Mohammed Hassan Nensok, Md Azree Othuman Mydin, H. Awang
Recent advancements in construction materials development have involved the utilization of plant-based natural fibers such as kenaf, sisal, coir and banana to replace conventional fibers such as carbon, steel, polypropylene and aramid. However, the main issue with using these fibers is the alkaline cement matrix's durability and compatibility due to high water absorption. Hence, this research focuses on the use of alkali treatment of banana fibers to enhance the mechanical properties of cellular lightweight concrete (CLC). Banana fibers were subjected to 2%, 4%, 6%, 8%, and 10% NaOH treatment before being included in 1200 kg/m3 density CLC. Plain CLC and untreated fiber composites (0% NaOH treatment) were used as the control. Results from the study indicate that compared to the untreated fibre composites and plain control CLC at 28 days, compressive, flexural and splitting tensile strengths increased simultaneously with 6% NaOH fibre treatment to peaks of 40.6% and 59.8%, 63.8% and 117.4%, and 77.4% and 157.8% respectively. The 6% NaOH treatment of BF tremendously improved the mechanical characteristics of single fibers and BFRCLC composites. It is therefore concluded that 6% NaOH treatment of banana fibre was the optimum percentage alkali treatment for use in CLC.
{"title":"Optimization of mechanical properties of cellular lightweight concrete with alkali treated banana fiber","authors":"Mohammed Hassan Nensok, Md Azree Othuman Mydin, H. Awang","doi":"10.7764/rdlc.20.3.491","DOIUrl":"https://doi.org/10.7764/rdlc.20.3.491","url":null,"abstract":"Recent advancements in construction materials development have involved the utilization of plant-based natural fibers such as kenaf, sisal, coir and banana to replace conventional fibers such as carbon, steel, polypropylene and aramid. However, the main issue with using these fibers is the alkaline cement matrix's durability and compatibility due to high water absorption. Hence, this research focuses on the use of alkali treatment of banana fibers to enhance the mechanical properties of cellular lightweight concrete (CLC). Banana fibers were subjected to 2%, 4%, 6%, 8%, and 10% NaOH treatment before being included in 1200 kg/m3 density CLC. Plain CLC and untreated fiber composites (0% NaOH treatment) were used as the control. Results from the study indicate that compared to the untreated fibre composites and plain control CLC at 28 days, compressive, flexural and splitting tensile strengths increased simultaneously with 6% NaOH fibre treatment to peaks of 40.6% and 59.8%, 63.8% and 117.4%, and 77.4% and 157.8% respectively. The 6% NaOH treatment of BF tremendously improved the mechanical characteristics of single fibers and BFRCLC composites. It is therefore concluded that 6% NaOH treatment of banana fibre was the optimum percentage alkali treatment for use in CLC.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Incorporation of fibers in concrete has been an efficient technique to prevent crack propagation, thus improving ductility, durability, toughness and strength of concrete. In this context, a comprehensive experimental study has been conducted concerning the compressive and flexural strength of fiber reinforced concrete, through preparing nine concrete batches with polypropylene fibers, steel fibers and macro synthetic fibers; and the hybrid forms combining polypropylene (PP) and steel, polypropylene and macro synthetic fibers. Fiber inclusion in concrete caused slight variations in compressive strength. However, the flexural strength for all sample sets was significantly increased. The highest values of strength increase relative to control concrete were 60.67%, 42.45% and 27.05% incorporating steel, polypropylene and macro synthetic fibers, respectively. It was also noted that the higher aspect ratio of steel fibers resulted with better flexural performance, among the steel fiber reinforced concrete samples. Hybrid forms of polypropylene-steel and polypropylene -macro synthetic fibers achieved the highest flexural strength compared with samples including single type of fiber. In blended groups, utilization of polypropylene fibers with steel fibers and with macro synthetic fibers resulted with 69.81% and 78.99% of increase in flexural strength relative to control specimens, respectively.
{"title":"The effect of polypropylene, steel, and macro synthetic fibers on mechanical behavior of cementitious composites","authors":"Ayşe Elif Özsoy Özbay, Orhan Erkek, S. Çeribaşı","doi":"10.7764/rdlc.20.3.591","DOIUrl":"https://doi.org/10.7764/rdlc.20.3.591","url":null,"abstract":"Incorporation of fibers in concrete has been an efficient technique to prevent crack propagation, thus improving ductility, durability, toughness and strength of concrete. In this context, a comprehensive experimental study has been conducted concerning the compressive and flexural strength of fiber reinforced concrete, through preparing nine concrete batches with polypropylene fibers, steel fibers and macro synthetic fibers; and the hybrid forms combining polypropylene (PP) and steel, polypropylene and macro synthetic fibers. Fiber inclusion in concrete caused slight variations in compressive strength. However, the flexural strength for all sample sets was significantly increased. The highest values of strength increase relative to control concrete were 60.67%, 42.45% and 27.05% incorporating steel, polypropylene and macro synthetic fibers, respectively. It was also noted that the higher aspect ratio of steel fibers resulted with better flexural performance, among the steel fiber reinforced concrete samples. Hybrid forms of polypropylene-steel and polypropylene -macro synthetic fibers achieved the highest flexural strength compared with samples including single type of fiber. In blended groups, utilization of polypropylene fibers with steel fibers and with macro synthetic fibers resulted with 69.81% and 78.99% of increase in flexural strength relative to control specimens, respectively.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to determine the parameters that are effective on sale prices and to obtain the functions that determine the appropriate sale price ranges of real estates. In this context, a total of 138 real estates, which are located in Bayraklı district of Izmir, Turkey and that were for sale between April and June 2019, were investigated. The effects of 17 parameters on the sale price of the real estates were examined through statistical analysis. Thirteen parameters that have been determined to be effective have been used in developing the distinctive functions that decide the sale price ranges of real estates. The results show that parameters such as real estate’s area, age, furniture status, central heating system, playground, pool and gym are statistically significant on the sale price of the real estates. In addition, the functions obtained by using these parameters classified 78.3% of real estate sale prices in the correct range.
{"title":"Sale price classification models for real estate appraisal","authors":"Merve Kuru, Onur Yiğit Erdem, G. Calis","doi":"10.7764/rdlc.20.3.440","DOIUrl":"https://doi.org/10.7764/rdlc.20.3.440","url":null,"abstract":"This study aims to determine the parameters that are effective on sale prices and to obtain the functions that determine the appropriate sale price ranges of real estates. In this context, a total of 138 real estates, which are located in Bayraklı district of Izmir, Turkey and that were for sale between April and June 2019, were investigated. The effects of 17 parameters on the sale price of the real estates were examined through statistical analysis. Thirteen parameters that have been determined to be effective have been used in developing the distinctive functions that decide the sale price ranges of real estates. The results show that parameters such as real estate’s area, age, furniture status, central heating system, playground, pool and gym are statistically significant on the sale price of the real estates. In addition, the functions obtained by using these parameters classified 78.3% of real estate sale prices in the correct range.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Considering the importance of the effect of concrete arch dam body strength on their seismic performance, this research evaluated the effect of Young Modulus of both the body concrete and foundation as strength parameters and examines the responses to achieve the optimal body stiffness using probabilistic and uncertainty method. The ANSYS software was used to complete the finite element analysis of the dam-reservoir-foundation system and the Monte Carlo method, which is a new method for parametric study and sensitivity analysis, was used for uncertainty analysis. For seismic analysis, the horizontal and vertical components of Northridge, San Fernando and El Centro earthquakes are separately applied in 3d directions. The earthquake components were scaled to the maximum credible level of ground motion acceleration. The foundation rock is simulated using a massless foundation model and dam-reservoir-foundation interaction is considered for seismic analysis of system. The results show the effect of the modulus of elasticity of the concrete which is directly related to the stiffness of the system. The results indicate the effect of the dam body concrete stiffness on the responses. According to the design criteria, it is possible to investigate the safety status of the dam and select the optimal state in terms of structural strength for the model. However, in order to properly select the modulus of elasticity of the concrete of the dam body, it is necessary to consider the simultaneous effect of the stiffness of the foundation and to select the optimal value.
{"title":"The effect of strength parameters on the seismic performance of an arch dam using an uncertainty model","authors":"M. Pasbani Khiavi, P. Ahmadi, R. Daneshfaraz","doi":"10.7764/rdlc.20.3.602","DOIUrl":"https://doi.org/10.7764/rdlc.20.3.602","url":null,"abstract":"Considering the importance of the effect of concrete arch dam body strength on their seismic performance, this research evaluated the effect of Young Modulus of both the body concrete and foundation as strength parameters and examines the responses to achieve the optimal body stiffness using probabilistic and uncertainty method. The ANSYS software was used to complete the finite element analysis of the dam-reservoir-foundation system and the Monte Carlo method, which is a new method for parametric study and sensitivity analysis, was used for uncertainty analysis. For seismic analysis, the horizontal and vertical components of Northridge, San Fernando and El Centro earthquakes are separately applied in 3d directions. The earthquake components were scaled to the maximum credible level of ground motion acceleration. The foundation rock is simulated using a massless foundation model and dam-reservoir-foundation interaction is considered for seismic analysis of system. The results show the effect of the modulus of elasticity of the concrete which is directly related to the stiffness of the system. The results indicate the effect of the dam body concrete stiffness on the responses. According to the design criteria, it is possible to investigate the safety status of the dam and select the optimal state in terms of structural strength for the model. However, in order to properly select the modulus of elasticity of the concrete of the dam body, it is necessary to consider the simultaneous effect of the stiffness of the foundation and to select the optimal value.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Statistics show that many workers have lost their lives because of trench collapse although the dangers of trenching are well known and defined. Thus, the question of “why” should be asked again. The most comprehensive data set in the literature has been created to determine the reason for the recurrence of accidents even though the risks are known. A total of 723 accidents caused by trench collapse in the last 25 years were selected from the Occupational Safety and Health Administration’s database. Variables were created using accident summaries, and the frequency distribution of the categories was interpreted. Results showed that these accidents have a high frequency and a high severity level (58.1% fatalities). The main reason for a half of the accidents was the lack of protective systems (49.7%). A total of 2596 violations including four main categories were detected for 723 accident reports. Employers paid approximately 23 million in penalties. The investigated accidents showed that trench collapse accidents are rarely survivable but can be completely prevented if necessary precautions are taken.
{"title":"Characteristic analysis and prevention strategy of trench collapse accidents in the U.S., 1995-2020","authors":"Özge Akboğa Kale","doi":"10.7764/rdlc.20.3.617","DOIUrl":"https://doi.org/10.7764/rdlc.20.3.617","url":null,"abstract":"Statistics show that many workers have lost their lives because of trench collapse although the dangers of trenching are well known and defined. Thus, the question of “why” should be asked again. The most comprehensive data set in the literature has been created to determine the reason for the recurrence of accidents even though the risks are known. A total of 723 accidents caused by trench collapse in the last 25 years were selected from the Occupational Safety and Health Administration’s database. Variables were created using accident summaries, and the frequency distribution of the categories was interpreted. Results showed that these accidents have a high frequency and a high severity level (58.1% fatalities). The main reason for a half of the accidents was the lack of protective systems (49.7%). A total of 2596 violations including four main categories were detected for 723 accident reports. Employers paid approximately 23 million in penalties. The investigated accidents showed that trench collapse accidents are rarely survivable but can be completely prevented if necessary precautions are taken.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Syyed Adnan Raheel Shah, A. Nawaz, M. Abid, Ahmed Salman Malik, Saleem Fakhar, Mudassir Elahi
Risk evaluation and its identification is one of the prominent fields in the construction industry concerning performance management and project success. Under the project mechanism and business development system, risk assessment and mitigation are compulsory components of a management network to achieve the project's success. In this study, the major focus of risk assessment and management revolves around the SCP (small construction projects) which are the backbone of the construction industry. Every stakeholder is involved in this process because the construction of the house is a basic need of humans for a living. Targeting the major stakeholders (contractors, consultants, and clients) as mixed-method (qualitative & quantitative) sequential approach has been adopted to evaluate the major risk factors and their occurrence with the assessment of risk management system at the country level in SCP (small construction projects). The data used in this research has been collected from sixty-two (62) small construction firms, thirty-two (32 projects), to attain the research objectives. The results indicate that the performances of most of the risk management system and organizations are responsive, shapeless, semi-stable, and unorganized with inexistent and confined compromised resources to respond with risks. The major issue was identified as the non-existence of a proper risk management system because no formal education is involved with the personals working in small construction projects. The five most important risks that should be preferable are quality and quantity dissimilarity, change in scope of work/design, deficiency of manpower, planning, and management, and technical errors. The prime hurdles which are analyzed for impressive risk management are the absence of connection between construction experts and contractors who have not been formally trained at any technical institute. This study will help in targeting the existing gap for implementation of the risk management system at small construction engineering projects. Furthermore, it will generate a pathway for the young enterprisers to come forward and take part in the development of the small construction industry by implementing effective risk management practices to achieve the project performance in terms of project success and fruitful outcomes for the upcoming projects.
{"title":"Identification of risk factors involved in SCP of developing coun-tries-establishing guidelines: an analysis of mixed method se-quential approach","authors":"Syyed Adnan Raheel Shah, A. Nawaz, M. Abid, Ahmed Salman Malik, Saleem Fakhar, Mudassir Elahi","doi":"10.7764/rdlc.20.3.407","DOIUrl":"https://doi.org/10.7764/rdlc.20.3.407","url":null,"abstract":"Risk evaluation and its identification is one of the prominent fields in the construction industry concerning performance management and project success. Under the project mechanism and business development system, risk assessment and mitigation are compulsory components of a management network to achieve the project's success. In this study, the major focus of risk assessment and management revolves around the SCP (small construction projects) which are the backbone of the construction industry. Every stakeholder is involved in this process because the construction of the house is a basic need of humans for a living. Targeting the major stakeholders (contractors, consultants, and clients) as mixed-method (qualitative & quantitative) sequential approach has been adopted to evaluate the major risk factors and their occurrence with the assessment of risk management system at the country level in SCP (small construction projects). The data used in this research has been collected from sixty-two (62) small construction firms, thirty-two (32 projects), to attain the research objectives. The results indicate that the performances of most of the risk management system and organizations are responsive, shapeless, semi-stable, and unorganized with inexistent and confined compromised resources to respond with risks. The major issue was identified as the non-existence of a proper risk management system because no formal education is involved with the personals working in small construction projects. The five most important risks that should be preferable are quality and quantity dissimilarity, change in scope of work/design, deficiency of manpower, planning, and management, and technical errors. The prime hurdles which are analyzed for impressive risk management are the absence of connection between construction experts and contractors who have not been formally trained at any technical institute. This study will help in targeting the existing gap for implementation of the risk management system at small construction engineering projects. Furthermore, it will generate a pathway for the young enterprisers to come forward and take part in the development of the small construction industry by implementing effective risk management practices to achieve the project performance in terms of project success and fruitful outcomes for the upcoming projects.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Spirally welded tube (SWT) members are predominantly used for offshore oil and gas transportation in the pipeline industry. The use of SWTs in construction is gaining attention with emerging and qualitative research. SWT columns have no parametric limitation in manufacturing. However, no specific research is available for the influence of helix angle in SWT columns as structural member. This investigation stresses on understanding the behavior of SWT columns with different helix angles. Seventy-two finite element (FE) models of SWT columns have been analyzed to study the influence of length to diameter (L/D) ratio, diameter to thickness (D/t) ratio and helix angle on the load-carrying capacity. Test results of two SWT columns available in the literature are used for validating the developed FE model. In addition, the capacity of the columns based on standard codes is computed and compared with the FE results. All the columns are axially compressed and the buckling and post-buckling behavior are simulated. Initial stiffness and ductility index of the columns are discussed. Helix angle between 40° to 50° are found to show the best results.
{"title":"Analytical study on the behavior of spirally welded steel columns","authors":"Bharathi K M, Jane Helena H","doi":"10.7764/rdlc.20.3.427","DOIUrl":"https://doi.org/10.7764/rdlc.20.3.427","url":null,"abstract":"Spirally welded tube (SWT) members are predominantly used for offshore oil and gas transportation in the pipeline industry. The use of SWTs in construction is gaining attention with emerging and qualitative research. SWT columns have no parametric limitation in manufacturing. However, no specific research is available for the influence of helix angle in SWT columns as structural member. This investigation stresses on understanding the behavior of SWT columns with different helix angles. Seventy-two finite element (FE) models of SWT columns have been analyzed to study the influence of length to diameter (L/D) ratio, diameter to thickness (D/t) ratio and helix angle on the load-carrying capacity. Test results of two SWT columns available in the literature are used for validating the developed FE model. In addition, the capacity of the columns based on standard codes is computed and compared with the FE results. All the columns are axially compressed and the buckling and post-buckling behavior are simulated. Initial stiffness and ductility index of the columns are discussed. Helix angle between 40° to 50° are found to show the best results.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pre-stressed members in various structures are gaining popularity among engineers in many parts of the world because pre-stressed strands offer better stability, serviceability, economy, aesthetics, and structural efficiency. The profile of the strand greatly influences the tensile strength of concrete. The force exerted by the strand on the concrete counterbalances internal tensile forces. A construction engineer’s principal goal is to build an excellent strength structure without sacrificing agility and cost-effectiveness. This study’s main objective is to model numerically different pre-stressed concrete slabs to understand and predict the upward deflection (camber) behavior of uniaxial and biaxial pre-stressing of unbonded concrete strands in the static and dynamic behavior and the maximum moments of pre-stressed concrete members by considering previous experimental work as a benchmark for validation. Particular emphasis was placed on the unbonded post-tensioned pre-stressed slab parameters that influence the mid-span upward deflections and internal moments in linear and nonlinear crack analysis. This study also investigated the effect of strand profiles, strand areas, number of strands, strand eccentricities, loading types, and level. It looked into full and partial pre-stressing with uniaxial and biaxial pre-stressing directions. The numerical dynamic characteristics in terms of members’ natural frequency with such parameters were found. This study used a finite element numerical model for the analysis of linear and cracked sections and concluded that the upward deflection (camber) of uniaxial and biaxial one-way and two-way partially unbounded pre-stressed concrete slabs is affected by the strand’s profile, area, and number and eccentricity; the loading type and value; and the pre-stressing level in static and dynamic analyses.
{"title":"Static and dynamic camber behavior of uniaxial and biaxial post-tensioned fully, limited, and partially unbonded pre-stressed concrete slab","authors":"Rana I. K. Zaki, Hussam K. Risan","doi":"10.7764/rdlc.20.3.544","DOIUrl":"https://doi.org/10.7764/rdlc.20.3.544","url":null,"abstract":"Pre-stressed members in various structures are gaining popularity among engineers in many parts of the world because pre-stressed strands offer better stability, serviceability, economy, aesthetics, and structural efficiency. The profile of the strand greatly influences the tensile strength of concrete. The force exerted by the strand on the concrete counterbalances internal tensile forces. A construction engineer’s principal goal is to build an excellent strength structure without sacrificing agility and cost-effectiveness. This study’s main objective is to model numerically different pre-stressed concrete slabs to understand and predict the upward deflection (camber) behavior of uniaxial and biaxial pre-stressing of unbonded concrete strands in the static and dynamic behavior and the maximum moments of pre-stressed concrete members by considering previous experimental work as a benchmark for validation. Particular emphasis was placed on the unbonded post-tensioned pre-stressed slab parameters that influence the mid-span upward deflections and internal moments in linear and nonlinear crack analysis. This study also investigated the effect of strand profiles, strand areas, number of strands, strand eccentricities, loading types, and level. It looked into full and partial pre-stressing with uniaxial and biaxial pre-stressing directions. The numerical dynamic characteristics in terms of members’ natural frequency with such parameters were found. This study used a finite element numerical model for the analysis of linear and cracked sections and concluded that the upward deflection (camber) of uniaxial and biaxial one-way and two-way partially unbounded pre-stressed concrete slabs is affected by the strand’s profile, area, and number and eccentricity; the loading type and value; and the pre-stressing level in static and dynamic analyses.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pablo Villalba Espinosa, David Hidalgo García, J. Díaz, J. Moreno
In the last decade he has caused himself an increase of the education of the interior ambient conditions of the buildings caused by the appearing of numerous scientific reports that they relate them to serious diseases. Between these, the education of concentration of radon branded like carcinogen wilfully publicise one. The present article parses the concentrations of this gas that have taken place in a single-family housing and as the ventilation system in work has influence upon her. For it, two samples in three outbuildings of the house have been taken, (car park, dining room and bedroom). The first unaccomplished sample the ventilation of the spaces and the second with ventilation. The obtained peak concentrations when the ventilation system does not find itself in operation evidence values from among 391 and 94 Bq/ m3 coming right across over the doorsteps established in the standard 2013/59 EURATOM. On the contrary, the peak concentrations of radon decrease to values from among 71 and 29 Bq/ m3 interveningventilation. In this sense, it is confirmed that the ventilation system in work is determining to decrease the concentration of the gas in the analysed sojourns getting an average efficacy from the 62 %.
{"title":"Study of Radon concentrations in a single-family home and their relationship with the ventilation system","authors":"Pablo Villalba Espinosa, David Hidalgo García, J. Díaz, J. Moreno","doi":"10.7764/RDLC.19.3.443","DOIUrl":"https://doi.org/10.7764/RDLC.19.3.443","url":null,"abstract":"In the last decade he has caused himself an increase of the education of the interior ambient conditions of the buildings caused by the appearing of numerous scientific reports that they relate them to serious diseases. Between these, the education of concentration of radon branded like carcinogen wilfully publicise one. The present article parses the concentrations of this gas that have taken place in a single-family housing and as the ventilation system in work has influence upon her. For it, two samples in three outbuildings of the house have been taken, (car park, dining room and bedroom). The first unaccomplished sample the ventilation of the spaces and the second with ventilation. The obtained peak concentrations when the ventilation system does not find itself in operation evidence values from among 391 and 94 Bq/ m3 coming right across over the doorsteps established in the standard 2013/59 EURATOM. On the contrary, the peak concentrations of radon decrease to values from among 71 and 29 Bq/ m3 interveningventilation. In this sense, it is confirmed that the ventilation system in work is determining to decrease the concentration of the gas in the analysed sojourns getting an average efficacy from the 62 %.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82445355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-28DOI: 10.7764/RDLC.19.3.457-473
H. Jalilifar, Fathollah Sajedi, Vahid Razavi Toosi
This experimental study evaluates the durability of recycled aggregate concrete (RAC) containing silica-fume (SF) and natural zeolite (NZ). For this purpose, four levels of recycled coarse concrete aggregates (RCA) were replaced with natural coarse aggregates (NCA). To compare the effect of pozzolans, three levels of SF (5%, 10%, and 15%) and three levels of NZ (10%, 20%, and 30%) were replaced with cement. To evaluate the durability of RAC, 28 mixed designs were made and the following were measured: compressive strength (CS), water absorption by immersion (WA by immersion), water absorption by capillary (WA by capillary), electrical resistance (ER), electrical conductivity (EC) and rapid chloride penetration test (RCPT). The results indicated that WA by immersion and WA by capillary of RAC increased with enhanced RCA incorporation. On the other hand, the pozzolanic reaction of 10% of SF and 10% of NZ decreased capillary pores and structural weakness of full-scale RAC. However, due to the internal chemical changes of RAC, contrary to the WA by immersion and WA by capillary, compared to conventional concrete (CC), a lower EC and unchanged ER values of RC100 containing pozzolans were seen. The scanning electron microscopy (SEM) revealed that compared to NZ, a 10% of SF significantly improved the microstructure of full scale RAC.
本实验研究评估了含硅灰(SF)和天然沸石(NZ)的再生骨料混凝土(RAC)的耐久性。为此，四个级别的再生粗混凝土骨料(RCA)被天然粗骨料(NCA)所取代。为了比较火山灰的效果，用水泥代替了三种级别的SF(5%， 10%和15%)和三种级别的NZ(10%， 20%和30%)。为了评价RAC的耐久性，制作了28种混合设计，并对其抗压强度(CS)、浸水吸水性(WA by immersion)、毛细吸水性(WA by毛细管)、电阻(ER)、电导率(EC)和快速氯化物渗透试验(RCPT)进行了测试。结果表明，随着RCA掺入量的增加，浸渍法和毛细管法的WA均增加。另一方面，10%的SF和10%的NZ的火山灰反应减少了全尺寸RAC的毛细孔隙和结构弱点。然而，由于RAC的内部化学变化，与浸渍WA和毛细WA相反，与常规混凝土(CC)相比，含有火山灰的RC100的EC值较低，ER值不变。扫描电镜(SEM)显示，与NZ相比，10%的SF显著改善了全尺寸RAC的微观结构。
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