Table of Content

15 September 2016, Volume 35 Issue 9

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Surface Chloride Concentration Profiles of Coral Concrete Exposed to Marine Environment

DOU Xue-mei;YU Hong-fa;MA Hai-yan;DA Bo;YUAN Yin-feng;MI Ren-jie;ZHU Hai-wei

2016, 35(9):  2695-2700. 

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The surface chloride concentration profiles of coral concrete exposed to substitute ocean water were investigated ,and influences of curing age , exposing time and strength grade of coral concrete on free chloride diffusion coefficients of coral concrete were discussed by using the natural diffusion method .Results show that surface chloride concentration profiles of coral concrete decreases with the passage of curing age and strength grade.However, that increases with the passage of exposure time and gradually tends to stabilize .The surface chloride concentration profiles of C 50 coral concrete is 3.5 times higher of C50 normal concrete in the same conditions.Under the same curing age and exposure time , the surface chloride ion concentration of the south china sea island and reef actual enviroment cubic specimen is 60%-90% higher than the laboratory data.The surface chloride ion concentration of coral in practical engineering concrete structure value is 1.2-1. 6 times higher than the laboratory data .Therefore, in terms of concrete structures under the actual marine environment , in order to ensure the structural strength and considering the influence of the surface chloride ion concentration, we should prolong wet curing time and adopt approximately strength grade of coral concrete have such great influence on extending the service life of coral concrete .

Experimental Research on Mechanical Performance of Inorganic Polymer Rubber Concrete

FAN Xiao-chun;CHEN Yun-wei;HU Yi-chang

2016, 35(9):  2701-2709. 

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As the energy-efficient and environment friendly materials , inorganic polymer and rubber powder have always been the hot issues in engineering application study .In this paper , we use 2-4 mm rubber particles instead of the fine aggregates in the same volume , making upinorganic polymer rubber concrete with different rubber contents ( 0%,5%,10%,15%,20%) .According to GB/T 50081-2002 standard of test method about the ordinary concrete ’ s basic mechanics performance , we make experiments to study the basic mechanics performance of the inorganic polymer rubber concrete .The results show that , relative to reference concrete , the cube compressive strength of inorganic polymer rubber concrete with 5% to 20% rubber contents decreased by 9 .5% to 35 .7%;the tensile splitting strength of inorganic polymer rubber concrete with 10% to 20% rubber contents decreased by 9.9% to 18.2%, the axial compressive strength decreased by 20.2%to 35.4%, the static modulus decreased by 3.2%to 7.8%.The early age strength of inorganic polymer rubber concrete is higher than ordinary rubber concrete, among them, the seven days relative intensity is 11.5% higher.With the increase of rubber content , the ratio of tension and compression of inorganic polymer rubber concrete increases , the strength ratio remain unchanged .The anti-cracking ability and deformability of inorganic polymer rubber concrete enhances with the increase of rubber concrete .

Chemical and Autogenous Shrinkages of Cement-based Composite Paste with the Addition of Inorganic Nano-powders

CHEN Yu;DENG Yi-fan;QIAN Yi-xiang

2016, 35(9):  2710-2716. 

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Based on ASTM standards and modified test method ,the chemical and autogenous shrinkages of cement composite paste were measured to investigate the influences of single addition of one of three inorganic nano-powder , such as amorphous nano-SiO2 with different particle sizes , hydrophilic or surface prewetted nano-CaCO3 , or nano-TiO2 with various crystal forms and particle sizes on the early-age shrinkage of paste .Results show that within a certain mass proportion , the addition of inorganic nano-powder obviously increases both chemical and autogenous shrinkages of composite paste , and with time passing,the increments become more evident .The addition of nano-SiO2 exerts the most effect, especially using the smaller nano-particle.Compared to the hydrophilic or surface prewetted nano-CaCO3 , the hydrophilic one leads to higher early-age shrinkage of paste under the condition of the same mass proportion.With 3.0%-5.0%of nano-TiO2 admixed, though the highest chemical shrinkage of paste is observed , there is no remarked growth for autogenous shrinkage , much less than that added with nano-SiO2 or nano-CaCO3 .It can be concluded that the influence of inorganic nano-powder on the early-age shrinkage behavior of composite paste depends on the type , crystal form, particle size, surface status and mass proportion of the added inorganic nano-powder .

Reaction Kinetics of Fly Ash Based Geopolymer Systems

CHEN Chen;CHENG Ting;GONG Wei-liang;ZHAI Jian-ping;ZHANG Min-te

2016, 35(9):  2717-2723. 

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In this paper , based on the experimental data , with the help of "Jander"kinetic equation and modern analytical methods , the reaction kinetics of fly ash geopolymer system were studied .The research content include:the effect of liquid-solid ratio on the reaction process , the reaction kinetics stage of fly ash based geopolymer , the effects of temperature and alkali concentration on the each reaction kinetics stage and generating mechanism of compressive strength .The results show that:Reducing liquid-solid ratio will cause a decline in the reaction rate , promote the formation of solid products and the structure change of reaction products .The main reaction kinetics stage belong to diffusion reaction stage ( model N=2 and N>2).Increasing temperature can improve each reaction rate and at same time reduce stage duration of each kinetics stage .Higher alkali concentration could effectively increase the reaction rate of each kinetics stage.The difference of chemical composition between fly ash particles and reaction produces is related to the geopolymer reaction process and the formation of compressive strength .

Effect of Basalt Fiber Content on Mechanical Performance of Concrete

ZHANG Lan-fang;YIN Yu-long;YUE Yu

2016, 35(9):  2724-2728. 

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The purpose of this paper is to study the effect of basalt fiber at the contents of 0.05%~0. 35%on compressive strength , splitting tensile strength and bending performance of concrete .Scanning electron microscope ( SEM ) is used to analyze the microscopic mechanism of basalt fiber-reinforced concrete.The results show that 3 d, 7 d and 28 d compressive strength and tensile strength of concrete have been improved to varying degrees when the fiber content is less than 0.3%.When the content of basalt fiber exceeds 0.3%,28 d compressive and tensile strength of concrete began to decline ,and the greater the content of fiber , the more strength decline .Bending test results show that the flexural strength of concrete increase by an average of 7.96%when the content of basalt fiber increases from 0.05%to 0. 25%, and the flexural strength of concrete increase by 17% when content is 0 .2%.and after the incorporation of basalt fiber , stress-strain curve for concrete have a well-marked yield point , ultimate tensile strain of concrete increases , the elastic modulus decreases , implying a decrease in the rigidity .On the other hand , Adding basalt fiber to concrete can improve ductility and flexibility of concrete , increase the crack resistance of concrete and extend the service life of concrete .

Hydration Degree and Property of Coal Gangue-Slag-Cement System

LI Yan;YANG Xu-guang;MA Yue;SUN Dao-sheng;WANG Ai-guo

2016, 35(9):  2729-2732. 

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Selective dissolution method and nonlinear fitting method were used to measure the hydration degree of three raw materials ( coal gangue , slag and cement ) in coal gangue-slag-cement ternary blended systems , respectively .The drying shrinkage and compressive strength of pastes which incorporated with coal gangue and slag of different mix proportions were determined and analyzed .The results show that the blended cement paste containing 5%coal gangue and 25% slag can meet the composite material which has small drying shrinkage , high compressive strength .

Stress-sensing Performance of MWCNTs Cement Composites

WANG Qin;WANG Jian;LIU Bo-wei;LYU Chun-xiang;DONG Yi-chen

2016, 35(9):  2733-2740. 

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Polycarboxylate superplasticizer was used to disperse multi-walled carbon nanotubes ( MWCNTs) and four electrode method was used to study the influence of MWCNTs on the electrical resistivity and stress-sensing properties of multi-walled carbon nanotube-based cement composites (MWNTs/CC).The effect of several variables on the stress-sensing function was studied, e.g. MWCNTs content , maximum stress applied and loading rate .The results show that with the increase of the dosage of MWCNTs , the electrical resistivity of composites decreases gradually , and the polarization time reduces gradually .When the dosage of MWCNTs between 0.06wt% to 0.3wt%, the MWNT/CC exhibit excellent stress-sensing property and the optimum dosage of MWCNTs is 0.1wt%.When the samples were progressively loaded until failure , the maximum fractional change of electrical resistance is up to 70%.With the increase of maximum loading stress and loading rate , the ratio of electrical resistivity change increases gradually .

Cementing Performance and Compressive Strength of Complex Cementitions-Sodium Silicate Two-shot Grouting Materials

WU Mao-yin;WANG Qi-cai;ZHANG Rong-ling;TIAN He-xiang;ZHANG Kai;WANG Xiao-long

2016, 35(9):  2741-2746. 

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Traditional cement silicate double solution grouting material has many advantages which contain the short gel time and large early compressive strength .So this material is widely used in consolidating soft formation or plugging .Based on the traditional material , fly ash and slag in cement-based was added and a kind of new complex cementitions-sodium silicate two-shot grouting materials was put out .This new material's cementing performance and 28 d compressive strength were studied .By changing the sodium silicate content , baume and mineral admixtures to study the variation of slurry's cementing performance and 28 d compressive strength .The compressive strength of stone body is the largest when the dosage of sodium silicate is 25%.Increasing modulus of sodium silicate or cement fly ash slag which are mixed can improve the compressive strength of stone body .

Process Optimization and Properties of Silicon Nitride Ceramics Prepared by Pressureless Sintering

WANG Huan;XUAN Wei-dong;YANG Zhi-gang;MA Chen-kai;ZHAO Deng-ke;REN Zhong-ming;WANG Bao-jun;WANG Jiang

2016, 35(9):  2747-2752. 

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Silicon nitride ceramics were prepared by pressureless sintering , using α-Si3 N4 as raw material, Y2 O3 and MgO as sintering additives .In order to optimize the experiment formulation and process parameters , the effects of forming pressure , pressure-holding time , holding time , sintering temperature , the content and the ratio of sintering additives on the apparent porosity and bending strength of the silicon nitride ceramics were investigated by using the orthogonal experiment .The results show that the content and the ratio of sintering additives mainly affect the apparent porosity of ceramics , but the ratio of sintering additives and sintering temperature mainly affect the bending strength of ceramics .The optimal parameters were as follows:pressure of 16 MPa, pressure-holding time of 120 s, holding time of 2 h, sintering temperature of 1750 ℃, the content of sintering additives of 12wt% and the ratio of sintering additives of 1∶1 .Silicon nitride ceramics sintered after the optimal parameters have the density of 94.53%, apparent porosity of 1.09%and bending strength of 410.73 MPa.

Adsorption and Desorption Characteristics of K+and Na+on C3 S-nano-SiO2 Pastes

QIAN Hai-long;DENG Min;CHEN Bi;WANG Zhi-lei;LU Guo-sen

2016, 35(9):  2753-2758. 

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C3 S synthesized with analytically pure compounds and nano-SiO2 were used to prepare pastes . The electrical properties , phase composition and specific surface area of the pastes were characterized by means of ζpotential measurement , X-ray diffraction and adsorption-desorption of N 2 , respectively .The adsorption and desorption properties of K +and Na +by the pastes mixed with de-ionized water or alkali solutions were investigated .The results show that the higher the replacement level of nano-SiO2 , the larger the ability of C 3 S-nano-SiO2 pastes to bind alkali .There is no obvious difference between amount of K+and Na +adsorbed by the pastes .Adsorption of K +and Na +by the pastes mixed with de-ionized water is mainly with physical adsorption .There are few residual alkali ions in the pastes mixed with alkali solutions after washed with enough de-ionized water .

Numerical Analysis of the Influence of Coarse Aggregate on Uniaxial Compressive Strength and Failure Characteristics of Concrete

WANG Yun-fei;ZHENG Xiao-juan;WANG Li-ping;JIAO Hua-zhe

2016, 35(9):  2759-2766. 

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Used to PFC2 D discrete element software to generate the concrete matrix , then the Clump technique was used to form different forms of coarse aggregate concrete model .Analyzed the influence of coarse aggregate content and forms on uniaxial compressive strength and damage evolution of concrete . Some main research results are as follows: concrete uniaxial compressive strength increases with the increase of the content of coarse aggregate .At the same content of coarse aggregate , the strength of triangular coarse aggregate concrete is the highest , followed by the pentagon coarse aggregate concrete , circular coarse aggregate concrete strength is the lowest .When the content of coarse aggregate is less than 50%, the growth rate of elastic modulus is lower with the content of coarse aggregate , when greater than 50%, the growth rate higher .The initial micro damage of concrete is mainly concentrated in the interface, micro cracks of circular coarse aggregate concrete develops along the tangent direction of interface, main cracks develops along the common tangent direction of adjacent coarse aggregates , micro cracks of polygon coarse aggregate concrete develops along edge then extend into the matrix , main crack is formed by micro cracks of the basically same angle edges of adjacent coarse aggregates .The damage evolution of concrete is divided into three stages:the random distribution of micro damage , the formation of micro crack and the formation of main crack through the coalescence of micro cracks .There are obvious main cracks formed by the concreted damage when the content of concrete coarse aggregate is lower , while concrete inter damage is serious and forms into network cracks when the content of concrete coarse aggregate is higher .

Band Gap Characteristics of Periodic the Double Cladding Layer Locally Resonant Phononic Crystal

ZHANG Jia-long;YAO Hong;DU Jun;ZHAO Jing-bo;DONG Ya-ke

2016, 35(9):  2767-2771. 

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The double cladding layer local resonance mechanism resonators in phononic crystal was proposed .The band gap formation mechanisms , the width of band gap affect factors , and sound insulation quantities with finite element methods were analyzed .These results show that starting frequency depends on higher elastic modulus of the double cladding layer elasticity , cut-off frequency depends on smaller bulk density of elasticity .These results that phononic crystal has a good the light quality , low-frequency , width band gap and the sound insulation of characteristics , provides potential applications prospect the reducing of low-frequency noise in the mechanical equipments and provides theoretical guidance for the design of the structure of the phonon crystal .

Preparation of High-Porosity Ce-TiO2 Micropowder and Its Photocatalytic Performance

WU Yong-hua;LAN Zi-jun;DU Wei-liang;MA Ping

2016, 35(9):  2772-2776. 

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Modified Ce-TiO2 micropowder were synthesized by microwave-assisted hydrothermal method with homemade Ce-doped titania nanopowder and were characterized by X-ray diffraction ( XRD ) , scanning electron microscopy ( SEM ) , nitrogen adsorption ( BET ) , and UV-visible ( UV-Vis ) diffuse reflectance spectroscopy .The results show that modified Ce-TiO2 micropowder has high porosity , the average pore diameter is 153.4 nm and the specific surface area is 154.9 m2/g.Ce-doping has little effect on the structure of the micropowder , but it can enlarge the ability of TiO 2 for absorbing visible light , which shiftes absorption edge of TiO 2 reaching the visible region .At the same time Ce-doping effectively inhibits grain growth, hinders the crystal type transform of TiO 2 from anatase to rutile. High-Porosity Ce-TiO2 micropowder meets good visible light catalytic activity in low concentration formaldehyde solution .

Effect of ZrO2 on Viscosity and Surface Tension of Borosilicate Glass

LIU Yao-long;LU Ping;CHENG Jin-shu

2016, 35(9):  2777-2780. 

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Due to the high melting temperature ,borosilicate glass erode refractory strongly .ZrO2 dissolved into the glass change viscosity and surface of mother glass , which also bring about many and various product defects .In this paper , a small amount of ZrO 2 were introduced into the mother glass .High temperature viscosity was tested by the rotating method and high temperature surface tension was tested by the sessile drop method .The results indicate that viscosity of the glass above 1530 ℃almost no change and viscosity of the glass below 1530 ℃ greatly increase with increasing ZrO 2 content .At same time , surface tension is increasing mono-tonically .Surface tension reduce as the temperature increases .

Experimental Analysis on Effects of Early Strength Agent on Compressive Strength of Composite Foamed Lightweight Concrete

WU Ya-fei;LIU De-ren

2016, 35(9):  2781-2786. 

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Unconfined uniaxial compression test was performed on composite foamed lightweight concrete specimen with wet density of 500 kg/m3 , 800 kg/m3 and 1000 kg/m3 to analyze the effects of two kinds of early strength agent , calcium chloride and sodium sulfate , on the early compressive strength of lightweight composite foamed concrete .Otherwise the Optical microscopy technology and image analysis technology were applied to discuss the effects of calcium chloride and sodium sulfate on the early compressive strength from the micro perspective .The results illustrate that both types of early strength agents affect the early compressive strength obviously .Especially the 3 d, 7 d, 14 d compressive strength increase by at least 44.3%, 25.4% and 11.2%, and the sodium sulfate performs better .The incorporation of early strength agents could make its micro pore structure index improved significantly from the micro perspective ,especially the sodium sulfate .

Water Resistance Property of FGD Building Gypsum

YANG Lei;JING Min;SONG Hai-xia

2016, 35(9):  2787-2792. 

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The effects of fly ash, cement, compound activator and organosilicon waterproofing agent on the water resistance of flue gas desulphurization ( FGD ) building gypsum were studied .The research results show that there is no great improvement on the water resistance of FGD building gypsum when fly ash and cement are added to the system respectively .However , the flexural strength of the sample is above 6 MPa, the compressive strength is above 22 MPa and the flexural softening coefficient is above 0. 6 when fly ash , cements and compound activator are added simultaneously to FGD building gypsum system .Furthermore , the organosilicon waterproofing agent is added to the mixture system of fly ash , cements , compound activator and FGD building gypsum , the flexural softening coefficient of the sample is 0.756 and the compressive softening coefficient is 0.791 with add 0.8%waterproof agent , which are 64. 3%and 108.1%higher than that of pure FGD building gypsum , respectively, Water absorption rate is only 3.7%.It is indicated that the addition of self-made waterproof agent can significantly improve the properties of PEG building gypsum .

Microwave Properties of(1-x) Ba3 (VO4) 2-xLi2 MoO4 Microwave Dielectric Ceramics Sintered at Low Temperature

SUN Cai-xia;GAO Jing-xia;ZHANG Jin-ping;WANG Er-ping;ZHANG Yang-yang

2016, 35(9):  2793-2797. 

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The(1-x) Ba3 ( VO4 ) 2-xLi2 MoO4 ceramics have been prepared by the conventional soli-state reaction method , the effects of different mass ratio of Li 2 MoO4 on the microstructures and microwave dielectric properties of Ba3(VO4)2 are studied.The X-ray diffraction (XRD)test results indicated that Ba3(VO4)2 and Li2MoO4 phase coexist in the composite,and no secondary phases can be detected .The sintering temperature of Ba 3 ( VO4 ) 2 could be reduced with low melting point and negative temperature coefficient Li2 MoO4 .The relative density, dielectric constant and quality factor Q ×f of the compound ceramics all increase firstly and then decrease with the increase of the amount of the Li 2 MoO4 addition , however , the temperature coefficient of resonant frequency τf decreases gradually .The density of the microwave dielectric ceramics with 0.3 Li2 MoO4 addition sintered at 660 ℃ can reach the excellent microwave dielectric properties with εr=11.99,Q ×f=39700 GHz,τf=-24 ppm/℃.

Synthesis of TEPA-functionalized Organized Mesoporous Alumina and Their Selective Adsorption of CO2

JIANG Xiao-ping;ZHOU Yu;XU Qi

2016, 35(9):  2798-2803. 

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Organized mesoporous alumina (OMA) was synthesized by Al(NO3)3· 9H2O, non-surfactant CA was used as template , dilute ammonia as precipitating agent .Solid amine adsorbents were prepared by introducing tetraethylenepentamine ( TEPA ) into OMA by physical impregnation method for CO 2 capture.The synthesized adsorbents were charactered by XRD , N2 adsorption-desorption and TEM .The adsorption separation properties of CH 4/CO2 were discussed by means of breakthrough curve analysis in self-made fixed bed and the effects of TEPA loadings and adsorption temperatures were investigated .The results show that the maximal adsorption capacities are 2 .598 mmol/g achieved as 50% TEPA loadings and 70 ℃ adsorption temperature.In addition, after ten cyclic adsorption-desorption tests, the CO2 adsorption capacity changes a little , just decreases about 8.65%, demonstrating the TEPA/OMA adsorbent displays am excellent regenerability .

Experimental Research on Properties of Foamed Concrete

JIA Yan-tao;YANG Yong-gan

2016, 35(9):  2804-2809. 

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The influence of the different densities (300-1200 kg/m3), water-binder ratio (0.3-0.6), the polypropylene fiber and the EPS particles were investigated .The microstructure of a variety of proportions was analyzed by SEM and then explain the change of the strength .The result shows that the density is the most important factors of foam concrete macroscopic and microscopic property .Through the density control ,the different needs of products can be obtained .The higher the density is ,the greater the strength will be.In addition, the polypropylene fiber mixed can increase the strength in a certain range .The addition of EPS particles can lower bulk density , but also can make strength decline .

Erosion Wear Performance of TiB2-Al2 O3 Argon Arc Cladding Iron-based Alloy Coating

MA Zhuang;WEI Bao-quan;DONG Shi-zhi;ZHANG Yan-xin;LI Zhi-chao

2016, 35(9):  2810-2815. 

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Fe based alloy TiB 2-Al2 O3 coating was prepared by argon arc cladding method in order to improve the erosion wear performance of Q 255 .The highest micro-hardness of the cladding layer is 913 .5 Hv0.2 and is 5.9 times of that of the matrix .The erosion wear resistance of the cladding layer is increased by 1.77-4.22 times comparing with that of the matrix .The micro-structure of the weld pool is small and uniform.XRD results show that the cladding layer is composed of Fe , Al, TiO2 , TiB2 , Fe2 B and Al2 O3 phases .

Preparation and Properties of B4 C/Al-Mg Composite Material

WANG Tao

2016, 35(9):  2816-2820. 

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The B4 C/Al-Mg composites were prepared by compression molding method , the crystal phases and micrographs were analyzed by XRD and SEM .The effect of Mg content and the sinter temperature on the volume density and mechanical properties of composite were studied .The results show:when Al and Mg contents are 37%and 3%, the sintering temperature is 1150 ℃,the mechanical properties of B 4 C/Al-Mg composites are best .The bending strength is 303.67 MPa, hardness is 79.4 HRC and volume density is 2 .40 g/cm3 .

Property Comparision of Ultra-fine Fly Ash with Different Fineness

LI Hui;ZHANG Zhi-ming;CHEN Yu-jia;XIE Song

2016, 35(9):  2821-2825. 

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The basic property of three kind of UFA with different fineness prepared by super -fine grinding progress, the mechanical properties of cement mortar and concrete samples added with 10%of these kind UFA ,as well as the workability of concrete mixture were investigated .The results show that , the activity of UFA enhanced with the increase of fineness .Involving of UFA improved the workability of concrete mixture and the mechanical properties of mortar and concrete samples significantly .By using UFA and superplasticizer without silica fume , C80 high performance concrete was prepared .The results of micro-pore structure revealed that the volume of harmless pores inside the concrete samples CUFA 4 blended with UFA4 was larger than the samples of CUFA 2 and CUFA6 , which was in accordance with the macroscopical mechanical experiment results of concrete .

Selective Grinding and Floating Test on Flakey Graphite in Africa

HE Pei-yong;ZHANG Ling-yan;DENG Cheng-cai

2016, 35(9):  2826-2831. 

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With the experimental research on selective grinding and floating offlakey graphitein Tanzania , compared to conventional beneficiation process and optimization process on the basis of the best roughing conditions and regrinding fineness of rough concentrate , the large scale of graphite was protected while improving the grade and recovery rate of graphite concentrate in the experimental conditions of optimization process .Finally, the fixed carbon content of the concentrate is 96.28%, and the recovery rate of concentrate is 90.69% and increased by 9.63% and 3.4%respectivelycompared with conventional beneficiation process .

Recent Development of Research on Durability of Geopolymer for Civil Structural Applications

ZHAO Jian-wei;CUI Chao;GE Ya-ping;XIAO Bin;PENG Hui;ZHANG Jian-ren

2016, 35(9):  2832-2840. 

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Geopolymer is a kind of cementitious materials with network structures and amorphous phase , which can be synthesized by activating aluminosilicate through alkaline solution .Due to the mechanical properties of geopolymer are better than those of ordinary portland cement , and the CO 2 emissions in production process are less than the latter , the geopolymer is regarded as a promising substitute for ordinary portland cement .Many researchers believe that the durability of geopolymer for civil structural applications is better than that of OPC , however some other researchers remain sceptical of that and consider the durability of geopolymer needs further studies .Based on most of the available literatures , the present paper reviews the researches on durability of geopolymer in civil engineering application , including the gas permeability and water absorption , the carbonization , the sulfate corrosion , the acid corrosion, the alkali aggregate reaction , and the chloride ingress .In addition, the mechanisms of the material resisting the attacks were summarized , and the problems in the current researches were discussed .

Progress of Monoclinic BiVO4 Photocatalyst with Highly Active{010} Facets

LIU Wei;ZHAO Guo-sheng;CHANG Li-min;AN Mao-zhong

2016, 35(9):  2841-2846. 

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Research Progress on Application of Nano Titanium Dioxide in Silicate Industry

ZHU Jian-ping;HOU Huan-huan;FENG Meng-meng;TIAN Meng-di;CHANG Da-huan;ZHANG Han;CHAO Ting-ting

2016, 35(9):  2847-2851. 

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Nano-sized TiO2 has been widely used in many field , such as air purification , sewage treatment ,self-cleaning due to its excellent photocatalytic properties .The latest research progress in nano-titanium dioxide used in ceramics , glass, cement, concrete and other materials in the silicate series were reviewed.And the application of TiO2 composites in the field of environmental protection , such as antibiosis , self-cleaning , and degradation of nitrogen oxides and so on were reviewed .

Status and Prospects of Research on Reducing the Water Absorption of Foamed Concrete

CHU Hui-chao;LYU Xian-jun;ZHANG Yan;WANG Zhi-qiang

2016, 35(9):  2852-2859. 

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Foamed concrete is widely applied in various fields as a new type of inorganic heat preservation material.But the foamed concrete has higher bibulous rate , which seriously affect the durability performance of foamed concrete . According to the research of domestic and external , this paper introduced the application performance of waterproofing agent and water reducing agent on foamed concrete,and the insufficient in the current study were pointed out .The paper also proposed the research direction and development proposals to reduce water absorption .

Current Status and Prospects on Utilization of Phosphogypsum in Cement Production

YANG Zhi-qiang;CHEN Qing;GUO Qing-chun;DANG Yu-dong;LI Xin-cheng;QIAN Jue-shi

2016, 35(9):  2860-2865. 

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Phosphogypsum ( PG) is an industrial by-product generated from the manufacture of phosphoric acid by the wet process .Considering a huge amount of PG discharge , and a wide demand of cement in infrastructure construction , utilizing PG in cement manufacture is an encouraging approach .This paper firstly reviewed the current challenges of using PG in ordinary Portland cement ( OPC ) and calcium sulfoaluminate cement (SAC) manufacturing.Then, the application of using PG in SAC production is discussed as a new promising way to utilize PG .When using PG to produce SAC as one of raw materials , PG can render calcareous material for OPC and SAC production .But the negative impact of impurities in PG on properties of SAC can also be eliminated by the calcination processing . However , further researches are needed to increase the decomposition rate of PG . Sulfate-rich SAC cement can be produced by adding excess PG in raw materials , in that way the decomposition rate of PG can be increased .In addition , the impurities in PG can be used as functional component to modify the setting of SAC .

Toughening Research and Prospect of Development on Alumina Matrix Ceramic Material

ZHAO Jie-nan;ZHANG Ning;ZHOU Bin-bin;KAN Hong-min;WANG Xiao-yang;LONG Hai-bo

2016, 35(9):  2866-2871. 

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The brittleness of alumina ceramic limits its application .In the paper , combination with home and abroad ceramic toughening technology research progress , detailedly expatiated the origin of ceramic material brittleness , methods and principle of the toughening . Discusses the advantages and disadvantages of toughening methods and develop direction in the future .

Research Status and Prospect of One-part"Just Add Water"Geopolymer

JIAO Xiang-ke;LI Tao;LUO Xian-ping;YAN Qun;NI Shuai-nan;HUANG Zi-jie

2016, 35(9):  2872-2878. 

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Geopolymer is an inorganic cementing material with alternately bonding network structure formed by activating siliceous-aluminous material .The present method of synthesizing geopolymer mainly includes the following two kinds:one is solidified after mixing the active aluminosilicate raw material with activator solution ( denoted as GS-1 for convenience ); the other is solidified after adding water to the solid precursor directly ( denoted as GS-2 for convenience ) .In this paper , the research status of GS-2 was reviewed , then GS-1 was compared with GS-2 in components of the reactants as well as the reaction process and mechanism , finally prospect of GS-2 in performance improvement for geopolymer was provided .

Research Progress on Optimizing the Structure and the Electronic Conductivity of TiO2/Graphene Composites

CHEN Ying;ZHAO Yu;HAN Xing-yue

2016, 35(9):  2879-2884. 

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The preparation methods of grapheme are introduced and the high properties of TiO 2/Graphene composites in the field of photocatalysis are analyzed .On this basis , the optimization research of the structure and the electronic conductivity of TiO 2/Graphene composites are concluded with emphasis , regarding to optimize the electronic structure of graphene and strengthen the interfacial contact between graphene and TiO 2 , and the research prospect of TiO 2/graphene composites was discussed .

Research Status,Existing Problems and Development Tendency on Effects of Alkali-Aggregate Reaction on Property of Marine Structures in Marine-Environment

YUAN Meng;ZHU Yu-wen;OUYANG Feng;ZHAO Hui;CHEN Da

2016, 35(9):  2885-2891. 

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The ingress of the harmful substance in the marine environment is main reason to cause the degradation of properties in the marine structures .This paper presents a review of research on the effect of the alkali-aggregate reaction on the properties of structures under marine environment from four aspects,i.e.the influence factors of the alkali-aggregate reaction expansion , the swelling behavior of alkali aggregate reaction , the chloride ion diffusion and chloride ion binding behavior , the mechanical properties damage and damage model under the combined action of the chloride ion and the alkali -aggregate reaction.Also,the existing problems in this study field are analyzed .The new research ideas on the effect of alkali-aggregate reaction on the properties of structures under marine environment are proposed.First,the new parameter must propose to more accurately reflect material damage degree under the alkali-aggregate reaction .Second , the study on the evolution of the long-term of the mechanical properties under the combined action of the chloride ion , the alkali-aggregate reaction and multi-dimensional stress need to increase .Finally,the constitutive model of concrete damage under three axis stress state is established .

Research Development of 3D Printing Ceramic Parts

LI Ling;GAO Yong;WANG Chong-hai;WANG Hong-sheng;ZHANG Ping-ping;ZHAO Xiao-bo;SONG Tao;WANG Ying-ying;DING Shen-liang

2016, 35(9):  2892-2897. 

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Three-dimensional network ceramic/metal composites combine wear ,high strength and hardness and oxidation resistance of ceramics as well as thermal conductivity and ductility of metal have attracted much attention in recent years .Nowadays ,the biggest difficulty to fabricate the co-continuous composites is preparing high-performance ceramic parts with complicated shape .3 D printing technology is tool-less manufacturing methods in which functional components are produced directly from a computer model . They can rapidly fabricate components with geometries that cannot be manufactured by other conventional methods,which will bring about enormous change in the ceramic /metal fields.In this paper,the technical principle,features,development and research status of 3D printing techniques are summarized .The future development of 3 D printing technology is also prospected .

Preparation of Wollastonite Glass-ceramics by Using Silicate-calcium Slag Generated in Process of Extracting Alumina from High-alumina Fly Ash

CHEN Jian;MA Hong-wen;JIANG Zhou-qing;ZHANG Pan

2016, 35(9):  2898-2903. 

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The silicate-calcium slag generated in process of extracting alumina from high-alumina fly ash was used as the main raw material to prepared wollastonite glass-ceramics by sintering method .The effect of amount of silicate-calcium slag additions and heat treatment conditions on crystallization process , microstructures and properties of the prepared glass-ceramics were studied by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods.The results indicate that prolong nucleation time and crystallization time could help to wollastonite crystal orientation grown up and closely arranged , and have a significant influence on mechanical properties of glass-ceramics, while the crystallization temperature and nucleation temperature have relatively small influence .With the amount of silicate-calcium slag increasing , wollastonite precipitation from matrix glass is enhancing and signal crystal phase of wollastonite glass-ceramics were prepared under the conditions of add 70 .98%silicate-calcium slag in raw material on the conditions of heat treating at 800 ℃for 90 min followed by crystallization at 920 ℃for 90 min.

Distribution of Chloride Transport in Concrete Based on the Compartment Model

CHAI Xu;WANG Bo-xin;WANG Qing;ZHANG Zhong-qiong

2016, 35(9):  2904-2908. 

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In order to study the distribution of chloride transport in concrete under dry-wet cycling condition , the compartment model in medical biological mathematics is applied . This model can dynamically calculate the concentration of chloride in the convective region and the diffusion region of concrete under dry-wet cycling condition under different time .In conjunction with experimental data and least square method , parameters in the model can be acquired .And then , the consequence of model can be gained .The form of consequence is not too much complex so that it can be easily applied in practice engineering .The model mentioned in this article provides references to chloride monitoring and concrete durability design for coastal engineering .

Influence of Different Acid Solvents on the Morphology of ZrW2 O8 Powders by Hydrothermal Method

SUN Xiu-juan;CHENG Xiao-nong;YANG Juan;LIU Qin-qin

2016, 35(9):  2909-2912. 

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Negative thermal expension ZrW 2 O8 powders were prepared by hydrothermal method , and influence of different acid solvents on the morphology was also studied .The precursors of ZrW 2 O8 were studied by Thermogravimetric and differential scanning calorimetry ( TG-DSC ) . The structure and morphology of the resulting powders were characterized by Powder X-ray diffraction ( XRD) and Scanning electron microscopy (SEM), respectively.The results show that when the mixtures of HCl and HNO 3 are used,the pure ZrW2O8 powders with high crystallinity are obtained.With the amount of HNO3 increasing, particle size decreases ,and their morphology changes from rod-like to spherical shape .The results of in situ X-ray diffraction measurement indicate that the materials have strong negative thermal expension properties .

Solvothermal Synthesis and Electrochemical Property of Sb2 Se3 Nanorods

YANG Jun-song;WEI Wei;ZHANG Sheng-yi

2016, 35(9):  2913-2916. 

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The Sb2 Se3 nanorods were synthesized in a solvothermal system , using Se nanotubes as template and NaBH 4 as reductant .A series of analytic instruments , such as scanning electron microscope ( SEM ) , X-ray powder diffraction ( XRD ) and thermogravimetric ( TG ) , were used to reveal the characterization of Sb 2 Se3 nanorods.The formation mechanism of Sb 2 Se3 nanorods was discussed , and the electrochemical property of Sb 2 Se3 nanorods was researched by cyclic voltammetry method .

Synthesis and Photocatalytic Properties of Nano-petal Co3 O4/NiO

GENG Tao;WANG Hong-yan;XU Ji-gui;ZHOU Xia

2016, 35(9):  2917-2921. 

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The Co3 O4/NiO precursor sample was synthesized by hydrothermal method using CoCl 2 · 6H2 O, NiCl2 · 6H2 O and hexamethylene tetramine as raw materials .After the heat treatment , the Co3O4/NiO sample was obtained.The Co3O4/NiO sample with different morphologies was prepared by changing calcination temperature . The structures and morphologies of nano-petal Co3 O4/NiO were investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM).The results indicate after the heat treatment at 400 ℃, the asobtained nano-petal Co 3 O4/NiO have porous surfaces with a thickness of about 50 nm.Comparing the degradation efficiency of PB under UV irradiation with nano-petal Co3 O4/NiO, Co3 O4 , NiO and without any catalyst , nano-petal Co3 O4/NiO photocatalysts possess higher photocatalytic efficiency .The results show that after 180 minutes under UV irradiation, the degradation rate of PB is close to 95%.

Preparation,Characterization and Magnetic Properties of Iron Oxide Nanomaterials

DU Qing-bo

2016, 35(9):  2922-2924. 

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Different morphology α-Fe2 O3 nanomaterials were successfully prepared by a facile hydrothermal method with PVP and CTAB as surfactant .The as obtained products were characterized by X-ray diffraction (XRD), scanning electron microscope ( SEM) and magneto-meter ( SQUID-VSM) . The α-Fe2 O3 nanorods and nanocubes can be obtained when used PVP and CTAB as surfactant , respectively , but none-morphology α-Fe2 O3 nanomaterials were synthesized without any surfactant .The results show that the nanorods are 70 nm in diameter and 300 nm in length;the nanocubes are 700 nm in sides.The magnetic investigation shows that the synthesized α-Fe2 O3 nanorod, nanocubes and none-morphology nanomaterials exhibit ferromagnetic property with Mr and Hc 0.07 emu/g, 2300 Oe; 0.2 emu/g, 3600 Oe;0.15 emu/g, 3100 Oe respectively, at room temperature.

Experimental Study on Adhesive Splitting Tensile Performance of Post Pouring Concrete on Precast Concrete

CAO Hai;MA Qin-yong;ZHANG Rong-rong;WANG Yang

2016, 35(9):  2925-2929. 

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Based on the experimental study of adhesive splitting tensile test of post pouring concrete on precast concrete , the effects of specific factors on the adhesive splitting tensile performance were investigated . These factors are as follows: pouring method of post pouring concrete , interfacial roughness , temperature .Results show that under the same working condition , the horizontal pouring concrete adhesive splitting tensile strength significantly is greater than the vertical to the casting adhesive splitting tensile strength , adhesive splitting tensile strength increases significantly with the increase of interfacial roughness , adhesive splitting tensile strength falls sharply with the increase of temperature , to 300 ℃, it is 50%lower than adhesive splitting tensile strength of the normal temperature .The obtained experimental results can provide the evidence for clarifying adhesive splitting tensile mechanism as well as the reference for the development of precast concrete structures .

Removal of Pb2+from Waste Water with High Purity Zeolite X Synthesized by Coal Fly Ash

KANG Yu-hong;MA Ya-jun;LI Jian;WANG Ai-min;YAN Long;HAO Hua-rui

2016, 35(9):  2930-2934. 

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High purity zeolite X was synthesized by hydrothermal method with coal fly ash pretreated by alkaline fusion and centrifugal extraction , the effects of alkali/ash and roasting temperature on the quantity of silicon aluminum dissolution were discussed , the influences of alkalinity , aging time, crystallization time and Si/Al ratio on synthesis zeolite were investigated and the adsorption performance of Pb2+-containing waste water has been researched .The results showed that the highest silicon aluminum dissolution quantity obtained at 680 ℃, alkali/ash =2 .3 and the high purity zeolite X synthesized at SiO2/Na2O=1, SiO2/Al2O3 =3.5, 5 h aging and 16 h crystallization.The obtained zeolite X showed fast adsorption to Pb 2+-containing waste water .The removal rate of Pb 2+can be up to 99 .6%for 30 min at the room temperature in the condition of pH =5, adding 0.23 g/100 mL in 500 mg/L Pb2+solution. The adsorption capacity of zeolite X was 216.8 mg/g.

Influence of Particle Size of Calcite on Alkali-dolomite Reaction of Dolomitic Limestone

XU Ming-feng;DENG Min;HUANG Bei;CHEN Bi

2016, 35(9):  2935-2940. 

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The influence of the calcite matrixes on migration of Na + and alkali-dolomite reaction was studied in dolomitic limestone .The sizes of the calcite particles in dolomitic limestones were measured by using microscopic image analysis method .The pore size distribution of dolomitic limestones was measured by using N2-adsorption method .The content of Na +ions in sections of the rock prisms was measured by flame emission spectroscopy . Brucite formed by alkali-dolomite reaction ( ADR ) was quantitatively analyzed by XRD in the dolomitic limestones .The results indicate that the median diameters of the calcite in the dolomitic limestones TS-1, TS-2, GS-2 and FHS-1 were 4 μm, 12 μm, 15 μm and 33 μm, respectively .The smaller the size of calcite particles was , the higher the content of Na +migrated in the rock, the higher the dedolomitization of dolomite in the rock would be .

Synthesis of Ultrafine SiO2 by Chemical Precipitation Method

ZHENG Jing;LIN Yin-qin

2016, 35(9):  2941-2945. 

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This article briefly summarizes the synthesis and characterization of ultrafine SiO 2 .Using Na2 SiO3 · 9H2 O as source of silica ultrafine SiO 2 were obtained by precipitatin process .In this work some influences of sodium silicate concentration , calcining heat and ultrasonic treatment on the synthesis of ultrafine SiO 2 were discussed .The results show that the optimal preparation condition Is , sodium silicate concentration is 0.20 g/mL, and calcination condition is 600 ℃, 4 h.N2 adsorption-desorption isotherms, XRD, FT-IR and some other experiment methods were used to investigate the structure and other physical properties of the samples .The results show that the SiO 2 are amorphous , and the BET specific surface areas of the samples are larger than 400 m2/g.

Key Process Research of Indium Gallium Zinc Oxide Thin Film Transistor with Etch Stop Layer

GAO Jin-cheng;LI Zheng-liang;CAO Zhan-feng;YAO Qi;GUAN Feng;HUI Guan-bao

2016, 35(9):  2946-2949. 

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In order to improve the performance of Indium Gallium Zinc Oxide Thin Film Transistor , IGZO-TFT with etch-stop layer was prepared in 2 .5 G experimental line .The effects of O 2 concentration during IGZO deposition , N2 O plasma treatment , the temperature of ESL deposition and the N 2 O/SiH4 ratio on the IGZO TFT Vth were systemically studied .The results show that the Vth would shift to positive position as the increasing of O 2 concentration , N2 O plasma treatment , and the decreasing of ESL deposition temperature .

Effect of Silane/Aluminate Coupling Agent Modifying Hydromagnesite on Properties of EVA

LIU Li-xin;TIAN Hai-shan;ZHENG Shui-lin;ZHANG Xue-rui

2016, 35(9):  2950-2955. 

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Halogen-free flame-retarded EVA composites were prepared in a melt process using hydromagnesite as inorganic flame retardant filler which was modified with the silane coupling agent SCA-1113 and alu minate coupling agent F-2 in this article .The effects of SCA-1113,F-2 and SCA-1113/F-2 on mechanical properties and flame retardant properties of the hydromagnestie/EVA composites had been studied ,while the mechanism of surface modification and micro-structure of the hydromagneste/EVA composites was investigated using the FTIR spectra and SEM image respectively as well .The results showed that three kinds of surface modifier formulations could improve the flame retardant properties of the composites ,the oxygen index was increased by 1.6%to 1.9%,UL-94 level was raised to V-0 level;1.5wt%SCA-1113/F-2( mass ratio of the two surface modifiers was 1∶2) made the tensile strength and elongation at break of composites increase to 9.50 MPa and 176.02% respectively; FTIR spectra showed that the surface modifier molecules of three kinds of surface modifier formulations had formed hydrogen bonding with the powder surface and reacted with the -OH of hydromagnesite;FTIR spectra of powders modified by SCA-1113/F-2 showed that SCA-1113 reacted with F-2 and formed a new type of chemical bond Si-O-Al;SEM image of composite material micro-fracture indicated that three kinds of surface modifier formulations could promote the dispersion of powder in the matrix , the effect of SCA-1113/F-2 was the best .

Chloride Binding Capacity of Portland Cement under the Condition of Different Cations

XIAO Jia;GUO Ming-lei;WANG Da-fu;YIN Zhe-wei;LI Yun

2016, 35(9):  2956-2961. 

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Effect of different cations on the chloride ion binding capability of Portland cement was studied.The chloride ion binding rate of cement pastes were obtained through free chloride ions concentrations testing and analyzed by XRD and pH testing techniques .The results show that the chloride ion binding rate of cement pastes reaches 50, 70, 80 and 90 percent respectively of 28 d at the age of 6 h, 12 h, 1 d and 3 d.The formation of Friedel's salt and binding of chloride ions take place in the early stage of hydration while the chloride binding capability is mainly C-S-H gel dependent and smaller at the later stage ..Different cations cause the difference of amount of formation of Friedel 's salt in cement pastes, with the chloride ion binding capability of Ca 2+>Mg2+>K+>Na+which is negatively related to its influence on the pH value .Na +and K +lead to the rise of the pH value and reduce the chloride ion binding capability, while Ca2+and Mg2+are just the opposite.The increase of the Mg2+concentration promotes the formation of Friedel's salt and chloride ion binding capability , while Na + concentration shows little effect .

Triaxial Creep Properties of Gussasphalt Concrete under the Thermal Coupling

JIANG Ming-yang;ZHANG Bin;SUN Qi

2016, 35(9):  2962-2966. 

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In order to further research the triaxial creep properties of bituminous mixture of gussasphalt concrete under the effect of temperature and stress coupling , MTS815 testing machine was adopted to carry out triaxial creep test under circumstance of different temperatures , different stress levels and confining pressures , and the corresponding creep curves were obtained , and generalizes the modified Burgers model to three dimensional form in order to describe the creep constitutive relation of gussasphalt concrete .The results show that the first phase of creep curve of gussasphalt concrete is not obvious ,which reflects that the internal void ratio is lower .The creep deformation value sharply increases with the rise of temperature and the increase of deviatoric stress level , which reflects that the combined action of high temperature heavy load is a decisive factor of the rutting on asphalt concrete pavement .The creep deformation slightly decreases with the increase of confining pressure , and the confining pressure has inhibitory effect on creep deformation .The creep rule got from the triaxial creep test , compared with uniaxial creep test , is more able to reflect the deformation law in the process of actual load ,and three-dimensional and modified Burgers model can accurately reflect the creep properties of bituminous mixture of gussasphalt concrete under the effect of temperature and stress coupling .

Effect of Steel Slag Substitution on the Properties of Composite Cementitious Backfill Material

DONG Yue;YANG Zhi-qiang;GAO Qian

2016, 35(9):  2967-2972. 

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The optimal ratio was obtained by range analysis of orthogonal test , and based on the optimal ratio, the content of GGBS was substituted by different content of steel slag , and those samples were characterized by compressive strength test , water absorption test and expansion-contraction test , the influence of steel slag substitution on the physical and mechanical properties of samples were analyzed . Studies have shown that:steel slag substitution have a significant impact on the physical and mechanical properties of samples , with the substitution of steel slag increased , the compressive strength of samples gradually reduced , water absorption gradually increased , shrinkage rate decreased; with the substitution of steel slag increased , plomberite-14A, xonotlite, hydrocalumite and C-S-H gradually reduced until disappeared , while plate-shaped hydration products gradually increased .

Effect of Mechanical Force on the Activation of Iron Ore Tailings

PIAO Chun-ai;WANG Dong-min;ZHANG Li-ran;WANG Chang-an;LIU Hai-liang

2016, 35(9):  2973-2979. 

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Effects of grinding time on density , ratio surface area , particle distribution and micrographs of iron tailing powder were discussed , it concluded that iron tailings powder particles was gradually refined , meanwhile the density first decreased and then increased , the specific surface area increased first and then decreased with the extension of grinding time .When the grinding time was 2 h, the specific surface area reached the maximum value of 700 m2/kg particle size (5 ±2) μm particle content is about 40%, less than 5.13 μm diameter of particles accumulate the highest .But excessive grinding will have weak agglomeration .It was suggested by the analysis of mechanical activation effect on the activity of the iron ore tailing and IR that, at 10%-50%content of the grinding of 2 h iron ore tailings, the flexural strength ratio and the activity index of 3 d, 7 d and 28 d were the maximum.The grinding time maximum activated iron ore tailing .The grain refinement disordered substances increased , resulting in enhanced activity by mechanical grinding .

Preparation of Modified Phosphorous Slag and Its Adsorption Performance of As(Ⅲ) from Wastewater

WANG Cui-cui;WAN Rong-hui;WANG Liu-sheng;CHEN Qiu-ling;LIU Shu-gen;HE Wen-hao;DONG Guo-li;Ning Ping;GAO Hua-ping

2016, 35(9):  2980-2985. 

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Phosphorus slag was modified by ferric salts dipping in order to improve the removing efficiency of As(Ⅲ)in wastewater .The effects of the classes and concentrations of ferric salts ,curing temperature , and curing time in the process of modification on the adsorbing capacity for As (Ⅲ) were investigated by using modified phosphorous slag .The optimal preparation conditions are as follows:0.8 mol/L of FeCl 3 dipping , curing temperature 80℃and curing time 6 h.The methods of BET , SEM and FT-IR were used to analyze the difference of surface structure and adsorption performance of the modified and un -modified phosphorous slag .After modification , the specific surface area of phosphorus slag increased , the content of Fe3+and-OH rised, and the removal rate of As (Ⅲ)in wastewater was improved to 99.1%.The surface of modified phosphorous slag with iron load , and adsorbing capacity for As (Ⅲ) in wastewater increased .

Preparation of Diatomite/Palygorskite Porous Ceramics and Performances of Adsorption Methylene Blue

KUANG Meng;WANG Ping;LUO Qiu-yun;WEI Zhong-hua;WEI Yu-hong;PENG Hu;XIE liang

2016, 35(9):  2986-2989. 

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Diatomite and palygorskite porous ceramics were prepared from diatomite and palygorskite by sintering method .The structures and micrographs of specimens were characterized by X-ray diffraction ( XRD ) and scanning electron microscopy ( SEM ) . The ability of adsorption dye wastewater was measured by adsorptions of methylene blue from aqueous solution .The results of experiment show that diatomite/palygorskite porous ceramics was prepared from diatomite and palygorskite of mass ratio was 20∶80 and sintered at 850 ℃has optimal performance , it water adsorption was 41.12%, flexural strength was 2.76 MPa and shrink rate was 4.95%.Some porous structure of diatomite were retained , the phase of enstatite has been transformed from palygorskite .The phenomenons of adsorption experiment show that sample had better adsorption effect of methylene blue solution and adsorbed amount was 3.634 mg/g.

Preparation and Characterization of New Modified Bentonite Compound Granules

XIE Wei-nan;NIE Jin-xu;ZOU Xiang-jun;WU Guang-feng;CHEN Shi-wen

2016, 35(9):  2990-2994. 

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In order to improve the effect of powder bentonite in water treatment solid-liquid separation , new modified bentonite compound granules ( MBG ) and natural bentonite granules ( NBG ) were prepared.MBG were prepared by using PVA, NaHCO3 and microwave enhanced Al-bentonite (Al-Bent) as raw materials.NBG were prepared by using PVA , NaHCO3 and raw bentonite ( Na-Bent ) as raw materials.These granules were characterized by EDS , XRD, FTIR, SEM, BET to confirm how the process of preparation would affect the internal structure of MBG .The results show that montmorillonite contained in MBG is better than the montmorillonite in NBG in the space structure .What's more, the pore structure of the MBG is better than that of the NBG .

Preparation and Characterization of Porous Ceramics from Oily Soil and Waste Glass

LI Jin;SHANG Shan-shan;CHEN Yan-lin

2016, 35(9):  2995-3000. 

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The porous ceramics were prepared by controlling the sinter process using the oily soil and waste glass consisting of the silica as the main material , and the limestone as the pore forming substance . The samples were characterized by the XRD , SEM and so on .An objective of this research was to investigate the influences of the amounts of oily soil/waste glass and CaCO 3 as well as of the sintering temperature on the porosity , mechanical strength , bulk density , water absorption , microstructure and crystalline phase .The results show that A 3 homogeneous microstructures of large pores could be obtained at low sintering temperature by adding about 35wt% oily soil, 40wt% waste glass, 20wt% CaCO3, 5wt%sodium silicate, leading to foams presenting porosity , compressive strength, flexural strength, bulk density, and water absorption values of about 52.38%, 4.43 MPa, 12.59 MPa, 1.07 g/cm3 , and 29. 56%, respectively .Good correlations among mechanical strength , water absorption and microstructure ( pore size and distribution ) were observed .

Shrinkage Performance of C35 Pavement Concrete Used BSF Admixture

LI Hui;CHEN Yu-jia;ZHANG Hao;ZHANG Dong-sheng;XIE Song;ZHANG Zhi-ming

2016, 35(9):  3001-3006. 

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The shrinkage performance of C 35 pavement concrete with BSF admixture , the influence of BSF admixture on the shrinkage of concrete as well as the effect mechanism of brick powder , fly ash and granulated blast furnace slag ( GBFS) powder on the shrinkage of concrete were investigated .The results showed that:clay brick powder and fly ash could compensate the shrinkage of concrete slightly , and with the increase of dosage of these two kind of materials , the drop amplitude of concrete shrinkage rate increased.On the contrary, GBFS powder could aggravate the shrinkage of concrete .The shrinkage performance of C35 pavement concrete was attributed to the interaction of brick powder , fly ash and GBFS, composite admixture .For the concrete shrinkage , the microhole smaller than 10 nm played dominate role .

Effect of Paraffin/Expanded Graphite Composite Phase Change Materials on the Hydration Performances of Magnesium Phosphate Cement

LI Yun-tao;YAN Hua;WANG Hong-tao;WANG Qun;ZHAO Si-xie

2016, 35(9):  3007-3013. 

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The thermal effect of paraffin/expanded graphite composite phase change materials ( CPCM ) was proposed to control the hydration heat of magnesium phosphate cement ( MPC) .By testing the setting time, fluidity, hydration temperature, compressive strength and thermal conductivity of CPCM , the effect of CPCM on the hydration properties of MPC was explored .The results showed that the hydration heat of MPC was controlled by the phase change .The hydration system temperature was reduced , and the hydration reaction rate was slowed down and the goal of reducing the hydration heat was accomplished .At the same time , the degree of crystallinity of MgKPO 4 · 6 H2 O was decreased lightly , and it made the compressive strength of MPC change small .CPCM did not participate in the hydration reaction of MPC , but combined by the physical effect with MPC , maintained their excellent performance , and ensured the stability and performance of the MPC system .

Influences of BSF Composite Mineral Admixture on the Mechanical Properties of Pavement Concrete

LI Hui;XIE Song;CHEN Yu-jia;ZHANG Hao;ZHANG Dong-sheng;ZHANG Zhi-ming

2016, 35(9):  3014-3019. 

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With the aid of Scanning Electron Microscope ( SEM ) and Mercury Intrusion Porosimetry ( MIP) , the influence of BSF composite mineral admixture on the mechanical properties of pavement concrete was investigated .The results show that ( 1 ) Involving BSF composite mineral admixture could enhance the flexural strength of concrete after curing for 28 d, decrease the ratio of compress strength to flexural strength significantly , as well as, improve the brittleness of concrete .( 2 ) The use of BSF composite mineral admixture was helpful for improving the microstructure of interface transition zone by densified microstructure and reduced harmful micropores . ( 3 ) During hydration , the brick and granulated blast furnace slag powder used to prepare BSF admixture could generate massive fibrous micro crystal , which is good for improving the flexural strength of concrete .

Effect of Iron Ore Tailing and Sand Mud Powder on Workability of Cement Paste with Water-reducer

LI Xiao-guang;YANG Jun;WAN Qiao;QU Ya-an

2016, 35(9):  3020-3024. 

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To reveal the effect of iron ore tailing(IOT) and sand mud powder(SMP)on workability of cement paste , measurement of electrokinetic potential and rheological parameters were employed as polycarboxylic superplasticizer ( PCA) and naphthalene superplasticizer ( FDN) respectively with the two sorts of powders were added into cement pastes .The results show that the influence of IOT and SMP on the workability of pastes make remarkable difference .The rate of change of plastic viscosity and change ofζpotential keep significantly lower in the paste containing IOT compared with SMP by adding PCA ,the influence of IOT to the slurry liquidity and rheological properties is significantly lower .As FDN is used as admixture,great fluctuation of plastic viscosities of the pastes occur with increasing amount of fine powder , however workability of pastes with SMP is superior to of IOT with prolongation of time .When the mass fraction of powder in paste is 7%,the fluxility of paste will decrease .

Preparation and Gas Sensitivity of Biomorphic SnO2 Porous Ceramics Doped Rare Earth

ZHANG Xiong-bin;HE Xin-hai;LIU Song-tao

2016, 35(9):  3025-3029. 

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La doped SnO 2 morph-genetic ceramic was prepared by doping rare-earth oxide using modified ramie fibers treated with alkali as biology templates . The microstructure and phase composition of prepared materials were discussed , and their specific surface area , pore size distribution and gas-sensitive property were tested .The results show that the rare earth oxide can be benefit to retain the growth of SnO2 grains and improve the C 2 H5 OH,CH3 COCH3 and H2 gas sensitive of SnO 2 gas sensitive material .

Influence of Muck on Mechanical Properties of C30 Concrete

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

2016, 35(9):  3030-3035. 

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At present, the muck from subway exits pile , low utilization and low added value , therefore, the influence of different contents of muck as admixtures on workability , mechanical properties and impermeability of C30 concrete are studied in this paper .The experimental results indicate that the slump decrease gradually with the increasing of muck contents .The compressive strengths of concrete is smaller than the reference group with the increasing of muck contents .The compressive strength of concrete at 28 days is similar with the reference group when the content of muck is 10%of cement contents .A moderate amount muck contents can improve the impermeability of C 30 concrete , when admixture of muck content is 15%, the concrete impermeability is the best .

Preparation Optimization and Frost Resistance of Silt Baking-free Bricks

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

2016, 35(9):  3036-3040. 

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The influence of lime , cement , curing temperature and time on the mechanical property of silt baking-free bricks was systematically investigated .Subsequently , the frost resistance of silt baking-free bricks was studied .The results show that 30%-40% of lime leads to the higher compressive strength . The increasing content of cement contributes to better mechanical performance and frost resistance . Curing temperature is set at 80 ℃for economic considerations .

Flotation Fluorite Extractive Technique from Polymetallic Scheelite Tailing

ZHANG Chun-lei

2016, 35(9):  3041-3046. 

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In order to alleviate fluorite resources situation , and enhance the utilization level of low grade refractory fluorite and intergrowth ( associated ) fluorite, and combined with an analysis on the ore properties , the author conduct series condition test , part of the process open circuit test , and whole process closed circuit test research .Study results confirms in a second of scavenging for rough , rough concentrate again five selected after grinding , the order of middlings was returned to the principle of process conditions , with oleic acid as the collecting agent , sodium silicate and sodium humate as the composite inhibitor , sodium carbonate as pH adjusting agent , which can realize the white tungsten polymetallic ore tailings of fluorite recycling secondary resources effectively .When the dosage of collector oleic acid 450 g/t, composite inhibitor 2.8 kg/t, sodium carbonate is 1 kg/t, under the condition of 16. 41%feed grade of CaF2 , obtained CaF2 grade of 87.92%, CaF2 fluorite concentrate recovery was 53. 53%.

Strength and Microstructure of Mortars Prepared with Magnesium Slag after Carbonation

HAO Yuan-yuan;MO Li-wu;YUN Jin-jin

2016, 35(9):  3047-3052. 

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Low carbon cementitious materials were prepared via carbonating magnesium slag mortars .The effects of water to cement ratio and carbonation curing duration on the compressive strength and microstructure of magnesium slag mortars were investigated .Results show that , the compressive strengths of mortars with a water to cement ratio of 0.4, after carbonation curing in CO 2 with a concentration of 99.9%and gas pressure of 0.1 MPa at 23 ℃ for 14 d, are increased by up to 9.9 times compared to those mortars without carbonation curing .The increase of carbonation curing duration increased the compressive strengths of the mortars .The influence of water to cement ratio on the strength of mortars was remarkable . The strength of specimens with lower water to cement ratio increased more after carbonation .According to microstructure analysis , it was found that the treatment of CO 2 enhanced the microstructures densification and decreased the amount of relatively coarse pores and total pore volume due to the formation of calcite ( CaCO 3 ) .

Phase Transition and Densification of Silicon Nitride Ceramics by Low-Temperature Pressureless Sintering

BAI Xing-liang;QIAO Rui-qing;ZHANG Cui-min

2016, 35(9):  3053-3056. 

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Silicon nitride was prepared by pressureless sintering technique using Al 2 O3 together with Y2 O3 as the sintering additives under low temperature .The phase composition and densification of silicon nitride ceramics at low temperature were investigated by using XRD and SEM .The results show that when the additive content is 10%and the sintering temperature is higher than that of 1430 ℃,αto βphases to transition faster .When the sintering temperature reaches 1510 ℃, allαphase shift βphase .

Effect of Adding Hercynite Synthesized by Reactive Sintering on the Properties of Magnesia-hercynite Refractory

LI Sen;FENG Li-jie;WANG Qian;JIA Yuan-ping;CHEN Xiao-liang;BAI Jia-hai;XU Feng-chao;LIU Jun-cheng;DU Qing-yang

2016, 35(9):  3057-3061. 

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Magnesia-hercynite refractory was prepared by reaction sintering , using magnesia and hercynite as raw materials.The influences of hercynite addition by 1%, 3%, 5%, 7%, 9% and 11% on the properties of magnesia-hercynite refractory were studied . The phase composition of specimens was determined by XRD and the microstructure was observed by SEM .The results show that the thermal shock resistance and coating adhesion ability of magnesia-hercynite refractory improve and the refractoriness under load decrease with the increasing of the content of hercynite within the range from 1% to 11%.The magnesia-hercynite refractory has bigger bulk density , higher cold crushing strength and smaller apparent porosity when the content of hercynite is 5%.

Mechanical Properties of Floating Bead Low-density Oil-well Cement Composites

AI Zheng-qing;LI Zao-yuan;LI Ning;LIN Luan;YUAN Zhong-tao;GUO Xiao-yang;CHENG Xiao-wei

2016, 35(9):  3062-3065. 

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Cenosphere used as a mitigation material in low density cement system which widely used in the formation of low pressure leaky cementing project .Aim to fully explore the mechanical properties of the floating bead low density cement , the manuscript investigated the compressive strength and tensile strength in different temperature condition .Simulated the underground environment to operate the stress-strain testing , and analyze the microscopic morphology and pore size distribution of the samples .The results showed that the cenosphere has a good compatibility with cement .Cenosphere has the rigid non-crack resistance properties and makes the cement stone has a higher compressive strength and lower tensile strength .The pore size distribution of cement stone cured in high temperature has a widely range compared with the cement cured in low temperature .The density of high temperature cured cement is lower too.

Effect of Curing Temperature on the Strength and Microstructure of Slag Cement Block

TIAN Lin-jie;WANG Qi-cai;DENG Xiao;WANG Fei

2016, 35(9):  3066-3071. 

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In order to study the early (28 d) strength and distribution of pore microstructure characteristics of slag cement block under different curing temperature , the water cement ratio of the cement block was 0.24, doped with different amounts of slag as admixture to the cement block , the cement blocks were maintained at minus three degrees Celsius and twenty degrees Celsius for twenty -eight days respectively , measure the compressive strength of cement block , analysis of the early pore structure of cement block by using the pore structure analyzer , then through the pore structure of cement block calculate the actual strength of cement blocke , comparative analysis of its law .The results show that:at the same amount of slag, the early compressive strength of the cement blocks at minus three degrees Celsius curing temperature is decreased significantly than at twenty degrees Celsius curing temperature , hardened cement air containing volume becomes small , the bubbles spacing factor and average pore chord length increase, pore coarsening seriously;With the increase of slag amount , the early compressive strength of cement block is decreased , hardened cement air containing volume increases , the bubbles spacing factor and average pore chord length increase ,the bubbles spacing factor , average pore chord length and early compressive strength of cement blocks at minus three degrees Celsius curing temperature change trend is more obviously than at twenty degrees Celsius .

Preparation of Cristobalite-based Ceramics Using the Discarded Quartz Crucible

SUN Jian;LI Jia-ke;WANG Yan-xiang;ZHU Hai-xiang

2016, 35(9):  3072-3076. 

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Cristobalite-based ceramics were prepared using the discarded quartz crucible , kaolin, feldspar and bauxite as raw materials .The effects of batch formula and firing temperature on phase composition , microstructure , coefficient of thermal expansion and mechanical performances of cristobalite-based ceramics were investigated by XRD , SEM, thermal dilatometer and material testing machine .The results show that cristobalite-based ceramics with good mechanical performances are obtained when discarded quartz crucible 40%, kaolin 40%, feldspar 15% and bauxite 5% at 1300 ℃ for 30 min .Bending strength and coefficient of thermal expansion of cristobalite-based ceramic are 76.45 MPa and 7.16 × 10 -6℃-1 ( RT~600 ℃) ,respectively .And thermal shock resistance (△T ) is above 180 ℃.

Preparation of Nanometer Dy/TiO2 Powder and Its Photocatalytic Performance

HUANG Feng-ping;CUI Meng-li;GUO Yu-yu;ZHANG Shuang;WANG Shuai

2016, 35(9):  3077-3081. 

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The nano TiO2 powder doping dysprosium were prepared by sol-microwave method using tetrabutyl titanate and dysprosium nitrate as material . Methyl orange solution was chosen as the degradation product , the effects of calcining temperature , calcining time,doping amount on photocatalytic activity of nano TiO2 powder and properties were investigated .The samples were analyzed by XRD , SEM, UV-vis-DRS, et al.The results show doping Dy content is 1.3%of Nano TiO2 powder calcined at 550 ℃ for 4 h, the degradation efficiency reaches 90%.Not only maded nano TiO 2 particle size decreased , the bandgap reduced and absorption wavelength red shifted about 30 nm, but also effectively inhibited the electron hole-pairs complexing .

Characterization of Efflorescence of Decorative Mortar Based on Image Gray Scale

ZHAO Hai-xin;SUN Ying;YUAN Ke-jia;LI Zhi-xin

2016, 35(9):  3082-3086. 

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In this paper , the effects of colors in different gray scales on mortar appearance were studied by the image processing techniques , and the characterization methods of the efflorescence degree of decorative mortar were studied on this basis .The results show that the gray scales of colors in efflorescence region would affect mortar appearance when they were 15 higher than that of matrix color . The percentage of the pixel in different gray values in the mortar sample image ( pi ) was extracted, and then a formula f =Σj=255i=bi+16 ri ×pi was proposed to evaluate the extent of efflorescence , ri represent influence modulus of colors in different gray values .P20,70 ×R70,1 =F20,1 were set up by combining with numerical evaluations of the mortar efflorescence degree by volunteers , and solution of the matrix equation represents ri,respectively,then ri and gi linear fit and get fit function:ri = gi -bi100 ×(240-bi) ×(255-bi), (gi>bi).Experimental results prove that the calculated value of the formula can not only feature the efflorescence extent well but has a good conformance with the evaluation value .