Download or read book Optimizing the Amount of Class C Fly Ash in Concrete Mixtures written by RM. Majko and published by . This book was released on 1984 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the results of a two part research program on several laboratory air-entrained concrete mixtures designed to contain increasing amounts of moderately cementitious Class C fly ash. In the first part of the paper, a Type A admixture was used in half of the mixtures, treating both the portland cement Type I and fly ash (15% calcium oxide). In the second part of the paper, three other Class C fly ashes (9 to 12% calcium oxide) were extensively tested in concrete that contained a Type A admixture (but this time treating only the cement). Two very high lime fly ashes (25 to 30% calcium oxide) were also tested in concrete mixtures.
Download or read book Discussion of Optimizing the Amount of Class C Fly Ash in Concrete Mixtures by R M Majko and M F Pistilli written by W. Barry Butler and published by . This book was released on 1985 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optimizing the Use of Fly Ash in Concrete written by M. D. A. Thomas and published by . This book was released on 2007 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The optimum amount of fly ash varies not only with the application, but also with composition and proportions of all the materials in the concrete mixture (especially the fly ash), the conditions during placing (especially temperature), construction practices (for example, finishing and curing) and the exposure conditions. This document discusses issues related to using low to very high levels of fly ash in concrete and provides guidance for the use of fly ash without compromising the construction process or the quality of the finished product. The nature of fly ashes including their physical, mineralogical and chemical properties is covered in detail, as well as fly ash variability due to coal composition and plant operating conditions. A discussion on the effects of fly ash characteristics on fresh and hardened concrete properties includes; workability, bleeding, air entrainment, setting time, heat of hydration, compressive strength development, creep, drying shrinkage, abrasion resistance, permeability, resistance to chlorides, alkali-silica reaction (ASR), sulfate resistance, carbonation, and resistance to freezing and thawing and deicer salt scaling. Case studies were selected as examples of some of the more demanding applications of fly ash concrete for ASR mitigation, chloride resistance, and green building.
Download or read book Optimization of Fly Ash Replacement in High Volume Fly Ash Concrete written by and published by . This book was released on 1991 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes research performed to determine the optimum fly ash content in the high volume system. Optimum is defined as the fly ash content for a given water-cementitious ratio which produces the most economical concrete on the basis of cost per MPa. Three series of concrete mixtures were evaluated. Mixtures were performed at a water cementitious ratio of 0.25, 0.27 and 0.32 at fly ash replacement (based on total cementitious) of 50, 55, 60 and 65 percent. The fly ash content varied from 45 to 60 percent for these tests. Materials included Portland cement; low calcium fly ash from the coal fired thermal generating plant in Lingan, NS; coarse aggregate from a Halifax quarry; fine aggregate (natural sand); superplasticizer; air-entraining mixtures; and concrete mixtures. Compressive strength specimens were cast for laboratory storage and testing at 3, 7, 28, and 91 days. Three specimens were tested at each age.
Download or read book Engineering Properties of High Performance Concrete Containing Large Volume of Class C Fly Ash written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation for the use of large volume of fly ash in concrete in combination with superplasticizer, was for the purpose of optimizing its mechanical properties while reducing its cost. Several concrete mixtures using coarse/fine aggregate ratio of 1.22 and aggregate/binder ratio of 5.1 were investigated. Fly ash was used as a partial replacement of type 10 Portland cement at levels ranging between 20-60% by weight of the total cementitious materials in the mixture. Use of superplasticizer allowed a reduction of the water/binder ratio to 0.28-0.33, while the K-slump of fresh concrete was kept at a practical level of 25%. The effect of fly ash on the development of the compressive strength of the hardened concrete was determined. The selection of a concrete mixture with an optimum fly-ash/cement ratio was based on compressive strength results and cost. Concrete with compressive strength levels of 50 MPa, applicable to mid-rise buildings, mine structural components and bridge construction, was obtainedby taking advantage of the water reducing properties of superplasticizers, and by replacing 50% of the cement with Class C fly ash. The 28-day compressive strength of the resultant concrete was approximately 80% of the strength of the identical control mixture containing no fly ash replacement of the cement; at 56 and 91 days, the strength of the resultant mixture improved and eventually became identical to that of the control mixture. The above results were achieved with a 10% reduction in cost, which is a significant savings for the construction industry. The selected mixture was tested for its engineering properties of strength, elasticity, shrinkage and creep, and the results were compared to the same properties of a control mixture. Creep and shrinkage are important concrete properties in prestressed and reinforced concrete structures. Time-dependent deformation of concrete due to creep and shrinkage, results in partial loss of the prestress force and produce.
Download or read book Optimization of Soil Stabilization with Class C Fly Ash written by John Michael Pitt and published by . This book was released on 1987 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous Iowa DOT sponsored research has shown that some Class C fly ashes are ementitious (because calcium is combined as calcium aluminates) while other Class C ashes containing similar amounts of elemental calcium are not (1). Fly ashes from modern power plants in Iowa contain significant amounts of calcium in their glassy phases, regardless of their cementitious properties. The present research was based on these findings and on the hyphothesis that: attack of the amorphous phase of high calcium fly ash could be initiated with trace additives, thus making calcium available for formation of useful calcium-silicate cements. Phase I research was devoted to finding potential additives through a screening process; the likely chemicals were tested with fly ashes representative of the cementitious and non-cementitious ashes available in the state. Ammonium phosphate, a fertilizer, was found to produce 3,600 psi cement with cementitious Neal #4 fly ash; this strength is roughly equivalent to that of portland cement, but at about one-third the cost. Neal #2 fly ash, a slightly cementitious Class C, was found to respond best with ammonium nitrate; through the additive, a near-zero strength material was transformed into a 1,200 psi cement. The second research phase was directed to optimimizing trace additive concentrations, defining the behavior of the resulting cements, evaluating more comprehensively the fly ashes available in Iowa, and explaining the cement formation mechanisms of the most promising trace additives. X-ray diffraction data demonstrate that both amorphous and crystalline hydrates of chemically enhanced fly ash differ from those of unaltered fly ash hydrates. Calciumaluminum- silicate hydrates were formed, rather than the expected (and hypothesized) calcium-silicate hydrates. These new reaction products explain the observed strength enhancement. The final phase concentrated on laboratory application of the chemically-enhanced fly ash cements to road base stabilization. Emphasis was placed on use of marginal aggregates, such as limestone crusher fines and unprocessed blow sand. The nature of the chemically modified fly ash cements led to an evaluation of fine grained soil stabilization where a wide range of materials, defined by plasticity index, could be stabilized. Parameters used for evaluation included strength, compaction requirements, set time, and frost resistance.
Download or read book Methods for Evaluating Fly Ash for Use in Highway Concrete written by Lawrence L. Sutter and published by Transportation Research Board. This book was released on 2013 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: "TRB's National Cooperative Highway Research Program (NCHRP) 749: Methods for Evaluating Fly Ash for Use in Highway Concrete presents suggested changes to coal fly ash specifications and test protocols contained in American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Transportation Materials and Methods of Sampling and Testing (AASHTO M 295). The changes suggested include modifications to the test methods currently specified for evaluating acceptability of fly ash for use in highway concrete as well as the introduction of new test methods for enhancing such evaluations. Attachment C: Details of the Research into Methods for Evaluating Fly Ash Use in Highway Concrete is only available online."--Publisher description.
Download or read book Optimization of Concrete Mixes with High Volume of Fly Ash written by Lieska Carrillo and published by . This book was released on 2002 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Guidelines for Concrete Mixtures Containing Supplementary Cementitious Materials to Enhance Durability of Bridge Decks written by John S. Lawler and published by Transportation Research Board. This book was released on 2007 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: NCHRP Report 566 is designed to help facilitate the use of supplementary cementitious materials to enhance durability of concrete used in highway construction, especially bridge decks. The report includes a methodology for selecting optimum concrete mixture proportions that focuses on durability aspects of concrete and the performance requirements for specific environmental conditions. The methodology is presented in a text format and as a computational tool, in the form of a Visual Basic?driven Microsoft Excel spreadsheet. Background information and a hypothetical case study was published as NCHRP Web-Only Document 110: Supplementary Cementitious Materials to Enhance Durability of Concrete Bridge Decks. The Statistical Experimental Design for Optimizing Concrete (SEDOC), the computational tool for the concrete mixture optimization methodology, and the user?s guide are available in a ZIP format for download.
Download or read book Optimization of Concrete Mixtures for Use in Structural Elements written by Waleed Faleh Almutairi and published by . This book was released on 2017 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Portland cement is an essential ingredient in concrete. The use of cement is to enhance the strength as well as other hardened properties of concrete mixtures. Determining the accurate amount of cement is important because the required strength may not be achieved if not enough cement is used. By contrast, when using too much cement, concrete cracking may occur that leads to reducing durability. Researchers at the University of Arkansas (UA) have shown that many bridge decks achieve their 28 day design strength of 4000 psi by 7 days of age. Bridge decks having high strength may experience cracking, which affects the durability. The Arkansas State Highway and Transportation Department (AHTD) classifies two types of concrete mixtures that can be used in bridges. The first is Class S concrete, and the second is Class S(AE). Class S is used for the structural components and does not contain air entrainment while Class S (AE) is mainly used for bridge decks and contains air entrainment. AHTD requires the same minimum cementitious material content for both classes of concrete. The purpose of this research is to determine if the cementitious material content of Class S mixtures can be reduced while still meeting AHTD specifications. The research program examined cementitious material content, Class C fly ash content, and water to cementitious material ratio (w/cm) . For all mixtures, selected fresh and hardened concrete properties were measured to ensure that they complied with AHTD requirements.
Download or read book Optimizing the Usage of Fly Ash in Concrete Mixes written by Sabelo N. F. Zulu and published by . This book was released on 2017 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fly Ash in Concrete written by R C Joshi and published by CRC Press. This book was released on 1997-11-13 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since it was first recognized as a mineral admixture for concrete in the 1930's, fly ash has been the subject of worldwide study as researchers work to maximize its economical and environmental benefits. In recent years, investigations have focused on the physical, chemical and mineralogical characteristics of fly ash and their specific correlation to the performance of concrete. This book collects the latest results from these various studies and offers a complete review of the advantages of fly ash as an admixture in concrete, including strength development and improved chemical resistance and durability. A review of the current international standards on fly ash usage is provided, in addition to an extensive reference list and a complete survey of various other fly ash products, such as bricks, mineral wool and gypsum wall boards, as well as the use of fly ash in waste management.
Download or read book Updating Physical and Chemical Characteristics of Fly Ash for Use in Concrete written by Prasanth Tanikella and published by . This book was released on 2018-02-15 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: When incorporated in concrete mixtures, fly ashes are known to influence both its fresh and hardened properties. An accurate and quick technique to predict the extent of this influence based on the characteristics of fly ash would be highly beneficial in terms of field applications. The current study was an attempt to quantify the effects of fly ashes on the properties of pastes as a function of: (a) the mean particle size of the fly ash particles, (b) their fineness and (c) their chemical composition. In addition, since the type and the amount of glass present in the fly ash significantly affect its reactivity, this property was also included in the investigation.Twenty different fly ashes (both, ASTM Class C and Class F), obtained from power plants in and around Indiana, were characterized during the Phase 1 of the study. The information collected included: physical characteristics, chemical composition and the amount and type of glass present. Phase 2 of the study consisted of evaluation of various properties of binary paste systems (portland cement with 20% of cement of fly replacement). The evaluated properties included: the set time, the heat of hydration, the strength activity index, the non-evaporable water content and the amount of calcium hydroxide formed at different ages.These results obtained from both phases of the study were used to build statistical models for prediction of previously evaluated properties for any hypothetical fly ash with similar characteristics. The models included only the most significant variables, i.e., those which were found to most strongly affect any specific property. The variables to be included in the model were selected based on the adjusted R2 values.As a result of the modeling process, it was found that the sets of statistically significant variables affecting the properties consisted of both physical and chemical characteristics of the fly ash and that the combination of these variables was unique for each property evaluated.
Download or read book Fly Ash in Concrete written by E. E. Berry and published by Energy, Mines and Resources Canada : CANMET, Canadian Centre for Mineral and Energy Technology. This book was released on 1986 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents a state-of-the-art review of the principaladvances in research, development, and practical application offly ash in concrete that have been made during the period 1976to 1984. Recommendations are made with regard to aspects of flyash concrete technology requiring further research.
Download or read book ICE Handbook of Concrete Durability written by Marios Soutsos and published by Emerald Group Publishing. This book was released on 2023-10-24 with total page 577 pages. Available in PDF, EPUB and Kindle. Book excerpt: ICE Handbook of Concrete Durability, second edition is a comprehensive practical reference for professionals involved in design and maintenance of concrete structures of all types. It is an invaluable guide for construction professionals, including design engineers, consultants and contractors, as well as postgraduate students.
Download or read book Supplementary Cementing Materials written by Rafat Siddique and published by Springer Science & Business Media. This book was released on 2011-03-28 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an attempt to consolidate the published research related to the use of Supplementary Cementing Materials in cement and concrete. It comprises of five chapters. Each chapter is devoted to a particular supplementing cementing material. It is based on the literature/research findings published in journals/conference proceeding, etc. Topics covered in the book are; coal fly ash, silica fume (SF), granulated blast furnace slag (GGBS), metakaolin (MK), and rice husk ash (RHA). Each chapter contains introduction, properties of the waste material/by-product, its potential usage, and its effect on the properties of fresh and hardened concrete and other cement based materials.
Download or read book High volume Fly Ash Concrete Technology written by and published by . This book was released on 1992 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
