Pub Date : 2018-12-22DOI: 10.21809/RILEMTECHLETT.2018.71
A. Fabbri, J. Morel, D. Gallipoli
After being almost abandoned at the end of the Second World War, the use of raw earth is currently regaining the interest of architects, engineers and policy makers for the construction of dwellings in industrialised countries. This renaissance is driven by growing ecological awareness and the promotion of construction techniques that minimize energy consumption and carbon emissions. Raw earth displays very interesting thermo-hygro-mechanical properties, which can contribute to the reduction of the environmental impact of buildings not only during construction but also during service life. Nevertheless, one of the reasons that still prevents dissemination of raw earth into construction practice is the lack of commonly agreed procedures for assessing material performance. The RILEM technical committee TCE 274 has been established as a first step for overcoming this obstacle. The objective of the technical committee is to critically examine current testing procedures in order to propose suitable experimental standards. The results of this work will be presented in future publications while the present paper summarizes the main challenges faced by the committee and briefly describes some of the existing procedures for measuring the engineering properties of earth materials.
{"title":"Assessing the performance of earth building materials: a review of recent developments","authors":"A. Fabbri, J. Morel, D. Gallipoli","doi":"10.21809/RILEMTECHLETT.2018.71","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.71","url":null,"abstract":"After being almost abandoned at the end of the Second World War, the use of raw earth is currently regaining the interest of architects, engineers and policy makers for the construction of dwellings in industrialised countries. This renaissance is driven by growing ecological awareness and the promotion of construction techniques that minimize energy consumption and carbon emissions. Raw earth displays very interesting thermo-hygro-mechanical properties, which can contribute to the reduction of the environmental impact of buildings not only during construction but also during service life. Nevertheless, one of the reasons that still prevents dissemination of raw earth into construction practice is the lack of commonly agreed procedures for assessing material performance. The RILEM technical committee TCE 274 has been established as a first step for overcoming this obstacle. The objective of the technical committee is to critically examine current testing procedures in order to propose suitable experimental standards. The results of this work will be presented in future publications while the present paper summarizes the main challenges faced by the committee and briefly describes some of the existing procedures for measuring the engineering properties of earth materials.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43303822","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 : 2018-12-20DOI: 10.21809/RILEMTECHLETT.2018.68
D. Garcia, S. Laurens, S. Panin
Steel corrosion is the most common reason for the premature deterioration of reinforced concrete structures. Consequently, cathodic protection of steel in concrete has been substantially developed during the past two decades. In particular, galvanic protection consists in generating a natural macrocell corrosion system in which a sacrificial metallic anode (zinc, typically) is involved to apply a cathodic polarization to the corroding steel layout, in order to mitigate or annihilate the corrosion kinetics. Whether the general principle of cathodic protection is not questionable, the global design process can be significantly improved by increasing the knowledge on electrochemical behaviours of the different components of the protecting system. Regarding zinc anodes in concrete, the literature is very scarce. The time evolution of such systems is also not rigorously addressed, aging effects are systematically ignored and zinc anodes are usually considered as non-polarizable and inert over time. In this paper, the polarization response of a zinc layer anode (ZLA) in concrete electrolyte and its time evolution are studied. The results show a rapid evolution of the ZLA behavior, once the protecting system is connected to steel reinforcements. Moreover, the characterization of ZLA provided relevant electrochemical properties for the numerical design of galvanic protection systems.
{"title":"Electrochemical behavior of zinc layer anodes used for galvanic protection of steel in reinforced concrete","authors":"D. Garcia, S. Laurens, S. Panin","doi":"10.21809/RILEMTECHLETT.2018.68","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.68","url":null,"abstract":"Steel corrosion is the most common reason for the premature deterioration of reinforced concrete structures. Consequently, cathodic protection of steel in concrete has been substantially developed during the past two decades. In particular, galvanic protection consists in generating a natural macrocell corrosion system in which a sacrificial metallic anode (zinc, typically) is involved to apply a cathodic polarization to the corroding steel layout, in order to mitigate or annihilate the corrosion kinetics. Whether the general principle of cathodic protection is not questionable, the global design process can be significantly improved by increasing the knowledge on electrochemical behaviours of the different components of the protecting system. Regarding zinc anodes in concrete, the literature is very scarce. The time evolution of such systems is also not rigorously addressed, aging effects are systematically ignored and zinc anodes are usually considered as non-polarizable and inert over time. In this paper, the polarization response of a zinc layer anode (ZLA) in concrete electrolyte and its time evolution are studied. The results show a rapid evolution of the ZLA behavior, once the protecting system is connected to steel reinforcements. Moreover, the characterization of ZLA provided relevant electrochemical properties for the numerical design of galvanic protection systems.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45614095","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 : 2018-12-06DOI: 10.21809/RILEMTECHLETT.2020.114
Y. Sakai
In this study, the relationship between air diffusivity and permeability in cementitious materials was investigated to theoretically investigate the relationship between diffusion and air permeability coefficients. First, an equation to correlate air diffusivity and permeability in a straight circular tube was derived. Then, existing studies that measured both air diffusivity and permeability and compared reported data were collected and the applicability of the derived equation to cementitious materials was verified. Although a correction factor was not used, the two sets of data showed good agreement quantitatively. This indicates that the derived equation can be applied to cementitious materials including concrete, and measured air diffusivity can be converted to permeability of concrete and vice versa using the derived equation.
{"title":"Relationship between air diffusivity and permeability coefficients of cementitious materials","authors":"Y. Sakai","doi":"10.21809/RILEMTECHLETT.2020.114","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2020.114","url":null,"abstract":"In this study, the relationship between air diffusivity and permeability in cementitious materials was investigated to theoretically investigate the relationship between diffusion and air permeability coefficients. First, an equation to correlate air diffusivity and permeability in a straight circular tube was derived. Then, existing studies that measured both air diffusivity and permeability and compared reported data were collected and the applicability of the derived equation to cementitious materials was verified. Although a correction factor was not used, the two sets of data showed good agreement quantitatively. This indicates that the derived equation can be applied to cementitious materials including concrete, and measured air diffusivity can be converted to permeability of concrete and vice versa using the derived equation.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42543062","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 : 2018-11-28DOI: 10.21809/RILEMTECHLETT.2018.72
Bernhard J. Müller, C. Grengg, Viktor Schallert, Marlene Sakoparnig, Christoph Staudinger, Johanna Breininger, F. Mittermayr, B. Ungerböck, S. Borisov, M. Dietzel, T. Mayr
The pH of concrete-based material is a key parameter for the assessment of its stability and durability, since a change in pH is usually associated with major types of chemical degradation such as carbonation, leaching and acid attacks. Conventional surface pH measurements with potentiometric flat surface electrodes have low spatial resolution, whereas optical pH visualization with indicator dyes (phenolphthalein) only indicates the areas with higher or lower pH than the pKa of the indicator. In this regard, it is key to develop wide-range imaging systems, enabling accurate and spatially resolved determination of pH variability for an advanced knowledge of degradation mechanisms. This contribution presents the enhancements made for a high-resolution optical pH imaging system based on fluorescent aza-BODIPY indicator dyes. The measurement range was increased to 6 pH units (pH 6.5 to pH 12.5) by a combination of two indicator dyes. Moreover, background scattering effects were sufficiently eliminated. With the improved sensor foils steep pH gradients (up to 3 pH units within 2 mm) were successfully recorded in various concrete specimens using a macro lens reaching a resolution of down to 35 µm per pixel.
{"title":"Wide-range optical pH imaging of cementitious materials exposed to chemically corrosive environments","authors":"Bernhard J. Müller, C. Grengg, Viktor Schallert, Marlene Sakoparnig, Christoph Staudinger, Johanna Breininger, F. Mittermayr, B. Ungerböck, S. Borisov, M. Dietzel, T. Mayr","doi":"10.21809/RILEMTECHLETT.2018.72","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.72","url":null,"abstract":"The pH of concrete-based material is a key parameter for the assessment of its stability and durability, since a change in pH is usually associated with major types of chemical degradation such as carbonation, leaching and acid attacks. Conventional surface pH measurements with potentiometric flat surface electrodes have low spatial resolution, whereas optical pH visualization with indicator dyes (phenolphthalein) only indicates the areas with higher or lower pH than the pKa of the indicator. In this regard, it is key to develop wide-range imaging systems, enabling accurate and spatially resolved determination of pH variability for an advanced knowledge of degradation mechanisms. This contribution presents the enhancements made for a high-resolution optical pH imaging system based on fluorescent aza-BODIPY indicator dyes. The measurement range was increased to 6 pH units (pH 6.5 to pH 12.5) by a combination of two indicator dyes. Moreover, background scattering effects were sufficiently eliminated. With the improved sensor foils steep pH gradients (up to 3 pH units within 2 mm) were successfully recorded in various concrete specimens using a macro lens reaching a resolution of down to 35 µm per pixel.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41960107","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 : 2018-11-15DOI: 10.21809/RILEMTECHLETT.2018.64
D. Snoeck
Superabsorbent polymers (SAPs) are promising admixtures to improve properties in cementitious materials. Not only useful to mitigate autogenous shrinkage and to increase the freeze-thaw resistance, SAP particles may enhance self-sealing and self-healing in cementitious materials. The self-sealing leads to a regain in water tightness and promoted autogenous healing may prove to be useful to limit repair works caused by concrete cracking. By providing sufficient building blocks for healing, limiting the crack width by means of synthetic microfibers and inducing water by means of SAPs, a smart cementitious material is obtained. This material can be an excellent material to use in future building applications such as tunnel works and ground-retaining structures. This paper gives an overview of the current status of the research on SAPs in cementitious materials to obtain sealing and healing.
{"title":"Superabsorbent polymers to seal and heal cracks in cementitious materials","authors":"D. Snoeck","doi":"10.21809/RILEMTECHLETT.2018.64","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.64","url":null,"abstract":"Superabsorbent polymers (SAPs) are promising admixtures to improve properties in cementitious materials. Not only useful to mitigate autogenous shrinkage and to increase the freeze-thaw resistance, SAP particles may enhance self-sealing and self-healing in cementitious materials. The self-sealing leads to a regain in water tightness and promoted autogenous healing may prove to be useful to limit repair works caused by concrete cracking. By providing sufficient building blocks for healing, limiting the crack width by means of synthetic microfibers and inducing water by means of SAPs, a smart cementitious material is obtained. This material can be an excellent material to use in future building applications such as tunnel works and ground-retaining structures. This paper gives an overview of the current status of the research on SAPs in cementitious materials to obtain sealing and healing.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44378011","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 : 2018-09-27DOI: 10.21809/RILEMTECHLETT.2018.55
Luping Tang, J. M. Frederiksen, U. Angst, R. Polder, M. C. Alonso, B. Elsener, Doug Hooton, J. Pacheco
Chloride threshold value is an important input parameter in service life predictions. There has been a need for a reliable method for testing this value in order to improve the understanding of basic factors influencing the corrosion initiation. For this reason RILEM technical committee (TC) 235-CTC was formed with the ultimate aim to recommend a suitable test method capable of delivering data with acceptable measurement uncertainty. During the TC’s life, a test method was proposed and a Round-Robin Test (RRT) was organised to evaluate it. Due to the unexpected results from the RRT, the ultimate aim of the TC was not reached. There were some experiences obtained from the TC’s work especially in designing the test method which are worthy for supporting future researchers continuing to search for a reliable test method for it. This technical letter presents the TC’s experiences.
{"title":"Experiences from RILEM TC 235-CTC in recommending a test method for chloride threshold values in concrete","authors":"Luping Tang, J. M. Frederiksen, U. Angst, R. Polder, M. C. Alonso, B. Elsener, Doug Hooton, J. Pacheco","doi":"10.21809/RILEMTECHLETT.2018.55","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.55","url":null,"abstract":"Chloride threshold value is an important input parameter in service life predictions. There has been a need for a reliable method for testing this value in order to improve the understanding of basic factors influencing the corrosion initiation. For this reason RILEM technical committee (TC) 235-CTC was formed with the ultimate aim to recommend a suitable test method capable of delivering data with acceptable measurement uncertainty. During the TC’s life, a test method was proposed and a Round-Robin Test (RRT) was organised to evaluate it. Due to the unexpected results from the RRT, the ultimate aim of the TC was not reached. There were some experiences obtained from the TC’s work especially in designing the test method which are worthy for supporting future researchers continuing to search for a reliable test method for it. This technical letter presents the TC’s experiences.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43576913","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 : 2018-09-17DOI: 10.21809/RILEMTECHLETT.2018.60
T. Ishida, Tiao Wang
The use of supplementary cementitious materials (SCMs) to improve concrete performance has increased around the world in recent decades. Engineering practices demand a unified model for SCMs to predict and optimise the performance of blended concrete.DuCOM-COM3 is a multi-chemo-physical and multiscale analysis platform that can trace the whole-life behaviour and performance of reinforced concrete structures. However, the intrinsic heterogeneity and variability of SCMs present great challenges to the modelling of blended concrete. This paper first reviews the challenges and difficulties of current models of blended concrete. A multiphase modelling scheme based on DuCOM-COM3 analysis platform is introduced to consider different SCMs. Using the modelling scheme, a research road map for blended concrete modelling is introduced for future study. It is hoped that the roadmap will help to reveal the mechanism of SCM reactions and their effect on concrete performance.
{"title":"Future of multiscale modelling of concrete - Toward a full integration of cement chemistry and concrete structural engineering","authors":"T. Ishida, Tiao Wang","doi":"10.21809/RILEMTECHLETT.2018.60","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.60","url":null,"abstract":"The use of supplementary cementitious materials (SCMs) to improve concrete performance has increased around the world in recent decades. Engineering practices demand a unified model for SCMs to predict and optimise the performance of blended concrete.DuCOM-COM3 is a multi-chemo-physical and multiscale analysis platform that can trace the whole-life behaviour and performance of reinforced concrete structures. However, the intrinsic heterogeneity and variability of SCMs present great challenges to the modelling of blended concrete. This paper first reviews the challenges and difficulties of current models of blended concrete. A multiphase modelling scheme based on DuCOM-COM3 analysis platform is introduced to consider different SCMs. Using the modelling scheme, a research road map for blended concrete modelling is introduced for future study. It is hoped that the roadmap will help to reveal the mechanism of SCM reactions and their effect on concrete performance. \u0000 ","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43166225","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 : 2018-09-14DOI: 10.21809/RILEMTECHLETT.2018.57
Matteo Stefanoni, Zhidong Zhang, U. Angst, B. Elsener
Corrosion products, originating from steel corrosion and precipitating in the concrete pore system, can lead to concrete cracking and to spalling of the concrete cover. Related premature structural repair causes high costs. Thus, reliable quantitative models are needed, which currently do not exist. Here, we present a new conceptual model to describe the fate of ferrous ions that are released at the steel surface during the corrosion process. The key novelty of our approach can be found in explicitly considering the kinetics of oxidation and transport of Fe2+ in the pore solution. These two processes constantly dilute the Fe2+ concentration and are in competition with the supply of Fe2+ from the anodic iron dissolution reaction. We use a numerical model to elucidate which of the described processes is the fastest. The results find good agreement with experimental data and reveal that under natural corrosion conditions, Fe2+ hardly reach the saturation level, which permits the diffusion of corrosion products up to millimeters away from the steel without necessarily leading to expansive stresses. Under accelerated corrosion conditions, however, precipitation is forced immediately at the steel surface. This fundamentally changes the cracking mechanism and questions the relevance of such tests and related models.
{"title":"The kinetic competition between transport and oxidation of ferrous ions governs precipitation of corrosion products in carbonated concrete","authors":"Matteo Stefanoni, Zhidong Zhang, U. Angst, B. Elsener","doi":"10.21809/RILEMTECHLETT.2018.57","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.57","url":null,"abstract":"Corrosion products, originating from steel corrosion and precipitating in the concrete pore system, can lead to concrete cracking and to spalling of the concrete cover. Related premature structural repair causes high costs. Thus, reliable quantitative models are needed, which currently do not exist. Here, we present a new conceptual model to describe the fate of ferrous ions that are released at the steel surface during the corrosion process. The key novelty of our approach can be found in explicitly considering the kinetics of oxidation and transport of Fe2+ in the pore solution. These two processes constantly dilute the Fe2+ concentration and are in competition with the supply of Fe2+ from the anodic iron dissolution reaction. We use a numerical model to elucidate which of the described processes is the fastest. The results find good agreement with experimental data and reveal that under natural corrosion conditions, Fe2+ hardly reach the saturation level, which permits the diffusion of corrosion products up to millimeters away from the steel without necessarily leading to expansive stresses. Under accelerated corrosion conditions, however, precipitation is forced immediately at the steel surface. This fundamentally changes the cracking mechanism and questions the relevance of such tests and related models.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43983853","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 : 2018-07-12DOI: 10.21809/RILEMTECHLETT.2018.54
D. Steiner, B. Hofko
The cooling test or Thermal Stress Restrained Specimen Test (TSRST) simulates fully restrained pavements, as they occur in field for laboratory assessment of the thermal cracking resistance of asphalt mixtures. In the TSRST, cryogenic stress builds up due to cooling and prevented shrinkage until the tensile strength of the specimen is exceeded and the specimen fails by cracking. By carrying out TSRST various viscoelastic parameters, e.g. relaxation, evolution of tensile stresses, and tensile strength can be analyzed. Thus, a comprehensive view on the low temperature performance is possible. Standard TSRST is controlled by setting the cooling rate of the air within the chamber at a fixed value, e.g. -10°C/h. In thermodynamics, the actual cooling rate of objects is not only influenced by the cooling but also by external conditions like humidity, air velocity, radiation condition, etc. A current study investigates the impact of additional cooling parameters rather than just the air cooling rate. Two test machines of the same manufacturer that differ in the year of production and the setup of the climate chamber are compared. An initial wide scatter of test results from the two devices could be explained by taking thermodynamics into account and the reproducibility could be significantly enhanced.
{"title":"On the influence of basic thermodynamics on thermal cracking resistance of asphalt mixtures in cooling tests","authors":"D. Steiner, B. Hofko","doi":"10.21809/RILEMTECHLETT.2018.54","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2018.54","url":null,"abstract":"The cooling test or Thermal Stress Restrained Specimen Test (TSRST) simulates fully restrained pavements, as they occur in field for laboratory assessment of the thermal cracking resistance of asphalt mixtures. In the TSRST, cryogenic stress builds up due to cooling and prevented shrinkage until the tensile strength of the specimen is exceeded and the specimen fails by cracking. By carrying out TSRST various viscoelastic parameters, e.g. relaxation, evolution of tensile stresses, and tensile strength can be analyzed. Thus, a comprehensive view on the low temperature performance is possible. Standard TSRST is controlled by setting the cooling rate of the air within the chamber at a fixed value, e.g. -10°C/h. In thermodynamics, the actual cooling rate of objects is not only influenced by the cooling but also by external conditions like humidity, air velocity, radiation condition, etc. A current study investigates the impact of additional cooling parameters rather than just the air cooling rate. Two test machines of the same manufacturer that differ in the year of production and the setup of the climate chamber are compared. An initial wide scatter of test results from the two devices could be explained by taking thermodynamics into account and the reproducibility could be significantly enhanced.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45273512","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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