Pub Date : 2022-09-23DOI: 10.21809/rilemtechlett.2022.161
Jaime Mata‐Falcón, P. Bischof, Tobias Huber, Ana Anton, Joris Burger, F. Ranaudo, Andrei Jipa, Lukas Gebhard, L. Reiter, E. Lloret-Fritschi, T. Van Mele, P. Block, F. Gramazio, M. Kohler, B. Dillenburger, T. Wangler, W. Kaufmann
The concrete used in floor slabs accounts for large greenhouse gas emissions in building construction. Solid slabs, often used today, consume much more concrete than ribbed slabs built by pioneer structural engineers like Hennebique, Arcangeli and Nervi. The first part of this paper analyses the evolution of slab systems over the last century and their carbon footprint, highlighting that ribbed slabs have been abandoned mainly for the sake of construction time and cost efficiency. However, highly material-efficient two-way ribbed slabs are essential to reduce the environmental impact of construction. Hence, the second part of this paper discusses how digital fabrication can help to tackle this challenge and presents four concrete floor systems built with digitally fabricated formwork. The digital fabrication technologies employed to produce these slab systems are digital cutting, binder-jetting, polymer extrusion and 3D concrete printing. The presented applications showcase a reduction in concrete use of approximately 50% compared to solid slabs. However, the digitally fabricated complex formworks produced were wasteful and/or labour-intensive. Further developments are required to make the digital processes sustainable and competitive by streamlining the production, using low carbon concrete mixes as well as reusing and recycling the formwork or structurally activating stay-in-place formwork.
{"title":"Digitally fabricated ribbed concrete floor slabs: a sustainable solution for construction","authors":"Jaime Mata‐Falcón, P. Bischof, Tobias Huber, Ana Anton, Joris Burger, F. Ranaudo, Andrei Jipa, Lukas Gebhard, L. Reiter, E. Lloret-Fritschi, T. Van Mele, P. Block, F. Gramazio, M. Kohler, B. Dillenburger, T. Wangler, W. Kaufmann","doi":"10.21809/rilemtechlett.2022.161","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.161","url":null,"abstract":"The concrete used in floor slabs accounts for large greenhouse gas emissions in building construction. Solid slabs, often used today, consume much more concrete than ribbed slabs built by pioneer structural engineers like Hennebique, Arcangeli and Nervi. The first part of this paper analyses the evolution of slab systems over the last century and their carbon footprint, highlighting that ribbed slabs have been abandoned mainly for the sake of construction time and cost efficiency. However, highly material-efficient two-way ribbed slabs are essential to reduce the environmental impact of construction. Hence, the second part of this paper discusses how digital fabrication can help to tackle this challenge and presents four concrete floor systems built with digitally fabricated formwork. The digital fabrication technologies employed to produce these slab systems are digital cutting, binder-jetting, polymer extrusion and 3D concrete printing. The presented applications showcase a reduction in concrete use of approximately 50% compared to solid slabs. However, the digitally fabricated complex formworks produced were wasteful and/or labour-intensive. Further developments are required to make the digital processes sustainable and competitive by streamlining the production, using low carbon concrete mixes as well as reusing and recycling the formwork or structurally activating stay-in-place formwork.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47547543","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 : 2022-09-16DOI: 10.21809/rilemtechlett.2022.157
G. Gluth, C. Grengg, N. Ukrainczyk, F. Mittermayr, M. Dietzel
Cementitious materials are frequently applied in environments in which they are exposed to acid attack, e.g., in sewer systems, biogas plants, and agricultural/food-related industries. Alkali-activated materials (AAMs) have repeatedly been shown to exhibit a remarkably high resistance against attack by organic and inorganic acids and, thus, are promising candidates for the construction and the repair of acid-exposed structures. However, the reaction mechanisms and processes affecting the acid resistance of AAMs have just recently begun to be understood in more detail. The present contribution synthesises these advances and outlines potentially fruitful avenues of research. The interaction between AAMs and acids proceeds in a multistep process wherein different aspects of deterioration extend to different depths, complicating the overall determination of acid resistance. Partly due to this indistinct definition of the ‘depth of corrosion’, the effects of the composition of AAMs on their acid resistance cannot be unambiguously identified to date. Important parallels exist between the deterioration of low-Ca AAMs and the weathering/corrosion of minerals and glasses (dissolution-reprecipitation mechanism). Additional research requirements relate to the deterioration mechanism of high-Ca AAMs; how the character of the corroded layer influences the rate of deterioration; the effects of shrinkage and the bond between AAMs and substrates.
{"title":"Acid resistance of alkali-activated materials: recent advances and research needs","authors":"G. Gluth, C. Grengg, N. Ukrainczyk, F. Mittermayr, M. Dietzel","doi":"10.21809/rilemtechlett.2022.157","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.157","url":null,"abstract":"Cementitious materials are frequently applied in environments in which they are exposed to acid attack, e.g., in sewer systems, biogas plants, and agricultural/food-related industries. Alkali-activated materials (AAMs) have repeatedly been shown to exhibit a remarkably high resistance against attack by organic and inorganic acids and, thus, are promising candidates for the construction and the repair of acid-exposed structures. However, the reaction mechanisms and processes affecting the acid resistance of AAMs have just recently begun to be understood in more detail. The present contribution synthesises these advances and outlines potentially fruitful avenues of research. The interaction between AAMs and acids proceeds in a multistep process wherein different aspects of deterioration extend to different depths, complicating the overall determination of acid resistance. Partly due to this indistinct definition of the ‘depth of corrosion’, the effects of the composition of AAMs on their acid resistance cannot be unambiguously identified to date. Important parallels exist between the deterioration of low-Ca AAMs and the weathering/corrosion of minerals and glasses (dissolution-reprecipitation mechanism). Additional research requirements relate to the deterioration mechanism of high-Ca AAMs; how the character of the corroded layer influences the rate of deterioration; the effects of shrinkage and the bond between AAMs and substrates.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45489508","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 : 2022-09-01DOI: 10.21809/rilemtechlett.2022.162
E. Bernard
This short letter summaries the latest research on the structure and thermodynamic modelling of the magnesium silicate hydrates (M-S-H) phases. M-S-H structure is comparable to hydrated clays, with a smaller and rounder microstructures compared to clay platelets. Similar to clay minerals, M-S-H can incorporate ions such as aluminium and hydrated exchangeable cations to compensate the negative surface charge. This fundamental understanding of M-S-H structure allowed to develop structure-based thermodynamic models, which can further help to optimise the conditions for M-S-H formation and its use as cementitious materials. Optimized binders containing M-S-H have the advantages of presenting: i) good mechanical properties, ii) dense microstructure and potentially good resistances to leaching and iii) low pH values. These types of binders could therefore be used for cement products with non-steel reinforcement, for the encapsulation of specific wastes, for products containing natural fibres or for the clay stabilisation, etc.
{"title":"Research progress on magnesium silicate hydrate phases and future opportunities","authors":"E. Bernard","doi":"10.21809/rilemtechlett.2022.162","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.162","url":null,"abstract":"This short letter summaries the latest research on the structure and thermodynamic modelling of the magnesium silicate hydrates (M-S-H) phases. M-S-H structure is comparable to hydrated clays, with a smaller and rounder microstructures compared to clay platelets. Similar to clay minerals, M-S-H can incorporate ions such as aluminium and hydrated exchangeable cations to compensate the negative surface charge. This fundamental understanding of M-S-H structure allowed to develop structure-based thermodynamic models, which can further help to optimise the conditions for M-S-H formation and its use as cementitious materials. Optimized binders containing M-S-H have the advantages of presenting: i) good mechanical properties, ii) dense microstructure and potentially good resistances to leaching and iii) low pH values. These types of binders could therefore be used for cement products with non-steel reinforcement, for the encapsulation of specific wastes, for products containing natural fibres or for the clay stabilisation, etc.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43051965","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 : 2022-08-15DOI: 10.21809/rilemtechlett.2022.155
Yury Villagrán-Zaccardi, Ricardo Pareja, Lina Rojas, E. Irassar, A. Torres‐Acosta, J. Tobón, V. John
Carbon neutrality to limit global warming is an increasing challenge for all industries, particularly for the cement industry, due to the chemical emission of the process. For decades, reducing the clinker factor has been one of the main strategies to reduce the carbon footprint. Additional cuttings in the clinker content of cements seem possible with the upsurge of novel supplementary cementitious materials. This potential contribution represents only a fraction of the required carbon reductions for achieving the goal of carbon neutrality in the coming decades. This paper describes the current situation of the cement industry in Latin America and the Caribbean and the global opportunities and strategies to reduce the carbon footprint of cement and concrete and their adaptation to the regional conditions. Besides describing emerging supplementary cementitious materials, the potential contributions of industrialization and quality control are discussed. Moreover, limitations related to geography and standardization are analyzed. Regional considerations are made given the specific prospects of human development.
{"title":"Overview of cement and concrete production in Latin America and the Caribbean with a focus on the goals of reaching carbon neutrality","authors":"Yury Villagrán-Zaccardi, Ricardo Pareja, Lina Rojas, E. Irassar, A. Torres‐Acosta, J. Tobón, V. John","doi":"10.21809/rilemtechlett.2022.155","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.155","url":null,"abstract":"Carbon neutrality to limit global warming is an increasing challenge for all industries, particularly for the cement industry, due to the chemical emission of the process. For decades, reducing the clinker factor has been one of the main strategies to reduce the carbon footprint. Additional cuttings in the clinker content of cements seem possible with the upsurge of novel supplementary cementitious materials. This potential contribution represents only a fraction of the required carbon reductions for achieving the goal of carbon neutrality in the coming decades. This paper describes the current situation of the cement industry in Latin America and the Caribbean and the global opportunities and strategies to reduce the carbon footprint of cement and concrete and their adaptation to the regional conditions. Besides describing emerging supplementary cementitious materials, the potential contributions of industrialization and quality control are discussed. Moreover, limitations related to geography and standardization are analyzed. Regional considerations are made given the specific prospects of human development.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42458429","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 : 2022-08-10DOI: 10.21809/rilemtechlett.2022.159
F. Gherardi, P. Maravelaki
The unpredictable effects of climate change impose the safeguarding of Cultural Heritage (CH) with effective and durable materials as a vital solution in the invaluable socioeconomic resource of CH. Conservation products and methodologies are addressed under recent advancements in colloidal science providing multi-functional solutions for cleaning, consolidation, protection, and monitoring of the architectural surfaces. Nanoscience significantly contributes to enrich the palette of materials and tools that can guarantee an effective response to aggressive environmental agents. Nanostructured multi-functional nanoparticles, nanostructured fluids, and gels for stone conservation are reviewed and future perspectives are also commented. The stability and high flexibility in designing tailored made nanoparticles according to the specific characteristics of the substrate enable their use in a variety of applications. Stemming from the well-performed in lab applications with nanomaterials, the testing onsite and the monitoring of their effectiveness are of crucial importance, considering also the constructive feedback from conservators and heritage stakeholders that can unquestionably contribute to the improvement and optimisation of the nanomaterials for CH protection.
{"title":"Advances in the application of nanomaterials for natural stone conservation","authors":"F. Gherardi, P. Maravelaki","doi":"10.21809/rilemtechlett.2022.159","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.159","url":null,"abstract":"The unpredictable effects of climate change impose the safeguarding of Cultural Heritage (CH) with effective and durable materials as a vital solution in the invaluable socioeconomic resource of CH. Conservation products and methodologies are addressed under recent advancements in colloidal science providing multi-functional solutions for cleaning, consolidation, protection, and monitoring of the architectural surfaces. Nanoscience significantly contributes to enrich the palette of materials and tools that can guarantee an effective response to aggressive environmental agents. Nanostructured multi-functional nanoparticles, nanostructured fluids, and gels for stone conservation are reviewed and future perspectives are also commented. The stability and high flexibility in designing tailored made nanoparticles according to the specific characteristics of the substrate enable their use in a variety of applications. Stemming from the well-performed in lab applications with nanomaterials, the testing onsite and the monitoring of their effectiveness are of crucial importance, considering also the constructive feedback from conservators and heritage stakeholders that can unquestionably contribute to the improvement and optimisation of the nanomaterials for CH protection.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49660187","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 : 2022-07-19DOI: 10.21809/rilemtechlett.2022.152
D. Mishra, Hao-liang Wu, Jing Yu, C. Leung
Engineered Cementitious Composites (ECC, also known as Strain-Hardening Cementitious Composites or SHCC) are a family of high-performance fibre-reinforced cement-based materials. With the ultimate tensile strain of over 1% and the self-controlled crack width of less than 100 μm, ECC enables high damage tolerance and outstanding durability under various environments for infrastructure. Owing to the absence of coarse aggregates and the low content of fine aggregates, the cement content in conventional ECC can be over 600 kg/m3, which is undesirable for low-carbon buildings and infrastructure. Ultrahigh-volume (over 60%) pozzolan has been explored to produce sustainable ECC. This article reviews recent advances of sustainable ECC with ultrahigh-volume Class F fly ash or limestone calcined clay. These sustainable ECC either match or surpass mechanical properties and durability characteristics of conventional ECC, while their carbon footprint and embodied energy are much lower than those of conventional ECC. This review article sheds light on fundamental and applied studies on sustainable ECC.
{"title":"Review on recent advances of sustainable engineered/strain-hardening cementitious composites (ECC/SHCC) with ultrahigh-volume pozzolan","authors":"D. Mishra, Hao-liang Wu, Jing Yu, C. Leung","doi":"10.21809/rilemtechlett.2022.152","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.152","url":null,"abstract":"Engineered Cementitious Composites (ECC, also known as Strain-Hardening Cementitious Composites or SHCC) are a family of high-performance fibre-reinforced cement-based materials. With the ultimate tensile strain of over 1% and the self-controlled crack width of less than 100 μm, ECC enables high damage tolerance and outstanding durability under various environments for infrastructure. Owing to the absence of coarse aggregates and the low content of fine aggregates, the cement content in conventional ECC can be over 600 kg/m3, which is undesirable for low-carbon buildings and infrastructure. Ultrahigh-volume (over 60%) pozzolan has been explored to produce sustainable ECC. This article reviews recent advances of sustainable ECC with ultrahigh-volume Class F fly ash or limestone calcined clay. These sustainable ECC either match or surpass mechanical properties and durability characteristics of conventional ECC, while their carbon footprint and embodied energy are much lower than those of conventional ECC. This review article sheds light on fundamental and applied studies on sustainable ECC.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43044186","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 : 2022-06-27DOI: 10.21809/rilemtechlett.2021.135
Shashank Bishnoi, J. Bullard
Microstructure models seek to explain or predict various material properties in terms of the structure or chemical composition at scales of several hundred nanometres to several hundred micrometres. Such models therefore bridge the scaling gap between atomistic models and continuum methods, and consequently can help establish and validate scaling relations across those scales. Microstructure models have been applied to cementitious materials for at least four decades to help understand setting, strength development, rheological properties, mechanical behavior, and transport properties. This letter describes the current state of cement microstructure modelling in several areas that are important for engineering. It is not meant to be an exhaustive review, instead highlighting the kinds of models that can now be applied to different aspects of cement binder behaviour. Special attention is paid to challenges or limitations of each kind of model. This is done to promote the judicious use and interpretation of models and especially to indicate where future research could make inroads on problems that are currently inaccessible to microstructure models.
{"title":"Microstructure models of cement: their importance, utility, and current limitations","authors":"Shashank Bishnoi, J. Bullard","doi":"10.21809/rilemtechlett.2021.135","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.135","url":null,"abstract":"Microstructure models seek to explain or predict various material properties in terms of the structure or chemical composition at scales of several hundred nanometres to several hundred micrometres. Such models therefore bridge the scaling gap between atomistic models and continuum methods, and consequently can help establish and validate scaling relations across those scales. Microstructure models have been applied to cementitious materials for at least four decades to help understand setting, strength development, rheological properties, mechanical behavior, and transport properties. This letter describes the current state of cement microstructure modelling in several areas that are important for engineering. It is not meant to be an exhaustive review, instead highlighting the kinds of models that can now be applied to different aspects of cement binder behaviour. Special attention is paid to challenges or limitations of each kind of model. This is done to promote the judicious use and interpretation of models and especially to indicate where future research could make inroads on problems that are currently inaccessible to microstructure models.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42839018","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 : 2022-03-28DOI: 10.21809/rilemtechlett.2021.151
A. Leemann, M. Bagheri, B. Lothenbach, K. Scrivener, S. Barbotin, E. Boehm-Courjault, G. Geng, R. Dähn, Zhenguo Shi, M. Shakoorioskooie, Michele Griffa, R. Zboray, P. Lura, E. Gallyamov, R. Rezakhani, J. Molinari
In the last four years, a multidisciplinary study involving several research groups in Switzerland tackled a number of unsolved, fundamental issues about the alkali-silica reaction (ASR) in concrete. The covered topics include SiO2 dissolution, the characterization of various ASR products formed at different stages of the reaction in both concrete and synthesis, crack formation and propagation. The encompassed scale ranges from nanometers to meters. Apart from conventional techniques, novel methods for the field of ASR have been used, e.g. combination of scanning electron microscopy with dissolution experiments, combination of focused ion beam with transmission electron microscopy, several synchrotron-based methods, synthesis of ASR products for in-depth characterization, time-lapse X-ray micro-tomography combined with contrast-enhancing measures and numerical models of ASR damage based on realistic crack patterns. Key achievements and findings are the quantification of the effect of aluminum on dissolution of different silicates, the variance in morphology and composition of initial ASR products, the differences and similarities between amorphous ASR products and calcium-silicate-hydrate, the link between temperature and the structure of the crystalline ASR products, the behavior of the crystalline ASR products at varying relative humidity, ASR propagation in 4D and numerical modelling based on realistic crack patterns.
{"title":"Alkali-silica reaction – a multidisciplinary approach","authors":"A. Leemann, M. Bagheri, B. Lothenbach, K. Scrivener, S. Barbotin, E. Boehm-Courjault, G. Geng, R. Dähn, Zhenguo Shi, M. Shakoorioskooie, Michele Griffa, R. Zboray, P. Lura, E. Gallyamov, R. Rezakhani, J. Molinari","doi":"10.21809/rilemtechlett.2021.151","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.151","url":null,"abstract":"In the last four years, a multidisciplinary study involving several research groups in Switzerland tackled a number of unsolved, fundamental issues about the alkali-silica reaction (ASR) in concrete. The covered topics include SiO2 dissolution, the characterization of various ASR products formed at different stages of the reaction in both concrete and synthesis, crack formation and propagation. The encompassed scale ranges from nanometers to meters. Apart from conventional techniques, novel methods for the field of ASR have been used, e.g. combination of scanning electron microscopy with dissolution experiments, combination of focused ion beam with transmission electron microscopy, several synchrotron-based methods, synthesis of ASR products for in-depth characterization, time-lapse X-ray micro-tomography combined with contrast-enhancing measures and numerical models of ASR damage based on realistic crack patterns. Key achievements and findings are the quantification of the effect of aluminum on dissolution of different silicates, the variance in morphology and composition of initial ASR products, the differences and similarities between amorphous ASR products and calcium-silicate-hydrate, the link between temperature and the structure of the crystalline ASR products, the behavior of the crystalline ASR products at varying relative humidity, ASR propagation in 4D and numerical modelling based on realistic crack patterns.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49324510","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 : 2022-02-28DOI: 10.21809/rilemtechlett.2021.116
R. François
This paper deals with the determination of the corrosion current density in chloride-induced corrosion in reinforced concrete structures. Because the corrosion of steel bars is generally localized, calculations of the densities of corrosion current need to take the real surface areas of anodic zones into account. Nowadays, in the lab or on site, the calculation of densities of corrosion are based on arbitrary steel surface areas, which merge anodic and cathodic zones. As a result, the order of magnitude of corrosion current density is not correct; it is underestimated. A second aspect of the paper is the relationship between corrosion current density and the prediction of service life in RC structure when including a part of the propagation phase. The consequences of the corrosion current density on mechanical properties such as corrosion-induced cracking or load-bearing capacity must consider that anodic areas grow both laterally and in-depth.
{"title":"A discussion on the order of magnitude of corrosion current density in reinforcements of concrete structures and its link with cross-section loss of reinforcement","authors":"R. François","doi":"10.21809/rilemtechlett.2021.116","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.116","url":null,"abstract":"This paper deals with the determination of the corrosion current density in chloride-induced corrosion in reinforced concrete structures. Because the corrosion of steel bars is generally localized, calculations of the densities of corrosion current need to take the real surface areas of anodic zones into account. Nowadays, in the lab or on site, the calculation of densities of corrosion are based on arbitrary steel surface areas, which merge anodic and cathodic zones. As a result, the order of magnitude of corrosion current density is not correct; it is underestimated. A second aspect of the paper is the relationship between corrosion current density and the prediction of service life in RC structure when including a part of the propagation phase. The consequences of the corrosion current density on mechanical properties such as corrosion-induced cracking or load-bearing capacity must consider that anodic areas grow both laterally and in-depth.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47694974","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 : 2021-12-30DOI: 10.21809/rilemtechlett.2021.147
Renee T. Rios, Christopher M. Childs, Scott H. Smith, N. Washburn, K. Kurtis
The massive scale of concrete construction constrains the raw materials’ feedstocks that can be considered – requiring both universal abundance but also economical and energy-efficient processing. While significant improvements– from more efficient cement and concrete production to increased service life – have been realized over the past decades through traditional research paradigms, non-incremental innovations are necessary now to meet increasingly urgent needs, at a time when innovations in materials create even greater complexity. Data science is revolutionizing the rate of discovery and accelerating the rate of innovation for material systems. This review addresses machine learning and other data analytical techniques which utilize various forms of variable representation for cementitious systems. These techniques include those guided by physicochemical and cheminformatics approaches to chemical admixture design, use of materials informatics to develop process-structure-property linkages for quantifying increased service life, and change-point detection for assessing pozzolanicity in candidate supplementary cementitious materials (SCMs). These latent variables, coupled with approaches to dimensionality reduction driven both algorithmically as well as through domain knowledge, provide robust feature representation for cement-based materials and allow for more accurate models and greater generalization capability, resulting in a powerful design tool for infrastructure materials.
{"title":"Advancing cement-based materials design through data science approaches","authors":"Renee T. Rios, Christopher M. Childs, Scott H. Smith, N. Washburn, K. Kurtis","doi":"10.21809/rilemtechlett.2021.147","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.147","url":null,"abstract":"The massive scale of concrete construction constrains the raw materials’ feedstocks that can be considered – requiring both universal abundance but also economical and energy-efficient processing. While significant improvements– from more efficient cement and concrete production to increased service life – have been realized over the past decades through traditional research paradigms, non-incremental innovations are necessary now to meet increasingly urgent needs, at a time when innovations in materials create even greater complexity. Data science is revolutionizing the rate of discovery and accelerating the rate of innovation for material systems. This review addresses machine learning and other data analytical techniques which utilize various forms of variable representation for cementitious systems. These techniques include those guided by physicochemical and cheminformatics approaches to chemical admixture design, use of materials informatics to develop process-structure-property linkages for quantifying increased service life, and change-point detection for assessing pozzolanicity in candidate supplementary cementitious materials (SCMs). These latent variables, coupled with approaches to dimensionality reduction driven both algorithmically as well as through domain knowledge, provide robust feature representation for cement-based materials and allow for more accurate models and greater generalization capability, resulting in a powerful design tool for infrastructure materials.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47904097","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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