A. Rutkauskas, D. Nagrockienė, G. Skripkiūnas, K. Barkauskas
Abstract Granite rubble is one of the most frequently used aggregates in concrete manufacturing. Granite rubble is considered to be a non-reactive aggregate, however, depending on the quarry, granite may have various impurities including harmful minerals containing active SiO2. The alkali – silica reaction is among the chemical reactions that have a significant effect on the durability of concrete. During the alkali – silica reaction certain forms of silica present in concrete aggregates react with high alkali content leading to formation of hygroscopic gel that expands in humid environment and slowly, although strongly enough degrades concrete structures. Concrete rubble of 3 different fractions was used for the test: 2/8 (Mix D); 11/16 (Mix E); 5/11 (Mix G). The tests revealed that granite rubble used for the tests contained few reactive rocks containing amorphous silica because after 14 days the expansion did not exceed 0.1 % ((D Mix expanded by 0.059 %, E Mix expanded by 0.066 %, G Mix expanded by 0.079 %) according to RILEM AAR-2 test method. After 56 days of testing none of the test specimens demonstrated significant micro-cracking and scaling specific to alkali corrosion; only gel deposits on the surface were observed.
{"title":"Determining Reactivity Level of Granite Aggregate for Concrete","authors":"A. Rutkauskas, D. Nagrockienė, G. Skripkiūnas, K. Barkauskas","doi":"10.2478/cons-2017-0005","DOIUrl":"https://doi.org/10.2478/cons-2017-0005","url":null,"abstract":"Abstract Granite rubble is one of the most frequently used aggregates in concrete manufacturing. Granite rubble is considered to be a non-reactive aggregate, however, depending on the quarry, granite may have various impurities including harmful minerals containing active SiO2. The alkali – silica reaction is among the chemical reactions that have a significant effect on the durability of concrete. During the alkali – silica reaction certain forms of silica present in concrete aggregates react with high alkali content leading to formation of hygroscopic gel that expands in humid environment and slowly, although strongly enough degrades concrete structures. Concrete rubble of 3 different fractions was used for the test: 2/8 (Mix D); 11/16 (Mix E); 5/11 (Mix G). The tests revealed that granite rubble used for the tests contained few reactive rocks containing amorphous silica because after 14 days the expansion did not exceed 0.1 % ((D Mix expanded by 0.059 %, E Mix expanded by 0.066 %, G Mix expanded by 0.079 %) according to RILEM AAR-2 test method. After 56 days of testing none of the test specimens demonstrated significant micro-cracking and scaling specific to alkali corrosion; only gel deposits on the surface were observed.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"12 1","pages":"33 - 37"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83311534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The paper addresses the criteria ensuring a sustainable structure and efficiency of thermal insulation straw-boon slabs in full-scale conditions. Sorption humidity of heat insulator and conditions for fungus build-up on the surface of plant-based filler have been studied. Additives providing high water resistance of silicate glass used as the binder for thermal insulation material have been determined. Tests considering an array of technological parameters and fire behavior of straw-boon slabs confirmed a sustainable structure in the process of installation of thermal insulation material and in case of fire.
{"title":"Ensuring a Sustainable Structure and Efficiency of Thermal Insulation Straw-Boon Slabs in Full-Scale Conditions","authors":"A. Bakatovich, N. Davydenko","doi":"10.2478/cons-2017-0001","DOIUrl":"https://doi.org/10.2478/cons-2017-0001","url":null,"abstract":"Abstract The paper addresses the criteria ensuring a sustainable structure and efficiency of thermal insulation straw-boon slabs in full-scale conditions. Sorption humidity of heat insulator and conditions for fungus build-up on the surface of plant-based filler have been studied. Additives providing high water resistance of silicate glass used as the binder for thermal insulation material have been determined. Tests considering an array of technological parameters and fire behavior of straw-boon slabs confirmed a sustainable structure in the process of installation of thermal insulation material and in case of fire.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"1 1","pages":"4 - 9"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87106770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Microalgae biomass production is recognized as a cost-effective and sustainable alternative to currently used approaches to tertiary wastewater treatment. However, such limitations, as algae biomass separation from water, process efficiency in cold climate and the algae biomass ability to reduce micropollutant content in wastewater hamper this method from full-scale use. This review discusses the identified drawbacks and offers possible improvements and modifications for wastewater phycobioremediation.
{"title":"Review on Challenges and Limitations for Algae-Based Wastewater Treatment","authors":"Aigars Lavrinovičs, T. Juhna","doi":"10.2478/cons-2017-0003","DOIUrl":"https://doi.org/10.2478/cons-2017-0003","url":null,"abstract":"Abstract Microalgae biomass production is recognized as a cost-effective and sustainable alternative to currently used approaches to tertiary wastewater treatment. However, such limitations, as algae biomass separation from water, process efficiency in cold climate and the algae biomass ability to reduce micropollutant content in wastewater hamper this method from full-scale use. This review discusses the identified drawbacks and offers possible improvements and modifications for wastewater phycobioremediation.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"10 1","pages":"17 - 25"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91164161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The research investigation was carried out to determine the effect of different modes of continuity of tension reinforcement bars on the flexural strength of reinforced concrete beams. Nine (9) full size beams (2150 mm × 250 mm × 180 mm) were cast with 2 numbers of 16 mm diameter high yield bars in tension and 10 mm diameter high yield stirrups at 100 mm centres at the shear spans. Three (3) beams each were cast with full length bars (reference), lap-spliced bars and butt-welded reinforcement bars in tension. Twenty-seven (27) 150 mm cubes were also cast to monitor concrete strength. The beams and cubes were cured for twenty-eight (28) days and tested in flexure under four points bending system and in compression respectively. The test results showed that full length bars, lap-spliced and butt-welded bars had an average moment capacity of 25.54 kN·m, 19.16 kN·m and 10.64 kN·m respectively. Lap-spliced beam gave a higher moment of resistance compared to the beams with butt welded steel reinforcing bars. The average midspan deflection of butt welded reinforcement was smaller than that of in the beam with lap spliced type of continuity. It was concluded that continuity using lap spliced bars in tension is more effective and efficient than butt welded continuity. 58.34 %, 25.00 % of the moment capacity of beams with full length reinforcement was lost by using butt weld, without a coupler, and lap spliced bars, respectively.
摘要为确定不同受拉钢筋连续方式对钢筋混凝土梁抗弯强度的影响，进行了研究调查。九(9)根全尺寸梁(2150 mm × 250 mm × 180 mm)浇铸了2根直径16 mm的高屈服筋和直径10 mm的高屈服马镫，位于剪跨中心100 mm处。三(3)根梁分别浇铸了全长钢筋(参考)、搭接钢筋和对焊钢筋。还浇铸了27(27)个150mm的立方体来监测混凝土强度。梁和立方体分别固化二十八(28)天，并分别在四点弯曲系统和压缩下进行弯曲试验。试验结果表明，全长筋、搭接筋和对焊筋的平均弯矩承载力分别为25.54 kN·m、19.16 kN·m和10.64 kN·m。搭接梁比搭接钢筋梁具有更高的抗弯矩。对焊钢筋的平均跨中挠度小于搭接连续梁的平均跨中挠度。结果表明，搭接钢筋的拉伸连续比对接焊接的拉伸连续更有效。采用对焊、不加耦合器和搭接钢筋分别使带全长配筋梁的弯矩承载力损失58.34%、25.00%。
{"title":"Effect of Mode of Continuity of Tension Reinforcement Bars on Flexural Strength of R.C. Beam","authors":"K. B. Osifala, O. Omokungbe, M. Salau","doi":"10.2478/cons-2017-0007","DOIUrl":"https://doi.org/10.2478/cons-2017-0007","url":null,"abstract":"Abstract The research investigation was carried out to determine the effect of different modes of continuity of tension reinforcement bars on the flexural strength of reinforced concrete beams. Nine (9) full size beams (2150 mm × 250 mm × 180 mm) were cast with 2 numbers of 16 mm diameter high yield bars in tension and 10 mm diameter high yield stirrups at 100 mm centres at the shear spans. Three (3) beams each were cast with full length bars (reference), lap-spliced bars and butt-welded reinforcement bars in tension. Twenty-seven (27) 150 mm cubes were also cast to monitor concrete strength. The beams and cubes were cured for twenty-eight (28) days and tested in flexure under four points bending system and in compression respectively. The test results showed that full length bars, lap-spliced and butt-welded bars had an average moment capacity of 25.54 kN·m, 19.16 kN·m and 10.64 kN·m respectively. Lap-spliced beam gave a higher moment of resistance compared to the beams with butt welded steel reinforcing bars. The average midspan deflection of butt welded reinforcement was smaller than that of in the beam with lap spliced type of continuity. It was concluded that continuity using lap spliced bars in tension is more effective and efficient than butt welded continuity. 58.34 %, 25.00 % of the moment capacity of beams with full length reinforcement was lost by using butt weld, without a coupler, and lap spliced bars, respectively.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"19 1","pages":"47 - 53"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78776373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The paper presents results of analysis of thermal insulation materials based on plant fibers. It is suggested to use secondary raw materials of flax processing plants – flax noils – as a fiberfill in production of insulating slabs. The paper presents results of research on the microstructure of flax noils and flax fibers conducted using light microscopy and electron microscopy, respectively. A set of experiments aimed at determining physical and mechanical characteristics of thermal insulation materials has been conducted. Test results attest higher efficiency of the insulating slabs made from flax noils in comparison with flax fiber-based thermal insulation material. The main factors facilitating reduction of thermal conductivity coefficient of thermal insulation material made from flax noils have been determined.
{"title":"Influence of the Fibrous Structure on the Physical and Mechanical Characteristics of Insulating Slabs from Flax Noils","authors":"A. Bakatovich, S. Romanovskiy","doi":"10.2478/cons-2017-0002","DOIUrl":"https://doi.org/10.2478/cons-2017-0002","url":null,"abstract":"Abstract The paper presents results of analysis of thermal insulation materials based on plant fibers. It is suggested to use secondary raw materials of flax processing plants – flax noils – as a fiberfill in production of insulating slabs. The paper presents results of research on the microstructure of flax noils and flax fibers conducted using light microscopy and electron microscopy, respectively. A set of experiments aimed at determining physical and mechanical characteristics of thermal insulation materials has been conducted. Test results attest higher efficiency of the insulating slabs made from flax noils in comparison with flax fiber-based thermal insulation material. The main factors facilitating reduction of thermal conductivity coefficient of thermal insulation material made from flax noils have been determined.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"94 1","pages":"10 - 16"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85852272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This paper reports the effect of transverse reinforcement on tensile reinforcement splice strength of epoxy coated reinforcing bars. Thirty six (36) full size beams of varying lengths and sectional dimensions with lap spliced bars in constant moment region were cast and tested in a four point bending system. The beams were cast with three high yield diameter bars, namely 16 mm, 20 mm and 28 mm. 8 mm and 10 mm diameter high yield stirrups were introduced over the lap in an attempt to study the effect of stirrups on bond performance of epoxy coated reinforcing bars. The ultimate moment from the tests were used to determine the stress developed in the steel rods. The ratios of the test bond stresses and bond stress values using the tensile reinforcement yield stress τt/τy were used for comparison of the parameter under investigation. Transverse reinforcement was found to increase the splice strength of epoxy coated reinforcing bars and the larger the diameter of stirrup the better the improvement of the bond efficiency.
{"title":"Influence of Stirrups on Overlap Splice Strength of Epoxy Coated Deformed Bars","authors":"K. B. Osifala, T. Akeju","doi":"10.2478/cons-2017-0006","DOIUrl":"https://doi.org/10.2478/cons-2017-0006","url":null,"abstract":"Abstract This paper reports the effect of transverse reinforcement on tensile reinforcement splice strength of epoxy coated reinforcing bars. Thirty six (36) full size beams of varying lengths and sectional dimensions with lap spliced bars in constant moment region were cast and tested in a four point bending system. The beams were cast with three high yield diameter bars, namely 16 mm, 20 mm and 28 mm. 8 mm and 10 mm diameter high yield stirrups were introduced over the lap in an attempt to study the effect of stirrups on bond performance of epoxy coated reinforcing bars. The ultimate moment from the tests were used to determine the stress developed in the steel rods. The ratios of the test bond stresses and bond stress values using the tensile reinforcement yield stress τt/τy were used for comparison of the parameter under investigation. Transverse reinforcement was found to increase the splice strength of epoxy coated reinforcing bars and the larger the diameter of stirrup the better the improvement of the bond efficiency.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"18 1","pages":"38 - 46"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75284145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Vaganov, A. Kireev, S. Avdeev, G. Sahmenko, M. Sinka
Abstract The article discusses possibilities for creating sustainable concrete compositions from local dolomite raw materials. In the first part of the article, practical examples of the use of dolomite quarry by-products (siftings) as a component of concrete mixes are summarized. The second part of article presents experimental study on obtaining caustic dolomite. This method allows obtaining the product with higher added value. Local dolomite raw materials are used and appropriate regimes of thermal treatment have been tested.
{"title":"Prospects for Effective Use of Dolomite in Concrete Compositions","authors":"V. Vaganov, A. Kireev, S. Avdeev, G. Sahmenko, M. Sinka","doi":"10.1515/cons-2016-0008","DOIUrl":"https://doi.org/10.1515/cons-2016-0008","url":null,"abstract":"Abstract The article discusses possibilities for creating sustainable concrete compositions from local dolomite raw materials. In the first part of the article, practical examples of the use of dolomite quarry by-products (siftings) as a component of concrete mixes are summarized. The second part of article presents experimental study on obtaining caustic dolomite. This method allows obtaining the product with higher added value. Local dolomite raw materials are used and appropriate regimes of thermal treatment have been tested.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"24 1","pages":"27 - 32"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89240657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This research aims to investigate the effect of introducing different mineral admixtures on the mechanical properties of concrete. The research is focused on optimizing the properties of fresh and hardened concrete, looking in particular at how factors such as slump, unit weight, air entrancement, compressive strength, tensile strength, flexural strength and modulus of elasticity are affected by different mineral admixtures in a concrete mix. Different mineral admixtures are used, namely silica fume, limestone and ultra-fine gypsum, and for the tests each mineral admixture replaced 25 % of the cement. The paper also compares the performance of the fresh and hardened properties of concrete.
{"title":"Influence of Mineral Admixtures on the Mechanical Properties of Fresh and Hardened Concrete","authors":"Sami Elshafie, M. Boulbibane, Gareth Whittleston","doi":"10.1515/cons-2016-0005","DOIUrl":"https://doi.org/10.1515/cons-2016-0005","url":null,"abstract":"Abstract This research aims to investigate the effect of introducing different mineral admixtures on the mechanical properties of concrete. The research is focused on optimizing the properties of fresh and hardened concrete, looking in particular at how factors such as slump, unit weight, air entrancement, compressive strength, tensile strength, flexural strength and modulus of elasticity are affected by different mineral admixtures in a concrete mix. Different mineral admixtures are used, namely silica fume, limestone and ultra-fine gypsum, and for the tests each mineral admixture replaced 25 % of the cement. The paper also compares the performance of the fresh and hardened properties of concrete.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"16 1","pages":"12 - 4"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80140928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Elvija Namsone, G. Sahmenko, A. Korjakins, E. Namsone
Abstract Nowadays energy-efficient use of building resources is getting more and more popular. Technological developments have promoted production of new building materials with improved physical, mechanical and thermal properties. Foamed concrete with porous aggregate can serve as an alternative material for the existing lightweight concrete materials. This building material shows good mechanical and thermal properties, as well as capillary absorption and shrinkage test results that attest the longevity of this building material.
{"title":"Influence of Porous Aggregate on the Properties of Foamed Concrete","authors":"Elvija Namsone, G. Sahmenko, A. Korjakins, E. Namsone","doi":"10.1515/cons-2016-0006","DOIUrl":"https://doi.org/10.1515/cons-2016-0006","url":null,"abstract":"Abstract Nowadays energy-efficient use of building resources is getting more and more popular. Technological developments have promoted production of new building materials with improved physical, mechanical and thermal properties. Foamed concrete with porous aggregate can serve as an alternative material for the existing lightweight concrete materials. This building material shows good mechanical and thermal properties, as well as capillary absorption and shrinkage test results that attest the longevity of this building material.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"44 1","pages":"13 - 20"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75434224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Prevalence of Legionella in drinking water distribution systems is a widespread problem. Outbreaks of Legionella caused diseases occur despite various disinfectants are used in order to control Legionella. Conventional methods like thermal disinfection, silver/copper ionization, ultraviolet irradiation or chlorine-based disinfection have not been effective in the long term for control of biofilm bacteria. Therefore, research to develop more effective disinfection methods is still necessary.
{"title":"Conventional and Alternative Disinfection Methods of Legionella in Water Distribution Systems – Review","authors":"Daina Pūle","doi":"10.1515/cons-2016-0007","DOIUrl":"https://doi.org/10.1515/cons-2016-0007","url":null,"abstract":"Abstract Prevalence of Legionella in drinking water distribution systems is a widespread problem. Outbreaks of Legionella caused diseases occur despite various disinfectants are used in order to control Legionella. Conventional methods like thermal disinfection, silver/copper ionization, ultraviolet irradiation or chlorine-based disinfection have not been effective in the long term for control of biofilm bacteria. Therefore, research to develop more effective disinfection methods is still necessary.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"46 1","pages":"21 - 26"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86128178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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