University of GuilanConcrete Research2008-42423220100701Investigation on Application of Low Percentages of Nano-Particles As A Replacement of Reduced Cement in The High Strength Concrete (Mechanical and Micro-Structural Investigation)Investigation on Application of Low Percentages of Nano-Particles As A Replacement of Reduced Cement in The High Strength Concrete (Mechanical and Micro-Structural Investigation)1725813FAPayamHosseiniHadiBahadoriEbrahimEslamiSiavashVahidiJournal Article19700101In this study the replacement of cement by nano-silica particles is investigated. This replacement ratio is not one by one. Up to now, the replacement of cement by any kind of pozzolanic or powder material has been held equal to the percent of cement reduction. Consequently, in this investigation, nano-silica particles were added in low quantities (0-3%), while concurrently the reduction of cement was applied with constant higher percentage (10% cement reduction). This trend was considered based on different reasons. Firstly, nano-particles do not scatter in the mixture appropriately because of their high specific surface area; so they may produce clogs with low strength transition zone. Hence the application of large amounts of nano-silica particles to develop the strength and durability of concrete is not practical and useful. The second reason, which is the main objective of this study, is replacement of high amount of cement by relatively low amount of nano-particles. Using nano-particles even with the existence of proper apparatus to disperse these particles are not economical regarding their high expenses. On the other hand, the reduction of cement in conventional and logical amounts have been applied which clearly manifests the nano-particles ability. According to the high usage of cement as the main binding material, the lower cement quantity will result in lower strength of secondary concretes respect to basic mixtureIn this study the replacement of cement by nano-silica particles is investigated. This replacement ratio is not one by one. Up to now, the replacement of cement by any kind of pozzolanic or powder material has been held equal to the percent of cement reduction. Consequently, in this investigation, nano-silica particles were added in low quantities (0-3%), while concurrently the reduction of cement was applied with constant higher percentage (10% cement reduction). This trend was considered based on different reasons. Firstly, nano-particles do not scatter in the mixture appropriately because of their high specific surface area; so they may produce clogs with low strength transition zone. Hence the application of large amounts of nano-silica particles to develop the strength and durability of concrete is not practical and useful. The second reason, which is the main objective of this study, is replacement of high amount of cement by relatively low amount of nano-particles. Using nano-particles even with the existence of proper apparatus to disperse these particles are not economical regarding their high expenses. On the other hand, the reduction of cement in conventional and logical amounts have been applied which clearly manifests the nano-particles ability. According to the high usage of cement as the main binding material, the lower cement quantity will result in lower strength of secondary concretes respect to basic mixturehttps://jcr.guilan.ac.ir/article_813_b990f7923d76e0038ac91ab31f4a0588.pdfUniversity of GuilanConcrete Research2008-42423220100701Development of Thin-Wall Element Construction by Utilization of Nano-SiO2 ParticlesDevelopment of Thin-Wall Element Construction by Utilization of Nano-SiO2 Particles916814FAPayamHosseiniAli RezaR.KhalooAbbasBooshehrianJournal Article19700101In this study, the application of high performance mortar in order to cast thin ferrocement element by the use of nano-silica particles is investigated. Variable parameters consist of the amount of nano-silica particles respect to cement quantity in the ordinary Portland cement mortar (1%, 2%, and 3%) and super-plasticizer used to achieve similar workability. To compare the mixes, mortars with high and similar workability were casted which guarantee the identical pomp-ability of ferrocement to cast the elements. In addition, regarding to examining the micro-structure and mechanical properties of recycled concrete, Scanning Electron Microscopy (SEM) test and compressive strength have been applied respectively.In this study, the application of high performance mortar in order to cast thin ferrocement element by the use of nano-silica particles is investigated. Variable parameters consist of the amount of nano-silica particles respect to cement quantity in the ordinary Portland cement mortar (1%, 2%, and 3%) and super-plasticizer used to achieve similar workability. To compare the mixes, mortars with high and similar workability were casted which guarantee the identical pomp-ability of ferrocement to cast the elements. In addition, regarding to examining the micro-structure and mechanical properties of recycled concrete, Scanning Electron Microscopy (SEM) test and compressive strength have been applied respectively.https://jcr.guilan.ac.ir/article_814_0749188c376879ab2ade018059048972.pdfUniversity of GuilanConcrete Research2008-42423220100701Increasment of Durability of Concre -te Against Sorrosion Acid With Li -me StoneIncreasment of Durability of Concre -te Against Sorrosion Acid With Li -me Stone7179815FAAbdollahRashidiSeyed MohsenSadatiyanFarshadVazin RamPietN.L. LensJournal Article19700101Concrete corrosion in Water and wastewater network pipes, treatment factory structures, slaughterhouse and structures in industrial zone with acidic rain always is a serious problem. Concrete corrosion in water and wastewater environment is usually generated and accelerated by biological activities. Hydrogen sulfide in wastewater, efflux in sewer atmosphere and with biologic activities of special bacteria on concrete surface, it changed to sulfuric acid. Generated sulfuric acid can corrode concrete. Also acidicrain in polluted industrial zones can corrode concrete structures in these locations.
In this research effect of using limestone Lime aggregate instead of silicic aggregate on concrete durability against 1 percent sulfuric Acid solution is evaluated. Only the paste of the concrete that was made by silicic aggregate can react with corrosive solution. So concrete surface becomes rough and there are many places for growing bacteria and penetrating corrosive solution between paste and aggregate. After corrosion development, uncorroded aggregate without paste, is disparted from concrete bulk. But in the case of the concrete that was made by limestone aggregate, paste and aggregate are corroded in same rate and there is more material to react with corrosive solution. Also in the case of limestone aggregate, there is a micro neutralized environment around concrete surface, that is prevent corrosion process.
For evaluating this change in concrete material, chemical accelerated corrosion test method according to ASTM-C267-01 standard is used. There are two sets of cylindrical concrete speci -men that was submerged into 1 percent sulfuric acid solution. These two sets are similar in water/ cement ratio, size of aggregates, cement type, molding and curing conditions. But there is just one difference about using silicic aggregate for first series and limestone aggregate for second series of samples. Weight, dimension, pressure strength and appearance of specimen were measured at different immersion periods. Data analyses showed that using limestone aggregate has a good effect on concrete durability. According to test results, in comparison to silicic concrete, the limestone concrete showed about 50% increase in durability against acidic corro -sion.Concrete corrosion in Water and wastewater network pipes, treatment factory structures, slaughterhouse and structures in industrial zone with acidic rain always is a serious problem. Concrete corrosion in water and wastewater environment is usually generated and accelerated by biological activities. Hydrogen sulfide in wastewater, efflux in sewer atmosphere and with biologic activities of special bacteria on concrete surface, it changed to sulfuric acid. Generated sulfuric acid can corrode concrete. Also acidicrain in polluted industrial zones can corrode concrete structures in these locations.
In this research effect of using limestone Lime aggregate instead of silicic aggregate on concrete durability against 1 percent sulfuric Acid solution is evaluated. Only the paste of the concrete that was made by silicic aggregate can react with corrosive solution. So concrete surface becomes rough and there are many places for growing bacteria and penetrating corrosive solution between paste and aggregate. After corrosion development, uncorroded aggregate without paste, is disparted from concrete bulk. But in the case of the concrete that was made by limestone aggregate, paste and aggregate are corroded in same rate and there is more material to react with corrosive solution. Also in the case of limestone aggregate, there is a micro neutralized environment around concrete surface, that is prevent corrosion process.
For evaluating this change in concrete material, chemical accelerated corrosion test method according to ASTM-C267-01 standard is used. There are two sets of cylindrical concrete speci -men that was submerged into 1 percent sulfuric acid solution. These two sets are similar in water/ cement ratio, size of aggregates, cement type, molding and curing conditions. But there is just one difference about using silicic aggregate for first series and limestone aggregate for second series of samples. Weight, dimension, pressure strength and appearance of specimen were measured at different immersion periods. Data analyses showed that using limestone aggregate has a good effect on concrete durability. According to test results, in comparison to silicic concrete, the limestone concrete showed about 50% increase in durability against acidic corro -sion.https://jcr.guilan.ac.ir/article_815_a5155227b115104c48ba3a6c209b84ec.pdfUniversity of GuilanConcrete Research2008-42423220100701Effect of Polypropylene Fiber on Sh -rinkage, Rheology and Mechanical Properties of Self Compacting MortarEffect of Polypropylene Fiber on Sh -rinkage, Rheology and Mechanical Properties of Self Compacting Mortar5969816FAImanMehdipourMohammadShekarchizadehN.Ali LiberJournal Article19700101Self-consolidating concrete (SCC) is a new generation of high-performance concrete that can exhibit high deformability and can be compacted under its own weight without any external consolidation and with limited signs of segregation. Mortar serves as the basis for the workability properties of self-compacting concrete (SCC) and these properties could be assessed by self-compacting mortars (SCM). In fact, assessing the properties of SCM is an integral part of SCC design. In general, the tested SCC mixtures had higher cracking potential than the reference high-performance and conventional concretes. This may be due to the higher paste volume of SCM that resulted in greater drying shrinkage. One of the most important properties regarding the design and the durability of structures is shrinkage which seems to be increased for SCC. One highly effective technique of controlling shrinkage cracking is by reinforcing concrete with fibers. Randomly distributed fibers of steel, polypropylene, etc. provide bridging forces across cracks and thus prevent them from growing.
This research focuses on the development of shrinkage in self-compacting mortar (SCM) cured at temperature of 20 ± 3°C and rein -forced with polypropylene fiber. Nine mortar mixtures are prepared containing 0 to 0.7 per -cent of 6 and 12 mm length polypropylene fibers. The shrinkage measurements of hard -ened mortar were obtained since removing the molds and the measurements were continued up to six months. The effect of fiber content on total shrinkage of mortar was investigated by the shrinkage curves. Besides, the rheological properties of fresh fiber reinforced mortar are investigated by mini-slump test and the 28 days compressive, tensile and flexural strength of the mixtures are determined. Test results indicated that synergistic effects resulting from fibers with optimum volume fraction allow to develop SCMs in which excellent shrinkage control and mechanical properties can be obtained without jeopardizing the flow properties.Self-consolidating concrete (SCC) is a new generation of high-performance concrete that can exhibit high deformability and can be compacted under its own weight without any external consolidation and with limited signs of segregation. Mortar serves as the basis for the workability properties of self-compacting concrete (SCC) and these properties could be assessed by self-compacting mortars (SCM). In fact, assessing the properties of SCM is an integral part of SCC design. In general, the tested SCC mixtures had higher cracking potential than the reference high-performance and conventional concretes. This may be due to the higher paste volume of SCM that resulted in greater drying shrinkage. One of the most important properties regarding the design and the durability of structures is shrinkage which seems to be increased for SCC. One highly effective technique of controlling shrinkage cracking is by reinforcing concrete with fibers. Randomly distributed fibers of steel, polypropylene, etc. provide bridging forces across cracks and thus prevent them from growing.
This research focuses on the development of shrinkage in self-compacting mortar (SCM) cured at temperature of 20 ± 3°C and rein -forced with polypropylene fiber. Nine mortar mixtures are prepared containing 0 to 0.7 per -cent of 6 and 12 mm length polypropylene fibers. The shrinkage measurements of hard -ened mortar were obtained since removing the molds and the measurements were continued up to six months. The effect of fiber content on total shrinkage of mortar was investigated by the shrinkage curves. Besides, the rheological properties of fresh fiber reinforced mortar are investigated by mini-slump test and the 28 days compressive, tensile and flexural strength of the mixtures are determined. Test results indicated that synergistic effects resulting from fibers with optimum volume fraction allow to develop SCMs in which excellent shrinkage control and mechanical properties can be obtained without jeopardizing the flow properties.https://jcr.guilan.ac.ir/article_816_4830a3026e076a62227c9d61fd681d4d.pdfUniversity of GuilanConcrete Research2008-42423220100701Impact of Plasticizers on The Quality of Concrete and The Reduction of The Cement ContentImpact of Plasticizers on The Quality of Concrete and The Reduction of The Cement Content4957817FAM.TadaionHaniHonarmandMoosaKalhoriJournal Article19700101Preservation of our environment, the need to a balanced consumption of the natural resources, particularly fossil fuels, and the need to reduce greenhouse gas emissions will all make us decrease our cement consumption especially clinker. As a result, in producing the concrete and the mortar, we must take a lower consumption of cement in to our account as much as possible without hurting the volume of construction in the country.
In this article, we have shown that cement content is reduced with a constant w/c ratio and its impacts on the fresh and hardened concrete are studied. In continuation of the research, we reduced the w/c ratio (in 4 different ratios) and again the cement content was reduced in order to study the impacts of this reduction on lower ratios of w/c.
It is clear that by reducing the cement mix (reducing cement content and w/c ratio), the workability of the concrete will be highly reduced. To treat this problem, we can use plasticizers and superplasticizers which are explained thoroughly in the following sections. According to the obtained test results on fresh and hardened concrete, it can be concluded that reducing cement content (360kg to 450kg per m3) at the constant water / cement ratio will result in better strength and slump. On the other hand with reduction of w/c and adding super plasticizers for having better workability and flows more durability and higher strength could be gained.Preservation of our environment, the need to a balanced consumption of the natural resources, particularly fossil fuels, and the need to reduce greenhouse gas emissions will all make us decrease our cement consumption especially clinker. As a result, in producing the concrete and the mortar, we must take a lower consumption of cement in to our account as much as possible without hurting the volume of construction in the country.
In this article, we have shown that cement content is reduced with a constant w/c ratio and its impacts on the fresh and hardened concrete are studied. In continuation of the research, we reduced the w/c ratio (in 4 different ratios) and again the cement content was reduced in order to study the impacts of this reduction on lower ratios of w/c.
It is clear that by reducing the cement mix (reducing cement content and w/c ratio), the workability of the concrete will be highly reduced. To treat this problem, we can use plasticizers and superplasticizers which are explained thoroughly in the following sections. According to the obtained test results on fresh and hardened concrete, it can be concluded that reducing cement content (360kg to 450kg per m3) at the constant water / cement ratio will result in better strength and slump. On the other hand with reduction of w/c and adding super plasticizers for having better workability and flows more durability and higher strength could be gained.https://jcr.guilan.ac.ir/article_817_8cceed967c0b741a1f8bcdb4b88759fb.pdfUniversity of GuilanConcrete Research2008-42423220100701Mechanical Properties of Waste Crumb Tire Rubberized ConcreteMechanical Properties of Waste Crumb Tire Rubberized Concrete3947818FAKiachehrBehfarniaMohsenHasanzadehMohsenEtemadiHomayoonBozorgpurJournal Article19700101One of the critical problems in the world is disposal of waste materials. One of this waste materials is tire rubber that is not decomposable and so is noticed. Annually exceeding of 10 million waste tire rubber are stockpiled in iran. Recycling of waste tire rubber is a suitable way for both disposal waste materials and reach to positive properties of concrete. On the basis of researchers studies, using of waste tire rubber in concrete cause to improve mechanical and dynamic properties of concrete such as energy absorption, ductility and cracking resistance. A series of experimental studies were carried out to evaluate mechanical properties of concrete containing waste crumb tire rubber. In this study, 12% and 18% of fine aggregates were replaced with truck waste crumb tire rubber without wire with mesh 15-20 in concrete mix design and then 3 groups of concrete, totally 18 samples, were constructed. Concrete mix design was according to BS and was 0.54 constantly. 3 day compression strength and water absorption percent of samples were studied. Dry and saturated specific weight also determined. On the basis of results, Use of crumb tire rubber in concrete cause to decrease compression strength and specific weight but increase water absorption percent of concrete. In this article, based upon the results, charts are presented and optimum data are also determined.One of the critical problems in the world is disposal of waste materials. One of this waste materials is tire rubber that is not decomposable and so is noticed. Annually exceeding of 10 million waste tire rubber are stockpiled in iran. Recycling of waste tire rubber is a suitable way for both disposal waste materials and reach to positive properties of concrete. On the basis of researchers studies, using of waste tire rubber in concrete cause to improve mechanical and dynamic properties of concrete such as energy absorption, ductility and cracking resistance. A series of experimental studies were carried out to evaluate mechanical properties of concrete containing waste crumb tire rubber. In this study, 12% and 18% of fine aggregates were replaced with truck waste crumb tire rubber without wire with mesh 15-20 in concrete mix design and then 3 groups of concrete, totally 18 samples, were constructed. Concrete mix design was according to BS and was 0.54 constantly. 3 day compression strength and water absorption percent of samples were studied. Dry and saturated specific weight also determined. On the basis of results, Use of crumb tire rubber in concrete cause to decrease compression strength and specific weight but increase water absorption percent of concrete. In this article, based upon the results, charts are presented and optimum data are also determined.https://jcr.guilan.ac.ir/article_818_d96c226c94f9a493b6d52b3340433f66.pdfUniversity of GuilanConcrete Research2008-42423220100701Durability of Concrete and Mortars Containing Lim Stone Powder in High Density Sulfate EnviromentDurability of Concrete and Mortars Containing Lim Stone Powder in High Density Sulfate Enviroment2737819FAMehdiMehdikhaniAli AkbarRamezanianpourEbrahimGhiyasvandMohammad EhsanKameliJournal Article19700101Sulfate attack is one of the most important problems concerning the durability of concrete structures. In this paper, the sulfate resistance of concrete and mortar specimens made from ordinary Portland cement containing limestone powder was studied. Strength reductions and mass changes of concrete specimens immersed in 10% Na2SO4 and MgSO4 solutions and Expansion of mortar prisms immersed in 5% and 10% Na2SO4 and MgSO4 solutions were monitored. It was observed that compressive strength decreases with the limestone replacement percent and also, deterioration is severer, the higher the concentration content sulfate.Sulfate attack is one of the most important problems concerning the durability of concrete structures. In this paper, the sulfate resistance of concrete and mortar specimens made from ordinary Portland cement containing limestone powder was studied. Strength reductions and mass changes of concrete specimens immersed in 10% Na2SO4 and MgSO4 solutions and Expansion of mortar prisms immersed in 5% and 10% Na2SO4 and MgSO4 solutions were monitored. It was observed that compressive strength decreases with the limestone replacement percent and also, deterioration is severer, the higher the concentration content sulfate.https://jcr.guilan.ac.ir/article_819_a1e16217b6d09a5e82ededcedaf328fc.pdf