دانلود رایگان مقاله لاتین اثر متقابل بین سودا کلسیم سیلیکات از سایت الزویر
عنوان فارسی مقاله:
اثر متقابل بین سودا کلسیم سیلیکات (C-S-H) و کلرید کلسیم، برمید و نیترات
عنوان انگلیسی مقاله:
Interactions between calcium silicate hydrate (C-S-H) and calcium chloride, bromide and nitrate
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
The study of the interactions between ionic species and products of hydrated portland cement is of primary importance. Indeed, the penetration of ions inside cementitious materials through the porosity plays an important part in the durability of such a material. In particular, links between the presence of anions and the durability of cement have been highlighted in the literature. For example, chlorides anion, present in the environment (sea water or de-icing agent) or directly in the binder (set accelerator), leads to the corrosion of the concrete rebars [1]. Then, the formation of corrosion products with higher volume will induce the cracking of the material [2]. Moreover, the bearing capacity of the reinforcement bars also decreased because of corrosion [3]. As calcium silicate hydrate (C-S-H) is the most abundant phase in a hydrated portland cement and develop the higher surface in interaction with solution, this study will focus on this hydrate. Several authors have already studied the interaction between C-S-H and anions, mainly sulphate and chloride. Concerning sulphate, the different studies are all in agreement: the adsorption of sulphate by C-S-H is specific and can be described as the formation of an ion pair “CaSO4 0 ” at the surface of the particles [4–8]. The situation for chlorides is different, as the different available data concerning the interaction with C-S-H are not in agreement. Indeed, some authors consider such interaction as physical interaction [9–11] and some other as chemical interaction [12–14]. Even among the first group, the different authors disagree: Elakneswaran et al. [9] suggests an adsorption of chloride by non-ionized silanol groups; for Nguyen [11] Cl− ions are trapped inside the interlayer of the C-S-H particles to compensate the charge after an adsorption of alkali ions; Hirao et al. [10] do not details the involved adsorption mechanism he considers. Concerning the second group of authors (chemical interaction), Ramachandran [14] distinguishes three different types of interactions between C-S-H particles and chloride (a chemisorbed layer at the surface, in the interlayer or intimately bound in the structure). Beaudouin et al. [12] clarify this study by separating the adsorbed chloride in two different groups: the first one is soluble in water and not in alcohol (and corresponds to the anions adsorbed at the surface and the interlayer) and the other one is soluble in alcohol but not in water (such chlorides are in minority and would be incorporated inside the structure). Beyond those different hypotheses for explaining the chloride adsorption by C-S-H, experimental data have also been produced. Unfortunately, the data cannot be compared because those different studies had not been realized under the same conditions (method used to synthesize C-S-H, liquid to solid ratio (L/S) of the samples, Ca/Si ratio of C-SH, temperature or type of added salt). Moreover, the adsorption data are not always represented in the same way: most of them are shown in terms of quantity of adsorbed chlorides by grams of C-S-H. Such a representation does not allow to make a comparison of all those data since the mass of synthetic C-S-H is only known after drying of the samples. This operation will not provide the same results depending on the drying method which has been used. Others authors prefer to represent the adsorption by the molar ratio Cl/Si, Cl representing the mole number of adsorbed chloride and Si the mole number of silica in the C-S-H. Thisrepresentation seems more adequate in the case of an adsorption on CS-H. Finally, the raw experimental data are not available, making impossible to convert a mode of representation to another. Thus, this study aims to clarify the interaction between C-S-H particles and chloride anion but also bromide and nitrate, which could present specificity of adsorption. An experimental approach has been chosen, using a non-classical method: an in situ analysis has been developed and used in order to avoid the separation between solid and liquid prior to analysis. Indeed, previous experiments show that the use of a classical analytical method by first separating the solid from the liquid have a huge influence and leads to an important dispersion of the experimental results and thus to non-reliable data [15]. Different parameters had been taken into account: the initial Ca/Si ratio of the C-S-H, the anion concentration, but also the effect of insertion of aluminum in C-S-H. The different anions are added as calcium salt. The in situ analysis device allows to follow the evolution, versus time, of the concentration of different ionic species (Ca2+, Cl− and Br−) in solution, and then, an adsorption of those species. The consequences of the adsorption on the solid/solution interfacial properties, if any, have also been investigated through zeta potential measurement on different samples.
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کلمات کلیدی:
Interaction between calcium silicate hydrate (C-S-H) and calcium ... https://www.researchgate.net/.../308747900_Interaction_between_calcium_silicate_hydr... Interaction between calcium silicate hydrate (C-S-H) and calcium chloride, bromide and nitrate on ResearchGate, the professional network for scientists. Calcium silicate hydrate - Wikipedia https://en.wikipedia.org/wiki/Calcium_silicate_hydrate Calcium silicate hydrate is the main product of the hydration of Portland cement and is primarily responsible for the strength in cement based materials. Chloride binding to calcium silicate hydrates (C-S-H) in cement paste ... www.tandfonline.com/doi/abs/10.1080/10298436.2010.488732 by T Pan - 2010 - Cited by 4 - Related articles This paper presents the findings of one primary focus of the study, i.e. studying the transport behaviour of chloride ions in the calcium silicate hydrate (C-S-H) ... [PDF]Interactions between calcium silicate hydrate (C-S-H) and calcium ... iranarze.ir/wp-content/uploads/2016/11/E2915.pdf Sep 30, 2016 - The interaction between C-S-H and anions, especially chloride, ... calcium silicate hydrate (C-S-H) is the most abundant phase in a hydrat-. The effect of sodium chloride on the dissolution of calcium silicate ... https://www.ncbi.nlm.nih.gov/pubmed/16531035 by J Hill - 2006 - Cited by 15 - Related articles Waste Manag. 2006;26(7):758-68. Epub 2006 Mar 13. The effect of sodium chloride on the dissolution of calcium silicate hydrate gels. Hill J(1), Harris AW, ... calcium-silicate-hydrate c-s-h gel: Topics by Science.gov https://www.science.gov/topicpages/c/calcium-silicate-hydrate+c-s-h+gel.html In this study, calcium silicate hydrate (C-S-H) is synthesized and characterized. C-S-H slurry was made with calcium oxide (CaO) to micro-silica (SiO{sub 2}) ... Calcium silicate hydrate (C-S-H) gel dissolution and pH buffering in a ... minmag.geoscienceworld.org/content/76/8/3045 by GMN Baston - 2012 - Cited by 13 - Related articles Jan 29, 2013 - Calcium silicate hydrate phases are expected to play a crucial role in ... by dispersing the required amount of analytical grade calcium oxide in ... Searches related to calcium silicate hydrate (C-S-H) and calcium chloride calcium silicate hydrate formula calcium silicate common name calcium silicate uses calcium aluminate hydrate csh phase calcium silicate in food calcium silicate formula calcium silicate insulation
