The effect of fly ash and early strength agent on resistance of concrete to the cyclic sulfate environment was studied.Concrete specimens made with ordinary portland cement or ordinary portland cement incorporating fl...The effect of fly ash and early strength agent on resistance of concrete to the cyclic sulfate environment was studied.Concrete specimens made with ordinary portland cement or ordinary portland cement incorporating fly ash with the replacement of 10% or 20%,or 1% early strength agent and fly ash with the replacement of 20%,were made and subjected to 250 cycles of exposure to the cyclic sulfate environment.Concrete properties including loss of mass,chloride ion diffusion coefficient,compressive strength and flexural strength were measured.Microstructure and chemical component of samples were determined by means of X-ray diffraction,scanning electron microscopy and energy dispersive spectroscopy.The experimental results indicated that effect of fly ash on the cyclic sulfate resistance of concretes was mostly dependent on the amount of fly ash.Early strength agent improved performances of concrete with 20% fly ash exposed to cyclic sulfate environment.展开更多
The synthesis of a novel type of polyacrylamide emulsion as dry-strengthing agent was studied in this paper. Several strength agents were obtained by changing reaction conditions such as reaction time, species and dos...The synthesis of a novel type of polyacrylamide emulsion as dry-strengthing agent was studied in this paper. Several strength agents were obtained by changing reaction conditions such as reaction time, species and doses of initiator, reaction concentration and so on. Meanwhile, the application of these strength agents in papermaking of wheat straw slurry was also discussed. In addition, the obvious increases in dry strength of paper comparable to using currently available cationic dry strength agents at the same dose were given by using these strength agents.展开更多
A combined method of discrete event and agent based modelling has been applied to the computer modelling and simulation of the tensile strength of one-dimensional fibrous materials (ODFM). This combined method is base...A combined method of discrete event and agent based modelling has been applied to the computer modelling and simulation of the tensile strength of one-dimensional fibrous materials (ODFM). This combined method is based on the concept of discrete event simulation as being applied to the modeling of the structure of the fiber flow and on the concept of agent based modelling for modelling and simulation of the fiber interaction within the structure of the fibrous material. Frictional and traction forces arise as the result of this fiber interaction. A model of the ODFM tensile strength, which is based on the slippage effect, is created and studied in this research. Only frictional and traction forces determine the tensile strength in this kind of the model. The article examines the validation problem of the slippage effect based tensile strength model and questions regarding the strength potential estimation through variation in the parameters of the model.展开更多
A novel flocking control approach is proposed for multi-agent systems by integrating the variables of velocities, motion directions, and positions of agents. A received signal strength indicator （RSSI） is applied as...A novel flocking control approach is proposed for multi-agent systems by integrating the variables of velocities, motion directions, and positions of agents. A received signal strength indicator （RSSI） is applied as a variable to estimate the inter-distance between agents. A key parameter that contains the local information of agents is defined, and a multi-variable controller is proposed based on the parameter. For the position control of agents, the RSSI is introduced to substitute the distance as a control variable in the systems. The advantages of RSSI include that the relative distance between every two agents can be adjusted through the communication quality under different environments, and it can shun the shortage of the limit of sensors. Simulation studies demonstrate the effectiveness of the proposed control approach.展开更多
In this paper,C50 ultra-high-early-strength concrete was prepared with rapid-harden sulphoaluminate cement,alkali carbonate early strength agent,inorganic tribasic acid retarder and polycarboxylate water reducing agen...In this paper,C50 ultra-high-early-strength concrete was prepared with rapid-harden sulphoaluminate cement,alkali carbonate early strength agent,inorganic tribasic acid retarder and polycarboxylate water reducing agent. The properties testing results of C50 ultra-high-early-strength concrete indicated that the compressive strength at 12 h exceeded 37 MPa and at 3 d exceeded 59 MPa. Compared to the C50 ordinary reference concrete,the durability of C50 ultra-high-early strength concrete was investigated. The results indicated that C50 ultra-high-early-strength concrete had the same chloride ion permeability resistance,carbonization resistance and abrasion resistance to the C50 ordinary concrete. As to the sulfate resistance,the ultra-high-early-strength concrete was much better than the ordinary concrete.展开更多
The effect of combination of steel fiber and MgO-type expansive agent （MEA） on strength, air-permeability and porosity of concrete was investigated. The porosity and air-permeability of concrete were determined by m...The effect of combination of steel fiber and MgO-type expansive agent （MEA） on strength, air-permeability and porosity of concrete was investigated. The porosity and air-permeability of concrete were determined by method of evaporated water and Torrent permeability tester, respectively. Pore structures of mortars in concrete were analyzed using mercury intrusion porosimetry （MIP）. Interfacial structures between steel fibers and matrix were examined by use of optical microscope. The experimental results show that improvement of pore structures of mortar and fiber-matrix interfacial structure in concrete by combination of steel fiber and MEA may remarkably increase properties of concrete. In comparison with plain concrete, compressive strength and splitting tensile strength of steel fiber reinforced expansive concrete increased by 15.3% and 38.1%, permeability coefficient Kt, penetration depth L and porosity of concrete decreased by 41.1%, 21.3% and 13.1% at 28 days, respectively.展开更多
Optimum applied technical conditions of wet strength agent for kenaf mulch were studied in this article. Breaking length, wet-dry strength ratio, tear index and burst index of kenaf mulch were measured and optimum wet...Optimum applied technical conditions of wet strength agent for kenaf mulch were studied in this article. Breaking length, wet-dry strength ratio, tear index and burst index of kenaf mulch were measured and optimum wet strength agent was selected. The aim is to make mulch have properties of heat preservation, humidity preservation, growth prompting, biodegradation and maximum wet strength and to improve impact resistance of mulch to rainwater so as to assure growth of plant and replace plastic film.展开更多
The self-stress trial of the fifteen high-strength, low-heat andmicro-expansion concrete-filled steel tube(CFST)is introduced, andthe generating and distributing features of pre-stress and itsrelation to add- ing quan...The self-stress trial of the fifteen high-strength, low-heat andmicro-expansion concrete-filled steel tube(CFST)is introduced, andthe generating and distributing features of pre-stress and itsrelation to add- ing quantity of expansive agent, which providespersuasive dependences for optimal design of high-strength, low- heatand micro-expansion CFST were investigated, especially for the designof added quantity of expansive agent.展开更多
Parallel and orthogonal tests are used to explore the influence law of the dosage and age of curing agent on the strength of solidified sludge. The test results show that: 1) The strength of solidified sludge is mainl...Parallel and orthogonal tests are used to explore the influence law of the dosage and age of curing agent on the strength of solidified sludge. The test results show that: 1) The strength of solidified sludge is mainly related to the cement content and dry soil content, and presents a good linear relationship. The influence of gypsum content is not significant. As the age increases, the strength is greatly affected by the cement content. 2) At different ages, the unconfined compression strength of solidified sludge presents a linear relationship, and the change law of later strength can be predicted by early strength. 3) Degree of influence of curing agent dosage: cement dosage > gypsum dosage > dry soil dosage. The optimal mixture ratio is 8% of cement content, 30% of gypsum content (proportion of cement content), and 4 times of dry soil content (multiple of cement content).展开更多
基金Funded by the Western Communication Construction Science and Technology Item (No. 200631822302-08)
文摘The effect of fly ash and early strength agent on resistance of concrete to the cyclic sulfate environment was studied.Concrete specimens made with ordinary portland cement or ordinary portland cement incorporating fly ash with the replacement of 10% or 20%,or 1% early strength agent and fly ash with the replacement of 20%,were made and subjected to 250 cycles of exposure to the cyclic sulfate environment.Concrete properties including loss of mass,chloride ion diffusion coefficient,compressive strength and flexural strength were measured.Microstructure and chemical component of samples were determined by means of X-ray diffraction,scanning electron microscopy and energy dispersive spectroscopy.The experimental results indicated that effect of fly ash on the cyclic sulfate resistance of concretes was mostly dependent on the amount of fly ash.Early strength agent improved performances of concrete with 20% fly ash exposed to cyclic sulfate environment.
文摘The synthesis of a novel type of polyacrylamide emulsion as dry-strengthing agent was studied in this paper. Several strength agents were obtained by changing reaction conditions such as reaction time, species and doses of initiator, reaction concentration and so on. Meanwhile, the application of these strength agents in papermaking of wheat straw slurry was also discussed. In addition, the obvious increases in dry strength of paper comparable to using currently available cationic dry strength agents at the same dose were given by using these strength agents.
文摘A combined method of discrete event and agent based modelling has been applied to the computer modelling and simulation of the tensile strength of one-dimensional fibrous materials (ODFM). This combined method is based on the concept of discrete event simulation as being applied to the modeling of the structure of the fiber flow and on the concept of agent based modelling for modelling and simulation of the fiber interaction within the structure of the fibrous material. Frictional and traction forces arise as the result of this fiber interaction. A model of the ODFM tensile strength, which is based on the slippage effect, is created and studied in this research. Only frictional and traction forces determine the tensile strength in this kind of the model. The article examines the validation problem of the slippage effect based tensile strength model and questions regarding the strength potential estimation through variation in the parameters of the model.
基金supported by the National Basic Research Program of China (973Program) under Grant No. 2010CB731800the National Natural Science Foundation of China under Grant No. 60934003 and 61074065the Key Project for Natural Science Research of Hebei Education Departmentunder Grant No. ZD200908
文摘A novel flocking control approach is proposed for multi-agent systems by integrating the variables of velocities, motion directions, and positions of agents. A received signal strength indicator （RSSI） is applied as a variable to estimate the inter-distance between agents. A key parameter that contains the local information of agents is defined, and a multi-variable controller is proposed based on the parameter. For the position control of agents, the RSSI is introduced to substitute the distance as a control variable in the systems. The advantages of RSSI include that the relative distance between every two agents can be adjusted through the communication quality under different environments, and it can shun the shortage of the limit of sensors. Simulation studies demonstrate the effectiveness of the proposed control approach.
基金the financial support from China Communications Construction Company Limited.
文摘In this paper,C50 ultra-high-early-strength concrete was prepared with rapid-harden sulphoaluminate cement,alkali carbonate early strength agent,inorganic tribasic acid retarder and polycarboxylate water reducing agent. The properties testing results of C50 ultra-high-early-strength concrete indicated that the compressive strength at 12 h exceeded 37 MPa and at 3 d exceeded 59 MPa. Compared to the C50 ordinary reference concrete,the durability of C50 ultra-high-early strength concrete was investigated. The results indicated that C50 ultra-high-early-strength concrete had the same chloride ion permeability resistance,carbonization resistance and abrasion resistance to the C50 ordinary concrete. As to the sulfate resistance,the ultra-high-early-strength concrete was much better than the ordinary concrete.
基金Funded by the National Basic Research Program of China (2009CB623105)the "11th Five-Year Plan" Scientific and Technological Support Project of China (2006BAF02A25)
文摘The effect of combination of steel fiber and MgO-type expansive agent （MEA） on strength, air-permeability and porosity of concrete was investigated. The porosity and air-permeability of concrete were determined by method of evaporated water and Torrent permeability tester, respectively. Pore structures of mortars in concrete were analyzed using mercury intrusion porosimetry （MIP）. Interfacial structures between steel fibers and matrix were examined by use of optical microscope. The experimental results show that improvement of pore structures of mortar and fiber-matrix interfacial structure in concrete by combination of steel fiber and MEA may remarkably increase properties of concrete. In comparison with plain concrete, compressive strength and splitting tensile strength of steel fiber reinforced expansive concrete increased by 15.3% and 38.1%, permeability coefficient Kt, penetration depth L and porosity of concrete decreased by 41.1%, 21.3% and 13.1% at 28 days, respectively.
文摘Optimum applied technical conditions of wet strength agent for kenaf mulch were studied in this article. Breaking length, wet-dry strength ratio, tear index and burst index of kenaf mulch were measured and optimum wet strength agent was selected. The aim is to make mulch have properties of heat preservation, humidity preservation, growth prompting, biodegradation and maximum wet strength and to improve impact resistance of mulch to rainwater so as to assure growth of plant and replace plastic film.
文摘The self-stress trial of the fifteen high-strength, low-heat andmicro-expansion concrete-filled steel tube(CFST)is introduced, andthe generating and distributing features of pre-stress and itsrelation to add- ing quantity of expansive agent, which providespersuasive dependences for optimal design of high-strength, low- heatand micro-expansion CFST were investigated, especially for the designof added quantity of expansive agent.
文摘Parallel and orthogonal tests are used to explore the influence law of the dosage and age of curing agent on the strength of solidified sludge. The test results show that: 1) The strength of solidified sludge is mainly related to the cement content and dry soil content, and presents a good linear relationship. The influence of gypsum content is not significant. As the age increases, the strength is greatly affected by the cement content. 2) At different ages, the unconfined compression strength of solidified sludge presents a linear relationship, and the change law of later strength can be predicted by early strength. 3) Degree of influence of curing agent dosage: cement dosage > gypsum dosage > dry soil dosage. The optimal mixture ratio is 8% of cement content, 30% of gypsum content (proportion of cement content), and 4 times of dry soil content (multiple of cement content).
