دانلود رایگان مقاله لاتین خواص حرارتی ژئوپلیمر کرنش از سایت الزویر
عنوان فارسی مقاله:
خواص حرارتی و مکانیکی ژئوپلیمر کرنش سختی کائوچو و مواد مرکب پایدار سبک
عنوان انگلیسی مقاله:
Thermal and mechanical properties of sustainable lightweight strain hardening geopolymer composites
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
In the construction industry, the use of lightweight concrete (with a density less than 1850 kg/m3 [1]) instead of normal weight concrete (2400 kg/m3 ) is favorable as it offers several advantages such as reduction in dead loads and section dimensions, enhanced thermal insulation, savings in steel reinforcement, ease of handling and transportation, and lower overall cost [2]. However, one of the major disadvantages of lightweight concrete is greater brittleness and lower fracture toughness compared to normal weight concrete of similar compressive strength [2,3]. For instance, Hengst and Tressler [4] reported that the fracture energy of lightweight foam concrete was significantly lower than that of normal weight concrete. According to Zhang and Gjvorv [5], the tensile to compressive strength ratio of high strength lightweight concrete was lower than that of high strength normal weight concrete. This is attributed to the use of lightweight aggregates, which are usually weaker than the cement matrix, which makes them susceptible to cracking [3]. In past studies, different fibers have been introduced in the mixture design of lightweight concrete to enhance its tensile and flexural strengths, and the flexural toughness. However, these fiberreinforced lightweight concretes, similar to conventional fiberreinforced concrete, exhibit tension softening behavior [6,7]. Thus, although the lower density of lightweight concrete promotes its application as an alternative to normal weight concrete, the low tensile ductility and fracture toughness hinder the widespread structural applications of lightweight concrete in the construction industry. Engineered cementitious composite (ECC) is a special class of high performance fiber reinforced cementitious composites (HPFRCCs) which exhibits strain hardening behavior under tension with very high tensile ductility [8]. The average density, compressive and tensile strengths, and tensile strain capacity of typical PVA-ECC mix 45 (M45) are about 2077 kg/m3 , 52.6 MPa, 6 MPa and 2.7%, respectively, at the age of 28 days [9]. Thus, the tensile ductility of typical ECC M45 is several hundred times the ductility of conventional concrete in tension. Several studies have been conducted to investigate the application of ECC in shear elements subjected to cyclic loading, in mechanical fuse elements in beam-column connections, in shear wall retrofitting of reinforced concrete (RC) buildings, in RC beams as durable cover for rebar corrosion control, and in general concrete structural repair. Other potential applications of ECC are in high-energy absorption structures including short columns, dampers, and connections for hybrid steel/RC structures [10]. Although the density of typical ECC M45 is lower than that of normal weight concrete (2400 kg/m3 ), it cannot be considered lightweight according to the definition of ACI Committee 213, which requires the density of concrete at 28 days to be less than 1850 kg/m3 to qualify as lightweight concrete [1]. Wang and Li [3] attempted to develop lightweight ECCs using four lightweight fillers including expanded perlite, hollow glass bubbles, polymeric microform, and air bubbles produced by air entrainment admixture. In that study, it was found that hollow glass bubbles were effective for lowering the density and improving the fiber dispersion and mechanical properties of ECC [3]. The average density, compressive and tensile strengths, and tensile strain capacity of 1450 kg/m3 , 41.7 MPa, 4.31 MPa and 4.24%, respectively, were reported for the lightweight ECC made by hollow glass bubbles with a mean size of 30 mm [3]. However, such lightweight ECC uses high amount of cement and high temperature-processed hollow glass bubbles [3], which results in high embodied energy and carbon footprint [11], lowering the environmental sustainability of the composite. Therefore, itis necessary to develop green and sustainable lightweight ECCs with significantly lower environmental footprints.
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کلمات کلیدی:
Safeguarding product structure and mechanical properties while ... https://www.nwo.nl/onderzoek-en-resultaten/.../i/53/28153.html Translate this page 'Safeguarding product structure and mechanical properties while using new sustainable sources and processing steps: a multiscale and interdisciplinary ... [PDF]a preliminary study of physical and mechanical properties of ... www.escm.eu.org/eccm15/data/assets/2553.pdf by A Motori - Cited by 5 - Related articles Jun 28, 2012 - PROPERTIES OF SUSTAINABLE HEMP FIBERS BASED ... Keywords: hemp fibers, sustainability, mechanical and physical properties, thermal. Design, Material Properties and Structural Performance of Sustainable ... www.sciencedirect.com/science/article/pii/S1877705817303065 by HS Mueller - 2017 Feb 21, 2017 - Green concretes, also termed eco-concretes, with reduced cement content may provide an alternative for improving concrete sustainability ... Physical Properties of Materials | Sustainability Workshop https://sustainabilityworkshop.autodesk.com/products/physical-properties-materials To select green materials, consider the material properties of your design. Properties of materials are the performance impact and environmental cost. [PDF]Qualities, Use, and Examples of Sustainable Building Materials www.umich.edu/~nppcpub/resources/compendia/ARCHpdfs/ARCHsbmIntro.pdf Qualities, Use, and Examples. December 1998. Sustainable Building Materials • 5. List of Figures. Figure 1. Three phases of the building material life cycle....8. Geopolymer, Green Chemistry and Sustainable Development Solutions: ... https://books.google.com/books?isbn=2951482000 Joseph Davidovits - 2005 - Artificial minerals Dynamic Mechanical Properties of Geopolymer-Organic Polymer Composites Propriétés mécaniques dynamiques des composés Géopolymère- polymère ...
