cracking. Place concrete bridge decks transverse cracking in a bridge deck wsdot. Additionally, silica fume reduces bleeding by physically blocking the pores in the fresh concrete. Bridge deck construction new york state dot highperformance concrete. Cip 5 plastic shrinkage cracking what is plastic shrinkage cracking.
Nov 12, 2018 cracking can occur in plastic concrete when rapid evaporation of bleedwater from the concrete surface causes the surface to dry out. Silica fume and kim media kryton international inc. Silica fume sf is the byproduct of the manufacture of silicon for the computer industry. According to a recent survey from respondents in the state departments of transportation dots, more than 100,000 bridge decks in the united states have suffered from early transverse cracking krauss and rogalla 1996. 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.
Use of silica fume does not signi cantly change the unit. The concrete was to exhibit superior durability characteristics when exposed to freezethaw, as well as resistance to other deleterious effects such as scaling, cracking and corrosion. Silica fume is defined by the american concrete institute as very fine noncrystalline silica produced in electric arc furnaces as a byproduct of the production. Longitudinal cracking noted, but not significant solutions for the built world page 20.
These bridge decks were monitored both during construction and after construction to evaluate their constructability and performance. Transverse cracking was relatively minor in the first six bridge decks. Verma7 found that silica fume increases the strength of concrete more 25%. Jan 30, 2018 it is generally recognized that cracks provide easy access to ingress of chlorides in concrete and hence, the initiation of corrosion of steel in cracked concrete occurs at early stage. For instance, it has higher compressive and flexural strength. Nchrp synthesis project 500 control of concrete cracking in bridges chapters. Tiwari and momin 12 presented a research study carried out to. Silicafume microsilica concrete in bridges in the united states. Cracking can occur in plastic concrete when rapid evaporation of bleedwater from the concrete surface causes the surface to dry out. 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. Fresh and hardened properties of silica fume concrete is superior to conventional concrete. Benefits of using silica fume in concrete civil engineer. Six fulldepth silica fume concrete bridge decks were constructed in minnesota between 1997 and 1999.
Their study intended to determine the contribution of silica fume on concrete over a wide range of wc ratio ranging from 0. Tests were performed on some 40 mixes made using silica fume as a replacement for cement in quantities of 15, 20, and 30 percent. Effect of silica fume on concrete properties and advantages. Guide to using silica fume in precastprestressed concrete.
Silica fume modified concrete sfmc is a concrete mixture used in rigid overlays to decrease the permeability of the concrete and thus increase the durability of the bridge deck. In this work, to make the concrete coarse aggregate of size 20mm, fine aggregates sand of zone, ordinary portland cement opc, and silica fume were mixed properly with appropriate. Read control of concrete cracking in bridges at nap. Bridge, concrete, cracking, decks, heat of hydration, shrinkage cracking is a major problem with newly placed concrete decks. Restrained shrinkage cracking of concrete bridge decks. There fore, immediate application of fog sprays or misting after placement is essential to avoid formation of plastic shrink age cracks in silica fume concrete ozyildirim 1991. Low cracking concretes for the closure pours and overlays. Silica fume concrete is widely used in concrete and fiber cement industries.
Cause and control of transverse cracking in concrete. Properties of the fumed silica and silica fume have been shown in table 1. It reacts with lime and water in a similar way to fly ash, also known as pulversided fuel ash pfa, to produce a binder. In addition to its pozzolanic properties its is also a very good filler due to its particle size. Pdf effect of silica fume on workability and compressive. The surface of silicafume concrete tends to dry quickly, sub.
National academies of sciences, engineering, and medicine. It is a very finely divided material, many hundreds of times finer than cement. Both repairs were performed by the same contractor and in both cases consisted of partial and fulldepth repairs followed by a 2 4 in. Investigation on the effect of silica fume on shrinkage. These bridge decks were monitored both during construction and after construction to evaluate their. Most of these bridge decks were composite steel girder construction built during 1985 to 1990. Control of concrete cracking in bridges provides information on methods used to control concrete cracking in bridge superstructures and substructures, and on the influence of cracking on longterm durability.
Why are silica fumes densified before their use as a. Structural shear behaviour of recycled concrete with silica fume. These combined properties lead to an extended life expectancy in corrosive environments resistance to chlorides, acids and sulphates and improved strength. Statistics on the amount of silica fume production, its composition, quality and the way it is handled and proportioned for making concrete are described briefly. 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 increases the drying shrinkage of mortar and concrete 10, 11. Portland cement 300 kgm3 fly ash 80 kgm3 silica fume 25 kgm3 wcm 0. Effect of cracking on corrosion of steel in concrete. Modelmethodsapproach in this work, a twodimensional model is used to represent the.
The use of silica fume in concrete has become widespread all over the world in the production of highstrength and durable concretes. This download a contains several papers, technical articles and two instructional videos on finishing, and curing, silica fume concrete an integral step in the producing crack free structures. This in turn leads to the corrosion of reinforcing steel and an accelerated deterioration of the concrete. Fresh concrete containing silica fume is more cohesive and less prone to segregation than concrete without silica fume. Evaluation of bridge deck overlays silica fume association. Through his employment at elkem hes been directly involved with silicafume concrete research and implementation into project applications for the past 20 years. Transverse cracking of high performance concrete bridge decks after one season or six to. Effect of cracking on chloride content in concrete bridge. Ala saadeghvaziri and rambod hadidi cause and control of transverse cracking in concrete bridge decks department of civil and environmental engineering new jersey institute of technology. Material effects as discussed next, concrete mixture proportions, and compressive strength play primary roles in bridge deck cracking.
Many concrete bridge decks develop transverse cracking and most of these cracks. Concrete resurfacing silica fume for sale, microsilica. 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. Silica fume reduces the permeability of the concrete. A total of eighteen concrete beams were fabricated and tested in this experimental program. This alternative is a fulldepth silica fume concrete bridge deck. It is generally recognized that cracks provide easy access to ingress of chlorides in concrete and hence, the initiation of corrosion of steel in cracked concrete occurs at early stage. Pdf study of partial replacement of cement by silica fume. Effect of wc, cement fineness, silica fume and admixtures on autogenous. Astm c1240 20 standard specification for silica fume used. If you thought cement dust was an issue, then think of silica fume dust and it is als. Fumed silica is being used in various fields such as pharmaceuticals, paints, adhesives and sealants, plastics, rubber and ink except for concrete. High heat of hydration caused the plastic concrete to expand.
Many articles have described silica fume sf and its effect on portland cement concrete 24. Apr 08, 2017 effect of fly ash and silica fume on concrete properties. Types and causes of concrete cracking in bridges 3. 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. Construction is strictly adhered to, the density of transverse deck cracks will be reduced. These properties indicated silica fume concrete would have a number of advantages when used for the repair of concrete structures. Fly ash, silica fume, slag, and natural pozzolans in. Figure 14 a shows the unrestrained expansion behavior of expansive cement pastes in the presence of class c fly ash, class f fly ash, and silica fume. Hooton 1993 reported that permeability of concrete decreased with addition of silica fume. Fresh concrete containing silica fume is more cohesive and less.
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