The development of recycled aggregate concrete(RAC)provides a new approach to limiting the waste of natural resources.In the present study,the mechanical properties and deformability of RACs were improved by adding ba...The development of recycled aggregate concrete(RAC)provides a new approach to limiting the waste of natural resources.In the present study,the mechanical properties and deformability of RACs were improved by adding basalt fibers(BFs)and using external restraints,such as a fiber-reinforced polymer(FRP)jacket or a PVC pipe.Samples were tested under axial compression.The results showed that RAC(50%replacement of aggregate)containing 0.2%BFs had the best mechanical properties.Using either BFs or PVC reinforcement had a slight effect on the loadbearing capacity and mode of failure.With different levels of BFs,the compressive strengths of the specimens reinforced with 1-layer and 3-layer basalt fiber reinforced polymer(BFRP)increased by 6.7%–10.5%and 16.5%–23.7%,respectively,and the ultimate strains increased by 48.5%–80.7%and 97.1%–141.1%,respectively.The peak stress of the 3-layer BFRP-PVC increased by 42.2%,and the ultimate strain improved by 131.3%,relative to the control.This reinforcement combined the high tensile strength of BFRP,which improved the post-peak behavior,and PVC,which enhanced the structural durability.In addition,to investigate the influence of the various constraints on compressive behavior,the stress-strain response was analyzed.Based on the analysis of experimental results,a peak stress-strain model and an amended ultimate stress-strain model were proposed.The models were verified as well;the result showed that the predictions from calculations are generally consistent with the experimental data(error within 10%).The results of this study provide a theoretical basis and reference for future applications of fiber-reinforced recycled concrete.展开更多
To improve the shear and flexural capacity of flexural members, the steel and basalt fibers were used in model beams tested under flexure. Three series of single span free supported model beams were prepared from SFRC...To improve the shear and flexural capacity of flexural members, the steel and basalt fibers were used in model beams tested under flexure. Three series of single span free supported model beams were prepared from SFRC （steel fiber reinforced concrete） with longitudinal steel reinforcement （steel ratio of 1.2 %） and varied spacing of steel stirrups and they were tested till failure. Another three series of BFRC （basalt fiber reinforced concrete） double-span model beams with a span of 2 mm~ 1,000 mm and cross section 180 mm ~ 80 mm were tested. During the tests till to the failure the beam reactions, vertical deflections and horizontal strains in concrete were registered, to clarify the range of redistribution of bending moments and shear forces over the span of the beams. Almost all the tested model beams failed in shear, showing visible influence of steel and basalt fibers on the shear capacity of the tested beams. The tests results confirmed that steel and basalt fibers in reinforced concrete beams can partially replace （in certain cases） the traditional steel stirrups calculated for shear.展开更多
Reinforced concrete （RC） beams externally bonded with basalt fiber reinforced polymer （BFRP） are experimentally investigated by using different numbers of bonding plies, transverse anchorages as well as the initia...Reinforced concrete （RC） beams externally bonded with basalt fiber reinforced polymer （BFRP） are experimentally investigated by using different numbers of bonding plies, transverse anchorages as well as the initial conditions of strengthened beams. The performances of the BFRP strengthening are compared with those of the carbon fiber reinforced polymer （CFRP） and the glass fiber reinforced polymer （GFRP） under the same experimental condition. Experimental results indicate that the strength and ductility of the strengthened beam with two plies of the BFRP are improved remarkably than those with one ply. The strengthening effects of the BFRP lie between those of the CFRP and the GFRP. The BFRP strengthening is little influenced by pre-cracks of concrete. Most failures are caused by interfaciai debonding induced by flexural cracks in the experiment. Clamping of Uwraps along the whole beam is less efficient than endpoint anchorage for increasing the ultimate load of the strengthened beam. Finally, the models suggested by the five guidelines for predicting the debonding strain of the CFRP are extended to the BFRP and the conservative estimates of the debonding strain of the BFRP are given as well.展开更多
This paper presents an experimental study on the alkali-resistant properties of basalt fiber reinforced polymers （BFRP） bars under a typical concrete environment. BFRP bars were embedded in concrete and exposed to d...This paper presents an experimental study on the alkali-resistant properties of basalt fiber reinforced polymers （BFRP） bars under a typical concrete environment. BFRP bars were embedded in concrete and exposed to different aggressive environments, including tap water, saline solution and ambient temperature environments, to study the effects of the type of solution and relative humidity （RH） on the durability of BFRP. Meanwhile, BFRP bars were directly immersed in an alkaline solution for comparison. The acceleration factor describing the relationship between the alkaline solution immersion and the moisture-saturated concrete was also obtained. Aging was accelerated with a temperature of 60 ℃. The results show that the chloridion in the saline solution does not have any harmful effects on the degradation of the concrete-encased BFRP bars. Contact with an alkaline （high pH） concrete pore-water solution is the primary reason for the degradation of the BFRP bars. The degradation rate of concrete-encased BFRP bars is accelerated when a high temperature and a high humidity are present simultaneously. The degradation rate of the BFRP bars is relatively quick at the initial stage and slows down with exposure time. Results show that the degradation of 2.18 years in moisture-saturated concrete at 60 ℃corresponds to that of one year when directly immersed in an alkaline solution （other conditions remaining the same） for the BFRP bars analyzed.展开更多
This paper discusses a new fibrous composite known as continuous basalt fiber reinforced polymer /plastic(BFRP).Compared with other fiber reinforced polymer/plastic,BFRP has many advantages,such as ductility,high ther...This paper discusses a new fibrous composite known as continuous basalt fiber reinforced polymer /plastic(BFRP).Compared with other fiber reinforced polymer/plastic,BFRP has many advantages,such as ductility,high thermal resistance,corrosion resistance and economic cost.To test mechanical properties and failure modes of flexural members strengthened with BFRP,flexural experiment is conducted on four two-span T-section continuous beams strengthened with BFRP and one un-strengthened comparative beam.The experimental result shows that the strengthened beams perform remarkably in terms of yield strength,ultimate strength and ductility.BFRP has good prospects in retrofitting and strengthening of concrete structures which require good ductility and corrosion resistance.展开更多
In this study,a novel diagonally inserted bar-type basalt fiber reinforced polymer(BFRP)connector was proposed,aiming to achieve both construction convenience and partially composite behavior in precast concrete sandw...In this study,a novel diagonally inserted bar-type basalt fiber reinforced polymer(BFRP)connector was proposed,aiming to achieve both construction convenience and partially composite behavior in precast concrete sandwich panels(PCSPs).First,pull-out tests were conducted to evaluate the anchoring performance of the connector in concrete after exposure to different temperatures.Thereafter,direct shear tests were conducted to investigate the shear performance of the connector.After the test on the individual performance of the connector,five façade PCSP specimens with the bar-type BFRP connector were fabricated,and the out-of-plane flexural performance was tested under a uniformly distributed load.The investigating parameters included the panel length,opening condition,and boundary condition.The results obtained in this study primarily indicated that 1)the bar-type BFRP connector can achieve a reliable anchorage system in concrete;2)the bar-type BFRP connector can offer sufficient stiffness and capacity to achieve a partially composite PCSP;3)the boundary condition of the panel considerably influenced the out-of-plane flexural performance and composite action of the investigated façade PCSP.展开更多
To explore the law of energy evolution and the change of damage before and after specimen failure,the conventional triaxial compression tests(5,10,15,20,and 30 MPa)of basalt fiber reinforced concrete(BFRC)with differe...To explore the law of energy evolution and the change of damage before and after specimen failure,the conventional triaxial compression tests(5,10,15,20,and 30 MPa)of basalt fiber reinforced concrete(BFRC)with different fiber volume fractions(0,0.2%and 0.4%)were carried out by MTS816 rock testing system,and the cyclic loading and unloading tests of BFRC with a fiber content of 0.2%were carried out.The experimental results show that the peak strength and strain of BFRC increase with the increase of confining pressure.Tensile failure occurs under low confining pressure,and shear failure occurs under high confining pressure.The best volume fraction of fiber is 0.2%.Under different confining pressures,the input energy,elastic energy,plastic properties,and dissipated energy of the samples first increase and then decrease to a stable level.The elastic energy and dissipated energy reach the maximum near the peak stress,while the input energy and plastic properties reach the maximum at the peak.At the same time,the damage increases continuously with the input of load under different confining pressures,indicating that the failure of the specimen is a process of energy accumulation.展开更多
基金supported by the Natural Science Foundation Project of Liaoning Provincial Department of Education of China under Grant No.JJL201915404,Zhejiang Provincial Natural Science Foundation of China under Grant No.LQ22E080024 and Zhejiang Province Department of Education Fund of China under Grant No.Y202146776.
文摘The development of recycled aggregate concrete(RAC)provides a new approach to limiting the waste of natural resources.In the present study,the mechanical properties and deformability of RACs were improved by adding basalt fibers(BFs)and using external restraints,such as a fiber-reinforced polymer(FRP)jacket or a PVC pipe.Samples were tested under axial compression.The results showed that RAC(50%replacement of aggregate)containing 0.2%BFs had the best mechanical properties.Using either BFs or PVC reinforcement had a slight effect on the loadbearing capacity and mode of failure.With different levels of BFs,the compressive strengths of the specimens reinforced with 1-layer and 3-layer basalt fiber reinforced polymer(BFRP)increased by 6.7%–10.5%and 16.5%–23.7%,respectively,and the ultimate strains increased by 48.5%–80.7%and 97.1%–141.1%,respectively.The peak stress of the 3-layer BFRP-PVC increased by 42.2%,and the ultimate strain improved by 131.3%,relative to the control.This reinforcement combined the high tensile strength of BFRP,which improved the post-peak behavior,and PVC,which enhanced the structural durability.In addition,to investigate the influence of the various constraints on compressive behavior,the stress-strain response was analyzed.Based on the analysis of experimental results,a peak stress-strain model and an amended ultimate stress-strain model were proposed.The models were verified as well;the result showed that the predictions from calculations are generally consistent with the experimental data(error within 10%).The results of this study provide a theoretical basis and reference for future applications of fiber-reinforced recycled concrete.
文摘To improve the shear and flexural capacity of flexural members, the steel and basalt fibers were used in model beams tested under flexure. Three series of single span free supported model beams were prepared from SFRC （steel fiber reinforced concrete） with longitudinal steel reinforcement （steel ratio of 1.2 %） and varied spacing of steel stirrups and they were tested till failure. Another three series of BFRC （basalt fiber reinforced concrete） double-span model beams with a span of 2 mm~ 1,000 mm and cross section 180 mm ~ 80 mm were tested. During the tests till to the failure the beam reactions, vertical deflections and horizontal strains in concrete were registered, to clarify the range of redistribution of bending moments and shear forces over the span of the beams. Almost all the tested model beams failed in shear, showing visible influence of steel and basalt fibers on the shear capacity of the tested beams. The tests results confirmed that steel and basalt fibers in reinforced concrete beams can partially replace （in certain cases） the traditional steel stirrups calculated for shear.
文摘Reinforced concrete （RC） beams externally bonded with basalt fiber reinforced polymer （BFRP） are experimentally investigated by using different numbers of bonding plies, transverse anchorages as well as the initial conditions of strengthened beams. The performances of the BFRP strengthening are compared with those of the carbon fiber reinforced polymer （CFRP） and the glass fiber reinforced polymer （GFRP） under the same experimental condition. Experimental results indicate that the strength and ductility of the strengthened beam with two plies of the BFRP are improved remarkably than those with one ply. The strengthening effects of the BFRP lie between those of the CFRP and the GFRP. The BFRP strengthening is little influenced by pre-cracks of concrete. Most failures are caused by interfaciai debonding induced by flexural cracks in the experiment. Clamping of Uwraps along the whole beam is less efficient than endpoint anchorage for increasing the ultimate load of the strengthened beam. Finally, the models suggested by the five guidelines for predicting the debonding strain of the CFRP are extended to the BFRP and the conservative estimates of the debonding strain of the BFRP are given as well.
基金The National Key Basic Research Program of China(973 Program)(No.2012CB026200)the Key Project of Chinese Ministry of Education(No.113029A)+1 种基金the National Key Technology R&D Program of China during the 12th Five Year Plan Period(No.2011BAB03B09)the Fundamental Research Funds for the Central Universities
文摘This paper presents an experimental study on the alkali-resistant properties of basalt fiber reinforced polymers （BFRP） bars under a typical concrete environment. BFRP bars were embedded in concrete and exposed to different aggressive environments, including tap water, saline solution and ambient temperature environments, to study the effects of the type of solution and relative humidity （RH） on the durability of BFRP. Meanwhile, BFRP bars were directly immersed in an alkaline solution for comparison. The acceleration factor describing the relationship between the alkaline solution immersion and the moisture-saturated concrete was also obtained. Aging was accelerated with a temperature of 60 ℃. The results show that the chloridion in the saline solution does not have any harmful effects on the degradation of the concrete-encased BFRP bars. Contact with an alkaline （high pH） concrete pore-water solution is the primary reason for the degradation of the BFRP bars. The degradation rate of concrete-encased BFRP bars is accelerated when a high temperature and a high humidity are present simultaneously. The degradation rate of the BFRP bars is relatively quick at the initial stage and slows down with exposure time. Results show that the degradation of 2.18 years in moisture-saturated concrete at 60 ℃corresponds to that of one year when directly immersed in an alkaline solution （other conditions remaining the same） for the BFRP bars analyzed.
基金the National Key Technology Research and Development Program(No.2009BAJ28B02)
文摘This paper discusses a new fibrous composite known as continuous basalt fiber reinforced polymer /plastic(BFRP).Compared with other fiber reinforced polymer/plastic,BFRP has many advantages,such as ductility,high thermal resistance,corrosion resistance and economic cost.To test mechanical properties and failure modes of flexural members strengthened with BFRP,flexural experiment is conducted on four two-span T-section continuous beams strengthened with BFRP and one un-strengthened comparative beam.The experimental result shows that the strengthened beams perform remarkably in terms of yield strength,ultimate strength and ductility.BFRP has good prospects in retrofitting and strengthening of concrete structures which require good ductility and corrosion resistance.
基金financially supported by the National Natural Science Foundation of China(Grant No.51878233)the Fundamental Research Funds for the Central Universities(No.JZ2021HGTA0164)+1 种基金the Key Research and Development Project of Anhui Province,China(No.202104a07020022)from Anhui Provincial Natural Science Foundation(No.2208085QE172).
文摘In this study,a novel diagonally inserted bar-type basalt fiber reinforced polymer(BFRP)connector was proposed,aiming to achieve both construction convenience and partially composite behavior in precast concrete sandwich panels(PCSPs).First,pull-out tests were conducted to evaluate the anchoring performance of the connector in concrete after exposure to different temperatures.Thereafter,direct shear tests were conducted to investigate the shear performance of the connector.After the test on the individual performance of the connector,five façade PCSP specimens with the bar-type BFRP connector were fabricated,and the out-of-plane flexural performance was tested under a uniformly distributed load.The investigating parameters included the panel length,opening condition,and boundary condition.The results obtained in this study primarily indicated that 1)the bar-type BFRP connector can achieve a reliable anchorage system in concrete;2)the bar-type BFRP connector can offer sufficient stiffness and capacity to achieve a partially composite PCSP;3)the boundary condition of the panel considerably influenced the out-of-plane flexural performance and composite action of the investigated façade PCSP.
基金Supported by the Project of China Geological Survey on Ministry of Natural Resources(DD20190647)the Project of Collaborative Innovation Among Universities in Anhui Province(21KZZ701)Anhui University Natural Science Research Major Project(KJ2020ZD73)。
文摘To explore the law of energy evolution and the change of damage before and after specimen failure,the conventional triaxial compression tests(5,10,15,20,and 30 MPa)of basalt fiber reinforced concrete(BFRC)with different fiber volume fractions(0,0.2%and 0.4%)were carried out by MTS816 rock testing system,and the cyclic loading and unloading tests of BFRC with a fiber content of 0.2%were carried out.The experimental results show that the peak strength and strain of BFRC increase with the increase of confining pressure.Tensile failure occurs under low confining pressure,and shear failure occurs under high confining pressure.The best volume fraction of fiber is 0.2%.Under different confining pressures,the input energy,elastic energy,plastic properties,and dissipated energy of the samples first increase and then decrease to a stable level.The elastic energy and dissipated energy reach the maximum near the peak stress,while the input energy and plastic properties reach the maximum at the peak.At the same time,the damage increases continuously with the input of load under different confining pressures,indicating that the failure of the specimen is a process of energy accumulation.
