The emissions of greenhouse gases such as carbon dioxide from the production of Ordinary Portland Cement and Blended Portland Cement have widely affected the environment with increase in infrastructure development worldwide. Secondly, due to the continuous mining of limestone for the production of cement there is also simultaneous depletion of natural resources and hardly will it last up to maximum 40 years. Hence we need to switch over to some other alternate binders for constructions purpose in future. Geopolymer Cement is one of the inventions which is produced by a polymeric chain reaction of alkali-activated alumino-silicate materials better known as alkali activator (NaOH/Na2SiO3) binders with the industrial by-product materials such as Fly Ash, Rice Husk Ash, Slag, Crusher Dust etc. and provides high compressive strength which is comparable to BPC and reduces the carbon foot print. The objective of our study is to prepare the low CO2 foot print green Geopolymer Cement which may substitute the Ordinary Portland Cement and Blended Portland Cement in future and will helpful to reduce the greenhouse effect up to some extent and takes an initiative towards the green revolution movement.
{"title":"Geopolymer Cement: an Initiative towards the Replacement of Grey Cement by Green Cement in Future","authors":"Mukesh Kumar, K. Kumar","doi":"10.5281/ZENODO.4445828","DOIUrl":"https://doi.org/10.5281/ZENODO.4445828","url":null,"abstract":"The emissions of greenhouse gases such as carbon dioxide from the production of Ordinary Portland Cement and Blended Portland Cement have widely affected the environment with increase in infrastructure development worldwide. Secondly, due to the continuous mining of limestone for the production of cement there is also simultaneous depletion of natural resources and hardly will it last up to maximum 40 years. Hence we need to switch over to some other alternate binders for constructions purpose in future. Geopolymer Cement is one of the inventions which is produced by a polymeric chain reaction of alkali-activated alumino-silicate materials better known as alkali activator (NaOH/Na2SiO3) binders with the industrial by-product materials such as Fly Ash, Rice Husk Ash, Slag, Crusher Dust etc. and provides high compressive strength which is comparable to BPC and reduces the carbon foot print. The objective of our study is to prepare the low CO2 foot print green Geopolymer Cement which may substitute the Ordinary Portland Cement and Blended Portland Cement in future and will helpful to reduce the greenhouse effect up to some extent and takes an initiative towards the green revolution movement.","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80715627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tensile structures represent a new chapter in the history of building structures. Tensile structure system are capable of spanning large distances while incurring very little weight on supporting structure, developments in the design of fabric structure can dramatically change the ways in which permanent building construction is conceptualized. This paper reviews the current methods and systems for design and construction of fabric structures. The paper begins with a brief historical evolution and explanation of the various types of fabric structure that have previously been built. Subsequent topics address the development of computational analysis methods, innovative construction techniques, fabric material types, properties and their characteristics. In this paper, a qualitative descriptive evaluation research method has been used. The research methodology comprises of case studies, visual observation and data collection. Finally, five case studies around the world have been presented to validate and illustrate the various modern trends and the direct application of design and construction methods of tensile structure system.
{"title":"An investigation into tensile structure system: construction morphology and architectural interventions","authors":"M. Kamal","doi":"10.5281/ZENODO.4308968","DOIUrl":"https://doi.org/10.5281/ZENODO.4308968","url":null,"abstract":"Tensile structures represent a new chapter in the history of building structures. Tensile structure system are capable of spanning large distances while incurring very little weight on supporting structure, developments in the design of fabric structure can dramatically change the ways in which permanent building construction is conceptualized. This paper reviews the current methods and systems for design and construction of fabric structures. The paper begins with a brief historical evolution and explanation of the various types of fabric structure that have previously been built. Subsequent topics address the development of computational analysis methods, innovative construction techniques, fabric material types, properties and their characteristics. In this paper, a qualitative descriptive evaluation research method has been used. The research methodology comprises of case studies, visual observation and data collection. Finally, five case studies around the world have been presented to validate and illustrate the various modern trends and the direct application of design and construction methods of tensile structure system.","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83738853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
New geopolymer-based materials offer excellent perspectives for the future; they should not be regarded as competitive materials for Portland cement, which has been the reference construction material for so long, but as alternative materials with a series of important advantages to be considered. Metakaolin (MK) produced from firing kaolin material up to 750 oC for 2 h with a heating rate of 5oC/min; leads to an enhancement in mechanical and microstructural properties of alkali activated geopolymer of water cooled slag material using (6:6, wt%) of sodium hydroxide and sodium silicate. In the present work the ratios of MK which will be added are less than 20% of the total mass, because of the used MK was very fine with average pore structure less than 30 mµ, which hinders the geopolymerization reaction if used as high ratio. Curing was performed under 100% relative humidity at a temperature of 38oC and ages of 7, 14, 28 & 90 days. The properties of geopolymer specimens have been studied through measurement of XRD, SEM imaging, FTIR, compressive strength and water absorption. Results showed that the mixes of metakaolin up to 15% results in an enhancement in the mechanical properties as compared with slag control mix up to 90 days.
{"title":"Production of Green Cement from Slag Enhanced by Egyptian Metakaolin Materials","authors":"A. E. Nagar","doi":"10.5281/ZENODO.4143536","DOIUrl":"https://doi.org/10.5281/ZENODO.4143536","url":null,"abstract":"New geopolymer-based materials offer excellent perspectives for the future; they should not be regarded as competitive materials for Portland cement, which has been the reference construction material for so long, but as alternative materials with a series of important advantages to be considered. Metakaolin (MK) produced from firing kaolin material up to 750 oC for 2 h with a heating rate of 5oC/min; leads to an enhancement in mechanical and microstructural properties of alkali activated geopolymer of water cooled slag material using (6:6, wt%) of sodium hydroxide and sodium silicate. In the present work the ratios of MK which will be added are less than 20% of the total mass, because of the used MK was very fine with average pore structure less than 30 mµ, which hinders the geopolymerization reaction if used as high ratio. Curing was performed under 100% relative humidity at a temperature of 38oC and ages of 7, 14, 28 & 90 days. The properties of geopolymer specimens have been studied through measurement of XRD, SEM imaging, FTIR, compressive strength and water absorption. Results showed that the mixes of metakaolin up to 15% results in an enhancement in the mechanical properties as compared with slag control mix up to 90 days.","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81596933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The traditional bricks are the main building materials that are used extensively in the construction and building industry. Autoclaved Aerated Concrete blocks are recently one of the newly adopted building materials. The Autoclaved aerated concrete (AAC) is a product of fly ash which is mixed with lime, cement, and water and an aerating agent. The AAC is mainly produced as cuboid blocks and prefabricated panels. The Autoclaved aerated concrete is a type of concrete that is manufactured to contain lots of closed air voids. The AAC blocks are energy efficient, durable, less dense, and lightweight. It is manufactured by adding a foaming additive to concrete in different sizes of molds as per requirement, then wire-cutting these blocks or panels from the resulting ‘cake lump’ and ‘heating them with steam. This process is called as Autoclaving. It has been observed that this material is an eco-friendly building material that is being manufactured from industrial waste and is composed of non-toxic ingredients. In this paper, an overview of AAC blocks with reference to its potential and sustainability as a novel building material has been presented. The paper also presents a comparative cost analysis of AAC Blocks with the Red clay bricks and its suitability and potential use in the construction in the building industry.
{"title":"Analysis of autoclaved aerated concrete (AAC) blocks with reference to its potential and sustainability","authors":"M. Kamal","doi":"10.5281/ZENODO.3950489","DOIUrl":"https://doi.org/10.5281/ZENODO.3950489","url":null,"abstract":"The traditional bricks are the main building materials that are used extensively in the construction and building industry. Autoclaved Aerated Concrete blocks are recently one of the newly adopted building materials. The Autoclaved aerated concrete (AAC) is a product of fly ash which is mixed with lime, cement, and water and an aerating agent. The AAC is mainly produced as cuboid blocks and prefabricated panels. The Autoclaved aerated concrete is a type of concrete that is manufactured to contain lots of closed air voids. The AAC blocks are energy efficient, durable, less dense, and lightweight. It is manufactured by adding a foaming additive to concrete in different sizes of molds as per requirement, then wire-cutting these blocks or panels from the resulting ‘cake lump’ and ‘heating them with steam. This process is called as Autoclaving. It has been observed that this material is an eco-friendly building material that is being manufactured from industrial waste and is composed of non-toxic ingredients. In this paper, an overview of AAC blocks with reference to its potential and sustainability as a novel building material has been presented. The paper also presents a comparative cost analysis of AAC Blocks with the Red clay bricks and its suitability and potential use in the construction in the building industry.","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91238057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to define with precision, the physicochemical characteristics of the architectural ceramic exhumed from the Qal'a of Bani Hammad’s site (inscribed on the UNESCO’s World Heritage List in 1980), our study was conducted on a set of ceramics. The first analyses were focused on the color of the glazes, by optical absorption spectrophotometry (also called optical absorbance spectroscopy), on the texture by X-Ray diffraction, and on the elemental composition of the various constituent stages of these glazes and their terra cotta, by scanning electron microscopy and X-Ray fluorescence. Indeed, the study combining optical absorbance spectroscopy and X-Ray fluorescence enabled us to determine the origin of the monochromic green coloring of the glazes in some samples. This coloring can be attributed to the presence of the Cu2+ chemical element; but these glazes darkened due to the high iron content they contain. This could be explained by an intentional addition of iron, in tin-opacified leaded glazes, baked in an oxidizing atmosphere and put on a limestone-rich marlacious paste. The chemical and mineralogical analyses of all shards show that their paste is calcareous. This dataset will be exploitable for re-creation experiments. It also represents a first exploitable referential system, for potential comparisons with other samples belonging to other Algerian sites and different periods of time.
{"title":"Study of Architectural Ceramics of the Qal'a of Bani Hammad","authors":"A. Brahmi, M. Hamiane","doi":"10.5281/ZENODO.1299318","DOIUrl":"https://doi.org/10.5281/ZENODO.1299318","url":null,"abstract":"In order to define with precision, the physicochemical characteristics of the architectural ceramic exhumed from the Qal'a of Bani Hammad’s site (inscribed on the UNESCO’s World Heritage List in 1980), our study was conducted on a set of ceramics. The first analyses were focused on the color of the glazes, by optical absorption spectrophotometry (also called optical absorbance spectroscopy), on the texture by X-Ray diffraction, and on the elemental composition of the various constituent stages of these glazes and their terra cotta, by scanning electron microscopy and X-Ray fluorescence. Indeed, the study combining optical absorbance spectroscopy and X-Ray fluorescence enabled us to determine the origin of the monochromic green coloring of the glazes in some samples. This coloring can be attributed to the presence of the Cu2+ chemical element; but these glazes darkened due to the high iron content they contain. This could be explained by an intentional addition of iron, in tin-opacified leaded glazes, baked in an oxidizing atmosphere and put on a limestone-rich marlacious paste. \u0000The chemical and mineralogical analyses of all shards show that their paste is calcareous. This dataset will be exploitable for re-creation experiments. It also represents a first exploitable referential system, for potential comparisons with other samples belonging to other Algerian sites and different periods of time.","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91033941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-02-01DOI: 10.3969/J.ISSN.1007-9629.2017.01.012
Jun Han, Guoqiang Li, Yongchang Wang
{"title":"Effect of top coating on insulating properties of intumescent coating","authors":"Jun Han, Guoqiang Li, Yongchang Wang","doi":"10.3969/J.ISSN.1007-9629.2017.01.012","DOIUrl":"https://doi.org/10.3969/J.ISSN.1007-9629.2017.01.012","url":null,"abstract":"","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86280293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under an exceptional event. According to the Eurocodes and some different other national design codes, the structural integrity of civil engineering structures should be ensured through appropriate measures but, in most cases, no precise practical guidelines on how to achieve this goal are provided. At Liege University, the robustness of building frames is investigated with the final objective to propose design requirements to mitigate the risk of progressive collapse considering the conventional scenario “loss of a column” further to an unspecified event. In particular, a complete analytical procedure has been developed for the verification of the robustness of steel or composite plane frames. For sake of simplicity, these first works have been based on the assumption that the dynamic effects linked to the column loss were limited and could therefore be neglected. More recently, complementary works have been carried out with the objective to address the dynamic effects. Besides that, the extension of the static procedure to actual 3D frames is under investigation in Liege. The present paper gives a global overview of the ongoing researches in the field of robustness at Liege University; in particular, the global strategy to derive design requirements is detailed.
{"title":"A \"new\" design requirement: the mitigation of the progressive collapse of buildings under exceptional loading","authors":"J. Jaspart, J. Demonceau","doi":"10.5281/ZENODO.241935","DOIUrl":"https://doi.org/10.5281/ZENODO.241935","url":null,"abstract":"Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under an exceptional event. According to the Eurocodes and some different other national design codes, the structural integrity of civil engineering structures should be ensured through appropriate measures but, in most cases, no precise practical guidelines on how to achieve this goal are provided. \u0000At Liege University, the robustness of building frames is investigated with the final objective to propose design requirements to mitigate the risk of progressive collapse considering the conventional scenario “loss of a column” further to an unspecified event. In particular, a complete analytical procedure has been developed for the verification of the robustness of steel or composite plane frames. For sake of simplicity, these first works have been based on the assumption that the dynamic effects linked to the column loss were limited and could therefore be neglected. More recently, complementary works have been carried out with the objective to address the dynamic effects. Besides that, the extension of the static procedure to actual 3D frames is under investigation in Liege. The present paper gives a global overview of the ongoing researches in the field of robustness at Liege University; in particular, the global strategy to derive design requirements is detailed.","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2014-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87970182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Based on shear tests,the shear behavior of perforated concrete brick masonry materials was systematically studied,a calculation equation for the shear strength of the material was deduced,a constitutive model for the mortar joint in perforated concrete brick masonry under shear was proposed,which provided the basic references for the development of "Technical Specifications for Concrete Perforated Brick Masonry Buildings"(CECS257:2009).The results indicate that the shear strength of perforated concrete brick masonry is higher than that of fired perforated brick masonry with the same brick and mortar strength.For the different type of bricks the shear strength of masonry materials are a little bit different,the shear strength of the masonry with initial compressive stress in construction is lower than that of the masonry without initial compressive stress,the shear strength of the masonry with loading history is higher than that of the masonry without loading history,and the shear strength of masonry under compression can be determined with the Mohr-Coulomb criterion in a certain range.The results also indicate that the initial slop of the shear stress-shear strain curve is big;when the stress approaches the ultimate stress,the strain increases rapidly,but the stress is almost a constant.
{"title":"Experimental study on flexural properties of perforated concrete brick masonry materials","authors":"C. Pu, X. Li, X. Gu","doi":"10.1201/B21889-226","DOIUrl":"https://doi.org/10.1201/B21889-226","url":null,"abstract":"Based on shear tests,the shear behavior of perforated concrete brick masonry materials was systematically studied,a calculation equation for the shear strength of the material was deduced,a constitutive model for the mortar joint in perforated concrete brick masonry under shear was proposed,which provided the basic references for the development of \"Technical Specifications for Concrete Perforated Brick Masonry Buildings\"(CECS257:2009).The results indicate that the shear strength of perforated concrete brick masonry is higher than that of fired perforated brick masonry with the same brick and mortar strength.For the different type of bricks the shear strength of masonry materials are a little bit different,the shear strength of the masonry with initial compressive stress in construction is lower than that of the masonry without initial compressive stress,the shear strength of the masonry with loading history is higher than that of the masonry without loading history,and the shear strength of masonry under compression can be determined with the Mohr-Coulomb criterion in a certain range.The results also indicate that the initial slop of the shear stress-shear strain curve is big;when the stress approaches the ultimate stress,the strain increases rapidly,but the stress is almost a constant.","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72751744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-01-01DOI: 10.3969/J.ISSN.1007-9629.2011.03.002
Zhen He, Lei Wang, Y. Shao, Xinhua Cai
Effect of decalcification on microstructure of C-S-H gel in ASTMⅠcement paste were studied by X-ray fluorescence spectrometer(XRF),X-ray diffraction(XRD),infrared spectroscopy with Fourier transform(FTIR) and ~(29)Si MAS NMR with deconvolution technique.It is shown from test results that the decalcification process can be divided into two stages.When the molar ratio of CaO to SiO_2 in the pastes at 3,28 d is lowered from～2.78 to～2.00,almost all of CH is removed and C-S-H gel is partially decalcified, the average chain length(ACL) of C-S-H is increased from 2.4 to 4.4 for 3 d paste and from 2.9 to 5.8 for 28 d paste respectively,and I(Q~2)/I(Q~1) is also increased.While the molar ratio of CaO to SiO_2 in the pastes comes to～1.83,decalcification of C-S-H gel occurs.C-S-H polymerizes and I(Q~2)/I(Q~1) increases largely in this stage,which results in further increase of ACL to 6.2 for 3 d paste and 9.9 for 28 d paste.The mechanism of increase of C-S-H polymerization could be transformation of dimeric C-S-H toward highly polymerized C-S-H.However,Al doping could affect the stability of C-S-H microstructure. In molecular level,the existence of the pure bridging silicon-oxy tetrahedrons in C-S-H is beneficial to the optimization of the microstructure.
采用x射线荧光光谱仪(XRF)、x射线衍射仪(XRD)、红外傅立叶变换光谱仪(FTIR)和~(29)Si MAS NMR反褶积技术研究了脱钙对ASTMⅠ水泥浆中C-S-H凝胶微观结构的影响。试验结果表明，脱钙过程可分为两个阶段。当膏体中CaO / SiO_2的摩尔比在3,28 d时从~2.78降低到~2.00时，CH几乎全部被去除，C-S-H凝胶部分脱钙，C-S-H的平均链长(ACL)从3 d的2.4增加到4.4,28 d的2.9增加到5.8,I(Q~2)/I(Q~1)也有所增加。当膏体中CaO与SiO_2的摩尔比达到~1.83时，C-S-H凝胶发生脱钙，C-S-H发生聚合，I(Q~2)/I(Q~1)大幅增加，使3 d膏体的ACL进一步提高到6.2,28 d膏体的ACL进一步提高到9.9。C-S-H聚合增加的机理可能是二聚体C-S-H向高聚合的C-S-H转化。Al掺杂会影响C-S-H微观结构的稳定性。在分子水平上，C-S-H中纯桥接硅氧四面体的存在有利于结构的优化。
{"title":"Effect of decalcification on C-S-H gel microstructure in cement paste","authors":"Zhen He, Lei Wang, Y. Shao, Xinhua Cai","doi":"10.3969/J.ISSN.1007-9629.2011.03.002","DOIUrl":"https://doi.org/10.3969/J.ISSN.1007-9629.2011.03.002","url":null,"abstract":"Effect of decalcification on microstructure of C-S-H gel in ASTMⅠcement paste were studied by X-ray fluorescence spectrometer(XRF),X-ray diffraction(XRD),infrared spectroscopy with Fourier transform(FTIR) and ~(29)Si MAS NMR with deconvolution technique.It is shown from test results that the decalcification process can be divided into two stages.When the molar ratio of CaO to SiO_2 in the pastes at 3,28 d is lowered from～2.78 to～2.00,almost all of CH is removed and C-S-H gel is partially decalcified, the average chain length(ACL) of C-S-H is increased from 2.4 to 4.4 for 3 d paste and from 2.9 to 5.8 for 28 d paste respectively,and I(Q~2)/I(Q~1) is also increased.While the molar ratio of CaO to SiO_2 in the pastes comes to～1.83,decalcification of C-S-H gel occurs.C-S-H polymerizes and I(Q~2)/I(Q~1) increases largely in this stage,which results in further increase of ACL to 6.2 for 3 d paste and 9.9 for 28 d paste.The mechanism of increase of C-S-H polymerization could be transformation of dimeric C-S-H toward highly polymerized C-S-H.However,Al doping could affect the stability of C-S-H microstructure. In molecular level,the existence of the pure bridging silicon-oxy tetrahedrons in C-S-H is beneficial to the optimization of the microstructure.","PeriodicalId":39562,"journal":{"name":"Jianzhu Cailiao Xuebao/Journal of Building Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90601093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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