In this study, roller compacted concrete was produced by using a modified lignosulfonate-based chemical admixture which is suitable for use in wet, semi-dry or zero slump concrete, and the effect of admixture dosage on the physical and mechanical properties of the concrete was investigated. In the production of roller compacted concrete, the cement content was 300 kg/m3 and the chemical admixture dosages have been changed as 0%, 0.3%, 0.6% and 0.9%. Percentage of compactibility, total water absorption, unit weight, ultrasonic pulse velocity, dynamic modulus of elasticity, concrete compressive strength at the ages of 3 and 28 days were determined for the roller compacted concrete specimens. Roller compacted concrete with the lowest percentage of water absorption, the highest percentage of compactibility, ultrasonic pulse velocity, compactness, compressive strength and dynamic modulus of elasticity was the concrete produced with 0.6% admixture dosage. With the concrete design and the chemical admixture in question, it has been observed that the optimum dosage of chemical admixture for the production of the best quality concrete in terms of the concrete properties examined was 0.6%.
{"title":"A study on investigating the effect of lignosulfonate-based com-paction aid admixture dosage on the properties of roller com-pacted concrete","authors":"Saadet Gokce Gok, I. Kilic","doi":"10.7764/rdlc.21.3.737","DOIUrl":"https://doi.org/10.7764/rdlc.21.3.737","url":null,"abstract":"In this study, roller compacted concrete was produced by using a modified lignosulfonate-based chemical admixture which is suitable for use in wet, semi-dry or zero slump concrete, and the effect of admixture dosage on the physical and mechanical properties of the concrete was investigated. In the production of roller compacted concrete, the cement content was 300 kg/m3 and the chemical admixture dosages have been changed as 0%, 0.3%, 0.6% and 0.9%. Percentage of compactibility, total water absorption, unit weight, ultrasonic pulse velocity, dynamic modulus of elasticity, concrete compressive strength at the ages of 3 and 28 days were determined for the roller compacted concrete specimens. Roller compacted concrete with the lowest percentage of water absorption, the highest percentage of compactibility, ultrasonic pulse velocity, compactness, compressive strength and dynamic modulus of elasticity was the concrete produced with 0.6% admixture dosage. With the concrete design and the chemical admixture in question, it has been observed that the optimum dosage of chemical admixture for the production of the best quality concrete in terms of the concrete properties examined was 0.6%.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71305905","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}
Cristian Farías, Sarah Pessi, Augusto Wanderlind, Jorge Henrique Piva, Elaine Pavei
In this study, a comparative experimental analysis is performed between steel-reinforced concrete beams, which are dimensioned based on NBR 6118 (2014), and beams reinforced with glass fiber-reinforced polymer (GFRP) rebar, which are dimensioned based on ACI 440.1R (2015) after being subjected to a four-point bending test. The beams are dimensioned to resist the same force and to satisfy the service limit state (SLS). Results show that the two groups of beams exhibit similar vertical displacement behaviors until the SLS-DEF, whereas the GFRP beams exhibit larger deflections. At the ultimate load, the beams with fiberglass bars indicate a higher resistance by approximately 64% compared with those with metal bars.
{"title":"Flexural behavior of concrete beams reinforced with glass fiber reinforced polymer and steel bars","authors":"Cristian Farías, Sarah Pessi, Augusto Wanderlind, Jorge Henrique Piva, Elaine Pavei","doi":"10.7764/rdlc.21.3.506","DOIUrl":"https://doi.org/10.7764/rdlc.21.3.506","url":null,"abstract":"In this study, a comparative experimental analysis is performed between steel-reinforced concrete beams, which are dimensioned based on NBR 6118 (2014), and beams reinforced with glass fiber-reinforced polymer (GFRP) rebar, which are dimensioned based on ACI 440.1R (2015) after being subjected to a four-point bending test. The beams are dimensioned to resist the same force and to satisfy the service limit state (SLS). Results show that the two groups of beams exhibit similar vertical displacement behaviors until the SLS-DEF, whereas the GFRP beams exhibit larger deflections. At the ultimate load, the beams with fiberglass bars indicate a higher resistance by approximately 64% compared with those with metal bars.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71305926","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}
As the COVID-19 pandemic continues, construction projects have struggled to be completed. As such, it is necessary to find alternatives that optimize the limited human resources that can be working on construction sites. One alternative to do so is using multiskilled workers so workers can be reassigned to construction activities minimizing projects’ disruption due to workers getting contagion with COVID-19. This study simulates the influence of multiskilled workers in the development of a construction project in the context of the COVID-19 pandemic using an agent-based modeling approach. The aim of the study is to quantify the influence of multiskilled workers in the deficit of construction workers due to COVID-19. The proposed model generates six scenarios to include the uncertainty from limited data from the field due to the pandemic context to quantify the deficit of workers to develop a construction project. This study found that using multiskilled workers reduces the deficit of workers required to perform critical activities in construction projects. More specifically, it can reduce the average deficit of workers roughly in half when compared with the alternative of using only single-skilled workers, from 33.4% to 16.7% of deficit. Consequently, multiskilled workers represents an alternative for construction managers to deal with the disruption from COVID-19 in construction projects from a workforce management standpoint. Understanding alternatives to minimize the impacts of COVID-19 in construction projects may assist engineers and managers in applying strategies to develop construction projects accounting the limitations that COVID-19 places on construction sites.
{"title":"Modeling the influence of multiskilled construction workers in the context of the covid-19 pandemic using an agent-based ap-proach","authors":"F. Araya","doi":"10.7764/rdlc.21.1.105","DOIUrl":"https://doi.org/10.7764/rdlc.21.1.105","url":null,"abstract":"As the COVID-19 pandemic continues, construction projects have struggled to be completed. As such, it is necessary to find alternatives that optimize the limited human resources that can be working on construction sites. One alternative to do so is using multiskilled workers so workers can be reassigned to construction activities minimizing projects’ disruption due to workers getting contagion with COVID-19. This study simulates the influence of multiskilled workers in the development of a construction project in the context of the COVID-19 pandemic using an agent-based modeling approach. The aim of the study is to quantify the influence of multiskilled workers in the deficit of construction workers due to COVID-19. The proposed model generates six scenarios to include the uncertainty from limited data from the field due to the pandemic context to quantify the deficit of workers to develop a construction project. This study found that using multiskilled workers reduces the deficit of workers required to perform critical activities in construction projects. More specifically, it can reduce the average deficit of workers roughly in half when compared with the alternative of using only single-skilled workers, from 33.4% to 16.7% of deficit. Consequently, multiskilled workers represents an alternative for construction managers to deal with the disruption from COVID-19 in construction projects from a workforce management standpoint. Understanding alternatives to minimize the impacts of COVID-19 in construction projects may assist engineers and managers in applying strategies to develop construction projects accounting the limitations that COVID-19 places on construction sites.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304114","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}
M. Öztürk, Y. Önal, G. Altay, Ebubekir Kaplan, C. Kayadelen
This paper focuses on serving twofold benefits for the environment by providing not only recycling of a waste material but also improving rutting performance of sand subgrade under cyclic traffic loads. In this context, a series of laboratory experiments have been conducted to benchmark the performance of commercially manufactured geotextile and palm tree pruning waste (PTPW) as soil improvement agents. Experimental results of the study were evaluated based on permanent (plastic), total, and elastic deformation, rut depth reduction (RDR), traffic benefit ratio (TBR), percentage of elastic deformation, and resilient modulus (MR). In the view of experimental results, geotextile and PTPW-reinforced sand subgrades demonstrated well performance in the sense of permanent and elastic deformations when compared to unreinforced case. It is also realized that the most satisfactory performance was obtained when geotextile or PTPW are located at a burial depth of both 50 mm and 100 mm. In that case, TBR values of geotextile and PTPW-reinforced subgrades were almost the same at 20 mm permanent deformation (i.e., 6.71 and 6.76, respectively). Furthermore, when the results were evaluated based on RDR, it is observed that geotextile and PTPW reinforcements reduced the rut depth at the rate of 49.31 % and 37.15 % at the end of 5000 load cycle, respectively.
{"title":"Experimental evaluation of the usability of palm tree pruning waste (PTPW) as an alternative to geotextile","authors":"M. Öztürk, Y. Önal, G. Altay, Ebubekir Kaplan, C. Kayadelen","doi":"10.7764/rdlc.21.1.69","DOIUrl":"https://doi.org/10.7764/rdlc.21.1.69","url":null,"abstract":"This paper focuses on serving twofold benefits for the environment by providing not only recycling of a waste material but also improving rutting performance of sand subgrade under cyclic traffic loads. In this context, a series of laboratory experiments have been conducted to benchmark the performance of commercially manufactured geotextile and palm tree pruning waste (PTPW) as soil improvement agents. Experimental results of the study were evaluated based on permanent (plastic), total, and elastic deformation, rut depth reduction (RDR), traffic benefit ratio (TBR), percentage of elastic deformation, and resilient modulus (MR). In the view of experimental results, geotextile and PTPW-reinforced sand subgrades demonstrated well performance in the sense of permanent and elastic deformations when compared to unreinforced case. It is also realized that the most satisfactory performance was obtained when geotextile or PTPW are located at a burial depth of both 50 mm and 100 mm. In that case, TBR values of geotextile and PTPW-reinforced subgrades were almost the same at 20 mm permanent deformation (i.e., 6.71 and 6.76, respectively). Furthermore, when the results were evaluated based on RDR, it is observed that geotextile and PTPW reinforcements reduced the rut depth at the rate of 49.31 % and 37.15 % at the end of 5000 load cycle, respectively.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304751","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}
Porous pavement applications, which is environmentally friendly, especially for residential areas, allow rainwater to remain clean and to feed groundwater through infiltration. Porous asphalt pavements, in which are among the pavement types used in porous pavements systems, also reduce environmental noise pollution. On the other hand, there is a need to improve the performance of these asphalt pavement mixtures, which have a short service life due to their porous structure. It has been considered to improve the performance of the pavement mixtures by using basalt fiber without compromising the hydraulic permeability level. The waste slag material released during the ferrochrome production process was used as aggregate in the porous asphalt mixture design. Thus, it is aimed to benefit from the economic and environmental aspects with the recycling of ferrochrome slag in an area suitable for its properties. In the study, the design performances of porous asphalt mixtures were determined with tests such as volume analysis, permeability, Cantabro particle loss, indirect tensile strength, and moisture susceptibility. Basalt fiber was added at 0.2%, 0.4%, 0.6% and 0.8% of the mixture weight. It has been determined that the mixtures of basalt fibers at 0.2% significantly improve the mechanical performance.
{"title":"Performance evaluation of porous asphalt mixtures modified with basalt fiber","authors":"Altan Cetin, Gokhan Oral","doi":"10.7764/rdlc.21.1.93","DOIUrl":"https://doi.org/10.7764/rdlc.21.1.93","url":null,"abstract":"Porous pavement applications, which is environmentally friendly, especially for residential areas, allow rainwater to remain clean and to feed groundwater through infiltration. Porous asphalt pavements, in which are among the pavement types used in porous pavements systems, also reduce environmental noise pollution. On the other hand, there is a need to improve the performance of these asphalt pavement mixtures, which have a short service life due to their porous structure. It has been considered to improve the performance of the pavement mixtures by using basalt fiber without compromising the hydraulic permeability level. The waste slag material released during the ferrochrome production process was used as aggregate in the porous asphalt mixture design. Thus, it is aimed to benefit from the economic and environmental aspects with the recycling of ferrochrome slag in an area suitable for its properties. In the study, the design performances of porous asphalt mixtures were determined with tests such as volume analysis, permeability, Cantabro particle loss, indirect tensile strength, and moisture susceptibility. Basalt fiber was added at 0.2%, 0.4%, 0.6% and 0.8% of the mixture weight. It has been determined that the mixtures of basalt fibers at 0.2% significantly improve the mechanical performance.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304837","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}
The objective of this study is to examine the seismic performance of exterior and interior types of an emulative precast beam to column connection, constructed with grouted steel dowel bar and cast-in-situ concrete under quasi-static reversed cyclic loading. The dowel bar connection between the precast structural elements is achieved by inserting the dowel bar into the column corbel's holes and the precast portion of the beam. To secure the dowel bar's anchorage, these holes are packed with non-shrinkage grout and then cast-in-situ concreting is done in the joint core and the entire upper segment of the precast beam. In the past, particularly after an earthquake in the Emilia-Romagna region of Italy in May 2012 (Ercolino, Magliulo, & Manfredi, 2016), witnessed damage to precast reinforced concrete structures was more likely to occur in the precast beam-column joint section. Hence, it’s essential to improve the performance of the beam-column joint to withstand all possible lateral load combinations, which are to be included in the design and detailing of the precast structural components. This study analyzed an eight-story RC frame building for earthquake loading using Staad.Pro software. The exterior and interior types of proposed beam-column connections were designed and detailed using the design forces and moments computed by the Staad.Pro analysis, in accordance with the Indian standard codes (IS 456, 2000), (IS 1893, 2016)and (IS 13920, 2016). The beam-column joint behavior under quasi-static cyclic loading was studied using one-third scaled-down test specimens, i.e., monolithic (MBC-EJ & MBC-IJ) and emulative beam-column (EBC-EJ & EBC-IJ) exterior and interior joints. In that proposed emulative connection, the structural continuity and compatibility between the precast elements were achieved through the corbel with the dowel bar and cast-in-situ concreting. The test specimen’s ultimate and yield load carrying capacity, energy dissipation capacity, stiffness degradation, and ductility parameters were determined based on the obtained load-displacement hysteresis relationship. Based on the findings, the precast exterior joint specimens (EBC-EJ) were found to be 14.36% more ductile and 13.23% more energy dissipative than monolithic exterior joint specimens (MBC-EJ). Similarly, precast interior joint specimens (EBC-IJ) outperformed monolithic interior joint specimens (MBC-IJ) by 6.27% more ductility and 16.86% more energy dissipation. Therefore, the experimental results confirmed that using grouted dowel bars and wet concreting in the joint area enhances rigidity and structural continuity, as well as improves the ultimate strength of precast connections to a level that closely resembles typical monolithic beam-column joints.
{"title":"Cyclic performance of emulative precast beam to column con-nection with corbel using dowel bar","authors":"R. M., Jaya Kp","doi":"10.7764/rdlc.21.2.354","DOIUrl":"https://doi.org/10.7764/rdlc.21.2.354","url":null,"abstract":"The objective of this study is to examine the seismic performance of exterior and interior types of an emulative precast beam to column connection, constructed with grouted steel dowel bar and cast-in-situ concrete under quasi-static reversed cyclic loading. The dowel bar connection between the precast structural elements is achieved by inserting the dowel bar into the column corbel's holes and the precast portion of the beam. To secure the dowel bar's anchorage, these holes are packed with non-shrinkage grout and then cast-in-situ concreting is done in the joint core and the entire upper segment of the precast beam. In the past, particularly after an earthquake in the Emilia-Romagna region of Italy in May 2012 (Ercolino, Magliulo, & Manfredi, 2016), witnessed damage to precast reinforced concrete structures was more likely to occur in the precast beam-column joint section. Hence, it’s essential to improve the performance of the beam-column joint to withstand all possible lateral load combinations, which are to be included in the design and detailing of the precast structural components. This study analyzed an eight-story RC frame building for earthquake loading using Staad.Pro software. The exterior and interior types of proposed beam-column connections were designed and detailed using the design forces and moments computed by the Staad.Pro analysis, in accordance with the Indian standard codes (IS 456, 2000), (IS 1893, 2016)and (IS 13920, 2016). The beam-column joint behavior under quasi-static cyclic loading was studied using one-third scaled-down test specimens, i.e., monolithic (MBC-EJ & MBC-IJ) and emulative beam-column (EBC-EJ & EBC-IJ) exterior and interior joints. In that proposed emulative connection, the structural continuity and compatibility between the precast elements were achieved through the corbel with the dowel bar and cast-in-situ concreting. The test specimen’s ultimate and yield load carrying capacity, energy dissipation capacity, stiffness degradation, and ductility parameters were determined based on the obtained load-displacement hysteresis relationship. Based on the findings, the precast exterior joint specimens (EBC-EJ) were found to be 14.36% more ductile and 13.23% more energy dissipative than monolithic exterior joint specimens (MBC-EJ). Similarly, precast interior joint specimens (EBC-IJ) outperformed monolithic interior joint specimens (MBC-IJ) by 6.27% more ductility and 16.86% more energy dissipation. Therefore, the experimental results confirmed that using grouted dowel bars and wet concreting in the joint area enhances rigidity and structural continuity, as well as improves the ultimate strength of precast connections to a level that closely resembles typical monolithic beam-column joints.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71305224","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 investigated the production and properties of lightweight hemp composites produced using waste industrial hemp stems cultivated in Turkey. Hemp stems were separated from their fibers and fragmented to obtain hemp shiv aggregates in the laboratory. Twelve mixtures were prepared with varied volumetric ratios of hemp: cement (H:C) and hemp: water (H: W) using different sizes of hemp shiv. The influence of mix proportions on the physical and mechanical properties of hemp composites were investigated. Besides, microstructure of hemp composites was examined. The hemp composites produced were in the apparent density range of 312 to 928 kg/m3 and exhibited 0.20 to 1.24 MPa compressive strength. The water absorptions of samples were in the range of 3.47 and 8.50 kg/m2.h1/2. The apparent density and compressive strength of hemp composites decreased with the increase of H:C ratio, but this situation is the opposite for increase of H: W ratio and hemp shiv size. Besides, increase in H:C ratio or hemp shiv size caused higher water absorptions.
{"title":"Influence of hemp shiv, cement, and water content on the properties of lightweight hemp composites produced using different sizes of hemp shiv","authors":"M. Şahin","doi":"10.7764/rdlc.21.3.570","DOIUrl":"https://doi.org/10.7764/rdlc.21.3.570","url":null,"abstract":"This study investigated the production and properties of lightweight hemp composites produced using waste industrial hemp stems cultivated in Turkey. Hemp stems were separated from their fibers and fragmented to obtain hemp shiv aggregates in the laboratory. Twelve mixtures were prepared with varied volumetric ratios of hemp: cement (H:C) and hemp: water (H: W) using different sizes of hemp shiv. The influence of mix proportions on the physical and mechanical properties of hemp composites were investigated. Besides, microstructure of hemp composites was examined. The hemp composites produced were in the apparent density range of 312 to 928 kg/m3 and exhibited 0.20 to 1.24 MPa compressive strength. The water absorptions of samples were in the range of 3.47 and 8.50 kg/m2.h1/2. The apparent density and compressive strength of hemp composites decreased with the increase of H:C ratio, but this situation is the opposite for increase of H: W ratio and hemp shiv size. Besides, increase in H:C ratio or hemp shiv size caused higher water absorptions.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71305546","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}
Measures taken against preventing damages in structures against explosive load are a popular matter of investigation among researchers. Generally, numerous studies were conducted on reinforcement materials for outer surfaces, reinforcement design, and utilizing fibers produced from various materials. In this study, a hollow-core slab was manufactured with concrete, which had a regular strength, and a design that discharged the explosive energy upon contact explosion via the hollow cores of the slabs and prevented the redirection of the explosive energy to the area below the slabs was investigated. Because the hollow-core slab in the study did not have any lateral reinforcement, the utilization of the tensile strength of the concrete proved advantageous. For this purpose, in the experimental tests of the study, contact explosions were conducted on hollow-core slabs with hollow diameters of 14 cm for each core. Before the explosion tests, the TNT equivalent of 910gr explosive was determined by performing the TNT equivalent tests. In the explosion tests of prepared hollow core concrete slabs, 125 gr, 250 gr, 375 gr, and 500 gr dynamites were used as the explosive materials. In conclusion, the explosive loads that the slabs could withstand were calculated and various slabs with distinctive hollow-core diameters were determined depending on the amount of the explosives.
{"title":"An experimental study on the blast responses of hollow core concrete slabs to contact explosions","authors":"Sedat Savaş, Dursun Bakir","doi":"10.7764/rdlc.21.3.587","DOIUrl":"https://doi.org/10.7764/rdlc.21.3.587","url":null,"abstract":"Measures taken against preventing damages in structures against explosive load are a popular matter of investigation among researchers. Generally, numerous studies were conducted on reinforcement materials for outer surfaces, reinforcement design, and utilizing fibers produced from various materials. In this study, a hollow-core slab was manufactured with concrete, which had a regular strength, and a design that discharged the explosive energy upon contact explosion via the hollow cores of the slabs and prevented the redirection of the explosive energy to the area below the slabs was investigated. Because the hollow-core slab in the study did not have any lateral reinforcement, the utilization of the tensile strength of the concrete proved advantageous. For this purpose, in the experimental tests of the study, contact explosions were conducted on hollow-core slabs with hollow diameters of 14 cm for each core. Before the explosion tests, the TNT equivalent of 910gr explosive was determined by performing the TNT equivalent tests. In the explosion tests of prepared hollow core concrete slabs, 125 gr, 250 gr, 375 gr, and 500 gr dynamites were used as the explosive materials. In conclusion, the explosive loads that the slabs could withstand were calculated and various slabs with distinctive hollow-core diameters were determined depending on the amount of the explosives.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71305552","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}
Magnesium phosphate cements are implemented for several purposes demonstrating significant mechanical properties in limited durations. However, brittle behavior of this material needs utmost concern and tensile performance may be enhanced with the proper application of fibers increasing both ductility and energy absorption capacity. This research studies the effect of basalt fibers (BF) and silica fume (SF) on the fracture parameters of magnesium phosphate cement (MPC). MPC mortar mixtures were prepared with different SF (0, 5, 10%) and BF amounts (0, 0.5, 0.75, 1 % by wt.). Also fly ash was adopted with a constant ratio for all mixes. Compressive strength and splitting tensile strength results indicated that addition of SF into mixtures extensively developed the matrix structure and improvements were noted with the increasing SF content. The inclusion of BF enhanced the flexural behavior although there were significant improvements in the fracture energy as well as the double-K parameters. Improvements in the tensile capacity of specimens with high BF were prone to the amount of SF percentage such that inclusion of 1 % BF performed best with 10 % SF added mixtures. Load-CMOD (crack mouth opening displacement) curves obtained from notched three-point tests were given for all specimen series and parameters were calculated according to the double-K criterion. Addition of BF resulted in higher toughness values however presence of SF was very significant in establishing appreciable development in toughness values. Brittleness index was implemented to establish clear conclusions on the findings and best performance was seen for specimens with 10% SF and 1% BF.
{"title":"Effect of silica fume and basalt fibers on the fracture parameters of magnesium phosphate cement incorporating fly ash","authors":"Ahmet Onur Pehlivan","doi":"10.7764/rdlc.21.3.523","DOIUrl":"https://doi.org/10.7764/rdlc.21.3.523","url":null,"abstract":"Magnesium phosphate cements are implemented for several purposes demonstrating significant mechanical properties in limited durations. However, brittle behavior of this material needs utmost concern and tensile performance may be enhanced with the proper application of fibers increasing both ductility and energy absorption capacity. This research studies the effect of basalt fibers (BF) and silica fume (SF) on the fracture parameters of magnesium phosphate cement (MPC). MPC mortar mixtures were prepared with different SF (0, 5, 10%) and BF amounts (0, 0.5, 0.75, 1 % by wt.). Also fly ash was adopted with a constant ratio for all mixes. Compressive strength and splitting tensile strength results indicated that addition of SF into mixtures extensively developed the matrix structure and improvements were noted with the increasing SF content. The inclusion of BF enhanced the flexural behavior although there were significant improvements in the fracture energy as well as the double-K parameters. Improvements in the tensile capacity of specimens with high BF were prone to the amount of SF percentage such that inclusion of 1 % BF performed best with 10 % SF added mixtures. Load-CMOD (crack mouth opening displacement) curves obtained from notched three-point tests were given for all specimen series and parameters were calculated according to the double-K criterion. Addition of BF resulted in higher toughness values however presence of SF was very significant in establishing appreciable development in toughness values. Brittleness index was implemented to establish clear conclusions on the findings and best performance was seen for specimens with 10% SF and 1% BF.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71305934","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 assessed the effect of lightweight expanded clay aggregate (LECA) grain size and curing with polyethylene concrete curing film (PCCF) on microstructure, interfacial transition zone (ITZ), and compressive strength of structural lightweight aggregate concrete (LWAC) produced with two different Dmax (16 or 22.4 mm). To this end, 2 series of normal weight aggregate concretes (NWAC) and 6 series of LWAC incorporating 40% by vol. unprewetted LECA having (0-3, 3-8, or 8-16 mm) grain sizes were evaluated by using unit weight, compressive strength tests at 1, 7, and 28 days and SEM-EDX observations. Preventing the moisture loss from fresh concrete through PCCF curing had positive effects on compressive strength up to 14 and 9% for 1 and 28 days respectively. Shell thickness of LECA considerably increased with the decrease in LECA grain size. Thus, the compressive strength of LECA and LWAC increased by the decrease in LECA grain size. LWAC containing 0-3 mm LECA, achieved up to 21% higher compressive strength to weight ratio compared with the NWAC with the aid of the pozzolanic reactivity of fine LECA particles.
{"title":"Effect of aggregate size and polyethylene sheet curing on me-chanical and microstructural properties of lightweight expanded clay aggregate concrete","authors":"Mehmet Uğur Toprak, C. Karakurt, Osman Güneş","doi":"10.7764/rdlc.21.1.145","DOIUrl":"https://doi.org/10.7764/rdlc.21.1.145","url":null,"abstract":"This study assessed the effect of lightweight expanded clay aggregate (LECA) grain size and curing with polyethylene concrete curing film (PCCF) on microstructure, interfacial transition zone (ITZ), and compressive strength of structural lightweight aggregate concrete (LWAC) produced with two different Dmax (16 or 22.4 mm). To this end, 2 series of normal weight aggregate concretes (NWAC) and 6 series of LWAC incorporating 40% by vol. unprewetted LECA having (0-3, 3-8, or 8-16 mm) grain sizes were evaluated by using unit weight, compressive strength tests at 1, 7, and 28 days and SEM-EDX observations. Preventing the moisture loss from fresh concrete through PCCF curing had positive effects on compressive strength up to 14 and 9% for 1 and 28 days respectively. Shell thickness of LECA considerably increased with the decrease in LECA grain size. Thus, the compressive strength of LECA and LWAC increased by the decrease in LECA grain size. LWAC containing 0-3 mm LECA, achieved up to 21% higher compressive strength to weight ratio compared with the NWAC with the aid of the pozzolanic reactivity of fine LECA particles.","PeriodicalId":54473,"journal":{"name":"Revista de la Construccion","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71304288","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}
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