دانلود رایگان مقاله لاتین دیواره سیمان مبتنی بر مواد از سایت الزویر
عنوان فارسی مقاله:
منطقه دیواره سیمان مبتنی بر مواد - سد یا خط سرعت برای تخریب شیمیایی؟
عنوان انگلیسی مقاله:
The rim zone of cement-based materials – Barrier or fast lane for chemical degradation?
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Maximizing the service life of concrete structures as well as achieving an utmost long-term stability of cement bound waste forms, resulting from the solidification and stabilization of hazardous waste as potential final treatment prior to the disposal (e.g. Ref. [1]), are important challenges in the context of a sustainable development in construction and waste treatment. This holds true in particular for cement-based materials, which are permanently exposed to aggressive aqueous environments. With this in mind, rating material performance and precisely assessing the detrimental impact of aqueous environments is a major issue. In this regard, refined approaches in terms of an evaluation for the longterm behavior and durability are needed. A precondition for promising modeling approaches, in particular for service-life prediction, is a detailed and fundamental understanding of deterioration reactions. However, past research activities often showed no clear and detailed picture of the reaction mechanism and the various factors determining the course of the damaging processes as denoted for sulfate attack [2] or in the context of the critical chloride content in steel reinforced concrete structures [3]. In order to characterize the material performance of cementitious systems, the behavior of these materials over time periods of weeks and months has mostly been studied [4]. Nevertheless, chemical reactions occur at the material/water interface and start immediately after exposure to aggressive environments. Transport processes are initiated due to concentration gradients between the alkaline pore solution of these highly porous materials and the surrounding aqueous media. Thus, chemical equilibrium between the pore solution and the solid phases will be disturbed and consequently dissolution and crystallization reactions are triggered. These reactive transport processes change the chemical and mineralogical composition of the material. The first location where this reaction takes place is the nearsurface region. This area also represents the first hurdle that must be overcome by an attacking aqueous solution. Thus, a crystalline covering layer on the surface of cement-based materials is said to act as a protective layer against reactive transport. This holds true in particular for carbonate precipitations on the surface of cement-based systems in contact with hard, carbonate-rich water, which hinders the transport and slows down e.g. the leaching process [5,6]. Also, the formation of Mg(OH)2 coatings as consequence of an attack by a MgSO4 solution is assumed to restrict reactive transport processes [7]. However, the presence of carbonic acid species does not always lead to the formation of covering layers. In recent studies regarding the reliability of a specific leaching test for the evaluation of the stability of cement bound waste, the formation of a complex composed rim zone due to the presence of CO2 was described. It was discussed whether this rim zone is potentially closely related to a non-satisfactory reproducibility of these tests [8e10]. It is announced that due to the development of complex chemical and mineralogical gradients, a modeling approach simply based on diffusion laws, in particular in an abundant presence of CO2, is not a promising way to extrapolate the long-term behavior based on the short-term experiment [9]. Similarly, the presumed protective effect of crystalline covering layers is closely related to the hydrochemistry of leachant and pore solutions, as well as to changes of the cement paste regarding permeability, cracking due to decalci- fication shrinkage [11], mineralogical and chemical composition [12]. In the case of calcium carbonate layers, it has been addressed that both the hydrochemical frame conditions during the growth of the covering layer and the mineralogical and structural evolution of the rim zone determine their effectiveness as a diffusion barrier [13]. Further, the reaction temperature is assumed to have an impact on the evolution of the properties of the rim zone due to reactive transport.
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کلمات کلیدی:
Research paper insights: The rim zone of cement-based materials ... https://www.researchgate.net/.../309223915_The_rim_zone_of_cement-based_materials... Dec 9, 2016 - References, authors & citations for 'The rim zone of cement-based materials – Barrier or fast lane for chemical degradation?' on ResearchGate. [PDF]The rim zone of cement-based materials - Barrier or fast lane for ... iranarze.ir/wp-content/uploads/2016/11/E2894.pdf Oct 14, 2016 - The rim zone of cement-based materials e Barrier or fast lane for chemical degradation? M. Schwotzer a, *. , K. Konno b, J. Kaltenbach a, ... The rim zone of cement based materials : barrier or fast lane for ... https://publikationen.bibliothek.kit.edu/170099184 Translate this page The rim zone of cement based materials : barrier or fast lane for chemical degradation? Schwotzer, M.; Konno, K.; Kaltenbach, J.; Heck, P.F.; Gerdes, A. The rim zone of cement-based materials – Barrier or fast lane for ... https://publikationen.bibliothek.kit.edu/1000061969 Translate this page The rim zone of cement-based materials – Barrier or fast lane for chemical degradation? Schwotzer, M.; Konno, K.; Kaltenbach, J.; Gerdes, A. [PDF]Bonded Cement-Based Material Overlays for the Repair, the ... - rilem www.rilem.org/docs/2013143728_unedited-version-193-rls.pdf TC 193-RLS: Bonded cement-based material overlays for the repair, the lining or the ...... should be taken on sound areas, and preferably between the wheel ... analysed and introduced in the same type of chart in such a way that zones can be ... [PDF]Frost Salt Scaling of Cement-Based Materials with a High Slag Content repository.tudelft.nl/islandora/object/uuid:c2511bac-c222-4cb2-9dc3.../view by O Copuroglu - Cited by 9 - Related articles microstructure which adhere to slag-matrix interfacial zones. ... The glue-spall theory suggests that cement-based material surface scaling ...... Magnesium chloride produces distinctive alteration rims at the margins of reactive dolomite aggre-. [PDF]using mercury intrusion porosimetry to study the interfacial properties ... jmst.ntou.edu.tw/marine/20-3/269-273.pdf by SW Cho - 2012 - Cited by 2 - Related articles Shih-Wei Cho. Key words: interface transition zone, mercury intrusion porosimetry, ... cement-based materials and classified five types of pores from the macro ..... McCarter, W. J., Emerson, M., and Ezirim, H., “Properties of concrete in the cover ... Searches related to rim zone of cement-based materials rimzone fuel rims tire rack
