Table of Content

15 March 2017, Volume 36 Issue 3

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Autogenous Shrinkage of Concrete with Magnesium Slag and Fly Ash

CUI Zi-zhi;CHEN Dong-dong;ZHANG Cheng

2017, 36(3):  759-764. 

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In order to explore the effect of magnesium slag and fly ash on autogenous shrinkage of concrete, a scheme of orthogonal test was designed with magnesium slag content and fly ash replacement ratio as variable factors.The autogenous shrinkage property of concrete was studied, and the micro morphology and action mechanism of the admixture were analyzed meanwhile.Experimental results show that magnesium slag and fly ash have significant inhibitory effect on autogenous shrinkage of concrete.The autogenous shrinkage of concrete at 180 d is reduced about 44.0% with the increase of the content of magnesium slag and fly ash from (10%, 15%) to (40%, 30%).The interval range of the concrete autogenous shrinkage increase 3.5 times when the interval of magnesium slag content changes from 10%-20% to 30%-40%.The sensitivity of concrete autogenous shrinkage to magnesium slag is relatively large when the magnesium slag content is high.The autogenous shrinkage of concrete mainly occurs in the early stage, 65.0%-80.0% of the total autogenous shrinkage of concrete has been generated in 28 d, the early stage is important in the control of concrete shrinkage deformation.The deviation between the predicted and measured values is small, therefore the model can be used for the analysis and prediction of autogenous shrinkage of concrete with magnesium slag and fly ash.

Infrared Thermal Image and CT Scan Analysis on C60 High Performance Concrete Exposed to High Temperature

CHEN Liang-hao;DU Hong-xiu

2017, 36(3):  765-769. 

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C60 high performance concrete with 0% and 0.2% polypropylene fiber were subjected to high temperature test of simulated fire.The uniaxial compressive strength of concrete were carried out before and after exposed to high temperature.Infrared thermography technique was used to study the infrared thermal image of concrete after high temperature.The relationship among the average temperature rise of infrared thermal image, the fire temperature and the ratio of uniaxial compressive strength was established.The CT scan test was conducted on the high-strength concrete specimens at room temperature and 300 ℃,400 ℃,500 ℃ respectively.The effect of fiber on crack generation and expansion in concrete was analyzed.

Preparation and Characterization of Single α-Cordierite Glass-ceramics from Perlite

2017, 36(3):  770-777. 

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Single α-cordierite glass-ceramics were prepared successfully from perlite as the basic raw material.The effects of sintering temperature and SiO2 contents on the crystallization behavior,crystal phase composition,microstructure and property of the glass-ceramics were characterized by differential scanning calorimetry (DSC),X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM).The results show that μ-cordierite phase gradually decreases and finally transformed into α-cordierite, and the porosity reduces in the glass-ceramics with sintering temperature increasing.As SiO2 contents increases, the precipitation temperature of α-cordierite firstly reduces and then increases, and the density and the flexural strength of the glass-ceramics increase first and then decrease, and its dielectric properties are deteriorated.The single α-cordierite glass-ceramics were achieved from the glass with composition of Mg∶Al∶Si=2∶2∶5.95 sintered at 900 ℃ for 6 h.The as-synthesized glass-ceramics possessed high flexural strength (116 MPa), low dielectric constants (5.72, 10 MHz), low dielectric losses (0.0059, 10 MHz), and matchable coefficient of thermal expansion (2.91×10-6 K-1,very close to Si), which can be used as a potential low temperature co-fired ceramics (LTCC) substrate materials.

Synthesis and Characterization of 13X Zeolite Prepared from Desilication Solution of High Alumina Fly Ash and Coal Gangue

2017, 36(3):  778-784. 

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In this study, 13X zeolite was prepared through hydrothermal process from coal gangue and the desilication solution,a kind of by-productin the alumina extraction from high alumina coal fly ash, in order to realize the low cost preparation of 13X zeolite and utilization of coal based solid waste.The effects of synthesis parameters, such as n(H2O/Na2O),n(SiO2/Al2O3),reaction temperature and stirring rate on the crystal structure and the BET surface area of the product were studied.The products was characterized by X-ray diffraction(XRD), fourier transform infrared spectroscopy(FTIR),and scanning electron microscopy(SEM).As a result, the optimum synthesis conditions of 13X zeolite is n(SiO2/Al2O3)=3.0, n(Na2O/SiO2) =1.9, n(H2O/Na2O) =60, after homogenization by aged at room temperature for 24 h, then crystallized at 95 ℃ for 8 h at 100 r·min-1.At this condition, relative crystallinity 94.59%, BET surface area up to 681.7 m2·g-1 is achieved.According to the analysis of the hydrothermal synthesized process,13X zeolite synthesis process is early mainly for coal gangue and desilication solution reaction form the amorphous gel, then gel phase dissolve and the growth of zeolite crystals.

Effect of Sintering System and Pore Former Content on the Properties of Fly Ash Based Porous Ceramic Membrane Support

ZHANG Jie;TIAN Meng-kui;ZHANG Yun-fei

2017, 36(3):  785-790. 

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Tubular porous ceramic membrane supports were prepared by extrusion molding and solid particle sintering method using fly ash as raw material.The thermal analysis of fly ash was determined by TG-DSC.The microstructure and phase composition of samples were analyzed by SEM and XRD.The property indexes such as the open porosity, compressive strength and air permeability were also measured.The influences of sintering temperature, holding time and pore former content on the performances of the supports were investigated.Results indicate that the phase of supports is mainly composed of hematite, andalusite and quartz.The excellent comprehensive performance tubular supports with open porosity of 44.95%, compressive strength of 8.92 MPa, and the air permeability of 2.57×104 m3·h-1·m-2·MPa-1 can be fabricated under the optimized conditions: sintering temperature being 1000 ℃, holding time of 2 h, binder of 1% and without adding pore former.

Adhesion Characteristics of Particles in Fluidized Decomposition Process of Phosphogypsum

WANG Rong-mou;MA Li-ping;ZHENG Da-long;WANG Qian-qian;TANG Jian-xiao

2017, 36(3):  791-796. 

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During the production of sulfuric acid integrated with cement from phosphogypsum, it is common to have wall adhesion in rotary kiln because of particle agglomeration, blocking the pipeline and thus the operation.By comparing the profiles of XRF, XRD and SEM of the deposit and the fluidized powder change of adhesion during the thermal decomposition of phosphogypsum were investigated.The results show that the Si-containing and Al-containing mineral level in the deposit substance are higher than those in the fluidized powder, indicating adhesion and enrichment of most clay mineral impurities on the wall.As the reaction proceeded, increasing calcium oxide content markedly eased particles' adhesion.Thus it was suggested that, for phosphogypsum power impurities like SiO2 and Al2O3 not only affected the decomposition but also severely influenced the agglomeration and adhesion of the particles during the fluidization process.

Effect of Waste Ceramic Tile Recycled Aggregate on Mortar and Concrete

PEI Qi-wen;WANG Gong-xun;SHEN Yang;ZHU Ming-qiao;QU Feng

2017, 36(3):  797-802. 

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Using waste ceramic tile as recycled coarse and fine aggregate to replace natural aggregate, effects of waste ceramic tile recycled aggregate on the performance of mortar and concrete were studied.Interfacial bonding properties of recycled aggregate and cement paste were measured by splitting test and bending test compared to natural aggregate.Results show that under the same mix proportion, waste tiles recycled aggregate improve compressive strength, reduce dry shrinkage and slump of concrete compared to natural aggregate.Under the same curing age condition, interfacial bond strength of different types of aggregate-cement pastes increase with the decrease of water to cement ratio.Under the same water cement ratio, the fracture strength and flexural strength at 28 d of the recycled aggregate-cement stone interface is higher than that of natural aggregate-cement stone interface.It is revealed that the performance of the interface between the recycled aggregate and cement paste is better than that of natural aggregate.

Similarity Relation in Time of Marine Concrete Surface Chloride Concentration

ZHOU Li-ping;LIU Rong-gui;CHEN Yu

2017, 36(3):  803-808. 

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According to classical similarity theory, based on the time-varying denaturation of surface chloride concentration, the similarity relation in time between actual environment structure and artificial erosion acceleration simulation environment test structure was established.After taking powder in marine concrete components and specimens respectively, measured the surface concentration of chloride ion by RCT and analyzed its time-varying model.Finally the expression of time similarity coefficient is put forward and its value is calculated, it provides the basis for life prediction of service structure.

Experimental Study on Load-Carrying Capacity of Basalt Fiber Reinforced Concrete Short Columns under Axial Compression

WANG Xin-zhong;LI Chuan-xi;ZHOU Wei

2017, 36(3):  809-815. 

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In order to study the reinforced function of the basalt fiber reinforced concrete compression members and to promote the application of basalt fiber, the optimal length of fiber was obtained by adding five basalt fiber concrete with 0.1% volume fraction.12 mm basalt fiber on the strength of the concrete cube reinforcing the best effect;followed by the choice of 12 mm and 24 mm of the two basalt fiber reinforced concrete the best amount to study the best dosage range is 0.15%.Finally, three basalt fiber short columns were made with 0.15% volume fraction, 12 mm length and 24 mm length basalt fiber concrete respectively.Three columns of ordinary reinforced concrete short columns were made and the axial compression limit of all test columns was made.The results show that the bearing capacity of reinforced concrete short columns with basalt fibers increases by 28% compared with ordinary reinforced concrete columns.Basalt fiber improves the ductility of reinforced concrete short columns.In addition, the bearing capacity of axially loaded columns of reinforced concrete short columns with basalt fiber is larger than the calculated value, indicating that basalt fiber not only improves the compressive strength of concrete, but also enhances the performance of reinforced concrete and concrete.

Microstructure and High Dielectric Performance of Na1/2La1/2Cu3Ti4O12 Powder and Ceramics by Sol-gel Method

LIU Zhan-qing

2017, 36(3):  816-821. 

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Na1/2La1/2Cu3Ti4O12 powder and ceramics were successfully achieved by sol-gel method.Effect of concentration, pH value and the molar ratio of the water and titanium of the sol on microstructure of NLCTO powder and ceramics were investigated in detail, respectively.The results found that the concentration, pH value and the molar ratio of the water and titanium of the sol for 0.75-1.0 mol/L, 0.3-1.3 and 11.0, respectively, after calcining at 800 ℃ for 10 h,NLCTO powder show more dispersion and homogeneity.Based on the superior NLCTO powder, dielectric constant of the prepared NLCTO ceramics increased to 1.9×104, and dielectric loss decreased to 0.039.

Finite Element Analysis on the Seismic Performance of Fiber Reinforced Concrete Column under Low Cyclic Loading

ZHAO Yan-ru;GUO Zi-lin;WANG Lei;XU Na;SHI Jin-na

2017, 36(3):  822-828. 

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Seismic behavior of fiber reinforced concrete columns under low cycle loading were studied by finite element analysis software.The influence of fiber content on hysteretic curve, skeleton curve, bearing capacity and ductility was analyzed, which was also compared with the test values.The results show that the bearing capacity and seismic energy dissipation capacity can be improved by the adding fiber.On the one hand, the bearing capacity can be significantly enhanced by just adding steel fiber, but not obviously by adding polypropylene fiber at the same time, which showes a little contribution to the bearing capacity.On the other hand, the ductility, which is a little improved by adding polypropylene fiber and steel fiber, is observably improved by just adding steel fiber.Therefore, the polypropylene fiber plays a certain role in improving the bearing capacity of the component.The bearing capacity coefficient of the components at a rate of 1.5% of steel fiber volume content is the largest.

Hydration Behavior of ρ-Al2O3 in Different Media

ZHANG Xin;LI Yuan-zheng;NIE Qiang-qiang;YAN Yu;TIAN Li

2017, 36(3):  829-832. 

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Hydration behaviors of the ρ-Al2O3 were investigated by the determinations of temperature and viscosity of the slurries and the phase composition analysis and microstructure observation of the hydrated products in 9 media.It has been shown that, hydration process of the ρ-Al2O3 will be prevent in acidic medium and promote in alkaline medium.Hydration products of the ρ-Al2O3 are mainly crystalline granular bayerite in water and alkaline media and amorphous boehmite in acidic medium.

Preparation of Mgnesia-Alumina Double-layered Metal Hydroxides with Coal Gangue as Aluminum Source

QIN Hua;MA Xiao-yan;XU Yan;FU Jia-lin

2017, 36(3):  833-838. 

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Obtained from coal gangue as raw matcrials of boehmite was through mechanical activation, thermal activation and acid extraction.Mg-Al layered double metal hydroxides(LDHs) was produced by co-precipitation method.The products were characterized by XRD,IR and scanning electron microscopy (SEM) measurements.Experimental results show that: Coal gangue is activated at the calcination temperature of 700 ℃, leaching temperature is 100 ℃, extraction time is 150 min,the quality ratio between solvent and sample is 2∶10,the concentration of sulfuric acid is 4 mol/L,the ratio between liquid and solid is 15∶1,the extraction rate of Al2O3 is 0.937.When the molar ratio of Mg and Al is 2∶1,pH is 10 and the reaction temperature is 60 ℃,Mg-Al layered double hydroxides with interlamellar spacing d(003) of 0.798 nm are prepared by co-precipitation method.

Thermal and Kinetic Study on Decomposition of Phosphogypsum by Carbon

XU Yue;LIN Qiang;LI Jian-xi;NING Ping;KAN Li-li

2017, 36(3):  839-845. 

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From the kinetic and thermodynamic point of view, the feasibility of phosphogypsum(PG) decomposition making cementitious material at low temperature was studied.The decomposition kinetics of PG with 10%-15% activated carbon(AC) were investigated at 1100-1250 ℃.The results show that the apparent activation energy of PG decomposition system is 299.88-382.85 kJ·mol-1, the pre-exponential factor is 18.64-25.61 s-1 and the most possible decomposition mechanism is Z-L-T function.The synthesis reaction of CaO and SiO2 was processing along with the decomposition during the calcination was confirmed by the thermodynamic calculation and microstructural analysis.According to the phase diagram of CaO-SiO2-CaSO4 system, adding some appropriate silicon aluminum modified components and adjusting the scope of raw material proportion have the potentiality to improve the compressive strength of cementitious material made from PG.

Basic Mechanics and Durability of Recycled Concrete

DING Tian-ting;LI Qi-hua;CHEN Shu-dong

2017, 36(3):  846-850. 

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The compressive strength,carbonation resistance and freezing resistance of recycled concrete were studied based on the basic mechanical method and the durability methods.And the pore structure of recycled concrete was analyzed by mercury intrusion porosimetry (MIP).The results show that the compressive strength of recycled concrete is slightly lower than that of ordinary concrete.The porosity of the recycled concrete is 49.5% higher than that of ordinary concrete.The carbonation resistance of recycled concrete is less than that of ordinary concrete.The freezing resistance of recycled concrete is much less than that of ordinary concrete, and its mass loss rate is 3 times of that of ordinary concrete after 180 cycles.

Analysis of Compressive Strength for Concrete Filled Circular Steel Tubular Column Based on Bayes

Lv Bei-bei;SHI Yi-xia

2017, 36(3):  851-858. 

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Probabilistic model for calculating the compressive strength of concrete filled circular steel tubular column was established based on Chinese code (GB 50396-2014) by Bayesian theory.Two types of information, the prior model that compressive capacity calculation formula in Chinese code, and the prior information that the collected 170 test results, were synthesized into Bayesian statistical inference and Bayesian posterior estimate for unknown parameters based on non-information prior distribution.It shows that the Bayesian probabilistic model based on GB 50396-2014 can be conveniently used for the calculation of the compressive capacity for concrete filled circular steel tubular column, and the calculated results are proved good by 170 test data.

Research Progress on Preparation of Silicon Tetrafluoride from Fluorosilicate

CAI Miao;TANG An-jiang;WANG Le-shen;HE Yuan-qin;HE Lei

2017, 36(3):  859-863. 

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SiF4 is widely used in the electronics industry and the semiconductor industry, preparation of SiF4 by fluorosilicate is a kind of preparation method.In this paper, the properties and preparation methods of fluorosilicate are introduced.The method of preparing SiF4 by fluorosilicate is introduced.The conditions and products of SiF4 prepared by fluorosilicate were compared.

Review on Preparation and Properties of Permeable Concrete

WANG Yue;YAN Bin;LI Cheng-lin

2017, 36(3):  864-869. 

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Material properties and mix proportions of permeable concrete have been reviewed.The methods of mathematical simulation and software modeling on researching compressive strength and pore structure of permeable concrete have been illustrated.The differences between permeable concrete and ordinary concrete about compressive strength calculation, size effect and stress-strain relationship have been compared and analyzed respectively.The two-dimension and three-dimension pore distribution of permeable concrete have been summarized, which provide a new idea to study pore structure of permeable concrete.In addition, great attention should be paid to researching microstructure of permeable concrete in the near future.

Experimental Study on Mechanical Properties of Cement Mortar Reinforced by Polypropylene Fiber

WANG Lai-gui;CHEN Qiang;PAN Ji-wei;ZHANG Yang;LIU Yu-lin

2017, 36(3):  870-877. 

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In order to study the deformation damage law of cement mortar samples mixed by polypropylene fiber under different curing ages, uniaxial compression test was conducted for cement mortar samples.Lateral deformation field was observed by digital speckle correlation method, and fracture morphology was observed by scanning electron microscope.The results show that compressive strength increases first and then decreased with the increase of polypropylene fiber content at the same curing age.In the range of variable gradient, the optimum quantity of polypropylene fiber is 0.5%.In post-peak, the samples containing polypropylene fiber exhibited a obvious plastic characteristics and the generalized stiffness coefficient changed greatly.The evolution of lateral deformation field was divided into four stages, uniform stage, nucleation stage, deformation localization stage and failure stage.Bond strength of polypropylene fiber and cement mortar was weaker than that of sand and cement.The failure mode of polypropylene fiber samples exhibited fissure but continuous.The microscopic bond contact model put forward in this research can be used to explain the characteristics of plastic improvement of polypropylene fiber samples in post-peak.

Thermal Oxidation Characteristics of PolycarbosilanePrecursor Fibers under Negative Pressure

YANG Lian;LI Yang

2017, 36(3):  878-882. 

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Polycarbosilane (PCS) precursor fibers were thermal oxidation treated under negative pressure.The effect of atmosphere pressure and heating temperature on weight gain, Si-H bond reaction degree, gel content, chemical structure and pyrolysis characteristics of the PCS precursor fibers were studied.The experimental results show that the weight gain, gel content, Si-H bond reaction degree and ceramic yield of the fibers are all decreased with decreasing atmosphere pressure and heating temperature.Under the atmosphere pressure of-0.02 MPa, with the temperature descended from 195 ℃ to 175 ℃, the weight gain was decreased from 9.98% to 2.80%, the Si-H bond reaction degree was decreased from 63.62% to 21.85%, the gel content was decreased from 73.53% to 1.98% and the ceramic yield was decreased from 87.81% to 81.29%.

Effects of Inorganic Flocculant on Dehydration of Waste Residue in the Mud

WANG Hai-liang;WANG Su-wen;RONG Hui;SONG Wei-jun;QI Zhan-guo;LI Xiang-hai;DI Zhi-kun

2017, 36(3):  883-887. 

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At present, the mud disposal from subway pollutes the environment seriously and has negative effect on construction.The mud disposal will be regarded as the research object in this test.The flocculation effects of inorganic flocculant (calcium hydroxide, ferric chloride and the double mixing) on the mud disposal are researched.The results show that: (1) When the water content is 99%,the optimal dosage of calcium hydroxide and Ferric chloride solution is 0.32% and 1.70%,besides the optimal dosage of mixture (calcium hydroxide and Ferric chloride solution) is 0.18% and 1.30%.(2) When the water content is 98% the optimal dosage of calcium hydroxide and Ferric chloride solution is 0.36% and 2.50%, besides the optimal dosage of mixture (calcium hydroxide and Ferric chloride solution) is 0.24% and 1.50%.(3) When the water content is 97%, the optimal dosage of calcium hydroxide and Ferric chloride solution is 0.38% and 4.30%, besides the optimal dosage of mixture (calcium hydroxide and Ferric chloride solution) is 0.23% and 1.00%.

Control of Sulfur-containing Gas During Drying of Sludge

FAN Hai-hong;ZHANG Shi-yang;LI Bin-bin;MA Xu

2017, 36(3):  888-892. 

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To reduce the emission of the sulfur-containing gas during drying of sludge and develop new type of drying technology, this paper studies the factors such as the temperature,time on the influence the release of the sulfurous gas and put forward the process and parameter to control the release the carbon disulfide, hydrogen sulfide and sulfur dioxide:reducing the drying temperature,shorting the drying time and adding calcium oxide all can control the release of the carbon disulfide, hydrogen sulfide and sulfur dioxide effectively.Control the drying temperature below 250 ℃and drying time within 30 s.When the proportion of sludge and calcium oxide is 1∶1, the rate of inhibition for the gas is close to one hundred percent.

Effect of Fly Ash and Slag on Performance of Mortar Exposed to Chloride Solution

ZHANG Shi-ping;SHA Xue-cheng;ZONG Lan

2017, 36(3):  893-898. 

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This paper presented the performance of mortar exposed to chloride solution.Effect of mineral admixture on chloride binding capacity was studied through testing the free chloride concentration and total chloride ion concentration of mortar specimens after soaking in sodium chloride solution.The result shows that the chloride binding capacity of mortar is improved with the increase of the content of mineral admixture.Chloride ions diffusion coefficient is measured according to RCM method, and results indicate that both of fly ash and slag can improve the resistance of chloride ions penetration, and the effect of slag on the improvement of chloride ion permeability is more significant.Change of porosity is also deduced based on chloride crystal, dissolution of Ca(OH)2 and Friedel's salt, and it showes porosity increased due to chloride solution, while mineral admixture can diminish this influence.

Outside-square Inside-circle Eccentric Confined Shrinkage Test of Semidry Hard Concrete

SHAO Jian-wen;ZHU Han;LI Jian-ju;TANG Bing;BAI Hong-tao

2017, 36(3):  899-904. 

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The confined shrinkage test of crumb rubber concrete with high content and ordinary concrete without rubber which are semidry hard were done with outside-square inside-circle eccentric constraint method.And the circumferential strain of 0° zone, 90° zone and 180° zone on the inner surface of steel ring within 120 h was collected by static resistance strain gauge.The research results indicate that every splitting section on 6 sets of outside-square inside-circle specimens come into being at its narrowest part(0°zone).The early shrinkage and contraction percentage of semidry hard crumb rubber concrete was less than that of rubber-free semidry hard ordinary concrete.The cracking time of semidry hard crumb rubber concrete specimen was later than that of semi-dry hard ordinary concrete.The crack width of the former is smaller than the latter.And the measured strain values verify a certain rule for the first time: 0° zone>90° zone>180° zone.The relative values of strain at 0° zone/90° zone and 0° zone/180° zone were calculated and it was found that these two values stabilized with time.This indicates that it is reasonable to use the static linear elastic finite element method to simulate the outside-square inside-circle eccentric confined shrinkage test.

Effect of Foam Content on the Properties and Pore Structure of Foamed Slag-based Geopolymer

SONG Xue-feng;YANG Ping

2017, 36(3):  905-909. 

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Alkali activated slag cement was used to prepare a foamed concrete, with compressed air foaming process.The pore structures of the foamed concretes were investigated by image process software(Image-Pro plus, IPP).The effects of foam content on the dry density, compressive strength and thermal conductivity of foamed slag-based geopolymers were studied.The results show that porosity, average pore diameter and roundness increase, when foam content increase from 4.45%-10.70%.A good negative exponent relationship between foam content and the main properties of the foamed slag-based geopolymers was observed.The dry density, compressive strength and thermal conductivity were in the range of 389-1325 kg/m3, 1.12-17.81 MPa, 0.0813-0.2211 W/(m·K), respectively, when foam content increased from 4.45%-12.00%.In comparison to Portland cement foam concrete,foamed slag-based geopolymers presented a lower thermal conductivity and a higher compressive strength.

Influence of Curing Agent on Properties of Epoxy Resin Based Organic Attapulgite Clay/Polyaniline Coating

LEI Xi-ping;LIU Zhong-yu;WANG Chong;FU Qiang;WANG Bing-xin

2017, 36(3):  910-915. 

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The curing agent has very important effects on the anticorrosion and mechanical performance of coatings.The organic attapulgite clay/polyaniline (OAT/PAn) based coatings were prepared by in-situ oxidative polymerization with epoxy resin (ER) as bottom coat and OAT/PAn as additive.The coatings were cured by three kinds of curing agents including modified aliphatic amine 593, phenolic aldehyde amine T-31 and low molecular polyamide 650.The structures, anticorrosion, mechanical performance and water resistance of these coatings were discussed.The results showed that the composite coatings were completely cured by these three kinds of curing agents according to FTIR.The coating cured by 593 was more compact than others by SEM observations.The electrochemical test showed that the coating cured by 593 had a better corrosion protection performance, which corrosion potential and corrosion current density arrived to-318 mV and 1.193×10-6 A·cm-2, respectively.The adhesion strength of the coating after being cured by 593 was better than others, which reached 5B grade.Comparison with water-resistance for 168 h, the result indicated that the water hindrance capacity of the coating cured by 593 was stronger than other curing agents.

Doping-Coating Surface Modification of Calcium Carbonate with Ti4+ and Its Application as Papermaking Filler

LIU Zhen-hua;XIE Wei

2017, 36(3):  916-919. 

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Chelated titanate coupling agent was used to modify precipitated calcium carbonate (PCC), after that the slurry was collected and calcined at 550 ℃ to obtain modified PCC.The modified PCC was characterized by XRD, XPS and FTIR.It can be inferred from the results that calcium titanate crystal and oxide of Ti4+ exist on the surface of the modified PCC.The modified PCC is used as filler to prepare handsheets.Brightness increases slightly, mechanical properties decrease to some extent and filler retention don't change apparently for handsheet with modified PCC as filler compared to control PCC.

In-situ Formation of Ti(C,N) in Al2O3-C Refractories and Their Gasifier Slag Corrosion Resistance

BIE Chuan-yu;LI Ya-wei;SANG Shao-bai;ZHANG Yu;LIANG Xiong

2017, 36(3):  920-926. 

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Chromia-free lining materials for gasifier have to be developed with due consideration to environmental requirements.Based on the theory that viscosity of Ti(C,N) containing slags are higher than others.In order to introduce in-situ formed Ti(C,N) and improve the corrosion resistance of refractories.TiO2 is added into novel Al2O3-C materials for gasifier lining, which has been reported in our previous work.The results show that pore structure of Al2O3-C materials is optimized when appropriate TiO2 is added, due to the in-situ formation of Ti(C,N).Moreover, slag viscosity will be increased when slag react with Ti(C,N) containing Al2O3-C materials, so corrosion resistance of this kind of materials is improved.If excessive TiO2 is added into Al2O3-C materials, TiO2 will dissolve into slag at high temperature and result in decreasing of slag viscosity.Corrosion resistance of Al2O3-C materials decreases.

Effect of Calcium and Magnesium Complex Chloride on β-SiC Shaping

LI Yan-xia;FAN Zi-min

2017, 36(3):  927-930. 

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Silicon carbide is used widely, the quality of the powder is critical to the preparation of high performance silicon carbide materials, the most commonly used method is mechanical shaping, but the results are less effective.The influence of MgCl2-CaCl2 molten salt system on grain morphology, particle size distribution, D50、D90 of silicon carbide powder was studied by chemical shaping.The results show that molten salt of MgCl2-CaCl2 helps the growth of β-SiC powder grains greatly, with the holding temperature increasing, grain morphology transforms from lamellar structure to a columnar structure, D50 and D90 increase;with the holding time increasing, grain morphology transits from small particles to large particles, D50 and D90 increase.

Effect of Co2O3/Co3O4 Dosage on the NTC Characteristics of the BaBiO3 Based Thermistor Ceramics

HUO Ran;LIU Xin-yu;YUAN Chang-lai;LIU Xiao

2017, 36(3):  931-935. 

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The effects of Co2O3/Co3O4-doped amount on the phase structure, microstructure and electrical properties of BaCoⅢxBi1-xO3 (x=0.02,0.04,0.06,0.08) and BaCoⅡx/3CoⅢ2x/3Bi1-xO3 (x=0.02,0.04,0.06,0.08) based thermistor ceramics were investigated by X-ray diffraction, scanning electron microscope and ρ-t characteristic tester.The results show that the matrix phase is a continuous solid solution with pervoskite structure.The content of Co2O3/ Co3O4 has dramatically impact on the electrical properties.With the increase of the Co2O3/ Co3O4-doped amount, both ρ25 and B25~85values of the ceramic sample reduce initially and then increased.The BaCoⅢ0.06Bi0.94O3 ceramics show excellent NTC properties of ρ25=12.19 Ω·cm, B25~85=717 K.A good NTC properties of ρ25=12.32 Ω·cm and B25~85=1069 K was also obtained for BaCoⅡ0.02CoⅢ0.04Bi0.94O3.

Rubber Modification and Its Influence on the Properties of Rubber Cement Matrix

HE Liang;LIU Yu-gui;MOU Yuan-hua

2017, 36(3):  936-941. 

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Based on the purpose of improving the mechanical properties of rubber-cement matrix, the rubber was modified by oxidation and urea, and the micro-macroscopic test techniques such as water contact angle, infrared spectrum, adhesive strength, and compressive strength and impact strength were used to investigate the properties of the modified rubber cement matrix.The results show that after the rubber is oxidized and urea-modified, a large amount of hydrophilic groups such as carbonyl and amide groups are introduced on the surface of the rubber, which change the rubber surface from hydrophobic to hydrophilic.So the interface action between the rubber and cement matrix is greatly increased, and the bonding strength between rubber and cement paste is increased by 33.4%.The rubber modification has definite effect in reducing the rubber cement matrix material compressive strength reduction, but this effect is more prominent in the rubber concrete than in the rubber mortar.When the rubber content is 30% or less of fine aggregate, the compressive strength of the modified rubber concrete can reach above 30 MPa, which can meet the requirements of medium strength concrete.

Preparation of Silane Grafted Kaolinite by Mechanochemically

ZHANG Qian;ZHANG Bai-mei;ZHANG Yu-de;LU Yin-ping

2017, 36(3):  942-946. 

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The silane grafted kaolinite was prepared by the wet milling mechanochemical technique.XRD, FT-IR, scanning electron microscopy and physical adsorption technique were employed to characterize the wet milled kaolinite and silane modified samples.The crystal structure and size were calculated according to HI index and Scherrer method.The results show that the staked kaolinite sheets are peeled into fine particle sheets by the wet milling, the crystal structure changes to much more disordered, the stacking body is stripped into tiny kaolinite layer, and the grain size is significantly reduced.Fourier transform infrared spectroscopy confirmes the existence of-CH3,-CH2-, C=O and Si-C from silane agent for the wet milling silane modified kaolinte rather than the directrly silane modified samples.

Mineralogical Properties of Electrolytic Manganese Slag from Guangxi

LI Jia;JIAO Xiang-ke;DU Dong-yun;YE Heng-peng;PENG Qiu-ju

2017, 36(3):  947-952. 

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Electrolytic manganese slag has become a characteristic industrial solid waste in China.Using electrolytic manganese slag to prepare fertilizer is one of the important ways to realize the resource utilization.This study comprehensively analyses the mineralogical properties of manganese slag from Guangxi by MLA, TG, SEM and TEM.The analysis includes the elements and mineral composition, mineral grain size distribution, mineral association relationship and liberation degree, mineral characteristics and micro-morphology.This study provides a theoretical basis for activating the manganese slag to preparation silico-manganese fertilizer.

Extraction of Gallium from Coal Gangue Pickle Liquor Based on Response Surface Methodology

LI Yin;XIA Ju-pei;LIU Hai-lang;LUO Zhong-qiu;YANG Jin

2017, 36(3):  953-959. 

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Using coal gangue pickle liquor as research object to extraction and explore gallium.Effect of extraction time, temperature, concentration and the kind of thinne on the extraction rates of galliumand were studied.Meanwhile, extraction of gallium from coal gangue pickle liquor by responce surface methodology were studied.The results show that:the result closes to the detected values, which indicating that the resulting model can reflect the true relationship between the parameters.This model can be used to analysising and forecasting for extraction rates of gallium.Determined the best molding process condition and providing the basis for industrial extraction of gallium from coal gangue pickle liquor production.

Different Water Reducing Agents on the Properties ofβ Type Building Phosphogypsum

GAO Feng;ZHAO Zhi-man;QUAN Si-chen;ZHANG Wen-jia;YAO Yi-hui;LUAN Yang

2017, 36(3):  960-964. 

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The effects of polycarboxylate superplasticizer and sulfonated melamine superplasticizer on the fluidity, water reducing rate, setting time and dry compression strength of β type building phosphogypsum were studied.At the same time, the nonlinear fitting of the best dry reducing strength of the best water reducing agent (polycarboxylic acid) was performed by software,the fitting results and experimental results were compared.The results show that polycarboxylic acid water reducing agent has obvious improvement on fluidity, setting time and dry compression strength of β type building phosphogypsum, and the water reducing effect is better;especially in setting time.Sulfonated melamine has a little influence on the performance of β type building gypsum.By fitting and experimental results,the dosage of 0.48% polycarboxylate superplasticizer is more suitable for the β type building phosphogypsum.

Testing the Curing Effect of Concrete Box Girder under Different Curing Methods in Gobi Area

2017, 36(3):  965-970. 

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In order to study the gobi region various properties of concrete box girder under different curing methods, in the special environment of practicality, in the field experiment and verify its curing effect.The results show: compared with the plastic film curing and geotextile curing, rubber and plastic plate curing early strength growth faster.The hydration heat of concrete under different curing methods are 20 h after the peak and presented the law of sine periodic change.The hydration heat temperature distribution law of box girder is presented;Box girder strain is produced by the autogenous shrinkage of concrete and temperature is the result of joint action.The effect of shrinkage strain and temperature strain was analyzed by curve law.Through the micro structure tests, the distribution characteristics of concrete pore structure under different curing methods are analyzed.Has a hole spacing coefficient of rubber plate curing mechanical property is better than the other two curing methods.

Corrosion Resistance of Polyvinyl Acetate Latex Modified Cement Mortars

YIN Yan-ping;CHEN Hua-xin;SONG Li-fang;ZHANG Min;KUANG Dong-liang

2017, 36(3):  971-978. 

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The modified cement mortar was prepared by polyvinyl acetate latex.After immersed in sulfuric acid, nitric acid, sodium hydroxide, sulfate solution and painted through gasoline,the residual strength ratio of mortar was measured to analyze the corrosion resistance.The scanning electron microscope (SEM) was conducted to observe the micro-morphology of modified cement mortar.The main chemical composition of corroded cement mortar was analyzed through X-ray Diffractometer (XRD) test.The results show that the mortar is easy to be corroded by acid solution, while the PVAc latex can improve the acid-resistance to some extent.The sulfate-resistance can be increased with the addition of the PVAc latex.The mortar with high content of PVAc can be used in alkaline environment.The gasoline has little effect on the corrosion resistance.The curing films of latex can fill the porous structures in modified mortar, which prevent the corrosive medium from entering the mortar.Meanwhile, the elastic films can absorb the swelling stress, and reduce the expanded destruction phenomenon, which can improve the corrosion resistance of cement mortar.

Strength and Leaching for Remediation of Chromium Contaminated Soil Using Cement

LI Xi-lin;ZHANG Jia-wen;CHEN Dong-qin;SUN Juan;HOU Zhe;SUN Bo-lin;WANG Chao

2017, 36(3):  979-983. 

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In order to solve the problems of soil and groundwater pollution caused by heavy metal chromium, the Cr (VI) and Cr (III) test research on the cement solidified soil was carried out in the polluted soil of Shenyang chromium slag.The determination of cement content, curing period, different content and valence of chromium were tested to affect the unconfined compressive strength and leaching characteristics of solidified soil.The results show that the cement is an effective curing agent for Cr (VI) and Cr (III) contaminated soil, and the cement content is 20%.Cr (VI) and Cr (III) have a weakening effect on the strength of solidified soil and Cr (III) weakening effect is more obvious.The change of the strength of the solidified chromium contaminated soil is explained from the SEM images, which is consistent with the experimental results of unconfined compressive strength.

Effect of Nano-SiO2 Dispersibility on the Strength of Cement Mortar

XIAO Jia;SHEN Chuang;WANG Da-fu;LI Yun;YIN Zhe-wei

2017, 36(3):  984-990. 

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Hand stirring, mechanical stirring and ultrasonic were used to disperse nano-SiO2.The nano-SiO2 dispersion was studied by measuring nano-SiO2 colloidal particle size and particle size distribution using Zeta potential analyzer and its effects on the strength and capillary water absorption of cement mortar were analyzed as well.The research results show that the dispersion effect of ultrasonic dispersion is the best among the three dispersion methods, the mechanical stirring is the second and the manual stirring is the worst.With the increase of ultrasonic time, the average particle diameter of nano-SiO2 colloid decreases, and dispersibility of nano-SiO2 increases.The time of ultrasonic is more than 10 min, small particles of nano-SiO2 colloid increase, but the particle size distribution curve shifts to the larger particles, resulting in no obvious improvement in dispersibility.The strength of cement mortar and capillary water absorption relate with the dispersibility of nano-SiO2.With the increase of nano-SiO2 dispersibility, strength of cement mortar increases, capillary water absorption coefficient decreases,and density of mortar is improved.

Preparation and Electrochemical Performance of Rice Husk-based Activated Carbon Electrode

SONG Xiao-lan;DUAN Hai-long;WANG Hai-bo;LIU Han-jun;LIU Shi-chao;ZHOU Yong-xin;ZHOU Zhi-hai

2017, 36(3):  991-995. 

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Activated carbon was prepared from rice husk, using sodium hydroxide as activator.Then activated carbon was selected as electrode to assemble supercapacitor with electrolyte of potassium hydroxide solution.X-ray diffraction (XRD),nitrogen adsorption-desorption (BET) and scanning electron microscopy (SEM) were used to study surface area and pore structure of carbon prepared at different temperatures.Meanwhile,the electrochemical performance of supercapacitor was investigated by constant current charge/discharge and cyclic voltammetry (CV).The results show that the specific surface area of carbon reaches the maximum value of 2760 m2/g at activation temperature of 800 ℃ with developed pore structure.Under the optimal activation condition, the specific capacitance of activated carbon recorded as the maximum value of 267.2 F/g in 6 mol/L of KOH solution,and the equivalent resistance was only 2.2 Ω with the good rate performance.The capacitance retention ratio was still keeping a high level of 83.7% after 5000 cycles.It indicates that the rice husk-based activated carbon exhibits good charge-discharge reversibility and cycle stability.

Experimental Study on the Compressive Strength Index Conversion Relationshipof Plastic Steel Fibers Reinforced Lightweight Aggregate Concrete

NIU Jian-gang;LIU Hong-zhen;ZUO Fu-liang;XIE Cheng-bin

2017, 36(3):  996-1002. 

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In order to study the conversion relationship on axial compressive strength and cubic compressive strength of plastic steel fibers reinforced lightweight aggregate concrete(PSFLC), cubic compressive strength and axial compressive strength were tested by 432 standard specimens respectively.The influence of the plastic steel fibers content, the water cement ratio and the type of lightweight aggregate on the compressive properties of PSFLC were investigated.The results show that the content of plastic steel fibers(5-13 kg/m3), the water cement ratio(0.32-0.4) and the type of lightweight aggregate(fc/fcu) make no difference on the ratios between axial compressive strength and cubic compressive strength.The linear equation between axial compressive strength and cubic compressive strength are obtained by regression analysis and it has good correlation.Based on analysis of regression and mathematical statistics to the ratios between axial compressive strength and cubic compressive strength, the conversion coefficient of axial compressive strength and cubic compressive strength was 0.80 for PSFLC.

Sodium Fluorosilicate Fractional Step Method for Preparing Silica and Sodium Fluoride

ZHENG Dian-mo;LIU Wei-wei;WEN Ai-peng;CHEN Xin;CHEN Qiu-xia;GUO Hong-xiang

2017, 36(3):  1003-1008. 

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Using sodium fluoride as the main raw material, silica and sodium fluoride were prepared by fractional step method.Under the optimized process conditions, silica has amorphous structure with loose secondary aggregates, silica DBP value of 3.52 mL/g, primary particle diameter of 20 nm, a silica content of 98.97%.Sodium fluoride having a cubic crystal structure, the average particle diameter of 110 μm, sodium fluoride content of 98.63%.The process can make full use of fluorine source and silicon source, ammonia recycling, improving the quality and yield of sodium fluoride, greatly reducing the amount of fluorine-containing waste water.

Effect of Molten Iron Desulphurization Slag as Filler on the Mechanical Properties of Rubber Materials

GU Heng-xing;LI Hui

2017, 36(3):  1009-1014. 

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The rubber materials were prepared from natural rubber filled with molten iron desulphurization slag.The effects of molten iron desulphurization slag/carbon black ratio, particle size of molten iron desulphurization slag and curing time on the mechanical properties of rubber materials were studied.The results show that the mechanical properties of rubber materials decreas slightly and the maximum utilization of the molten iron desulphurization slag can be achieved when the ratio of molten iron desulphurization slag/carbon black is 20∶30.No matter the particle size of the molten iron desulphurization slag among rubber materials was too large or too small, the dispersion and compatibility of the molten iron desulphurization slag in natural rubber deteriorated, which led the decrease of the mechanical properties.When the curing time was about 30 min, the mechanical properties of the rubber materials were optimal.

Gelcasting Process of Graphite

LIU Xiu;QI Long-hao;HE Zhi-yong;ZHANG Qi-fu

2017, 36(3):  1015-1019. 

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Graphite slurry was prepared by gelcasting process.The influences of types of graphite powders, pH value, dispersant and solid loading on the viscosity of slurry were investigated.The effects of slurry temperature on gel time and acetylacetone on the flexural strength of graphite green body were studied.The results show that the fluidity properties of graphite has the best when type of graphite is isostatic pressing graphite powder, pH value is 7, content of dispersant solution(respect to graphite weight) is 4wt%, and solid loading is 50vol%.When the slurry temperature is 3 ℃,the gel time is 5.6 min.Flexural strength of green body is 15.8 MPa when the content of acetylacetone is 0.6wt%.

Preparation and Characterization of Sulphur-free Expanded Graphite

XU Shan;CAO Bao-yue;NIU Cheng-ji

2017, 36(3):  1020-1024. 

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For the high sulfur content of expanded graphite prepared and an unstable expansion volume by the traditional method, natural graphite flake graphite was used as raw material, KMnO4 as oxidant, HClO4 and H3PO4 as intercalating agent, the expansion of expandable graphite by microwave oven and muffle furnace.The orthogonal experiment was used to determine the optimum process conditions.The results show that the optimum reaction conditions are as follows: graphite (g)∶mixed acid (mL)∶potassium permanganate (g) =1∶4.5 mL (3.6 mL perchloric acid∶0.9 mL phosphoric acid)∶0.3, reaction temperature 30 ℃, reaction time 60 min, filtering and washing to pH 5-7, drying at 80 ℃, and expanding in the microwave oven, the expanded graphite has the largest volume of 350 mL/g.

Chloride Penetration and Frost Resistance Properties of C60 Self-Compacting Concrete

HOU Jing-peng;WANG Quan;SHI Wei;CHEN Qun;XU Han-si

2017, 36(3):  1025-1029. 

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The C60 self-compacting concrete was designed by the absolute volume method.The workability, compressive strength at different age, chloride permeability and frost resistance were studied.The results show that the fluidity of the fresh concrete meets level 2 standard of self compacting concrete.The compressive strengths develop very well after standard curing for 28 d;The 6 h elective flux of the self compacting concrete is very low, proving the excellent chloride penetration resistance.After 200 freeze-thaw cycles ,the loss of the dynamic elastic modulus is 26.05%, smaller than the values in standard, and the mass loss ratio is less than 1.86%, proving the excellent frost-resistance properties.The results provide the references for the application of self compacting concrete.

Effect of Microdosage Phosphate on Enhanced of the Strength of Steam-Curing Concrete

HE Ting-shu;XIE Biao

2017, 36(3):  1030-1034. 

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Effects of microdosage phosphate (≤0.05%) on the compressive strength of steam-curing concrete were investigated, the effects of the different dosage of CaCl2 and Na2SO4 on the compressive strength of steam-curing concrete were compared with mircodosage phosphate, and the microstructure of samples with different phosphate was also analyzed.The results show that the compressive strength of steam-curing concrete increases and then decreases with the dosage of phosphate increasing.In the dosage of 0.01%, the early compressive strength increases 14.7%, 28 d strength increased 15.3%, in the dosage of 0.05%, it is harmful for the strength.The microdosage CaCl2 and Na2SO4 have no influence on the compressive strength of steam curing concrete.Phosphate can promote the hydration of cementand make the cement hydration crystal growth regularly and well-distributed in the dosage of 0.01%, which is benefit to the development of the strength;In the dosage of 0.05%, phosphate have an ability to delay cement hydration, it is most detrimental to the development of steam-curing concrete strength.

Measures for Reducing Amount of Tin Infiltration and Its Qualitative Detection

WANG Zhou

2017, 36(3):  1035-1039. 

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In float process, glass formed in tin bath, which caused of tin penetration.Tempering bloom would appear when glass that had tin infiltration over a certain amount was tempered, thus affecting the appearance quality of glass.In this paper, the relationship between the formation of tempering bloom and the amount of tin infiltration was analyzed.The rapid qualitative detection methods were recommended to avoid waste in subsequent processing.The measures to reduce the amount of tin infiltration were discussed to guide the glass production.

Preparation of Boron Cross Linking Agent for Fracturing Fluid Using Waste Fly Ash

CHEN Fu;YANG Yang;BU Tao;HE Xue-mei

2017, 36(3):  1040-1045. 

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Taking advantage of fly ash to prepare poly silicic acid, setting polysilicate and borax as the raw materials,a kind of high temperature retarding crosslinking agent was synthesized.With the single factor method and measuring the performance of boron crosslinking agent,the optimum process parameters was obtained that borax mass fraction was 5wt%, ligand mass fraction was 28.5wt%, the reaction temperature was 80 ℃, catalyst mass fraction was 1.5wt%.The target product was characterized by IR,the rheological property of the cross-linked HPG gel fracturing fluid was evaluated on the condition that the concentration of the HPG was 0.45wt%,cross ratio was 100∶0.8 (volume ratio),110 ℃, 170 s-1,shearing 2 h, which turned out that the viscosity of cross-linked HPG gel fracturing fluid was more 130 MPa·s.It proved that the crosslinking agent had better effect on HPG.The breaking test's results shown that the crosslinked fracturing gel had the characteristics of easily breaking and low residue.

Forecast f-CaO Content of Steel Slag in Sodden Aging by Soft Sensor Modeling Based on Gaussian Process Regression

CHEN Hua;LI Hui;GU Heng-xing;YANG Gang;CHEN Wei;XU De-long

2017, 36(3):  1046-1050. 

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Sodden aging method was used to deal with BSSF steel slag, and the content of free calcium (f-CaO) in BSSF steel slag was traced and checked.Soft sensor modeling based on gaussian process regression was established by gaussian process regression to forecast the f-CaO content in steel slag by sodden aging.The results show that f-CaO content in BSSF steel slag is effective reduced by sodden aging method to meet the requirements of the safe use, namely f-CaO content in A-BSSF steel slag is about 3.98%-4.03% after 120 d and f-CaO content in B-BSSF steel slag is about 9.84%-10.03% after 105 d.Soft sensor modeling based on gaussian process regression real value agree well with the forecast value, the relative error is-1.493%-0.748%, which increases the prediction accuracy efficiently of the f-CaO content in steel slag by sodden aging.

Manufacture of Paraffin-Based Capsule and the Influence on the Thermal Conductance and Mechanical Properties of Mortar

LI Jin;CHEN Pei-yuan;MA Hai-bin;WANG Yu-xuan;WANG Dong-ping

2017, 36(3):  1051-1055. 

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To resolve the sealing problem of solid-liquid phase change materials when transforming into liquid, a novel paraffin-based capsule was prepared with paraffin as the core material, ceramsite particles as the carrier and cement paste as the coating material.The basic properties of the paraffin-based capsule were tested, and the test of DSC was conducted.In addition, the thermal conductance and mechanical properties of mortar incorporated with paraffin-based capsule were tested.Results reveal that cement paste helpes the paraffin-based capsule maintain a good hold ability of the loaded paraffin, without leakage under high temperature.The incorporation of paraffin-based capsule into mortar does not negatively affect the mechanical property of mortar, moreover, it reduces the thermal conductivity and hydration temperature of cement paste and delayes the appearance of the highest hydration temperature.

Influence Analysis of Material Intrinsic Parameters and Test Conditions on Asphalt-Stone Adhesion

HAN Qing-kui;TAN Xin-gui;ZHAN Zhe-hong;LI Quan;LUO Li

2017, 36(3):  1056-1063. 

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It is a hot spot to study the asphalt-stone adhesion to prevent the water damage of asphalt mixture by the contact angle method.In this paper, seven kinds of stone materials and three kinds of asphalt commonly used in road construction are studied by contact angle method in order to obtain the same and stable experimental conditions to study the influence of the intrinsic parameters of materials on the adhesion of asphalt-stone.The results show that the contact angle test is carried out at the temperature of 60 ℃ when the sample is polished by 15.9 mm polishing degree, washed with distilled water-anhydrous ethanol-cyclohexane-distilled water.The obtained asphalt-stone adhesion work corresponds to the result of the material intrinsic parameter affecting the asphalt-stone adhesion.

Optimization of Coarse Aggregate Gradation Based on Rheological Behavior

JIAO Deng-wu;SHI Cai-jun;AN Xiao-peng;LIU Yu;HE Fu-qiang

2017, 36(3):  1064-1070. 

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Based on Bingham model, the rheological properties of fresh concrete with varied coarse aggregate gradation of three sizes were tested using an ICAR rheometer.The effects of coarse aggregate gradation on slump flow, yield stress and plastic viscosity of concrete were investigated and then the coarse aggregate gradation were optimized.Results indicate that the gradation of coarse aggregate has significant effects on flowability and rheological parameters of fresh concrete.On the other hand, the optimum composition of three sizes aggregate could be determined by controlling the rheological parameters of concrete.Therefore, it is a better way to optimize the concrete mixture design by limiting the range of rheological parameters.

Preparation and Negative Thermal Expansion of Er2W3O12 Ceramics

ZHANG Zhi-ping;ZHANG Jia-cheng;LIU Hong-fei;YANG Lu;CHEN Xiao-bing

2017, 36(3):  1071-1074. 

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Negative thermal expansion Er2W3O12 ceramics were successfully prepared, using solid state reaction of Er2O3 and WO3 as raw materials.The microstructure,composition and hygroscopicity of the Er2W3O12 samples were investigated by X-ray diffraction (XRD),field emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TG).The negative thermal expansion of the Er2W3O12 ceramics was studied using the thermal mechanical analysis (TMA) and high temperature X-ray diffraction (HTXRD).Results indicate that the Er2W3O12 ceramics sintered at 950 ℃ for 6 h are well crystallized.TG analysis shows that Er2W3O12 is hygroscopic.The dehydration starts at 120 ℃, and the Er2W3O12 crystals are in orthorhombic structure after dehydration.The orthorhombic Er2W3O12 ceramics show excellent negative thermal expansion.The thermal expansion coefficient of the orthorhombic Er2W3O12 ceramics is-7.94×10-6 K-1 at 138-700 ℃.HTXRD results indicate that the Er2W3O12 ceramics show negative thermal expansion along three axes, and the average thermal expansion coefficient of the orthorhombic Er2W3O12 ceramics is calculated to be-7.81×10-6 K-1 at 100-600 ℃ based on the HTXRD results.

Preparation of LDHs Thin Films with Different Compositions and Its Adsorption Properties

YU Huan;WANG Wei-wei

2017, 36(3):  1075-1079. 

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Three kinds of LDHs thin films were prepared by hydrothermal method with molar ratio of M2+/M3+ being 2/1 and urea as the precipitant.The structure, size and morphology of LDHs thin films were characterized by X-ray diffraction (XRD), Scanning Electronic Microscopy(SEM), energy-dispersive spectroscopy(EDS) and Fourier transform infrared spectroscopy(FT-IR).Experimental results show that the different solubility constants (Ksp) between M2+ and M3+, the composition of LDHs result in different morphologies and particle sizes.When the solubility constants of M2+ and M3+ were similar, NiAl-LDHs and MgAl-LDHs films have platelet-like shape.The ab plane of MgAl-LDHs sheets grew perpendicular to the surface of conductive fabric substrate.When the solubility constant of M2+ and M3+ were different, NiFe-LDHs films with spherical aggregation was observed.Compared with that of NiAl-LDHs and NiFe-LDHs films, MgAl-LDHs films showed better adsorption property.

Effect of Poly Hydroxyl Saccharide Content on the Sintering Properties of Magnesia-Calcia Tundish Dry Material

ZHENG Yu;ZHANG Guo-dong;GAO Hong-yue;CHEN Qi

2017, 36(3):  1080-1084. 

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The effect of poly hydroxyl saccharide(white granulated sugar and anhydrous glucose)content on the properties of magnesia-calcia dry material was introduced.The addition amount of poly hydroxyl saccharide is 3wt%、4wt%、5wt%、6wt%.The samples were formed through ramming vibration and sintered separately at the low temperature (150 ℃), middle temperature(1100 ℃) and high temperature(1550 ℃).The cold bending strength and compressive strength, volumedensity, linear change and porosity of samples were measured.Experimental results show that white granulated sugar and anhydrous glucose can be used as binder at 150 ℃.The linear change of white granulated sugar is fewer change at 1100 ℃ and 1550 ℃.Using poly hydroxyl saccharide produce less smoke.This method conform to the requirements of environmental protection.

Comparative Study on the Flame Retardant Properties of Medium Density Fiberboard Covered by NaOH and Na2SiO3

WANG Ya-chao;ZHAO Jiang-ping;TONG Yuan-yuan;DING Jian-xiong

2017, 36(3):  1085-1089. 

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The effects of covering NaOH and Na2SiO3 solution on the flame retardant properties of medium density fiberboard were investigated based on the techniques of chamber combustion method, the vertical combustion apparatus and limit oxygen index.The results show that various flame retardant performance of fiberboard are follows: fiberboard covered Na2SiO3 > NaOH + Na2SiO3 > NaOH > untreated fiberboard > bubble water treatment, the single-side pasting presented a higher flame retardant performance than the double-side pasting, the limit oxygen index could reach 25.2%.It is proposed the flame retardant mechanism of NaOH and Na2SiO3 on the medium density fiberboard, coating NaOH solution makes the flame retardant substances migrate out the surface, coating Na2SiO3 is benefit to form a cross-linking siliceous layer containing (=)Si-O-Si(=) chains, leading to an improvement of the flame retardant performance.

Effect of H3BO3 on the Low Temperature Sintering and Microwave Dielectric Properties of Li2Zn3Ti4O12 Ceramics

TANG Hua;WU Hai-bang;MENG Fan-cheng

2017, 36(3):  1090-1093. 

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Li2Zn3Ti4O12 (LZT) ceramics doped with H3BO3 addition were prepared using conventional solid-state reaction method.X-ray diffraction,scanning electron microscopy,the drainage method and dielectric measurements were introduced to investigate the phase, microstructure, sintering behavior and microwave dielectric properties of the LZT specimens with different amounts of H3BO3.The results show that the Li2Zn3Ti4O12 ceramics sintered at 900 ℃ with 3wt% H3BO3 for 2 h shows high density and good microwave dielectric properties(ρ=4.15 g/cm3,εr=17.916,Q×f=61200 GHz,Tf=-52.87×10-6/℃).

Influence of Basalt Fiber Content on Strength Properties of Shale Lightweight Aggregate Concrete

LIU Yun-peng;GUO Rong-xin;LIN Zhi-wei;XIA Hai-ting;YAN Feng;ZHANG Yu-bo

2017, 36(3):  1094-1100. 

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The influence of different basalt fiber volume content on the strength of shale lightweight aggregate concrete was studied.The results of test show that basalt fiber can improve the lightweight aggregate concrete compressive strength, flexural strength and elasticity modulus in a certain extent.When the volume content of fiber is 0.2%, the compressive strength and flexural strength reach the maximum, which is increased by 11.49% and 20% respectively.The splitting tensile strength of lightweight aggregate concrete increased with the increase of fiber content;When the fiber content is 0.3%, the splitting tensile strength reached the maximum, and is increased by 54.59%.That basalt fiber shale lightweight aggregate concrete not only increases the strength of each phase, but also improves the brittleness of lightweight aggregate concrete defects in a certain extent and playes a role in strengthening and toughening.

Effect of TiO2 Addition on Densification Behavior of Magnesium Aluminate Spinel Synthesized by Solid-state Sintering

XIE Peng-yong;HAO Chang-an;LUO Xu-dong

2017, 36(3):  1101-1105. 

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Magnesium aluminate spinel (MgAl2O4) was synthesized by solid-state sintering using low-grade magnesite and industrial α alumina fine powder as raw materials.The effect of TiO2 addition on densification behavior of magnesium aluminate spinel synthesized was discussed.The phase composition and microstructure of specimens were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The results show that the replacement solid solution of TiO2 addition and formed magnesium aluminate spinel is the significant mechanism to promote the densification of magnesium aluminate spinel synthesized by solid-state sintering.The generation of cation vacancy and the lattice defect of magnesium aluminate spinel are in favor of crystal growth of magnesium aluminate spinel under high temperature which obtains the purpose of densification by excluding pores due to the role of steric hindrance.The extent of densification of magnesium aluminate spinel gradually increases with the increasing in amount of TiO2 content which improves the sintering properties and microstructure of magnesium aluminate spinel effectively.