Pub Date : 2023-01-01DOI: 10.1051/matecconf/202337804004
G. Anglani, P. M. Montanari, Jean Marc Tulliani, G. Lacidogna, P. Antonaci
Due to its low tensile strength and the presence of defects brought on by improper construction methods or other factors, cracks in concrete are practically inevitable. For reinforced-concrete structures, even if cracks do not necessarily increase the risk of collapse, they unquestionably hinder aspects such as service life. Self-healing cementitious materials have been developed because of growing concern for the security and sustainability of structures. For these new materials to be used in actual structures, it is essential to conduct research into the self-repair effect that they may offer, and possibly quantify it directly on-site, by means of non-destructive methods. In this sense, the objective of this work is to use Acoustic Emission (AE) analyses to non-destructively characterise the response of an autonomic capsule-based system, as a function of the specific polymeric healing agents contained in the capsules. Comparisons will be made between the reference and selfhealing specimens, and between the different self-healing specimens themselves, through the analysis of such parameters as the ultimate load, absorbed fracture energy, and emitted Acoustic Emission (AE) energy. Such type of analysis can give valuable insights not only on quantitative but also on qualitative aspects (such as the level of brittleness or ductility introduced by the specific self-healing system adopted) in view of possible applications in real structures.
{"title":"Evaluation of the self-healing effect in cement-based materials with embedded cementitious capsules by means of Acoustic Emission techniques","authors":"G. Anglani, P. M. Montanari, Jean Marc Tulliani, G. Lacidogna, P. Antonaci","doi":"10.1051/matecconf/202337804004","DOIUrl":"https://doi.org/10.1051/matecconf/202337804004","url":null,"abstract":"Due to its low tensile strength and the presence of defects brought on by improper construction methods or other factors, cracks in concrete are practically inevitable. For reinforced-concrete structures, even if cracks do not necessarily increase the risk of collapse, they unquestionably hinder aspects such as service life. Self-healing cementitious materials have been developed because of growing concern for the security and sustainability of structures. For these new materials to be used in actual structures, it is essential to conduct research into the self-repair effect that they may offer, and possibly quantify it directly on-site, by means of non-destructive methods. In this sense, the objective of this work is to use Acoustic Emission (AE) analyses to non-destructively characterise the response of an autonomic capsule-based system, as a function of the specific polymeric healing agents contained in the capsules. Comparisons will be made between the reference and selfhealing specimens, and between the different self-healing specimens themselves, through the analysis of such parameters as the ultimate load, absorbed fracture energy, and emitted Acoustic Emission (AE) energy. Such type of analysis can give valuable insights not only on quantitative but also on qualitative aspects (such as the level of brittleness or ductility introduced by the specific self-healing system adopted) in view of possible applications in real structures.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87450868","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 : 2023-01-01DOI: 10.1051/matecconf/202337701005
Ming Hao Lee, A. Saptoro, K. Lim, H. Chua, T. Vu, Nurleyna Yunus, Hasnain Hussain
The general public perspective on sago flour quality is based on the perceived colour appearances. This contributed to the potential of food fraud by excessive usage of bleaching agents such as calcium hypochlorite (CHC) to alter the product’s colour. Conventional methods to detect and quantify CHC such as titration and chromatography are time-consuming, expensive and limited to laboratory setups only. In this research, visible near-infrared hyperspectral imaging (Vis-NIR HSI) was combined with partial least squares regression (PLSR) model to quantify CHC in pure sago flour accurately and rapidly. Hyperspectral images with the spectral region of 400 nm to 1000 nm were captured for CHC-pure sago mixture samples with CHC concentration ranging from 0.005 w/w% to 2 w/w%. Mean reflectance spectral data was extracted from the hyperspectral images, and was used as inputs to develop the PLSR model to predict the CHC concentration. The PLSR model achieved the commendable predictive results in this study, with Rp = 0.9509, RMSEP = 0.1655 and MAPEP of 3.801%, proving that Vis-NIR HSI can effectively predict the concentration of CHC in sago flour.
{"title":"Feasibility of Visible Near-Infrared Hyperspectral Imaging in Detection of Calcium Hypochlorite in Sago Flour","authors":"Ming Hao Lee, A. Saptoro, K. Lim, H. Chua, T. Vu, Nurleyna Yunus, Hasnain Hussain","doi":"10.1051/matecconf/202337701005","DOIUrl":"https://doi.org/10.1051/matecconf/202337701005","url":null,"abstract":"The general public perspective on sago flour quality is based on the perceived colour appearances. This contributed to the potential of food fraud by excessive usage of bleaching agents such as calcium hypochlorite (CHC) to alter the product’s colour. Conventional methods to detect and quantify CHC such as titration and chromatography are time-consuming, expensive and limited to laboratory setups only. In this research, visible near-infrared hyperspectral imaging (Vis-NIR HSI) was combined with partial least squares regression (PLSR) model to quantify CHC in pure sago flour accurately and rapidly. Hyperspectral images with the spectral region of 400 nm to 1000 nm were captured for CHC-pure sago mixture samples with CHC concentration ranging from 0.005 w/w% to 2 w/w%. Mean reflectance spectral data was extracted from the hyperspectral images, and was used as inputs to develop the PLSR model to predict the CHC concentration. The PLSR model achieved the commendable predictive results in this study, with Rp = 0.9509, RMSEP = 0.1655 and MAPEP of 3.801%, proving that Vis-NIR HSI can effectively predict the concentration of CHC in sago flour.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87470789","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 : 2023-01-01DOI: 10.1051/matecconf/202337501002
R. Zinko, O. Polishchuk, I. Demchuk, Olexsand Shpak, J. Wilczarska
Airless tires are used not only in cars, but also in vehicles used in the construction, road, forestry, and robotics industries. In order to develop the construction of an airless tire, its optimization at the stage of their design, a comprehensive method of researching the operational properties of an airless tire is proposed. The methodology includes stress-strain analysis, modal and thermal analysis of an airless tire using three-dimensional modeling using the finite element method. The airless tire was studied in the following modes of uniform movement of the wheel on a solid base: driven wheel; driving wheel; free wheel; neutral wheel; brake wheel. An example of the study of an airless tire of a mobile robot is given.
{"title":"Research on a tubeless tire for a mobile robot","authors":"R. Zinko, O. Polishchuk, I. Demchuk, Olexsand Shpak, J. Wilczarska","doi":"10.1051/matecconf/202337501002","DOIUrl":"https://doi.org/10.1051/matecconf/202337501002","url":null,"abstract":"Airless tires are used not only in cars, but also in vehicles used in the construction, road, forestry, and robotics industries. In order to develop the construction of an airless tire, its optimization at the stage of their design, a comprehensive method of researching the operational properties of an airless tire is proposed. The methodology includes stress-strain analysis, modal and thermal analysis of an airless tire using three-dimensional modeling using the finite element method. The airless tire was studied in the following modes of uniform movement of the wheel on a solid base: driven wheel; driving wheel; free wheel; neutral wheel; brake wheel. An example of the study of an airless tire of a mobile robot is given.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"123 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85692153","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 : 2023-01-01DOI: 10.1051/matecconf/202337802003
Muath Abu Askar, T. Zdeb, J. Chwastowski, L. Ferrara
The enormous quantity of sewage water produced each day continues to present a serious challenge for its treatment and management. Sewage water is one of the most abundant sources of biomass, such as bacteria. Concrete, on the other hand, is the second most widely employed substance on the planet, after freshwater. Cracking of concrete is a major factor affecting the strength and durability of the material. The development of a crack pattern can contribute to increasing the permeability of concrete, which is typically associated with a significant decrease in its durability. Under specific circumstances, bio concrete is a self-healing biomaterial. Bacteria have the ability to precipitate calcite in concrete or form a layer of calcite precipitation, which plays a crucial role in the remediation of plastic shrinkage microcracks, thereby enhancing the structural integrity and durability of concrete over the long term. This paper summarises the study of investigating the possibility of using sewage water as a self-healing agent, using bacteria from different stages of treatment to heal cracks in concrete samples, and evaluating the effect of sewage water from different stages of treatment on fresh and hardened concrete properties. Based on the data collected from the experiments. Complete replacement of ordinary tap mixing water with sewage water from the Biological Reactor oxygen Zone achieved cracks healing of a crack width of 200 μm in less than 14 days without compromising the binder and mortar properties such setting time, slump value, compressive and flexural strength when compared to a reference sample made with tap mixing water.
{"title":"Self-healing abilities of cement mortars containing microorganisms produced in the process of sewage sludge treatment","authors":"Muath Abu Askar, T. Zdeb, J. Chwastowski, L. Ferrara","doi":"10.1051/matecconf/202337802003","DOIUrl":"https://doi.org/10.1051/matecconf/202337802003","url":null,"abstract":"The enormous quantity of sewage water produced each day continues to present a serious challenge for its treatment and management. Sewage water is one of the most abundant sources of biomass, such as bacteria. Concrete, on the other hand, is the second most widely employed substance on the planet, after freshwater. Cracking of concrete is a major factor affecting the strength and durability of the material. The development of a crack pattern can contribute to increasing the permeability of concrete, which is typically associated with a significant decrease in its durability. Under specific circumstances, bio concrete is a self-healing biomaterial. Bacteria have the ability to precipitate calcite in concrete or form a layer of calcite precipitation, which plays a crucial role in the remediation of plastic shrinkage microcracks, thereby enhancing the structural integrity and durability of concrete over the long term. This paper summarises the study of investigating the possibility of using sewage water as a self-healing agent, using bacteria from different stages of treatment to heal cracks in concrete samples, and evaluating the effect of sewage water from different stages of treatment on fresh and hardened concrete properties. Based on the data collected from the experiments. Complete replacement of ordinary tap mixing water with sewage water from the Biological Reactor oxygen Zone achieved cracks healing of a crack width of 200 μm in less than 14 days without compromising the binder and mortar properties such setting time, slump value, compressive and flexural strength when compared to a reference sample made with tap mixing water.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79705958","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 : 2023-01-01DOI: 10.1051/matecconf/202337809005
Yangqing Liu, Bo Wu, J. Qiu
The self-healing of strain-hardening cementitious composites (SHCCs) causes the recovery of the debonded fiber-to-matrix interface by the products of autogenous healing (mainly calcium carbonates). The recovery of chemical bond Gd has been detected in the reactive magnesia cement (RMC)-based SHCC (SHMC), and the recovery of frictional bond τ0 has been detected in both SHMCs and normal SHCCs. While these phenomena can significantly alter the fiber-bridging σ-w relationship in SHCCs, they have not been quantified in any existing analytical models. In this work, we present a new fiber-bridging model that captures the effect of self-healing of RMC-based SHCC. On the single-fiber level, the debonding and slip-hardening of the fiber-to-matrix interface induced by a tensile preloading as well as the recovery of the interface properties by self-healing are coherently quantified in a clear kinetic process. On the fiber-bridging level, the tensile stress vs. crack width curve is formed by summing individual fibers’ tensile load vs. displacement relationship. The modeling results can well capture the fiber-bridging behavior of the self-healed SHCC specimens. Further, a parametric study is conducted to investigate the tensile behavior of SHCC after self-healing. The effects of preloading levels, recovered τ0, and fiber strength are discussed.
{"title":"Tensile behavior of strain-hardening cementitious composites after self-healing based on a novel fiber-bridging model considering preloading and reloading","authors":"Yangqing Liu, Bo Wu, J. Qiu","doi":"10.1051/matecconf/202337809005","DOIUrl":"https://doi.org/10.1051/matecconf/202337809005","url":null,"abstract":"The self-healing of strain-hardening cementitious composites (SHCCs) causes the recovery of the debonded fiber-to-matrix interface by the products of autogenous healing (mainly calcium carbonates). The recovery of chemical bond Gd has been detected in the reactive magnesia cement (RMC)-based SHCC (SHMC), and the recovery of frictional bond τ0 has been detected in both SHMCs and normal SHCCs. While these phenomena can significantly alter the fiber-bridging σ-w relationship in SHCCs, they have not been quantified in any existing analytical models. In this work, we present a new fiber-bridging model that captures the effect of self-healing of RMC-based SHCC. On the single-fiber level, the debonding and slip-hardening of the fiber-to-matrix interface induced by a tensile preloading as well as the recovery of the interface properties by self-healing are coherently quantified in a clear kinetic process. On the fiber-bridging level, the tensile stress vs. crack width curve is formed by summing individual fibers’ tensile load vs. displacement relationship. The modeling results can well capture the fiber-bridging behavior of the self-healed SHCC specimens. Further, a parametric study is conducted to investigate the tensile behavior of SHCC after self-healing. The effects of preloading levels, recovered τ0, and fiber strength are discussed.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83921454","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 : 2023-01-01DOI: 10.1051/matecconf/202337802016
G. Anglani, J. Tulliani, P. Antonaci
The use of polymer precursors as repairing agents in capsule-based self-healing systems has been extensively studied in recent years. In particular, the effectiveness of macro-encapsulated polyurethane in restoring both watertightness and mechanical properties has been demonstrated at the laboratory level, and the experimental methods to test the effectiveness have been validated following pre-standard procedures. However, the use of macro-capsules containing polyurethane precursors for field applications has not been sufficiently implemented yet. For these systems to become appealing to the construction industry, it is essential to further characterize the self-healing effect in terms of stability in time, namely, to investigate the behavior of the self-healing system when subjected to recurring actions that can affect structures in time, after cracking and subsequent self-repairing. The goal of this study was to characterize the ability of commercial polyurethane foams to withstand cyclic flexural actions and repeated temperature variations after release from cementitious macro-capsules embedded in mortar specimens. The specimens were tested immediately after pre-cracking and self-repairing to characterize the initial sealing efficiency through a water-flow test. The same test was repeated at prescribed time intervals to analyze the evolution of the sealing efficiency with the applied mechanical and thermal stresses. The results showed that the proposed system has good stability against the selected damaging actions and confirmed the potential of encapsulated polyurethane for self-healing applications.
{"title":"Experimental investigation on the ability of macro-encapsulated polyurethane to resist cyclic damaging actions in self-repaired cement-based elements","authors":"G. Anglani, J. Tulliani, P. Antonaci","doi":"10.1051/matecconf/202337802016","DOIUrl":"https://doi.org/10.1051/matecconf/202337802016","url":null,"abstract":"The use of polymer precursors as repairing agents in capsule-based self-healing systems has been extensively studied in recent years. In particular, the effectiveness of macro-encapsulated polyurethane in restoring both watertightness and mechanical properties has been demonstrated at the laboratory level, and the experimental methods to test the effectiveness have been validated following pre-standard procedures. However, the use of macro-capsules containing polyurethane precursors for field applications has not been sufficiently implemented yet. For these systems to become appealing to the construction industry, it is essential to further characterize the self-healing effect in terms of stability in time, namely, to investigate the behavior of the self-healing system when subjected to recurring actions that can affect structures in time, after cracking and subsequent self-repairing. The goal of this study was to characterize the ability of commercial polyurethane foams to withstand cyclic flexural actions and repeated temperature variations after release from cementitious macro-capsules embedded in mortar specimens. The specimens were tested immediately after pre-cracking and self-repairing to characterize the initial sealing efficiency through a water-flow test. The same test was repeated at prescribed time intervals to analyze the evolution of the sealing efficiency with the applied mechanical and thermal stresses. The results showed that the proposed system has good stability against the selected damaging actions and confirmed the potential of encapsulated polyurethane for self-healing applications.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82593025","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 : 2023-01-01DOI: 10.1051/matecconf/202337805001
Gabriele Milone, J. Tulliani, A. Al-Tabbaa
Sensing coatings are rapidly entering the field of non-destructive tests. While cement-based composites are proving an excellent interaction with new/recent structures, polymer-based coatings, already employed for structural retrofitting purposes, can provide a valuable alternative. This study investigated the production, application, and use of poly(vinylidene fluoride) (PVDF) coatings. A 10w/v% PVDF-to-solvent ratio became the best trade-off between electrical conductivity and bond strength with the substrate. Different concentrations of Carbon Nanotubes (CNT) were investigated: 0.05, 0.10, 0.25, 0.50, and 0.75% by weight of PVDF. The conductive PVDF-CNT composites were brushed on the casted mortar beams with screws embedded as electrodes. The mortar beams and attached polymer coatings were then subjected to bending stress. The Gauge Factor was obtained by comparing the substrate’s strain with the coating’s electric response. The sensing intervals in the Fractional Change of Resistance-strain curves varied in relation to the CNT concentration. For instance, adding 0.50w/v% of CNT gave the highest sensitivity up to 0.2‰ strain, followed by a lower – still sufficient – gauge factor. PVDF-based coatings with CNT additions of 0.25 and 0.75w/v% witnessed a comparable sensing performance in the same strain limits, abruptly increasing and finally stabilizing to a low gauge factor. In contrast, both 0.05 and 0.10w/v% resulted in a low monitoring potential overall. The varying sensing zones experienced by the coating were attributed to the microscopical behavior of CNT within the PVDF matrix. In conclusion, the results highlighted the potentiality of polymeric coatings for sensing, monitoring, and inspection of concrete structures.
{"title":"PVDF-based coatings with CNT additions for strain monitoring of mortar substrates subjected to bending","authors":"Gabriele Milone, J. Tulliani, A. Al-Tabbaa","doi":"10.1051/matecconf/202337805001","DOIUrl":"https://doi.org/10.1051/matecconf/202337805001","url":null,"abstract":"Sensing coatings are rapidly entering the field of non-destructive tests. While cement-based composites are proving an excellent interaction with new/recent structures, polymer-based coatings, already employed for structural retrofitting purposes, can provide a valuable alternative. This study investigated the production, application, and use of poly(vinylidene fluoride) (PVDF) coatings. A 10w/v% PVDF-to-solvent ratio became the best trade-off between electrical conductivity and bond strength with the substrate. Different concentrations of Carbon Nanotubes (CNT) were investigated: 0.05, 0.10, 0.25, 0.50, and 0.75% by weight of PVDF. The conductive PVDF-CNT composites were brushed on the casted mortar beams with screws embedded as electrodes. The mortar beams and attached polymer coatings were then subjected to bending stress. The Gauge Factor was obtained by comparing the substrate’s strain with the coating’s electric response. The sensing intervals in the Fractional Change of Resistance-strain curves varied in relation to the CNT concentration. For instance, adding 0.50w/v% of CNT gave the highest sensitivity up to 0.2‰ strain, followed by a lower – still sufficient – gauge factor. PVDF-based coatings with CNT additions of 0.25 and 0.75w/v% witnessed a comparable sensing performance in the same strain limits, abruptly increasing and finally stabilizing to a low gauge factor. In contrast, both 0.05 and 0.10w/v% resulted in a low monitoring potential overall. The varying sensing zones experienced by the coating were attributed to the microscopical behavior of CNT within the PVDF matrix. In conclusion, the results highlighted the potentiality of polymeric coatings for sensing, monitoring, and inspection of concrete structures.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82627617","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 : 2023-01-01DOI: 10.1051/matecconf/202337807004
S. Rengaraju, C. Vlachakis, Vahid Afroughsabet, A. Al-Tabbaa
Prolonging the life of the reinforced concrete structure is the most promising solution to reduce the carbon emissions from concrete. To achieve that, the structure should be protected from crack formation, which acts as an easy pathway for deleterious agents. Self-healing technologies are intended to provide long-term resilience against cracking due to various deterioration processes. Technologies that performed well in small, laboratory-scale studies are taken to the next level to assess their performance on a larger scale and monitored using various NDT equipment. A 1m long beam with a cross-section (140×120 mm) was cast with two rebars – one with a cover depth of 50 mm from the top and another with a cover depth of 20 mm from the bottom. The mix design consists of CEM IIIA (50 OPC: 50 Slag) cement and 30% lightweight aggregate as a replacement for coarse aggregate. At 28 days of curing, the concrete beams are subjected to accelerated corrosion (by applying a voltage to the bottom rebar) to induce internal cracking. Once internal cracking is induced, the beams are subjected to another 28 days under water for healing. The performance of the beams is monitored via ultrasonic pulse velocity and half-cell potential before and after voltage application. This paper shows the preliminary results and the self-healing efficiency and corrosion resistance of these beams are continuously being monitored under severe chloride conditions to predict the long-term performance.
{"title":"Large-Scale Laboratory Trials of Self-Healing Technologies","authors":"S. Rengaraju, C. Vlachakis, Vahid Afroughsabet, A. Al-Tabbaa","doi":"10.1051/matecconf/202337807004","DOIUrl":"https://doi.org/10.1051/matecconf/202337807004","url":null,"abstract":"Prolonging the life of the reinforced concrete structure is the most promising solution to reduce the carbon emissions from concrete. To achieve that, the structure should be protected from crack formation, which acts as an easy pathway for deleterious agents. Self-healing technologies are intended to provide long-term resilience against cracking due to various deterioration processes. Technologies that performed well in small, laboratory-scale studies are taken to the next level to assess their performance on a larger scale and monitored using various NDT equipment. A 1m long beam with a cross-section (140×120 mm) was cast with two rebars – one with a cover depth of 50 mm from the top and another with a cover depth of 20 mm from the bottom. The mix design consists of CEM IIIA (50 OPC: 50 Slag) cement and 30% lightweight aggregate as a replacement for coarse aggregate. At 28 days of curing, the concrete beams are subjected to accelerated corrosion (by applying a voltage to the bottom rebar) to induce internal cracking. Once internal cracking is induced, the beams are subjected to another 28 days under water for healing. The performance of the beams is monitored via ultrasonic pulse velocity and half-cell potential before and after voltage application. This paper shows the preliminary results and the self-healing efficiency and corrosion resistance of these beams are continuously being monitored under severe chloride conditions to predict the long-term performance.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82564591","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 : 2023-01-01DOI: 10.1051/matecconf/202337907005
Ronny Gueguen, Guillaume Sahuquet, S. Mer, A. Toutant, Françoise Bataille, G. Flamant
The concept of solar receiver using fluidized particles as heat transfer fluid is attractive from the point of view of its performance but also of the material used. In this concept, the receiver is composed of tubes subjected to concentrated solar radiation in which the fluidized particles circulate vertically. Circulation in the tubes, immersed in a “nurse” fluidized bed, is ensured thanks to a controlled pressure difference imposed on the latter and secondary aeration. This ventilation located at the bottom of the absorber tubes makes it possible to control the fluidization regimes. The latter strongly influence the parietal heat transfers and therefore the performance of the receiver. In order to better understand the conditions of appearance of these regimes and to better identify them, a study at room temperature was carried out with a tube 45 mm in internal diameter and 3.63 m in height. The tube is instrumented with several pressure sensors distributed over its height. More than 170 experiments have been performed exploring wide ranges of particle and aeration flow rates, with and without particle circulation. Signal processing methods, classically used in the scientific literature of fluidized beds, are applied. Combined together, these methods have enabled the identification of bubbling, pistoning (of the wall and axisymmetric), turbulent fluidization and rapid fluidization regimes. The pooling of all this information allows the establishment of a diagram of the fluidization regimes and their transition, showing that the local slip velocity is the key parameter governing the structure of the flow.
{"title":"Experimental Study of an upflow Fluidized Bed: Identification of Fluidization Regimes","authors":"Ronny Gueguen, Guillaume Sahuquet, S. Mer, A. Toutant, Françoise Bataille, G. Flamant","doi":"10.1051/matecconf/202337907005","DOIUrl":"https://doi.org/10.1051/matecconf/202337907005","url":null,"abstract":"The concept of solar receiver using fluidized particles as heat transfer fluid is attractive from the point of view of its performance but also of the material used. In this concept, the receiver is composed of tubes subjected to concentrated solar radiation in which the fluidized particles circulate vertically. Circulation in the tubes, immersed in a “nurse” fluidized bed, is ensured thanks to a controlled pressure difference imposed on the latter and secondary aeration. This ventilation located at the bottom of the absorber tubes makes it possible to control the fluidization regimes. The latter strongly influence the parietal heat transfers and therefore the performance of the receiver. In order to better understand the conditions of appearance of these regimes and to better identify them, a study at room temperature was carried out with a tube 45 mm in internal diameter and 3.63 m in height. The tube is instrumented with several pressure sensors distributed over its height. More than 170 experiments have been performed exploring wide ranges of particle and aeration flow rates, with and without particle circulation. Signal processing methods, classically used in the scientific literature of fluidized beds, are applied. Combined together, these methods have enabled the identification of bubbling, pistoning (of the wall and axisymmetric), turbulent fluidization and rapid fluidization regimes. The pooling of all this information allows the establishment of a diagram of the fluidization regimes and their transition, showing that the local slip velocity is the key parameter governing the structure of the flow.","PeriodicalId":18309,"journal":{"name":"MATEC Web of Conferences","volume":"97 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82687371","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 : 2023-01-01DOI: 10.1051/matecconf/202337809004
S. Sayadi, E. Ricketts, E. Schlangen, P. Cleall, I. Mihai, A. Jefferson
Self-healing cementitious materials with microcapsules are complex multiscale and multiphase materials. The random microstructure of these materials governs their mechanical and transport behaviour. The actual microstructure can be represented accurately with a discrete lattice model, but computational restrictions mean that the size of domain that can be considered with this approach is limited. By contrast, a smeared approach, based on a micromechanical formulation, provides an approximate representation of the material microstructure with low computational costs. The aim of this paper is to compare simulations of a microcapsule-based self-healing cementitious system with discrete-lattice and smeared-micromechanical models, and to assess the relative strengths and weaknesses of these models for simulating distributed fracture and healing in this type of self-healing material. A novel random field generation technique is used to represent the microstructure of a cementitious mortar specimen. The meshes and elements are created by the triangulation method and used to determine the input required for the lattice model. The paper also describes the enhancement of the TUDelft lattice model to include self-healing behaviour. The extended micromechanical model considers both microcracking and healing. The findings from the study provide insight into the relative merits of these two modelling approaches.
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