C. A. Benedetty, Ingrid R. Irreño, J. J. Martínez, L. C. Almeida, L. Trautwein, P. A. Krahl
In this study, the capacity and ultimate behavior of Reinforced Concrete (RC) and Steel Fiber Reinforced Concrete (SFRC) beams are evaluated. Nonlinear Finite Element Analysis (NLFEA) and the inverse analysis technique were used to model its structural response using the ATENA finite element software. The smeared crack approach, the crack band model, and advanced constitutive models were used to reproduce concrete fracture. The analyzed beams were subjected to rupture in a four-point bending test setup. The relationship between the shear span and the depth of the beams was 1.5. Four scenarios were analyzed, RC beams with and without stirrups, and SFRC beams without stirrups with volumes of 0.57% and 0.76%. The results obtained in the modeling are discussed in terms of the ability of the models to numerically reproduce the relationships: load versus displacement, load versus strain, crack patterns, and failure modes. The analysis techniques allowed to reproduce the experimental response of the beams with good agreement. They show great potential to solve structural engineering problems
{"title":"Ultimate capacity prediction of RC and SFRC beams with low shear span-depth ratio using NLFEA and inverse analysis","authors":"C. A. Benedetty, Ingrid R. Irreño, J. J. Martínez, L. C. Almeida, L. Trautwein, P. A. Krahl","doi":"10.7764/rdlc.21.3.717","DOIUrl":"https://doi.org/10.7764/rdlc.21.3.717","url":null,"abstract":"In this study, the capacity and ultimate behavior of Reinforced Concrete (RC) and Steel Fiber Reinforced Concrete (SFRC) beams are evaluated. Nonlinear Finite Element Analysis (NLFEA) and the inverse analysis technique were used to model its structural response using the ATENA finite element software. The smeared crack approach, the crack band model, and advanced constitutive models were used to reproduce concrete fracture. The analyzed beams were subjected to rupture in a four-point bending test setup. The relationship between the shear span and the depth of the beams was 1.5. Four scenarios were analyzed, RC beams with and without stirrups, and SFRC beams without stirrups with volumes of 0.57% and 0.76%. The results obtained in the modeling are discussed in terms of the ability of the models to numerically reproduce the relationships: load versus displacement, load versus strain, crack patterns, and failure modes. The analysis techniques allowed to reproduce the experimental response of the beams with good agreement. They show great potential to solve structural engineering problems","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":"71305898","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 effect of supplementary cementitious materials (SCMs) with pozzolanic nature fly-ash (FA), silica fume (SF), and ground granulated blast furnace slag (GGBFS) on the properties of cement mortar with pyrogenic silica addition. First, standard reference (SR) samples were prepared using CEM I 42.5 R-type cement. Pyrogenic silica was added to cement (0.5% by weight) to prepare another group of reference (PR) mortar samples. Cement in PR mortars was replaced with FA, SF, and GGBFS up to 10, 20, and 30%. The mortar samples were placed in 40x40x160 mm metal molds using a vibrating table. The following day the samples were removed from the molds and water cured for 7, 28, and 90 days. The results showed that increases in curing times helped improve the mechanical properties of the mortars. Moreover, the physical properties of PR mortars were affected more positively than the SR mortars. SF-substituted mortars had highest compressive strength, followed by GGBFS- and FA- substituted mortars. In conclusion, pyrogenic silica contributed to some extent to early strength, followed by a decrease.
研究了火山灰性质的粉煤灰(FA)、硅灰(SF)和磨碎的高炉矿渣(GGBFS)作为补充胶凝材料(SCMs)对添加了热原二氧化硅的水泥砂浆性能的影响。首先，使用CEM I 42.5 r型水泥制备标准参比(SR)样品。在水泥中加入热原二氧化硅(按重量计0.5%)，制备另一组参考(PR)砂浆样品。用FA、SF和GGBFS代替PR砂浆中的水泥，分别达到10%、20%和30%。使用振动台将砂浆样品放置在40x40x160 mm的金属模具中。第二天，将样品从模具中取出，水固化7、28和90天。结果表明，延长养护时间有助于改善砂浆的力学性能。此外，PR砂浆的物理性能比SR砂浆受到更积极的影响。sf -取代砂浆的抗压强度最高，其次是GGBFS-和FA-取代砂浆。综上所述，热原二氧化硅对材料的早期强度有一定的贡献，随后又降低。
{"title":"Investigation of properties of mortar containing pyrogenic silica-added supplementary cementitious materials","authors":"Gökhan Görhan, Ahmet Mücahit Bozkurt","doi":"10.7764/rdlc.21.1.118","DOIUrl":"https://doi.org/10.7764/rdlc.21.1.118","url":null,"abstract":"This study investigated the effect of supplementary cementitious materials (SCMs) with pozzolanic nature fly-ash (FA), silica fume (SF), and ground granulated blast furnace slag (GGBFS) on the properties of cement mortar with pyrogenic silica addition. First, standard reference (SR) samples were prepared using CEM I 42.5 R-type cement. Pyrogenic silica was added to cement (0.5% by weight) to prepare another group of reference (PR) mortar samples. Cement in PR mortars was replaced with FA, SF, and GGBFS up to 10, 20, and 30%. The mortar samples were placed in 40x40x160 mm metal molds using a vibrating table. The following day the samples were removed from the molds and water cured for 7, 28, and 90 days. The results showed that increases in curing times helped improve the mechanical properties of the mortars. Moreover, the physical properties of PR mortars were affected more positively than the SR mortars. SF-substituted mortars had highest compressive strength, followed by GGBFS- and FA- substituted mortars. In conclusion, pyrogenic silica contributed to some extent to early strength, followed by a decrease.","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":"71304160","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}
In this study the optimum replacement percentage of sintered fly ash aggregates in M30 grade of concrete was identified based on 28 days cubical compressive strength value. The optimum replacement of Sintered Fly ash Aggregates (SFA) is 40 %. Before identifying the optimum replacement percentage, the SFAs were tested for suitability test such as crushing strength test, impact test and water absorption test. Further, the optimum 40 % SFAs in concrete is tested for punching shear on the Reinforced Concrete (RC) slabs for a dimension of 1000 mm x 1000 mm x 100 mm. In addition to know the effect of steel fibers in RC slabs subjected to punching. A hook ended steel fibers having an aspect ratio of 55, 80 and 100 is selected and varied by volume of concrete for the punching shear values on RC slabs. The RC slabs concrete contains aspect ratio of steel fibers 55 is varied for 0.25 %, 0.5 %, 0.75 % and 1 % for volume of concrete. In addition to that a constant volume of steel fiber 0.5 % is selected for the aspect ratios of 80 and 100 for the punching shear tests. The punching shear values for the RC slabs shows that partial replacement of SFAs and steel fibers in concrete enhances the punching shear strength. These experimental tested results are compared with finite element programming (ABAQUS) and international codes such as IS 456 and ACI 2011. The experimental punching shear results were higher when compared to international codes.
根据28天立方体抗压强度值，确定了M30级混凝土中粉煤灰骨料的最佳替代比例。烧结粉煤灰骨料(SFA)的最佳替代量为40%。在确定最佳替代率之前，对sfa进行了抗压强度试验、冲击试验和吸水试验等适用性试验。此外，在钢筋混凝土(RC)板上进行了尺寸为1000 mm x 1000 mm x 100 mm的冲剪试验，测试了混凝土中最佳的40% sfa。此外，还了解了钢纤维在钢筋混凝土板冲压中的作用。选择长径比为55、80和100的钩端钢纤维，并根据混凝土体积的不同，用于混凝土板的冲孔剪切值。钢筋混凝土板含钢纤维长径比55为0.25%，0.5%，0.75%和1%的混凝土体积变化。此外，在长径比为80和100的情况下，选择恒体积0.5%的钢纤维进行冲剪试验。混凝土的冲剪值表明，部分替换混凝土中的sfa和钢纤维提高了混凝土的冲剪强度。这些试验测试结果与有限元程序(ABAQUS)和国际规范如IS 456和ACI 2011进行了比较。试验冲剪结果高于国际规范。
{"title":"Behaviour of sintered fly ash aggregates and steel fibers on reinforced concrete slabs subjected to punching","authors":"R. Babu B., T. R","doi":"10.7764/rdlc.21.2.228","DOIUrl":"https://doi.org/10.7764/rdlc.21.2.228","url":null,"abstract":"In this study the optimum replacement percentage of sintered fly ash aggregates in M30 grade of concrete was identified based on 28 days cubical compressive strength value. The optimum replacement of Sintered Fly ash Aggregates (SFA) is 40 %. Before identifying the optimum replacement percentage, the SFAs were tested for suitability test such as crushing strength test, impact test and water absorption test. Further, the optimum 40 % SFAs in concrete is tested for punching shear on the Reinforced Concrete (RC) slabs for a dimension of 1000 mm x 1000 mm x 100 mm. In addition to know the effect of steel fibers in RC slabs subjected to punching. A hook ended steel fibers having an aspect ratio of 55, 80 and 100 is selected and varied by volume of concrete for the punching shear values on RC slabs. The RC slabs concrete contains aspect ratio of steel fibers 55 is varied for 0.25 %, 0.5 %, 0.75 % and 1 % for volume of concrete. In addition to that a constant volume of steel fiber 0.5 % is selected for the aspect ratios of 80 and 100 for the punching shear tests. The punching shear values for the RC slabs shows that partial replacement of SFAs and steel fibers in concrete enhances the punching shear strength. These experimental tested results are compared with finite element programming (ABAQUS) and international codes such as IS 456 and ACI 2011. The experimental punching shear results were higher when compared to international codes.","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":"71304844","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 compares the rutting and cracking resistance and fatigue parameters of crumb rubber (CR) modified warm asphalt binders, which were determined by viscoelastic continuum damage (VECD) theory. The effect of the combination of CR modification and Sasobit, a warm mix additive, was investigated. Performance of CR + Sasobit compound was compared with styrene-butadiene-styrene (SBS) modification. Newly developed rheological tests such as multi stress creep recovery (MSCR), lineer amplitude sweep (LAS) and conventional tests were applied to modified binders. It was determined that the CR + Sasobit modified binders improved the rutting parameter better in comparison to SBS-added binders. Although the CR additive improved the rheological properties of the binder at low and medium temperatures, this effect was reduced when used with Sasobit additive. Sasobit additive increased the stiffness and decreased the fatigue parameter at low temperatures. Besides, the results of the LAS test revealed that at high strain values (i.e.> 6%), the fatigue life of CR and Sasobit modified binders was lower than the fatigue life of the pure binder. In other words, CR and Sasobit modified binders could not preserve material integrity.
{"title":"Investigation of rutting, fatigue and cracking resistance parame-ters of CR modified warm asphalt binders compare with SBS modified binders","authors":"M. Akpolat","doi":"10.7764/rdlc.21.2.309","DOIUrl":"https://doi.org/10.7764/rdlc.21.2.309","url":null,"abstract":"This study compares the rutting and cracking resistance and fatigue parameters of crumb rubber (CR) modified warm asphalt binders, which were determined by viscoelastic continuum damage (VECD) theory. The effect of the combination of CR modification and Sasobit, a warm mix additive, was investigated. Performance of CR + Sasobit compound was compared with styrene-butadiene-styrene (SBS) modification. Newly developed rheological tests such as multi stress creep recovery (MSCR), lineer amplitude sweep (LAS) and conventional tests were applied to modified binders. It was determined that the CR + Sasobit modified binders improved the rutting parameter better in comparison to SBS-added binders. Although the CR additive improved the rheological properties of the binder at low and medium temperatures, this effect was reduced when used with Sasobit additive. Sasobit additive increased the stiffness and decreased the fatigue parameter at low temperatures. Besides, the results of the LAS test revealed that at high strain values (i.e.> 6%), the fatigue life of CR and Sasobit modified binders was lower than the fatigue life of the pure binder. In other words, CR and Sasobit modified binders could not preserve material integrity.","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":"71305352","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}
Liquefaction is a loss in soil’s resistance which can lead to disastrous and expensive consequences in terms of human lives and material damages, hence the interest of this laboratory study. The article explores the relative density influence in addition to the main parameter of the fines content on the liquefaction potential of soils. The study is based on a very large number of undrained monotonic triaxial tests undertaken on samples of reconstituted saturated sand and silt mixtures with 6 levels of initial relative density ranging from 15 to 90%. The materials used are levied from different level of deepness in the coastal region of Kharouba in the wilaya of Mostaganem. In this experiment, the sand-silt mixtures were separated to form the study samples. The aim of this work is, on one hand, to confirm and update the results of previous works (Bensoula et al., 2018) and on the other hand the study of the influence of relative density on the liquefaction potential of soils and the introduction of the concept of relative density threshold. The results of the tests confirm that the studied soil is most likely to be liquefied at a fines content between 0 and 30% depending on the equivalent intergranular voids and the equivalent relative density. These parameters are primordial for the characterization of soils sensitivity to liquefaction. In this study, the results showed that the resistance to liquefaction increases in a linear way with the relative density up to a threshold relative density value according to the fines content, which means that increasing the relative density improves the liquefaction resistance but only up to a threshold value of relative density given according to fines content
液化是一种土壤抵抗力的丧失，在人类生命和物质损失方面可能导致灾难性和昂贵的后果，因此本实验室研究的兴趣。本文探讨了除细粒含量这一主要参数外，相对密度对土壤液化势的影响。该研究基于大量不排水的单调三轴试验，这些试验是对初始相对密度为15%至90%的6个水平的饱和砂和粉土混合物进行的。所使用的材料是从Mostaganem省Kharouba沿海地区的不同深度征收的。在本实验中，砂粉混合物被分离形成研究样品。本工作的目的一方面是确认和更新先前工作的结果(Bensoula et al.， 2018)，另一方面是研究相对密度对土壤液化潜力的影响，并引入相对密度阈值的概念。试验结果证实，根据等效粒间空隙和等效相对密度，所研究的土壤在0 ~ 30%的细粒含量之间最可能液化。这些参数是表征土壤液化敏感性的基本参数。本研究结果表明，随着相对密度的增大，液化阻力呈线性增长，直至根据细粒含量给定的阈值相对密度值，这意味着增加相对密度可以提高液化阻力，但仅达到根据细粒含量给定的相对密度阈值
{"title":"Relative density influence on the liquefaction potential of sand with fines","authors":"Mohamed Bensoula, Mohammed Bousmaha, H. Missoum","doi":"10.7764/rdlc.21.3.692","DOIUrl":"https://doi.org/10.7764/rdlc.21.3.692","url":null,"abstract":"Liquefaction is a loss in soil’s resistance which can lead to disastrous and expensive consequences in terms of human lives and material damages, hence the interest of this laboratory study. The article explores the relative density influence in addition to the main parameter of the fines content on the liquefaction potential of soils. The study is based on a very large number of undrained monotonic triaxial tests undertaken on samples of reconstituted saturated sand and silt mixtures with 6 levels of initial relative density ranging from 15 to 90%. The materials used are levied from different level of deepness in the coastal region of Kharouba in the wilaya of Mostaganem. In this experiment, the sand-silt mixtures were separated to form the study samples. The aim of this work is, on one hand, to confirm and update the results of previous works (Bensoula et al., 2018) and on the other hand the study of the influence of relative density on the liquefaction potential of soils and the introduction of the concept of relative density threshold. The results of the tests confirm that the studied soil is most likely to be liquefied at a fines content between 0 and 30% depending on the equivalent intergranular voids and the equivalent relative density. These parameters are primordial for the characterization of soils sensitivity to liquefaction. In this study, the results showed that the resistance to liquefaction increases in a linear way with the relative density up to a threshold relative density value according to the fines content, which means that increasing the relative density improves the liquefaction resistance but only up to a threshold value of relative density given according to fines content","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":"71305677","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}
impact resistance represents a key property of fiber reinforced concrete (FRC). To study this property, a test method was recently proposed; which consists in repeated drops of a projectile on simply supported prisms, and allows to evaluate FRC behavior both at cracking and after cracking. With the aim of verifying the sensitiveness of this method, this paper analyzes the influence of the compressive strength of the FRC matrix on each parameter of the impact test. Three FRC incorporating 30 kg/m3 of hooked-end steel fibers were prepared, varying the water/cement ratio (0.59, 0.50 and 0.43). It was found that although only small effects on the cracking energy were observed as the concrete compressive strength increases, the post-cracking energy increased in a greater proportion. However, the cracking growth rate, an impact parameter strongly sensitive to the type and content of fibers, remained practically constant for different compressive strength levels.
{"title":"Compressive resistance level effect on impact performance of fi-ber reinforced concrete","authors":"J. C. Vivas","doi":"10.7764/rdlc.21.1.135","DOIUrl":"https://doi.org/10.7764/rdlc.21.1.135","url":null,"abstract":"impact resistance represents a key property of fiber reinforced concrete (FRC). To study this property, a test method was recently proposed; which consists in repeated drops of a projectile on simply supported prisms, and allows to evaluate FRC behavior both at cracking and after cracking. With the aim of verifying the sensitiveness of this method, this paper analyzes the influence of the compressive strength of the FRC matrix on each parameter of the impact test. Three FRC incorporating 30 kg/m3 of hooked-end steel fibers were prepared, varying the water/cement ratio (0.59, 0.50 and 0.43). It was found that although only small effects on the cracking energy were observed as the concrete compressive strength increases, the post-cracking energy increased in a greater proportion. However, the cracking growth rate, an impact parameter strongly sensitive to the type and content of fibers, remained practically constant for different compressive strength levels.","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":"71304265","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}
F. Silva, M.T.A. Silva, J. Delgado, A. Azevedo, Gabriel F. Pereira
The proper management of demolition construction waste from the construction industry is an issue that has gained relevance over the last years in several research centers around the world and, in this context, researches on the potential of using construction and demolition waste to execute pavement layers have been stood out. The paper presented results of a research performed to evaluate the characteristics of the material produced by a waste treatment/beneficiation industrial plant. Tests to verify the suitability of the material as pavement subbase material were performed according Brazilian code - grain-size distribution composition, maximum characteristic dimension, shape particle index (SPI), contaminant percentage and sieving process. The results obtained indicated that the recycled aggregates investigated performed well in all the requirements of the reference standards used and only one correction, related to grain size distribution, was performed using a sieving process. It is important to highlight that the tests and analyses must be performed constantly when forming each aggregate batch, since the recycled aggregates are usually quite heterogeneous, with characteristics that may vary depending on the type of work, construction materials used or period of the year.
{"title":"Construction and demolition waste as raw material in pavements layers","authors":"F. Silva, M.T.A. Silva, J. Delgado, A. Azevedo, Gabriel F. Pereira","doi":"10.7764/rdlc.21.1.184","DOIUrl":"https://doi.org/10.7764/rdlc.21.1.184","url":null,"abstract":"The proper management of demolition construction waste from the construction industry is an issue that has gained relevance over the last years in several research centers around the world and, in this context, researches on the potential of using construction and demolition waste to execute pavement layers have been stood out. The paper presented results of a research performed to evaluate the characteristics of the material produced by a waste treatment/beneficiation industrial plant. Tests to verify the suitability of the material as pavement subbase material were performed according Brazilian code - grain-size distribution composition, maximum characteristic dimension, shape particle index (SPI), contaminant percentage and sieving process. The results obtained indicated that the recycled aggregates investigated performed well in all the requirements of the reference standards used and only one correction, related to grain size distribution, was performed using a sieving process. It is important to highlight that the tests and analyses must be performed constantly when forming each aggregate batch, since the recycled aggregates are usually quite heterogeneous, with characteristics that may vary depending on the type of work, construction materials used or period of the year.","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":"71304567","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}
Tunnel entrances are among the most likely places for rock fall events. For this reason, concrete tubes are constructed before tunnel entrances against rock falls. In this study, the normal stress and the deformation in both horizontal and vertical directions occurred by crashing rock on concrete tunnel tubes were investigated using finite element method in three dimensional conditions. Different velocities and masses of falling rock analyzed to demonstrate effect of velocity on normal stress and deformations. It was observed that deformations on the concrete tube increased as the impact energy increased due to increasing velocity and mass. The mass of crashed rock, M, is changes from 3 kN to 200 kN and peak deformations could reach approximately 150 cm when the mass of falling rock was M=200 kN and V = 30 m/s. When the velocity of rock V=10 m/s just before the impact, the ratios of deformations to rock mass of 3 kN, 25 kN, and 200 kN were approximately 0.00066 m/kN, 0.0014 m/kN and 0.00175 m/kN, respectively.
隧道入口是最容易发生岩崩事件的地方之一。因此，在隧道入口之前要建造混凝土管，以防止岩崩。在三维条件下，采用有限元方法研究了岩石冲击对混凝土隧管产生的正应力和水平、垂直方向的变形。分析了不同速度和不同质量的落石，论证了速度对正应力和变形的影响。结果表明，随着速度和质量的增加，冲击能量的增加，混凝土管的变形也随之增加。落石质量M=200 kN, V = 30 M /s时，落石质量M从3 kN变化到200 kN，峰值变形可达150 cm左右。冲击前岩石速度V=10 m/s时，3 kN、25 kN和200 kN的变形与岩体的比值分别约为0.00066 m/kN、0.0014 m/kN和0.00175 m/kN。
{"title":"Numerical modelling of concrete tunnels exposed to rock fall","authors":"B. Baǧrıaçık, G. Altay, S. Önal, C. Kayadelen","doi":"10.7764/rdlc.21.2.215","DOIUrl":"https://doi.org/10.7764/rdlc.21.2.215","url":null,"abstract":"Tunnel entrances are among the most likely places for rock fall events. For this reason, concrete tubes are constructed before tunnel entrances against rock falls. In this study, the normal stress and the deformation in both horizontal and vertical directions occurred by crashing rock on concrete tunnel tubes were investigated using finite element method in three dimensional conditions. Different velocities and masses of falling rock analyzed to demonstrate effect of velocity on normal stress and deformations. It was observed that deformations on the concrete tube increased as the impact energy increased due to increasing velocity and mass. The mass of crashed rock, M, is changes from 3 kN to 200 kN and peak deformations could reach approximately 150 cm when the mass of falling rock was M=200 kN and V = 30 m/s. When the velocity of rock V=10 m/s just before the impact, the ratios of deformations to rock mass of 3 kN, 25 kN, and 200 kN were approximately 0.00066 m/kN, 0.0014 m/kN and 0.00175 m/kN, 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":"71304738","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}
In this study, the mechanical, thermal and porosity properties of mortar samples containing aerogel and silica fume under different curing conditions were investigated. For this purpose, 0%, 0.25% and 0.50% by weight of silica aerogel as a cement additive and 10% silica fume as an industrial waste material were incorporated in the cement mixtures. The prepared mortar samples were exposed to curing process in water, the wetting-drying effect and MgSO4 effect for 16 weeks. The highest thermal conductivity reduction of 31.2% was obtained from the water curing sample with silica fume addition at an aerogel content of 0.25%. Maximum compressive and flexural strengths were determined respectively from samples with silica fume addition at an aerogel content 0.50% as 74.5 MPa and no aerogel content as 11.3 MPa by wetting-drying curing. However, the lowest thermal conductivity coefficient was measured as 1.458 W/mK from the sample at an 0.25% aerogel content containing silica fume which completed the curing process under the influence of MgSO4 with a highest compressive strength increase by 24.6%.
{"title":"Effect of aerogel/silica fume under curing methods on properties of cement-based mortars","authors":"Ozlem Uatundag, Ozlem Celik Sola","doi":"10.7764/rdlc.21.2.368","DOIUrl":"https://doi.org/10.7764/rdlc.21.2.368","url":null,"abstract":"In this study, the mechanical, thermal and porosity properties of mortar samples containing aerogel and silica fume under different curing conditions were investigated. For this purpose, 0%, 0.25% and 0.50% by weight of silica aerogel as a cement additive and 10% silica fume as an industrial waste material were incorporated in the cement mixtures. The prepared mortar samples were exposed to curing process in water, the wetting-drying effect and MgSO4 effect for 16 weeks. The highest thermal conductivity reduction of 31.2% was obtained from the water curing sample with silica fume addition at an aerogel content of 0.25%. Maximum compressive and flexural strengths were determined respectively from samples with silica fume addition at an aerogel content 0.50% as 74.5 MPa and no aerogel content as 11.3 MPa by wetting-drying curing. However, the lowest thermal conductivity coefficient was measured as 1.458 W/mK from the sample at an 0.25% aerogel content containing silica fume which completed the curing process under the influence of MgSO4 with a highest compressive strength increase by 24.6%.","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":"71305230","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}
R. Hameed, Zaib un-Nisa, M. Rizwan Riaz, S. A. Ali Gillani
Effect of compression casting technique on the water absorption characteristics of low grade 100% Recycled Aggregate Concrete (RAC) of target strength range 11 to 15 MPa to be used in the manufacturing of masonry units is investigated. Water absorption characteristics were determined by performing sorptivity test. Recycled aggregates were produced by crushing laboratory-tested concrete samples of strength ranging from 21 MPa to 28 MPa. Two different ratios of recycled coarse aggregate and recycled fine aggregates were investigated using two different cement contents. For comparison, natural aggregate concrete mixes were also tested. The study parameter included effect of aggregates type, casting pressure, casting technique and cement content on the water absorption properties of RAC. Further, depth of penetration of salt was observed using silver nitrate solution after 3-month immersion in 10% NaCl solution. The results of sorptivity test showed positive impact of compression casting technique on water absorption properties of low grade 100% RAC. Further, results showed that RAC mixes exhibited inferior water absorption properties compared to natural aggregates concrete mixes. Various equations were proposed to predict water absorption of 100% RAC under different conditions of casting pressure and cement content based on initial and secondary rate of water absorption.
{"title":"Effect of compression casting technique on the water absorption properties of concrete made using 100% recycled aggregates","authors":"R. Hameed, Zaib un-Nisa, M. Rizwan Riaz, S. A. Ali Gillani","doi":"10.7764/rdlc.21.2.387","DOIUrl":"https://doi.org/10.7764/rdlc.21.2.387","url":null,"abstract":"Effect of compression casting technique on the water absorption characteristics of low grade 100% Recycled Aggregate Concrete (RAC) of target strength range 11 to 15 MPa to be used in the manufacturing of masonry units is investigated. Water absorption characteristics were determined by performing sorptivity test. Recycled aggregates were produced by crushing laboratory-tested concrete samples of strength ranging from 21 MPa to 28 MPa. Two different ratios of recycled coarse aggregate and recycled fine aggregates were investigated using two different cement contents. For comparison, natural aggregate concrete mixes were also tested. The study parameter included effect of aggregates type, casting pressure, casting technique and cement content on the water absorption properties of RAC. Further, depth of penetration of salt was observed using silver nitrate solution after 3-month immersion in 10% NaCl solution. The results of sorptivity test showed positive impact of compression casting technique on water absorption properties of low grade 100% RAC. Further, results showed that RAC mixes exhibited inferior water absorption properties compared to natural aggregates concrete mixes. Various equations were proposed to predict water absorption of 100% RAC under different conditions of casting pressure and cement content based on initial and secondary rate of water absorption.","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":"71305237","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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