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Rafat Siddique - One of the best experts on this subject based on the ideXlab platform.
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effect of polyester fibres on the compressive strength and abrasion resistance of hvfa Concrete
Construction and Building Materials, 2012Co-Authors: Rafat Siddique, Kushal Kapoor, Elhadj Kadri, Rachid BennacerAbstract:Abstract Approximately 95 million tones of Fly is generated in India yearly, and most of the Fly Ash is of Class F type. Out of which only around 15–20% is utilized in cement production and cement/Concrete related activities. Since large scale utilization of large volumes of Fly Ash in various Concrete applications is a becoming a more general practice, an investigation was carried out to investigate the compressive strength and abrasion resistance of high volume Fly Ash Concrete (HVFA) Concrete with polyester fibres. In this paper, abrasion resistance of high volume Fly Ash (HVFA) Concretes made with 30%, 40%, and 50% of cement replacement was evaluated in terms of its relation with compressive strength. Comparison was made between ordinary Portland cement and Fly Ash Concrete. Test results indicated that abrasion resistance of Concrete having cement replacement up to 30% was comparable to the normal Concrete mixture with out Fly Ash. Beyond 30% cement replacement, Fly Ash Concretes exhibited slightly lower resistance to abrasion relative to non-Fly Ash Concretes. Inclusion of polyester fibres in HVFA Concretes improved the abrasion resistance of Concrete. Test results further indicated that abrasion resistance of Concrete is closely related with compressive strength, and had a very good correlation between abrasion resistance and compressive strength ( R 2 ) value between 0.9208 and 0.804 depending upon Fly Ash content, testing age, and percentage of polyester fibres.
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influence of bacteria on the compressive strength water absorption and rapid chloride permeability of Fly Ash Concrete
Construction and Building Materials, 2012Co-Authors: Navneet Chahal, Rafat Siddique, Anita RajorAbstract:This paper presents the results of an experimental investigation carried out to evaluate the influence of Sporoscarcina pasteurii bacteria on the compressive strength and rapid chloride permeability of Concrete made without and with Fly Ash. Cement was replaced with three percentages (10, 20 and 30) with Fly Ash by weight. Three different cell concentration (0, 10 3 ,10 5 ,10 7 cells/ml) of bacteria were used in making the Concrete mixes. Tests were performed for compressive strength, water absorption and rapid chloride permeability at the age of 28 days. Test results indicated that inclusion of S. pasteurii in Fly Ash Concrete enhanced the compressive strength, reduced the porosity and permeability of Fly Ash Concrete. Maximum increase (22%) in compressive strength and four-times reduction in water absorption was observed with 10 5 cells/ml of bacteria. This improvement in compressive strength was due to deposition on the bacteria cell surfaces within the pores. Calcite deposition in Concrete observed nearly eight times reduction in chloride permeability of Fly Ash Concrete. The present work highlights the influence of bacteria on the properties of Concrete made with supplementing cementing material such as like Fly Ash. Usage of bacteria like S. pasteurii improves strength and durability and strength of Fly Ash Concrete through self-healing effect.
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fracture toughness and impact strength of high volume class f Fly Ash Concrete reinforced with natural san fibres
2008Co-Authors: Rafat SiddiqueAbstract:Results of experimental investigation carried out to study the effects of addition of natural san fibres on the fracture toughness and impact strength of high-volume Fly Ash Concrete are presented in this paper. San fibres belong to the category of ‘Natural Bast Fibres’, also known as ‘Sunn Hemp’. Its scientific (botanical) name is Crotalaria Juncea. It is mostly grown in the Indian Sub-Continent, Brazil, Eastern and Southern Africa, and in some parts of the U.S.A. Initially, a control mixture without Fly Ash was designed. Then, cement was replaced with three percentages (30, 40 and 50%) of low-calcium (Class F) Fly Ash. Three percentages of san fibres (0.30, 0.60 and 0.90%), having 25 mm length, were used. Tests were performed for compressive strength, fracture toughness, and impact strength at the ages of 28 and 91 days. The test results indicated that the replacement of cement with Fly Ash decreased the compressive strength and fracture toughness, and had no significant effect on the impact strength of plain (control) Concrete. Addition of san fibres did not affect significantly the compressive strength, increased the fracture toughness and impact strength of high-volume Fly Ash Concrete as the percentage of fibres increased.
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performance characteristics of high volume class f Fly Ash Concrete
Cement and Concrete Research, 2004Co-Authors: Rafat SiddiqueAbstract:Abstract More than 88 million tonnes of Fly Ash is generated in India each year. Most of the Fly Ash is of Class F type. The percentage utilization is around 10 to 15%. To increase its percentage utilization, an extensive investigation was carried out to use it in Concrete. This article presents the results of an experimental investigation dealing with Concrete incorporating high volumes of Class F Fly Ash. Portland cement was replaced with three percentages (40%, 45%, and 50%) of Class F Fly Ash. Tests were performed for fresh Concrete properties: slump, air content, unit weight, and temperature. Compressive, splitting tensile, and flexural strengths, modulus of elasticity, and abrasion resistance were determined up to 365 days of testing. Test results indicated that the use of high volumes of Class F Fly Ash as a partial replacement of cement in Concrete decreased its 28-day compressive, splitting tensile, and flexural strengths, modulus of elasticity, and abrasion resistance of the Concrete. However, all these strength properties and abrasion resistance showed continuous and significant improvement at the ages of 91 and 365 days, which was most probably due to the pozzolanic reaction of Fly Ash. Based on the test results, it was concluded that Class F Fly Ash can be suitably used up to 50% level of cement replacement in Concrete for use in precast elements and reinforced cement Concrete construction.
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properties of Concrete incorporating high volumes of class f Fly Ash and san fibers
Cement and Concrete Research, 2004Co-Authors: Rafat SiddiqueAbstract:Abstract The results of an experimental investigation to study the effects of replacement of cement (by mass) with three percentages of Fly Ash and the effects of addition of natural san fibers on the slump, Vebe time, compressive strength, splitting tensile strength, flexural strength and impact strength of Fly Ash Concrete are presented. San fibers belong to the category of “natural bast fibers.” It is also known as “sunn hemp.” Its scientific (botanical) name is Crotalaria juncea . It is mostly grown in the Indian subcontinent, Brazil, eastern and southern Africa and some parts of the United States (Hawaii and Florida). A control mixture of proportions 1:1.4:2.19 with W/Cm of 0.47 and superplasticizer/cementitious ratio of 0.015 was designed. Cement was replaced with three percentages (35%, 45% and 55%) of class F Fly Ash. Three percentages of san fibers (0.25%, 0.50% and 0.75%) having 25-mm length were used. The test results indicated that the replacement of cement with Fly Ash increased the workability (slump and Vebe time), decreased compressive strength, splitting tensile strength and flexural strength and had no significant effect on the impact strength of plain (control) Concrete. Addition of san fibers reduced the workability, did not significantly affect the compressive strength, increased the splitting tensile strength and flexural strength and tremendously enhanced the impact strength of Fly Ash Concrete as the percentage of fibers increased.
Cengiz Duran Atis - One of the best experts on this subject based on the ideXlab platform.
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the durability properties of polypropylene fiber reinforced Fly Ash Concrete
Materials & Design, 2011Co-Authors: Okan Karahan, Cengiz Duran AtisAbstract:Abstract This paper reports of a comprehensive study on the durability properties of Concrete containing polypropylene fiber and Fly Ash. Properties studied include unit weight and workability of fresh Concrete, and compressive strength, modulus of elasticity, porosity, water absorption, sorptivity coefficient, drying shrinkage and freeze–thaw resistance of hardened Concrete. Fly Ash content used in Concrete mixture was 0%, 15% and 30% in mass basis, and fiber volume fraction was 0%, 0.05%, 0.10% and 0.20% in volume basis. The laboratory results showed that inclusion of Fly Ash improves; however, polypropylene fiber decreases the workability of Concrete. Moreover, polypropylene fiber addition, either into Portland cement Concrete or Fly Ash Concrete, did not improve the compressive strength and elastic modulus. The positive interactions between polypropylene fibers and Fly Ash lead to the lowest drying shrinkage of fibrous Concrete with Fly Ash. Freeze–thaw resistance of polypropylene fiber Concrete was found to slightly increase when compared to Concrete without fibers. Moreover, Fly Ash increased the freeze–thaw resistance more than the polypropylene fibers did.
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properties of steel fiber reinforced Fly Ash Concrete
Construction and Building Materials, 2009Co-Authors: Cengiz Duran Atis, Okan KarahanAbstract:Abstract This paper reports on a comprehensive study on the properties of Concrete containing Fly Ash and steel fibers. Properties studied include unit weight and workability of fresh Concrete, and compressive strength, flexural tensile strength, splitting tensile strength, elasticity modulus, sorptivity coefficient, drying shrinkage and freeze–thaw resistance of hardened Concrete. Fly Ash content used was 0%, 15% and 30% in mass basis, and fiber volume fraction was 0%, 0.25%, 0.5%, 1.0% and 1.5% in volume basis. The laboratory results showed that steel fiber addition, either into Portland cement Concrete or Fly Ash Concrete, improve the tensile strength properties, drying shrinkage and freeze–thaw resistance. However, it reduced workability and increase sorptivity coefficient. Although Fly Ash replacement reduce strength properties, it improves workability, reduces drying shrinkage and increases freeze–thaw resistance of steel fiber reinforced Concrete. The performed experiments show that the behaviour of Fly Ash Concrete is similar to that of Portland cement Concrete when Fly Ash is added.
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high volume Fly Ash abrasion resistant Concrete
Journal of Materials in Civil Engineering, 2002Co-Authors: Cengiz Duran AtisAbstract:In this work, the abrasion resistance of high volume Fly Ash Concrete was investigated. Concrete mixtures containing a large amount of Fly Ash replacing the cement in mass basis at 50 and 70% were prepared with various water-cementitious material ratios. A specially selected superplasticizer was employed to maintain the workability of the Concrete. Volume loss of the specimen was considered as the abrasion value measured using a Dorry abrasion machine. Comparisons were made between normal portland cement (NPC) Concrete and Fly Ash Concrete. Comparisons were also made between Fly Ash Concretes with 50 and 70% replacement. Investigation results have shown that the abrasion resistance increased as compressive strength increased. Analysis of the results showed that, for high strength grades (>40 MPa), the abrasion resistance of high volume Fly Ash Concrete with 70% replacement with cement was found to be higher than that of counterpart control NPC Concrete and Concrete made with 50% Fly Ash. Superplasticizer and curing conditions have no significant influence on the general trend of the abrasion of Concrete studied.
Okan Karahan - One of the best experts on this subject based on the ideXlab platform.
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transport properties of high volume Fly Ash or slag Concrete exposed to high temperature
Construction and Building Materials, 2017Co-Authors: Okan KarahanAbstract:Abstract In this study, transport properties of high volume Fly Ash or slag incorporated Concretes after exposure to high temperature were investigated experimentally. Concretes with the content of 0%, 30%, 50%, 70% and 90% Fly Ash or slag were prepared and moist cured until 28 days. Fly Ash and slag Concrete samples were exposed to high temperatures at 400 °C, 600 °C and 800 °C for an hour in a computer controlled, electrically heated kiln. Then, the specimens were left to cool down to the laboratory temperature. Subsequently, absorption, void ratio, sorptivity, chloride ion permeability and compressive strength tests were carried out on the specimens. Test results showed that transport properties of Concrete increased significantly after exposure to 400 °C, as well as, compressive strength dropped remarkably. Test results also revealed that inclusions of Fly Ash or slag influenced the transport properties considerably. It is concluded that a blend of, at about, 30–50% Fly Ash and 50–70% slag as a cement replacement is found to be the optimal content for exposure to high temperature. Rapid chloride permeability test results revealed that slag Concrete bound more chloride than Fly Ash Concrete. Slag Concrete behaved better than Fly Ash Concrete did under high temperature exposure for all case, some of slag Concrete even behaved better than Portland cement Concrete in terms of compressive strength reduction.
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the durability properties of polypropylene fiber reinforced Fly Ash Concrete
Materials & Design, 2011Co-Authors: Okan Karahan, Cengiz Duran AtisAbstract:Abstract This paper reports of a comprehensive study on the durability properties of Concrete containing polypropylene fiber and Fly Ash. Properties studied include unit weight and workability of fresh Concrete, and compressive strength, modulus of elasticity, porosity, water absorption, sorptivity coefficient, drying shrinkage and freeze–thaw resistance of hardened Concrete. Fly Ash content used in Concrete mixture was 0%, 15% and 30% in mass basis, and fiber volume fraction was 0%, 0.05%, 0.10% and 0.20% in volume basis. The laboratory results showed that inclusion of Fly Ash improves; however, polypropylene fiber decreases the workability of Concrete. Moreover, polypropylene fiber addition, either into Portland cement Concrete or Fly Ash Concrete, did not improve the compressive strength and elastic modulus. The positive interactions between polypropylene fibers and Fly Ash lead to the lowest drying shrinkage of fibrous Concrete with Fly Ash. Freeze–thaw resistance of polypropylene fiber Concrete was found to slightly increase when compared to Concrete without fibers. Moreover, Fly Ash increased the freeze–thaw resistance more than the polypropylene fibers did.
Maria C. G. Juenger - One of the best experts on this subject based on the ideXlab platform.
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the role of activating solution concentration on alkali silica reaction in alkali activated Fly Ash Concrete
Cement and Concrete Research, 2016Co-Authors: Trevor Williamson, Maria C. G. JuengerAbstract:To enable commercial use of alkali-activated Fly Ash Concrete, its durability must be better understood. Alkali–silica reaction is a primary concern since highly alkaline solutions are generally used for activation. This study investigated the effect of NaOH activating solution concentration on pore solution alkalinity and subsequent alkali–silica reaction in alkali-activated Fly Ash Concrete. It was found that pore solution alkalinity increased with increasing activating solution NaOH concentration, and this effect was amplified at concentrations above an optimum, defined as the concentration that resulted in the highest mortar compressive strength. Expansion of Concrete prisms containing highly reactive fine aggregate and activating solution concentrations above the optimum concentration was approximately three times that of Concrete with optimum activating solution concentrations, but only about 5% of the expansion observed in the ordinary portland cement control. The low expansion may be attributed to the low calcium levels in the alkali-activated Fly Ash Concrete.
Jeffery S Volz - One of the best experts on this subject based on the ideXlab platform.
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effect of total cementitious content on shear strength of high volume Fly Ash Concrete beams
Materials & Design, 2013Co-Authors: Mahdi Arezoumandi, Jeffery S Volz, Carlos A Ortega, John J MyersAbstract:Abstract The production of portland cement – the key ingredient in Concrete – generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, Concrete is the most consumed manmade material on the planet. One method of reducing Concrete’s contribution to greenhouse gas emissions is the use of Fly Ash to replace a significant amount of the cement. This paper compares two experimental studies that were conducted to investigate the shear strength of full-scale beams constructed with high-volume Fly Ash Concrete (HVFAC) – Concrete with at least 50% of the cement replaced with Fly Ash. The primary difference between the two studies involved the amount of cementitious material, with one mix having a relatively high total cementitious content (502 kg/m 3 ) and the other mix having a relatively low total cementitious content (337 kg/m 3 ). Both mixes utilized a 70% replacement of portland cement with a Class C Fly Ash. Each of these experimental programs consisted of eight beams (six without shear reinforcing and two with shear reinforcing in the form of stirrups) with three different longitudinal reinforcement ratios. The beams were tested under a simply supported four-point loading condition. The experimental shear strengths of the beams were compared with both the shear provisions of selected standards (US, Australia, Canada, Europe, and Japan) and a shear database of conventional Concrete (CC) specimens. Furthermore, statistical data analyses (both parametric and nonparametric) were performed to evaluate whether or not there is any statistically significant difference between the shear strength of both mixes. Results of these statistical tests show there is no significant difference between the shear strength of these two HVFAC mixes for the beams tested in this investigation.
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a comparative study of the bond strength of reinforcing steel in high volume Fly Ash Concrete and conventional Concrete
Construction and Building Materials, 2013Co-Authors: Mahdi Arezoumandi, Michael H Wolfe, Jeffery S VolzAbstract:Abstract The production of Portland cement – the key ingredient in Concrete – generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, Concrete is the most consumed manmade material on the planet. One method of reducing Concrete’s contribution to greenhouse gas emissions is the use of Fly Ash to replace a significant amount of the cement. An experimental investigation was conducted to compare the bond strength of reinforcing steel in high-volume Fly Ash Concrete (HVFAC) – Concrete with at least 50% of the cement replaced with Fly Ash – with conventional Concrete (CC). This experimental program consisted of 12 pull-out specimens as well as 12 full-scale beams (three unconfined and three confined by transverse reinforcement for each Concrete type). The pull-out specimens were based on RILEM recommendations, and the beam specimens were tested under a simply supported four-point loading condition. The CC test results served as a control and were used to evaluate the results from the HVFAC pull-out and beam specimen tests. Furthermore, a comparison was performed between results of this study and a bond database of CC specimens. These comparisons indicate that HVFAC beams possess comparable bond strength as CC beams.