Pub Date : 2019-03-18DOI: 10.21809/RILEMTECHLETT.2018.81
I. Papayianni, J. Hughes
Lime-based mortars (LM(s)) seem to be preferred in repairing historic structures. The long-term performance of repair LM(s) is closely related to durability issues concerning the old structure substrate, the new repair mortars and interface between the two aforementioned materials, which is also much influenced by the technique of mortars application. Durability is a multifunctional property affected by a number of parameters, including local environmental conditions. However, experience showed that some of the characteristics of materials play a dominant role in assessing the durability of repair LM(s) and have a direct impact on longevity of the repaired structure. This paper presents review of research/case studies papers and Master/PhD theses supervised by the members of RILEM TC 277 LHS. Through the review and evaluation of research and common practice concerning durability challenges, we anticipate to find answers to questions arising in assessing durability of repair LM(s), such as: The most often encountered failures due to mortar durability inadequacy The mortar properties/characteristics that seem to be influential on durability The test methods used for testing the durability of LM(s) and comments related to their applicability and performance The importance of quality control and on site execution practices
{"title":"Testing properties governing the durability of lime-based repair mortars","authors":"I. Papayianni, J. Hughes","doi":"10.21809/RILEMTECHLETT.2018.81","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.81","url":null,"abstract":"Lime-based mortars (LM(s)) seem to be preferred in repairing historic structures. The long-term performance of repair LM(s) is closely related to durability issues concerning the old structure substrate, the new repair mortars and interface between the two aforementioned materials, which is also much influenced by the technique of mortars application. \u0000Durability is a multifunctional property affected by a number of parameters, including local environmental conditions. However, experience showed that some of the characteristics of materials play a dominant role in assessing the durability of repair LM(s) and have a direct impact on longevity of the repaired structure. \u0000This paper presents review of research/case studies papers and Master/PhD theses supervised by the members of RILEM TC 277 LHS. Through the review and evaluation of research and common practice concerning durability challenges, we anticipate to find answers to questions arising in assessing durability of repair LM(s), such as: \u0000 \u0000The most often encountered failures due to mortar durability inadequacy \u0000The mortar properties/characteristics that seem to be influential on durability \u0000The test methods used for testing the durability of LM(s) and comments related to their applicability and performance \u0000The importance of quality control and on site execution practices \u0000","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48154419","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 : 2019-03-12DOI: 10.21809/RILEMTECHLETT.2018.78
Shiju Joseph, S. Uppalapati, Ö. Cizer
Alkali activated materials (AAM) are generally cured at high temperatures to compensate for the low reaction rate. Higher temperature accelerates the reaction of AAM as in cement-based materials and this effect is generally predicted using Arrhenius equation based on the activation energy. While apparent activation energy is calculated from parallel isothermal calorimetry measurements at different temperatures, instantaneous activation energy is typically measured using a differential scanning calorimeter. Compared to the apparent activation energy, instantaneous activation energy has minimal effects on the microstructural changes due to the variation in temperature. In this work, the evolution of activation energy was determined by traditional methods and was compared with the instantaneous activation energy. It was found that while the activation energy changed with the progress of reaction over traditional methods, the instantaneous activation energy did not show any changes / or remained the same. The instantaneous activation energy was also found to be higher compared to the apparent activation energy determined with traditional methods.
{"title":"Instantaneous activation energy of alkali activated materials","authors":"Shiju Joseph, S. Uppalapati, Ö. Cizer","doi":"10.21809/RILEMTECHLETT.2018.78","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.78","url":null,"abstract":"Alkali activated materials (AAM) are generally cured at high temperatures to compensate for the low reaction rate. Higher temperature accelerates the reaction of AAM as in cement-based materials and this effect is generally predicted using Arrhenius equation based on the activation energy. While apparent activation energy is calculated from parallel isothermal calorimetry measurements at different temperatures, instantaneous activation energy is typically measured using a differential scanning calorimeter. Compared to the apparent activation energy, instantaneous activation energy has minimal effects on the microstructural changes due to the variation in temperature. In this work, the evolution of activation energy was determined by traditional methods and was compared with the instantaneous activation energy. It was found that while the activation energy changed with the progress of reaction over traditional methods, the instantaneous activation energy did not show any changes / or remained the same. The instantaneous activation energy was also found to be higher compared to the apparent activation energy determined with traditional methods.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44439961","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 : 2019-03-07DOI: 10.21809/RILEMTECHLETT.2018.76
P. Lourenço, G. Karanikoloudis
Built cultural heritage is at risk due to manmade and natural hazards. The seismic vulnerability of ancient masonry buildings is particularly difficult to assess and requires specialized technical skills. Key aspects are the materials properties and nonlinear effects, the morphology of the structural elements, the connections between structural elements, the stiffness of horizontal diaphragms and the building condition. This paper addresses the holistic approach recommended for the structural assessment of historic masonry buildings and the developments in the areas of inspection, diagnosis, monitoring and non-destructive testing, with applications to emblematic monuments. The methodology covers a step-by-step approach, based on historical research, an inductive study on similar structures, and a range of surveying, experimental, analytical and numerical tools, all aimed at evaluating the structural response and defining safety levels. Attention is given to the need of conservation engineering background of professionals and ways to attain this goal.
{"title":"Seismic behavior and assessment of masonry heritage structures. Needs in engineering judgement and education","authors":"P. Lourenço, G. Karanikoloudis","doi":"10.21809/RILEMTECHLETT.2018.76","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.76","url":null,"abstract":"Built cultural heritage is at risk due to manmade and natural hazards. The seismic vulnerability of ancient masonry buildings is particularly difficult to assess and requires specialized technical skills. Key aspects are the materials properties and nonlinear effects, the morphology of the structural elements, the connections between structural elements, the stiffness of horizontal diaphragms and the building condition. This paper addresses the holistic approach recommended for the structural assessment of historic masonry buildings and the developments in the areas of inspection, diagnosis, monitoring and non-destructive testing, with applications to emblematic monuments. The methodology covers a step-by-step approach, based on historical research, an inductive study on similar structures, and a range of surveying, experimental, analytical and numerical tools, all aimed at evaluating the structural response and defining safety levels. Attention is given to the need of conservation engineering background of professionals and ways to attain this goal.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44131049","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 : 2019-03-01DOI: 10.21809/RILEMTECHLETT.2018.83
W. Schmidt, I. L. Tchetgnia Ngassam, K. Olonade, R. Mbugua, H. Kühne
While today, engineers can choose from a wide range of rheology modifying admixtures, in some parts of the world, these are difficult to access, due to their complex processing. However, alternatives can be bio-based polymers such as polysaccharides from various sources. These are easily accessible all over the world, do not demand for complicated processing, and typically they are more sustainable than many established materials, which are crude oil-based. The paper presents the effects of acacia gum, cassava starch and the gum of triumfetta pendrata A. Rich on the rheological performance of cementitious systems. It is shown that acacia gum can be as efficient as polycarboxylate based superplasticisers, cassava starch can reduce the yield stress slightly with little effect on the plastic viscosity, and the gum of triumfetta pendrata A. Rich increases the thixotropy of cement pastes with plasticizing polymers significantly.
{"title":"Plant based chemical admixtures – potentials and effects on the performance of cementitious materials","authors":"W. Schmidt, I. L. Tchetgnia Ngassam, K. Olonade, R. Mbugua, H. Kühne","doi":"10.21809/RILEMTECHLETT.2018.83","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.83","url":null,"abstract":"While today, engineers can choose from a wide range of rheology modifying admixtures, in some parts of the world, these are difficult to access, due to their complex processing. However, alternatives can be bio-based polymers such as polysaccharides from various sources. These are easily accessible all over the world, do not demand for complicated processing, and typically they are more sustainable than many established materials, which are crude oil-based. \u0000The paper presents the effects of acacia gum, cassava starch and the gum of triumfetta pendrata A. Rich on the rheological performance of cementitious systems. It is shown that acacia gum can be as efficient as polycarboxylate based superplasticisers, cassava starch can reduce the yield stress slightly with little effect on the plastic viscosity, and the gum of triumfetta pendrata A. Rich increases the thixotropy of cement pastes with plasticizing polymers significantly.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47562710","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 : 2019-02-19DOI: 10.21809/RILEMTECHLETT.2018.63
T. Williamson, Joonkyoung Han, L. Katz, G. Sant, M. Juenger
Inorganic polymer binders, also sometimes called geopolymers or alkali-activated cements, can serve as an alternative to ordinary portland cement (OPC) in concrete. The development of thermodynamic models to predict phase development and, ultimately, engineering properties, of inorganic polymer binders is an important step toward enabling their widespread use. However, such models require self-consistent solubility data of the primary phase in inorganic polymer binders, sodium aluminosilicate hydrate(s). To date, there is very little solubility information available for this phase. Here, a rigorous method for synthesizing sodium aluminosilicate hydrate(s) of controlled composition, and for measuring its solubility is presented. This approach allows complete stoichiometric control over the (initial) solution composition to elucidate directly the development of N-A-S-H composition as it relates to a given solution composition. A review of previous literature related to the solubility of other cementitious materials is presented, and the need for thermodynamic data is discussed. Finally, a sample calculation is presented for determining the solubility product (Ksp) of a laboratory synthesized sodium aluminosilicate hydrate.
{"title":"Method for experimentally determining N-A-S-(H) solubility","authors":"T. Williamson, Joonkyoung Han, L. Katz, G. Sant, M. Juenger","doi":"10.21809/RILEMTECHLETT.2018.63","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.63","url":null,"abstract":"Inorganic polymer binders, also sometimes called geopolymers or alkali-activated cements, can serve as an alternative to ordinary portland cement (OPC) in concrete. The development of thermodynamic models to predict phase development and, ultimately, engineering properties, of inorganic polymer binders is an important step toward enabling their widespread use. However, such models require self-consistent solubility data of the primary phase in inorganic polymer binders, sodium aluminosilicate hydrate(s). To date, there is very little solubility information available for this phase. Here, a rigorous method for synthesizing sodium aluminosilicate hydrate(s) of controlled composition, and for measuring its solubility is presented. This approach allows complete stoichiometric control over the (initial) solution composition to elucidate directly the development of N-A-S-H composition as it relates to a given solution composition. A review of previous literature related to the solubility of other cementitious materials is presented, and the need for thermodynamic data is discussed. Finally, a sample calculation is presented for determining the solubility product (Ksp) of a laboratory synthesized sodium aluminosilicate hydrate.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45179865","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 : 2019-02-18DOI: 10.21809/RILEMTECHLETT.2018.74
Shi Xu, Xueyan Liu, A. Tabaković, E. Schlangen
Induction healing is a proven technology which is able to improve the self-healing capacity of asphalt concrete. Healing is achieved via electromagnetic current produced by passing induction machine, where steel asphalt constituents heat up which in turn soften the bitumen in the asphalt layer, allowing it to flow and close cracks, repairing the damage. This paper reports on the study which investigated the influence of ageing on the healing capacity of Porous Asphalt (PA) concrete. Porous Asphalt concrete mix was prepared first, then subjected to an accelerated (laboratory) ageing process using a ventilated oven. In order to further evaluate the induction healing efficiency of asphalt concrete, Semi-circular bending (SCB) and healing cycles were performed on asphalt concrete specimens. The results show that with an increase of the ageing level of porous asphalt concrete, the induction healing efficiency decreases.
{"title":"The influence of asphalt ageing on induction healing effect on porous asphalt concrete","authors":"Shi Xu, Xueyan Liu, A. Tabaković, E. Schlangen","doi":"10.21809/RILEMTECHLETT.2018.74","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.74","url":null,"abstract":"Induction healing is a proven technology which is able to improve the self-healing capacity of asphalt concrete. Healing is achieved via electromagnetic current produced by passing induction machine, where steel asphalt constituents heat up which in turn soften the bitumen in the asphalt layer, allowing it to flow and close cracks, repairing the damage. This paper reports on the study which investigated the influence of ageing on the healing capacity of Porous Asphalt (PA) concrete. Porous Asphalt concrete mix was prepared first, then subjected to an accelerated (laboratory) ageing process using a ventilated oven. In order to further evaluate the induction healing efficiency of asphalt concrete, Semi-circular bending (SCB) and healing cycles were performed on asphalt concrete specimens. The results show that with an increase of the ageing level of porous asphalt concrete, the induction healing efficiency decreases.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46782515","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 : 2019-02-13DOI: 10.21809/RILEMTECHLETT.2018.75
A. Perrot, D. Rangeard, V. Nerella, V. Mechtcherine
Extrusion is a process that consists in forcing a formable material to pass through a die having the cross-section of the part to be obtained. This way of processing is used with conventional and fibre-reinforced cement-based materials to fabricate various construction elements such as panels, pipes and roadside curbs. Recently, with the development of digital fabrication methods and especially 3D concrete printing by selective deposition, the extrusion techniques have experienced a significant increase in interest. This letter describes the screw and ram extrusion techniques and their applications in construction industry. Furthermore, the underlying mechanisms involved during extrusion flow are delineated and the roles of rheological and hydro-mechanical behaviours (the latter one in a soil mechanics sense) in defining the extrudability – ability of being extruded – of the cementitious materials are highlighted. Finally, specific points such as flow-induced anisotropy of fibre reinforced cementitious materials or surface defects are addressed.
{"title":"Extrusion of cement-based materials - an overview","authors":"A. Perrot, D. Rangeard, V. Nerella, V. Mechtcherine","doi":"10.21809/RILEMTECHLETT.2018.75","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.75","url":null,"abstract":"Extrusion is a process that consists in forcing a formable material to pass through a die having the cross-section of the part to be obtained. This way of processing is used with conventional and fibre-reinforced cement-based materials to fabricate various construction elements such as panels, pipes and roadside curbs. Recently, with the development of digital fabrication methods and especially 3D concrete printing by selective deposition, the extrusion techniques have experienced a significant increase in interest. \u0000This letter describes the screw and ram extrusion techniques and their applications in construction industry. Furthermore, the underlying mechanisms involved during extrusion flow are delineated and the roles of rheological and hydro-mechanical behaviours (the latter one in a soil mechanics sense) in defining the extrudability – ability of being extruded – of the cementitious materials are highlighted. Finally, specific points such as flow-induced anisotropy of fibre reinforced cementitious materials or surface defects are addressed.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46050623","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 : 2019-01-18DOI: 10.21809/RILEMTECHLETT.2018.67
S. Cavalaro, A. Blanco, R. Pieralisi
In the construction industry, the design of dimensions and material properties is generally separated from the design of material composition and of the production processes used. Such divide is enabled by robust construction materials (like concrete) little affected by production processes if minimum precautionary measures are in place. The same does not hold true for special concrete types; whose higher sensibility compels a shift towards more comprehensive approaches that assimilate the production process in a holistic design. The design driven by integrated numerical simulations encompassing from production to the long-term performance is already ordinary in the manufacturing of plastic and metallic parts. Nevertheless, it remains an alien to the construction industry. The objective of this paper is to review existing studies that might underpin this holistic design approach in construction and show some of its capabilities. Advanced modelling strategies available to simulate the behaviour from the fresh- to the hardened-state are discussed for the cases of pervious concrete and fibre reinforced concrete. This approach provides a deeper insight about the material behaviour and aids to a new level of numerical optimisation of their compositions and production processes, unlocking a potential transformation of the modus operandi of the construction industry.
{"title":"Holistic modelling approach for special concrete: from fresh- to hardened-state","authors":"S. Cavalaro, A. Blanco, R. Pieralisi","doi":"10.21809/RILEMTECHLETT.2018.67","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.67","url":null,"abstract":"In the construction industry, the design of dimensions and material properties is generally separated from the design of material composition and of the production processes used. Such divide is enabled by robust construction materials (like concrete) little affected by production processes if minimum precautionary measures are in place. The same does not hold true for special concrete types; whose higher sensibility compels a shift towards more comprehensive approaches that assimilate the production process in a holistic design. The design driven by integrated numerical simulations encompassing from production to the long-term performance is already ordinary in the manufacturing of plastic and metallic parts. Nevertheless, it remains an alien to the construction industry. The objective of this paper is to review existing studies that might underpin this holistic design approach in construction and show some of its capabilities. Advanced modelling strategies available to simulate the behaviour from the fresh- to the hardened-state are discussed for the cases of pervious concrete and fibre reinforced concrete. This approach provides a deeper insight about the material behaviour and aids to a new level of numerical optimisation of their compositions and production processes, unlocking a potential transformation of the modus operandi of the construction industry.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42060011","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 : 2019-01-16DOI: 10.21809/RILEMTECHLETT.2018.70
I. Ogunsanya, C. Hansson
Knowledge of the critical chloride content in concrete required to initiate corrosion of reinforcing steel is economically beneficial for the assessment and maintenance of existing structures. Also, many building codes now specify a service life of 75 – 100 years for highway bridges and the critical chloride content is an essential input parameter in the models used in design of structures. There have been numerous studies aimed at determining this parameter but there is no consensus because of the many factors influencing the corrosion. The current standard methods, e.g. ASTM G109, require many weeks or months of testing and are not appropriate for testing large numbers of specimens in different conditions. This project has demonstrated that a fairly rapid potentiodynamic polarization technique can be applied to carbon steel reinforcing bars in synthetic concrete pore solution to determine the critical value, as illustrated in the figure. The importance of selecting the appropriate synthetic concrete pore solution for this application is demonstrated by the different critical values obtained for different solutions. The success of this test will allow the influence of different reinforcing alloys and different cementitious material mixes on the critical chloride content to be determined in a reasonable period of time.
{"title":"Detection of the critical chloride threshold of carbon steel rebar in synthetic concrete pore solutions.","authors":"I. Ogunsanya, C. Hansson","doi":"10.21809/RILEMTECHLETT.2018.70","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.70","url":null,"abstract":"Knowledge of the critical chloride content in concrete required to initiate corrosion of reinforcing steel is economically beneficial for the assessment and maintenance of existing structures. Also, many building codes now specify a service life of 75 – 100 years for highway bridges and the critical chloride content is an essential input parameter in the models used in design of structures. There have been numerous studies aimed at determining this parameter but there is no consensus because of the many factors influencing the corrosion. The current standard methods, e.g. ASTM G109, require many weeks or months of testing and are not appropriate for testing large numbers of specimens in different conditions. \u0000This project has demonstrated that a fairly rapid potentiodynamic polarization technique can be applied to carbon steel reinforcing bars in synthetic concrete pore solution to determine the critical value, as illustrated in the figure. The importance of selecting the appropriate synthetic concrete pore solution for this application is demonstrated by the different critical values obtained for different solutions. \u0000The success of this test will allow the influence of different reinforcing alloys and different cementitious material mixes on the critical chloride content to be determined in a reasonable period of time. \u0000 ","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42998948","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 : 2018-12-31DOI: 10.21809/RILEMTECHLETT.2018.66
A. Tomoyose, T. Noguchi, K. Sodeyama, K. Higashi
The reaction of natural pozzolans is caused by volcanic glass composed of amorphous silicate; however, volcanic ejecta also contains crystal mineral, pumice, and sometimes weathered clay fraction in their natural conditions. By focusing on the differences of physical properties between these components, high-purity volcanic glass powder (VGP) was manufactured by dry gravity classification and pulverization. This paper reports the results of investigations to utilize pyroclastic flow deposits as a supplementary cementitious material (SCM). Through this method, the glass content of VGP increased to 88% with a mean particle size of 1 μm, when that of the raw material is about 60%. Chemical analysis indicated that VGP is principally composed of silica (about 72%) and alumina (about 13%). The performance of VGP as a SCM was evaluated by conducting tests on concrete mixtures, replacing 0% to 30% by weight of portland cement by VGP with a 20% to 60% water to cement ratio. VGP concrete showed better results of 7-and 28-day compressive strength compared to control concrete in all experiments. In particular, VGP demonstrated better flowability and strength development in concrete with a low water-binder ratio in comparison to silica fume.
{"title":"Utilization of volcanic ejecta as a high-performance supplementary cementitious material by gravity classification and pulverization","authors":"A. Tomoyose, T. Noguchi, K. Sodeyama, K. Higashi","doi":"10.21809/RILEMTECHLETT.2018.66","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.66","url":null,"abstract":"The reaction of natural pozzolans is caused by volcanic glass composed of amorphous silicate; however, volcanic ejecta also contains crystal mineral, pumice, and sometimes weathered clay fraction in their natural conditions. By focusing on the differences of physical properties between these components, high-purity volcanic glass powder (VGP) was manufactured by dry gravity classification and pulverization. This paper reports the results of investigations to utilize pyroclastic flow deposits as a supplementary cementitious material (SCM). \u0000Through this method, the glass content of VGP increased to 88% with a mean particle size of 1 μm, when that of the raw material is about 60%. Chemical analysis indicated that VGP is principally composed of silica (about 72%) and alumina (about 13%). \u0000The performance of VGP as a SCM was evaluated by conducting tests on concrete mixtures, replacing 0% to 30% by weight of portland cement by VGP with a 20% to 60% water to cement ratio. VGP concrete showed better results of 7-and 28-day compressive strength compared to control concrete in all experiments. In particular, VGP demonstrated better flowability and strength development in concrete with a low water-binder ratio in comparison to silica fume.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44966114","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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