دانلود رایگان مقاله لاتین حجم خاکستر بادی بتن از سایت الزویر
عنوان فارسی مقاله:
حجم زیاد خاکستر بادی بتن: تاثیر عملی با استفاده از دوز وفور کاهنده آب محدوده بالا
عنوان انگلیسی مقاله:
High volume fly ash concrete: The practical impact of using superabundant dose of high range water reducer
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
The unsustainability of concrete is generally largely due to its cement content. Of all concrete constituents, cement is highly energy intensive in production and is the costliest [42]. Fly ash on the other hand is a troublesome land fill waste causing massive disposal problems especially because of its relentless mass production and severe environmental problems/hazards; it is normally produced from coal combustion during electricity production. The use of fly ash as partial replacement of cement in concrete, usually at 15–25%, is not new and has numerous advantages which mainly fall in to two categories: performance enhancement and improved sustainability [31,42]. Performance enhancements are mainly in the areas of improved relative workability, reduced bleeding, reduced heat of hydration, increased later strength among others. The improved sustainability feature is mainly in the reduction of the amount of fly ash was that goes to the landfill thereby making it a by-product. However, the impact of this reduction is considered to be minimal, or at best inadequate, because of the continual, if not continuous, production of massive tonnes of fly ash. This directly led to research into high volume fly ash (HVFA) concrete, with the hope of getting further enhanced concrete performance. One of the key problems faced in HVFA concrete research was the very little early strength of the material [43]. Fly ash is a pozollan and hence stays inactive until the little cement in the mix reacts and develops some calcium hydroxide which then activates and reacts with the fly ash to provide extra strength for the HVFA mix. The cement is thus the only binder in the mix responsible for early strength and given its reduced availability in HVFA concrete, only a reduced early strength can be achieved. The best known solution to this problem is to reduce the water content or water/binder (cement + fly ash) ratio of HVFA concrete mixes to a minimum since reduced mixing water has long been known to improve concrete properties, including early strength [40]. However, fly ash loses its ability to improve rheological properties of concrete when used in large proportion. The only way to achieve very low water/binder is thus to use superplasticizer hence it became an essential constituent of HVFA concrete. HVFA concrete was consequently defined in terms of constituent materials proportion asconcrete with fly ash content of 50% or above as replacement of cement by mass; with water content not beyond 130 kg/m3 or 0.3 water/binder ratio; with cement of 200 kg/m3 or less; and mandatory use of high range water reducer i.e. superplasticizer [35,40].
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کلمات کلیدی:
Using High-Volume Flyash Concrete| Concrete Construction ... www.concreteconstruction.net/how-to/.../using-high-volume-flyash-concrete_o Jan 6, 2006 - So, technically, there is a higher than normal volume of ash within the mix design, and because of the specific gravity difference between cement (3.15) and a standard fly ash (2.54 to 2.65), the volume of total cementitious material can increase. [PDF]High-Volume Fly Ash Concrete - UWM www4.uwm.edu/cbu/Aci/Malhotra.HVFA.March2004.pdf Laboratoire de la technologie des matériaux. CANMET. Properties of the High-Volume Fly. Ash Concrete, and its Role in. Sustainability of Cement and. Concrete. Mechanical Properties of High Volume Fly Ash Concrete Reinforced ... https://www.hindawi.com/journals/amse/2016/1638419/ by R Chakravarthy - 2016 - Related articles Nov 9, 2016 - Abstract. Fly ash substitution to cement is a well-recognized approach to reduce CO2 emissions. Although fly ash concrete is prone to brittle ... Properties of high-volume fly ash concrete incorporating nano-SiO 2 www.sciencedirect.com/science/article/pii/S0008884603004095 by G Li - 2004 - Cited by 402 - Related articles This paper presents a laboratory study on the properties of high-volume fly ash high-strength concrete incorporating nano-SiO2 (SHFAC). The results were ... [PDF]Optimizing the Use of Fly Ash in Concrete - The Portland Cement ... www.cement.org/docs/...concrete.../is548-optimizing-the-use-of-fly-ash-concrete.pdf by M Thomas - Cited by 67 - Related articles The improved rheological properties of high-volume fly ash (HVFA) concrete make it suitable for use in self-consolidating concrete (SCC). (Bouzoubaa 2001 and ... Strength and durability of high-volume fly ash concrete | Structural ... www.icevirtuallibrary.com › Structural Concrete › List of Issues › Volume 9, Issue 2 by G Baert - 2008 - Cited by 10 - Related articles May 25, 2015 - The effects of replacing 10, 40 or 60% of the cement content by low-calcium fly ash on the compressive strength and durability of the concrete ... [PDF]Benefits of High Volume Fly Ash - FHWA https://www.fhwa.dot.gov/advancedresearch/pubs/10051/10051.pdf High volume fly ash (HVFA) concrete mixtures offer many benefits, includ- ing reduced cost, reduced energy content, enhanced environmental sustainability,. High-Volume Fly Ash Concrete: Analysis and Application | Practice ... ascelibrary.org/doi/full/10.1061/(ASCE)1084-0680(2006)11%3A1(58) by M Reiner - 2006 - Cited by 41 - Related articles Although fly ash as a partial replacement for cement has been utilized for many years, it has been almost exclusively used in low-volume percentages, such as ... Searches related to volume fly ash concrete what is high volume fly ash concrete high volume fly ash concrete wiki high volume fly ash concrete definition high volume fly ash concrete mix design high volume fly ash concrete in india fly ash in concrete properties and performance fly ash concrete ppt volume of a housefly
