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هدیکچ و يداب رتسکاخ ،یعیبط نلاوزوپ ینیزگیاج رثا یسررب ،رضاح قیقحت عوضوم سیلیسورکیم رب نامیس نزو زا يدصرد اب تسا دایز تمواقم اب نتب یلخاد ذفانم مجح و يراشف تمواقم يور . نیدب روظنم 13 نامیـس هـب بآ تبسن ود اب طلاتخا حرط 46 / 0 و 3 / 0 دش... more
هدیکچ و يداب رتسکاخ ،یعیبط نلاوزوپ ینیزگیاج رثا یسررب ،رضاح قیقحت عوضوم سیلیسورکیم رب نامیس نزو زا يدصرد اب تسا دایز تمواقم اب نتب یلخاد ذفانم مجح و يراشف تمواقم يور . نیدب روظنم 13 نامیـس هـب بآ تبسن ود اب طلاتخا حرط 46 / 0 و 3 / 0 دش هتخاس . نامیس هب بآ تبسن ود ره رد رادـقم هـب یـعیبط نلاوزوـپ ینیزگیاـج ،دهاـش حرط رب هولاع ، 15 و 30 و دـصرد نازیم هب يداب رتسکاخ ینیزگیاج 15 و 25 دش ماجنا نامیس ینزو دصرد . سیلیسورکیم نامیـس هب بآ تبسن اب نتب رد اهنت زین 3 / 0 و نازیم هب 5 ، 8 و 11 دش نیزگیاج دصرد . جیاتن هب تسد ناشن هدمآ یم دهد اج هک رد تـمواقم شهاـک ثـعاب یـعیبط نلاوزوپ ینیزگی ییاهن و هیلوا نینس یم دوش تدم زارد يراشف تمواقم ،نتب هیلوا تمواقم شهاک دوجو اب ،يداب رتسکاخ اما شیب رت ي هنومن هب تبسن دراد دهاش . مه نینچ ریثأت هدمع سیلیسورکیم نس زا دعب نتب يراشف تمواقم رب 2 زاغآ زور یم دوش . انم مجح تـمواقم هدر اب نتب ذف نییاپ ینیزگیاج اب ،رت نلاوزوپ اه شهاک یم دبای . هک یلاح رد نلاوزوپ اه تـمواقم اـب نتـب رد شیـب رـت نـس اـت ، 28 ،زور ریثأـت لـباق هظحلام دنرادن نتب ذفانم رب يا .
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This paper presents the effects of silica fume and steel fiber on the mechanical properties and impact behavior of recycled aggregate concrete containing two types of recycled coarse aggregates (RCAs). In total, 20 series of concretes are... more
This paper presents the effects of silica fume and steel fiber on the mechanical properties and impact behavior of recycled aggregate concrete containing two types of recycled coarse aggregates (RCAs). In total, 20 series of concretes are considered and they are divided into 4 groups. The first group consisted of 1 control concrete containing natural coarse aggregate and 4 control recycled aggregates concretes containing 50 and 100% RCA of two types (A and B). The second and third series are similar to the first series in every aspect except the former contained 8% silica fume as partial replacement of ordinary Portland cement and the latter contained 1% steel fiber by volume. In the fourth series, both 8% silica fume and 1% steel fiber are used. Compressive and split tensile strengths of all concretes are measured in terms of mechanical properties evaluation and low velocity impact hammer test is conducted to evaluate the impact behavior of all concretes. Results show that the concrete containing RCA obtained from high strength parent concrete exhibited better mechanical properties than that containing RCA made low strength concrete. The addition of silica fume improved the split tensile and compressive strengths of recycled aggregate concretes containing both types of coarse aggregates. The addition of steel fibers significantly increased the compressive and split tensile strengths of all concretes, especially recycled aggregate concretes. The simultaneous use of silica fume and steel fibers had a significant effect on the compressive and split tensile strengths of all recycled aggregate concretes, probably due to better bond of steel fibers with mortar containing silica fume as well as improved ITZ between RCA and mortar. The addition of 100% RCA of both types significantly reduced the impact resistance of recycled aggregate concretes. The same is also true even when silica fume is added. The addition of steel fibers significantly improved the impact behavior of recycled aggregate concretes. The addition of silica fume, however, did not show any significant improvement in impact resistance of steel fiber-reinforced recycled aggregate concretes.
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Research Interests: Mechanical Engineering, Civil Engineering, Ocean Engineering, Aerospace Engineering, Materials Science, and 12 moreMechanics of Materials, Automotive Engineering, Mechanical properties, Composite Material, Flexural Strength, Impact Engineering, Fiber Steel Reinforced Concrete, Silica Fume, Aspect Ratio, Civil and Structural Engineering, Impact Resistance, and Volume Fraction
Research Interests: Mechanical Engineering, Civil Engineering, Ocean Engineering, Aerospace Engineering, Materials Science, and 13 moreModeling, Impact Mechanics, Mechanics of Materials, Automotive Engineering, Finite Element Analysis, Fiber, Mechanical properties, Polypropylene, Composite Material, Impact Engineering, Fiber Reinforced Concrete, Civil and Structural Engineering, and Impact Resistance
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ABSTRACT Impact resistance and strength performance of concrete mixtures with 0.36 and 0.46 water–cement ratios made with polypropylene and silica fume are examined. Polypropylene fiber with 12-mm length and four volume fractions of 0%,... more
ABSTRACT Impact resistance and strength performance of concrete mixtures with 0.36 and 0.46 water–cement ratios made with polypropylene and silica fume are examined. Polypropylene fiber with 12-mm length and four volume fractions of 0%, 0.2%, 0.3% and 0.5% are used. In pre-determined mixtures, silica fume is used as cement replacement material at 8% weight of cement. The results show that incorporating polypropylene fibers improves mechanical properties. The addition of silica fume facilitates the dispersion of fibers and improves the strength properties, particularly the impact resistance of concretes. It is shown that using 0.5% polypropylene fiber in the silica fume mixture increases compressive split tensile, and flexural strength, and especially the performance of concrete under impact loading.
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Research Interests: Materials Engineering, Materials Science, Metallurgy, Titanium, Heat Treatment, and 13 moreDislocations, Composite Material, Thermal, Nickel, Mechanical Testing, Phase Transformation, Differential Scanning Calorimeter, Shape Memory, Nickel Titanium, Martensitic Transformation, Bending Test, Intermetallic Compound, and Titanium alloy
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Monitoring the Electrical Resistance of Concrete During One Slow Freeze Thaw Cycle, A Method for Assessing The Water-Cement Ratio M. Nili Associate professor, Civil Eng., Dept., Bu-Ali Sina University, Hamedan, I.R.Iran A. Moradi Msc,... more
Monitoring the Electrical Resistance of Concrete During One Slow Freeze Thaw Cycle, A Method for Assessing The Water-Cement Ratio M. Nili Associate professor, Civil Eng., Dept., Bu-Ali Sina University, Hamedan, I.R.Iran A. Moradi Msc, Civil Eng., Dept., Bu-Ali Sina University, Hamedan, I.R.Iran M. Nili Msc, Civil Eng., Dept., Bu-Ali Sina University, Hamedan, I.R.Iran ( Received: 2014/7/21 Accepted: 2015/4/29) Abstract Many attempts have been done to increase the service life of the concrete structures. In this regard, the concrete properties should be evaluated by non destructive testing methods (NDT) periodically to estimate how the structures may behave in the future. It is so important to select a proper and simple method to examine the concrete properties during the service life. In the present paper, try has been done to evaluate the water cement ratio of the hardened concrete via non destructive measurement of the electrical resistance the concrete during one freeze thaw cycle...
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ABSTRACT The long-term compressive strength and durability properties of concrete specimens produced by incorporating polypropylene fibers and silica fume were investigated. Silica fume, a cement replacement, was used at 8% (by weight of... more
ABSTRACT The long-term compressive strength and durability properties of concrete specimens produced by incorporating polypropylene fibers and silica fume were investigated. Silica fume, a cement replacement, was used at 8% (by weight of cement) and the volume fractions of the polypropylene fibers were 0%, 0.2%, 0.3% and 0.5%. Water-binder ratios were 0.46 and 0.36. The results indicate that the inclusion of fiber and particularly silica fume into the specimens led to an increased long-term compressive strength. Electrical resistance of the silica fume specimens improved remarkably, but decreased slightly due to the fiber inclusion. Water absorption of the fiber–silica fume specimens decreased exclusively compared to the reference samples. Inclusion of fiber and silica fume into the specimens had no considerable effect on the dynamic frequency results.
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Today, the use of recycled aggregates as a substitute for a part of the natural aggregates in concrete production is increasing. This approach is essential because the resources for natural aggregates are decreasing in the world. In the... more
Today, the use of recycled aggregates as a substitute for a part of the natural aggregates in concrete production is increasing. This approach is essential because the resources for natural aggregates are decreasing in the world. In the present study, the effects of recycled concrete aggregates as a partial replacement for fine (by 50%) and coarse aggregates (by 100%) were examined in the self-compacting concrete mixtures which contain air-entraining agents and silica fumes. Two series of self-compacting concrete mixes have been prepared. In the first series, fine and coarse recycled mixtures respectively with 50% and 100% replacement with air entraining agent were used. In the second series, fine recycled (with 50% replacement) and coarse recycled (with 100% replacement) were used with silica fume. The rheological properties of the self-compacting concrete (SCC) were determined using slump-flow and J-ring tests. The tests of compressive strength, tensile strength, and compressive s...
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Concrete performance is affected by aggregates, the bulk cement paste and particularly the interfacial transition zone (ITZ). In this regard, the ITZ is generally weaker than either of two main components of concrete, namely the aggregate... more
Concrete performance is affected by aggregates, the bulk cement paste and particularly the interfacial transition zone (ITZ). In this regard, the ITZ is generally weaker than either of two main components of concrete, namely the aggregate and the bulk hydrated cement paste. On the other hand, the strength properties are highly influenced by the ITZs complex microstructure (which has a dynamic nature) and its gradual variations as a result of environmental conditions. Many attempts have been made to overcome the heterogonous deficiencies of concrete through the utilization of different pozzolanic materials such as nanosilica (nS) and silica fume (SF). In the present work, nS at 0%, 1.5%, 3%, 5% and 7.5% and SF at 0%, 5% and 7.5% by weight of cement were utilized to investigate their effect on the strength properties of concrete and corresponding cement paste at early and older ages. A microstructure study was also performed by SEM, XRD and EDS to realize the reasons for the obtained results. The results demonstrated that adding 3% or 5% nS to specimens free of SF would increase both cement paste and concrete compression strength. The microstructure analysis revealed that modification of the ITZ was responsible for this strength enhancement.
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Recycling is the best solution for the crisis resulting from huge volumes of wastes and includes economic and environmental benefits. In the present work, waste glass (WG) was used as partial replacement for fine aggregate as much as 0,... more
Recycling is the best solution for the crisis resulting from huge volumes of wastes and includes economic and environmental benefits. In the present work, waste glass (WG) was used as partial replacement for fine aggregate as much as 0, 10, 20 and 30%, while recycled concrete aggregate was used as replacement for coarse aggregate at 0%, 20%, 35% and 50% (by weight of coarse aggregate). The results show that the presence of both RCA and WG in the concrete mixes improved compressive strength and the electrical resistance of the specimens. Furthermore, a reduction in water absorption capacity of RCA-WG specimens was attained.
In this paper, impact loading results from numerical simulations of plain concrete (PC) and fiberreinforced concrete (FRC) are compared with experimental testing data, which were based on a testing procedure recommended by ACI committee... more
In this paper, impact loading results from numerical simulations of plain concrete (PC) and fiberreinforced
concrete (FRC) are compared with experimental testing data, which were based on
a testing procedure recommended by ACI committee 544. Concrete specimens were prepared with two
waterecement ratios 0.36 and 0.46. Hooked-end steel fibers with an aspect ratio equal of 80 at 0.5% and
1% volume fractions and polypropylene fibers at 0.2%, 0.3% and 0.5% volume fractions were used. Both the
numerical and experimental analysis results indicated that increasing the fiber volume fraction increased
the impact resistance of the concrete specimens. The impact resistance increase was greater for normalstrength
than that for high-strength concrete. The results also demonstrated that steel fibers are more
effective at increasing impact resistance than polypropylene fibers.
concrete (FRC) are compared with experimental testing data, which were based on
a testing procedure recommended by ACI committee 544. Concrete specimens were prepared with two
waterecement ratios 0.36 and 0.46. Hooked-end steel fibers with an aspect ratio equal of 80 at 0.5% and
1% volume fractions and polypropylene fibers at 0.2%, 0.3% and 0.5% volume fractions were used. Both the
numerical and experimental analysis results indicated that increasing the fiber volume fraction increased
the impact resistance of the concrete specimens. The impact resistance increase was greater for normalstrength
than that for high-strength concrete. The results also demonstrated that steel fibers are more
effective at increasing impact resistance than polypropylene fibers.
The long-term compressive strength and durability properties of concrete specimens produced by incorporating polypropylene fibers and silica fume were investigated. Silica fume, a cement replacement, was used at 8% (by weight of cement)... more
The long-term compressive strength and durability properties of concrete specimens produced by incorporating
polypropylene fibers and silica fume were investigated. Silica fume, a cement replacement, was
used at 8% (by weight of cement) and the volume fractions of the polypropylene fibers were 0%, 0.2%,
0.3% and 0.5%. Water-binder ratios were 0.46 and 0.36. The results indicate that the inclusion of fiber and
particularly silica fume into the specimens led to an increased long-term compressive strength. Electrical
resistance of the silica fume specimens improved remarkably, but decreased slightly due to the fiber
inclusion. Water absorption of the fiber–silica fume specimens decreased exclusively compared to the
reference samples. Inclusion of fiber and silica fume into the specimens had no considerable effect on the
dynamic frequency results.
polypropylene fibers and silica fume were investigated. Silica fume, a cement replacement, was
used at 8% (by weight of cement) and the volume fractions of the polypropylene fibers were 0%, 0.2%,
0.3% and 0.5%. Water-binder ratios were 0.46 and 0.36. The results indicate that the inclusion of fiber and
particularly silica fume into the specimens led to an increased long-term compressive strength. Electrical
resistance of the silica fume specimens improved remarkably, but decreased slightly due to the fiber
inclusion. Water absorption of the fiber–silica fume specimens decreased exclusively compared to the
reference samples. Inclusion of fiber and silica fume into the specimens had no considerable effect on the
dynamic frequency results.
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ABSTRACT
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When silica fume was used as a cement replacement, it enhanced the effectiveness of added steel fibre on the properties of concrete. Three different steel fibres were used at 0.0%, 0.5% and 1.0% by volume of concrete. Silica fume was... more
When silica fume was used as a cement replacement, it enhanced the effectiveness of added steel fibre on
the properties of concrete. Three different steel fibres were used at 0.0%, 0.5% and 1.0% by volume of concrete.
Silica fume was introduced at 8% by weight of cement into the concrete mixtures that were made
with water–cement ratios of 0.46 and 0.36. The early- and later-stage compressive strength, the electrical
resistivity, the water absorption and the dynamic frequency of the specimens were examined. The results
indicate that the inclusion of steel fibre in silica fume specimens led to the highest long-term compressive
strength and the lowest resistivity. Furthermore, an improvement in the dynamic frequency and a
decrease in water absorption were attained in 1% steel fibre silica fume specimens.
the properties of concrete. Three different steel fibres were used at 0.0%, 0.5% and 1.0% by volume of concrete.
Silica fume was introduced at 8% by weight of cement into the concrete mixtures that were made
with water–cement ratios of 0.46 and 0.36. The early- and later-stage compressive strength, the electrical
resistivity, the water absorption and the dynamic frequency of the specimens were examined. The results
indicate that the inclusion of steel fibre in silica fume specimens led to the highest long-term compressive
strength and the lowest resistivity. Furthermore, an improvement in the dynamic frequency and a
decrease in water absorption were attained in 1% steel fibre silica fume specimens.
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Roller compacted concrete pavements (RCCP) are widely used for a variety of industrial and heavy-duty pavement applications that involve low speed traffic. The aim of this investigation is to evaluate the effects of using supplementary... more
Roller compacted concrete pavements (RCCP) are widely used for a variety of industrial and heavy-duty pavement applications that involve low speed traffic. The aim of this investigation is to evaluate the effects of using supplementary cementitious materials – silica fume and pumice – on the workability, compressive strength, and frost resistance of non-air-entrained low-cement content RCCP mixtures.Eight different RCCP mixtures
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... Natural pozzolan, fly ash, and silica fume were included in the specimens. ... It was found that the best mixture, the highest early-age strength and the lowest heat liberation, corresponded to the specimen containing fly ash at 15%... more
... Natural pozzolan, fly ash, and silica fume were included in the specimens. ... It was found that the best mixture, the highest early-age strength and the lowest heat liberation, corresponded to the specimen containing fly ash at 15% (be cement weight). ...
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This paper investigates the effects of various pozzolans on the fresh and hardened performance of non-air-entraining, roller-compacted concrete pavement. Deicer salt-scaling resistance of the specimens was evaluated for freeze–thaw cycle... more
This paper investigates the effects of various pozzolans on the fresh and hardened performance of non-air-entraining, roller-compacted concrete pavement. Deicer salt-scaling resistance of the specimens was evaluated for freeze–thaw cycle conditions with either a long or a short freezing period. Water–cement ratios were 0.36 and 0.43. Natural pozzolan, fly ash and silica fume were used as partial replacements for the