Table of Content

15 June 2018, Volume 37 Issue 6

Previous Issue    Next Issue

Effect of Fiber Properties on Mechanical Properties and Microstructures of Autoclaved Aerated Concrete

YANG Lei;HE Ting-shu;GAI Guo-sheng;HE Juan;CHEN Chang

2018, 37(6):  1813-1817. 

Asbtract ( 44 )   PDF (2414KB) ( 42 )  

Related Articles | Metrics

Autoclaved aerated concrete is easy to appear the phenomenon of lack of edge drop horn during the production process because of its poor toughness.The effects of fiber content on the compressive and flexural strength were researched by adding fibers with different length-diameter ratio and elastic modulus in autoclaved aerated concrete.The microstructures were determined by X-ray diffraction and scanning electron microscopy analysis.The toughening mechanism of fibers on autoclaved aerated concrete was studied.The results show that the optimum content of polypropylene fiber and glass fiber is 0.3%.The compressive strength of the autoclaved aerated concrete increased by 22.0% and 27.8%, respectively and the flexural strength increased by 20.0%and 26.0%, respectively.The fibers have a certain effect on the hydration products content for the autoclaved aerated concrete, but new phases don't occur.A three-dimensional network skeleton in the matrix is formed when fibers are added in the autoclaved aerated concrete, which slow down or prevent the expansion of the crack by slowing the stress concentration at the crack tip.The main work is to overcome the resistance to pulling out the fibers for autoclaved aerated concrete, so the effect of fibers on the strength of the autoclaved aerated concrete is not related to the elastic modulus of fibers.

Experiment Research of Carbonation Durability of Shotcrete Lining under Bending Loading

WANG Jia-bin;NIU Di-tao

2018, 37(6):  1818-1824. 

Asbtract ( 52 )   PDF (2085KB) ( 28 )  

Related Articles | Metrics

In order to investigate carbonation durability of tunnel lining shotcrete, using spring-four points bending loading method, considering the influence of forming mode and steel fiber mixing, carbonation durability of shotcrete under bending loading ratio of 0.25, 0.50 and 0.75 was carried out.Meantime, compressive, splitting tensile and flexural strengths of carbonation concrete specimens were measured. Based on Zhang's carbonization model, instructing the effective coefficient of bending loading, steel fiber and forming mode, the carbonation depth predictive model of bending loading shotcrete was established. The result shows that carbonation depth of concrete with bending stress obeys Fick's first law. Carbonation coefficient has relationship with force mode, bending ratio, steel fiber mixing and forming mode.Shotcrete has better carbonation durability than ordinary concrete.Furthermore, steel fiber mixing can improve shotcrete carbonation resistance.With carbonation depth increasing, compressive and splitting tensile strengths of carbonation concrete increase.However, flexural strength of those is first decreased quickly and then stable.Comparison with predictive values and experiment data, the mean deviation is less than 10% and the standard deviation is 0.07.It has good applicability for predicting carbonation depth of bending loading shotcrete.

Powders Preparation and Dielectric Properties of (K,Na) (Nb,Ta,Sb) O3 Ceramics

ZHOU Yuan;LI Yu-xiang;CAI Yan-zhi

2018, 37(6):  1825-1828. 

Asbtract ( 34 )   PDF (2882KB) ( 50 )  

Related Articles | Metrics

Sb/Ta co-doped lead-free K0.5Na0.5Nb0.7TaxSb0.3-xO3(abbreviated KNNSTx, x＝0.06, 0.09, 0.12, 0.15, 0.18, 0.21, 0.24) were synthesized using the hydrothermal method.The influence of Ta, Sb content on phase、morphology of powders were systematically studied.The results of microstructure, dielectric properties of sintered KNNSTx ceramics from the obtained powders show that: the KNNSTx ceramics exhibit pure perovskite structure; the partical size become larger as Ta content increases, when x＝0.09, 0.12 the fine grains fill the gaps between large grains, make enhancing ceramic density; The dielectric constant first decrease as Ta content increases from x＝0.06 to 0.12 and then increase with from x＝0.15 to 0.24, and the cure temperature is all at about 350 ℃, x＝0.09, 0.12 both have lower dielectric loss.

Analysis on Thermal Insulation Thickness of Different Wall Structures in Hot Summer and Cold Winter Zone

HUANG Ren-da;LI Li;WU Hui-jun;ZHANG Hui

2018, 37(6):  1829-1835. 

Asbtract ( 54 )   PDF (1457KB) ( 28 )  

Related Articles | Metrics

Selection of appropriate insulation materials and thickness is an important way to realize the building energy saving.A mathematical model to calculate the optimum insulation thickness of materials is established in hot summer and cold winter zone.The economy of XPS, EPS, PU, glass wool and aerogel insulation materials was analyzed for three different wall structures which was shale hollow brick, aerated concrete block and reinforced concrete.It is indicated that the economic thickness of the PU used in shale hollow brick, aerated concrete block and reinforced concrete are 53 mm, 43 mm, 62 mm, respectively.The adaptability of PU for primary wall is better compare to other conventional insulation materials for its appropriate economic thickness, low total cost and shorter payback period.Moreover, the adaptability of aerogel insulation materials for three wall structures was analyzed.It is evident that the reinforced concrete wall is better suitable for aerogel insulation materials due to the shorter payback period and better economic benefits.The results are of great significance for the structural design of composite wall and building energy saving of aerogel insulation materials.

Pull-out Test and Tensile of Geogrids and Tailings

YI Fu;ZHANG Yi-ni;WANG Shi-jie;ZHANG Yang;MA Jin;BAO Xiao-yu;BAO Xiu

2018, 37(6):  1836-1840. 

Asbtract ( 55 )   PDF (1174KB) ( 28 )  

Related Articles | Metrics

In order to analyzed the change law of tension along geogrid in the pull-out test of geogrid and tailings.Through the relationship between the tensile force, the shear stress and the strain of geogrid in the test.The tension coefficient a which affected the interface characteristics of geogrid and tailings was proposed.The distribution formula of tension along geogrid was derived, and the feasibility of the formula was verified by the measured data.In the reinforced tailings structure, when the pull-out displacement of reinforced material was not very large, this formula could be used to predicted tensile of geogrid in different positions.The results provided the basis for the application of geogrid in reinforced tailings dam.

Damage Mechanisms of Ti3AlC2 by Ion Irradiation

LIU Ke;FENG Yi;HUANG Xiao-chen;ZHANG Jing-cheng;QIAN Gang;SONG Zhao-kun

2018, 37(6):  1841-1846. 

Asbtract ( 49 )   PDF (2665KB) ( 35 )  

Related Articles | Metrics

The effects of He ion irradiation on the morphology and structure of Ti3AlC2 were studied by He ion implantation with energy of 70 keV, dose of 1 ×1017 ions/cm2 and 16.4 dpa peak.It was found that the He ion concentration was related to the irradiation damage of Ti3AlC2 material.With the increasing of concentration of He ion, the degree of irradiation damage of Ti3AlC2 increases.It was found that He ion irradiation resulted in the formation of holes, cracks, bumps, He bubbles and the phase transformation in the Ti3AlC2 material.The related mechanism was analyzed.

Corrosion Potential Detection of Internal Reinforcing Bar in High Performance Concrete after High Temperature

ZHANG Yi-fan;DU Hong-xiu

2018, 37(6):  1847-1851. 

Asbtract ( 38 )   PDF (1147KB) ( 40 )  

Related Articles | Metrics

In order to study the damage of steel bars in high performance concrete after high temperature effect, the Half-cell potential method was used to detect the corrosion potential of the internal reinforcement of C60 high performance concrete,which mixed with and without polypropylene fiber and after a different temperature effect.The results show that steel corrosion potential value in the plain concrete and polypropylene fiber reinforced concrete generally have little difference with the increase of temperature.The change rule of absolute value is as follows: In the range of 20-500 ℃, the absolute value of the corrosion potential increases with temperature; In the range of 500-700 ℃, the absolute value of the corrosion potential is almost unchanged with the temperature rise; The reinforcement diameter and the different cooling method have little effect on the corrosion potential value of the steel inside the concrete.

Synthesis and Early Performance of Amphoteric Polycarboxylate Superplasticizers

HE Ting-shu;ZOU Ya-ting;YANG Ren-he;XU Yi-lun;LI Tong-xin

2018, 37(6):  1852-1855. 

Asbtract ( 48 )   PDF (1168KB) ( 39 )  

Related Articles | Metrics

A amphoteric polycarboxylate superplasticizer ( APC ) ZQ-3 with length side chain, 2-acrylamido-2-methylpropane sulfonic acid ( AMPS ) and cationic monomer methacrylatoethyl trimethyl ammonium chloride ( DMC ) was synthesized through radical polymerization. The structure was determined by FTIR.The properties of ZQ-3 were studied and compared with other three polycarboxylate superplasticizer.The results show that ZQ-3 has better dispersion and better retention of dispersion, and little effect on paste setting time.Concrete test and XRD analysis show that ZQ-3 can promote the early hydration of cement, and obviously improve the early strength of steam-curing concrete.

Properties of Solid Polycarboxylate Superplasticizer Prepared by Precipitation Method

WANG Jian-kang;SONG Ai-ying;LI Shi-jun;CHEN Xiao-ming;LI Jing

2018, 37(6):  1856-1860. 

Asbtract ( 53 )   PDF (1103KB) ( 40 )  

Related Articles | Metrics

Preparation of solid polycarboxylate superplasticizer by precipitation method.The macroscopic performance was tested according to the national standard method and the structure was characterized by IR、 GPC analysis technology. Comparing its properties with liquid polycarboxylate superplasticizer prepared by traditional method and commercial solid polycarboxylate superplasticizer.The results show that the water reducing rate of solid polycarboxylate superplasticizer prepared by precipitation method is 28%, and small slump loss with the initial slump of 160 mm, the curing process for polycarboxylate superplasticizer had no negative effect on the functional groups, molecular weight and polydispersity, as well as on the absorbability on cement particles.All the parameters can meet the requirements of national standard, indicating that precipitation method is a feasible way to prepare solid polycarboxylate superplasticizer.

Reinforcing for Slag-based Lightweight Foamed Concrete

JI Ying;WU Yan-wen;YANG Kang;ZHANG Jun

2018, 37(6):  1861-1867. 

Asbtract ( 54 )   PDF (1861KB) ( 48 )  

Related Articles | Metrics

Alkali activated slag, as the main gelling ingredients, was used to prepare slag polymer foamed concrete by the physical foaming technology.The influence of different composition foamed concrete matrix on the phase composition can be indicated by XRD, the affected air-void structures of the foamed concrete were investigated by image process software ( Image-Pro Plus ). This study presents the comprehensive analysis about the effect that different composition foamed concretes matrix make for the matrix compressive strength and the air-void structures, this study is mainly focused on the low density of the slag polymer foamed concrete strength optimization.The results indicate that the matrix strength is the basement strength of the slag polymer foamed concrete, and the air-void structure represent the ability that the polymer foamed concrete preserve its strength with the foam added.For low density foamed concrete, the improvement of its ability to retain basement strength is the fundamental starting point of the strength optimization.Based on the above theory, adding fly ash to the foamed concrete to optimize the pore structure first, then introducing cement to the foamed concrete to reinforce the strength of the matrix.The compressive strength of the slag-based foam concrete, with 1800 mL foam volume ( about 400 kg/m3), increase to 103%, its compressive strength increased from 1.43 MPa to 2.91 MPa.

Adsorption Behavior of Heavy Metal Ions by Desulfurization Gypsum in Water

MA Yi;YANG Jin;HAN Feng-lan;QI Li-min

2018, 37(6):  1868-1876. 

Asbtract ( 57 )   PDF (1997KB) ( 36 )  

Related Articles | Metrics

The use of industrial waste desulfurization gypsum (flue gas desulfurization gypsum, FGDG) as a adsorbent, under the condition of static adsorption, the adsorption process of FGDG on various heavy metal ions and the coexistence of various heavy metal ions were investigated from the aspects of temperature, pH value.Based on the influence of the hydration radius and the electric charge on the adsorption process, a mass transfer model is proposed.In the system of the existence of multiple heavy metal ions, the hydration radius and charge size have a significant effect on the competitive adsorption results, the competitive ability of five heavy metal ions as the follows: Pb2+＞Cr3 +＞Cd2 +＞Mn2+＞Cu2+.The Langmuir model infers that chemical adsorption is mainly a single layer adsorption process in adsorption model, and Freundlich model can describe FGDG and heavy metal ions physical adsorption belongs to multilayer adsorption process.After XRD analysis, FGDG and heavy metal ions can form Cu-S, Cd-S, Cr-S, Mn-S, Pb-S.

Effect of the Particle Size Distribution on the Performance of Dry-mixed Mortar with High Loading Fly Ash

WANG Xia;ZHUO Jin-de;JI Hong-wei;DONG Yang;LI Qiao;WANG Ke

2018, 37(6):  1877-1880. 

Asbtract ( 58 )   PDF (1066KB) ( 42 )  

Related Articles | Metrics

Based on particle dense packing theory, the Andreasen equation is generally used to calculate powder packing for evaluating the grading of powder particles.By studying the effect of the same fly ash with different particle sizes on the performance of high loading fly ash dry-mixed mortar, the result shows that the packing curve using ultrafine fly ash significantly deviates from the original dense packing state. This micro-filling cannot achieve the reinforcing effect but also greatly reduce the strength.Therefore, using fly ash to replace cement in dry-mixed mortar, particularly for high loading fly ash, the complementary role of all particles should be considered for the better dense packing to increase the density and maintain the performance of dry mortar.

Experimental Study on Cement Clinker Made of Sludge Ash Instead of Clay

WU Ya-lei;ZHA Shao-xiang;ZHANG Wei-wei;FAN Hai-hong

2018, 37(6):  1881-1886. 

Asbtract ( 44 )   PDF (1726KB) ( 48 )  

Related Articles | Metrics

Under the premise of constant rate (IM＝1.31, SM＝2.62, KH＝0.89), cement clinker was calcined with sludge ash instead of(0wt%, 25wt%, 50wt%, 75wt%and 100wt%)clay.The change of calcination of cement raw meal was studied.By analyzing the XRD pattern and NMR map of cement clinker, the change of mineral composition and content of cement clinker was studied.The influence of sludge ash on the microstructure of cement clinker was studied by means of SEM.The research shows that the addition of sludge ash will not change the rate of raw materials, however, it will reduce the portability of cement raw meal, increase the content of C2S in cement clinker, and reduce the content of C3S, which indicates that sludge ash can replace clay as raw material of cement.

Research and Analysis on the Performance of Modified Concrete with Different Materials

HUANG Hua;ZHU Liang;HUANG Min;WANG Ying-hua;DING Ze-kun

2018, 37(6):  1887-1896. 

Asbtract ( 38 )   PDF (1455KB) ( 39 )  

Related Articles | Metrics

The traditional cement concrete has the shortcomings such as low tensile strength, large brittleness, slow condensation hardening, large shrinkage, and so on.So it cannot meet the needs of the actual engineering.At present, domestic and foreign researchers have studied the modification of ordinary concrete by mineral additives, polymers, fibers and other materials to improve its comprehensive performance, and achieved remarkable results.The results of concrete modification are systematically summarized from the above three aspects.The modification mechanism of modified concrete and its effect on concrete performance are analyzed comprehensively.It is considered that the choice of modified materials is related to the economy of materials, the test technology, the modification effect, and so on. The polymer emulsion and the fiber material are the most widely studied materials.The concrete modification should pay attention to improve the cohesive force between the modified material and the uniform dispersion of the aggregate in the concrete. Although the existing polymer modification mechanism model is constantly improving, it cannot fully explain the modification mechanism of soluble polymer to concrete.The performance of modified concrete by graphene, graphene fiber and nano carbon fiber materials should to be further studied, which materials have a good prospect of application.

Research Status on Water Absorption and Desorption Properties of Lightweight Aggregate

SU Li;NIU Di-tao;LUO Da-ming

2018, 37(6):  1897-1902. 

Asbtract ( 58 )   PDF (1190KB) ( 46 )  

Related Articles | Metrics

In recent years, high-performance concrete has been applied more and more in various types of building structures, but self-shrinkage and self-weighting have become the major problems in the application of high-performance concrete, the porous structure of lightweight aggregate ( LWA) has its unique properties compared with ordinary aggregate-absorption and desorption.therefore, the use of pre-wet lightweight aggregate enables water from the LWA to be supplied to the concrete after setting, thereby reducing the effects of self-desiccation.Based on the current domestic and foreign research, this paper reviews the mechanism of internal curing and experiment methods of absorption and desorption on lightweight aggregate. However, there are few researches on the water absorption and desorption characteristics of light aggregate, and the effect of water absorption and desorption on the internal curing of concrete is still under exploration.

Meso-dynamic Damage of EPS Concrete under Shock Loading

HU Jun;REN Jian-wei;WU De-yi

2018, 37(6):  1903-1907. 

Asbtract ( 44 )   PDF (2065KB) ( 42 )  

Related Articles | Metrics

It simulated the dynamic responses of EPS concrete models in impact loading that resembled with diverse proportions of EPS beads by FEM software based on random distribution of weibull in foundation of dynamical shocking experiments.According to the aspects of proportion of EPS beads, interfaces between EPS particle and cement, degree of damage and fracture rate, the diversities of failure situation and the dynamic properties of EPS concrete with EPS beads proportions were demonstrated.The study results showed that the deformation's capacities were improved overall, which made the failure styles evolved from quasi-brittleness to ductility and extrusion flow damage; and the values of damage degree magnified while the ultimate values of strain could be enhanced by several times; and the time of summit value for fracture rates was decreased by half-times and the curve of fracture rates was like hump with the increases of EPS beads proportion and the summation of interfaces between EPS beads and cement.

Research on Preparation and Photocatalytic Application of Two-dimensional Crystal MXene

ZHENG Hui-qi;CHEN Jin;LI Yan-jun

2018, 37(6):  1908-1913. 

Asbtract ( 56 )   PDF (1328KB) ( 39 )  

Related Articles | Metrics

Two-dimensional materials, which are the materials that can only move freely on non-nanometer scales of two dimensions, have become a hot topic in recent years due to its unique and excellent physical and chemical properties.The two-dimensional crystal MXene materials has good thermal conductivity, high thermal stability and oxidation resistance.The catalytic field shows great potential for degrading pollutants, hydrolyzing hydrogen, and reducing carbon dioxide.We introduce the structure of MXene and the preparation method of chemical liquid etching, high temperature decomposition and gas etching.The application of MXene in the field of photocatalysis was reviewed.The prospect and future research direction of MXene in photocatalysis are prospected.

Prospect and Development in Beneficiation of Complex Multi Gangue Fluorite

ZHANG Qian;WEN Shu-ming;FENG Qi-cheng;LIU Jian

2018, 37(6):  1914-1919. 

Asbtract ( 49 )   PDF (988KB) ( 35 )  

Related Articles | Metrics

Fluorite, as a non-renewable resource, is an important nonmetal mineral, is the main raw material of commerical fluoride products and widely used in metallurgy, chemical, building materials, light industry, optical, sculpture, defense and other fields.With the growing applications of fluorite, the demands for fluorite are also increasing, therefore, more and more attention also has been paid to the development and use of fluorite ores.The mineral processing methods and the reagent system of quartz fluorite, calcite fluorite, barite fluorite and sulfide ore fluorite are reviewed, in order to improve the selectivity of the reagent, adopting automatic control and accurate dosing to control combination and dosage of the reagent is proposed; the flotation column is used to reduce concentration times and the process is simplified; used a combined mineral processing and chemical treatment to improve the quality of concentrate and so on are effective means of improve the efficiency of fluorite recovery, the future research direction and development trend of fluorite ore dressing are pointed out.

Application and Development of Fracturing Proppant

LI Xiao-gang;LIAO Zi-jia;YANG Zhao-zhong;ZHU Li-yong;TANG Fang-xuan

2018, 37(6):  1920-1923. 

Asbtract ( 95 )   PDF (967KB) ( 55 )  

Related Articles | Metrics

Hydraulic fracturing is a technology widely used in oil and natural gas exploitation.Proppant is a key material in the hydraulic fracturing process.Proppants are brought into the underground fracture by fracturing fluid, and directly affect the fracturing effect.Currently, proppants mainly refer to quartz sand, ceramic proppant and resin coated proppant.With the development of proppant technology, many new proppants have been developed.This paper briefly summarizes the advantages and disadvantages of proppant, and mainly introduces some new features of the supporting agent.The proppant of lightweight, surface modification, and liquid will be discussed, and future development of these proppant is involved. It has great realistic significance to study of fracturing proppant and the related industries.

Research Progress on Poly Silicate Aluminium Ferric Flocculant

REN Yuan-yuan;CHEN Fu-jin;LI Guo-bin;SU Yi

2018, 37(6):  1924-1928. 

Asbtract ( 61 )   PDF (991KB) ( 47 )  

Related Articles | Metrics

Polysilicate aluminum ferrite flocculant represents superior performance of sewage treatment. Reported in the literatures, as a new type of polymer inorganic flocculant, polysilicate aluminum ferrite flocculant shows great abilities of removing sewage turbidity, color and COD.The preparation method of poly aluminum silicate flocculant, flocculation process exist in the main mechanism of action and treatment effect are mainly described.The preparation methods include: compound method, copolymerization method, acid solution neutralization method.The mechanism of flocculation process includes the theory of compressive double layer, the role of adsorption and neutralization, adsorption bridging, net catching effect, synergistic action in a variety of mechanisms in the flocculation process, and then for water treatment better than other flocculants.The main influencing factors are Al /Fe /Si molar ratio, flocculant dosage, flocculant pH value and so on.Finally, the problems existing in the current research are briefly described.In the end, the paper pointed out the prospect and developing trends of Polysilicate aluminum ferrite flocculant.

Preparation Process and Application of Hexagonal Boron Nitride Coating by Chemical Vapor Deposition

GAO Shi-tao;LI Bin;LI Duan;ZHANG Chang-rui;LIU Rong-jun;WANG Si-qing

2018, 37(6):  1929-1935. 

Asbtract ( 98 )   PDF (1025KB) ( 52 )  

Related Articles | Metrics

Hexagonal boron nitride(h-BN) coating is one of the most promising functional ceramics due to its remarkable properties.In this paper, the preparation process of h-BN coating by chemical vapor deposition ( CVD ) was introduced, and the excellent performances and applications were reviewed. Moreover, the development trend of the research was prospected.Several problems in the CVD process of h-BN coating were discussed such as the defect of the boron nitride precursors, the complexity of the deposition mechanism, the poor controllability and high cost of the process.In order to realize the industrialization and application of the h-BN coating by CVD, it is recommended to have a more in-depth research in the fields of precursor, deposition mechanism, optimization and scale-up of the process.

Prediction Formula of Water Consumption of Recycled Coarse Aggregate Concrete Based on Multiple Factors

GUO Yuan-xin;LI Qiu-yi;SU Dun-lei;GAO Song;YUE Gong-bing

2018, 37(6):  1936-1940. 

Asbtract ( 45 )   PDF (1541KB) ( 30 )  

Related Articles | Metrics

In order to ensure the appropriate construction performance of recycled concrete, and to explore the influence of recycled coarse aggregate on the water consumption of recycled concrete In the present paper, the influences of recycled coarse aggregate quality and replacement on the absolute water consumption of recycled coarse aggregate concrete were systemically studied.Therefore, three types of recycled coarse aggregate with different quality were used to prepare recycled concrete.On the basis of absolute water consumption of ordinary concrete, the predicting equation for the absolute water consumption of recycled coarse aggregate concrete based on aggregate quality and replacement rate for the first time was proposed hereby, and the error of the prediction formula was compared based on the test date.The results indicate that there is a linear relationship between the absolute water consumption and the replacement rate of recycled coarse aggregate concrete. The absolute water consumption is significantly reduced with the improvement of recycled coarse aggregate.The maximum calculation error of recycled aggregate concrete is -1.97%, which has a high accuracy and good applicability.

Investigation on the Manufacturing Process and Properties of Ceramic Wall Brick and Floor Tile with Fly Ash

ZHANG Fan;NIU Huan-huan;LI Wen;FAN Bing-bing;ZHANG Rui

2018, 37(6):  1941-1945. 

Asbtract ( 61 )   PDF (2615KB) ( 30 )  

Related Articles | Metrics

Ceramic wall brick and floor tile with fly ash was prepared by traditional sintering method with the solid waste fly ash and K2CO3 as raw materials.The sintering temperature was 850 ℃, 875 ℃, 900℃, 925 ℃, 950 ℃, respectively.XRD and SEM techniques were used to investigate determine the phase composition and microstructure of the samples. Combined with the measurement of water absorption, bulk density and hardness of the samples, we analyzed the effects of sintering technology on the properties of this ceramic wall brick and floor tile.The results show that, the content of liquid phase increase as the sintering temperature increased, under the functions of liquid flowing, the pores in the green body are filled, the solid particles are bonded together to form a compact porcelain structure.The water absorption and microhardness is 0.07%and 5.9 Gpa, respectively, when the sintering temperature is 925℃.As the dwelling time increasing, the crystal size of KAlSiO4 increase due to the sufficient mass migration and liquid phase flow, while it hasn't any distinct impact on the phase composition and their mechanical properties.

Effect of Basalt Fiber Content on Sulfate Resistance and Impermeability of Concrete

ZHANG Lan-fang;WANG Dao-feng

2018, 37(6):  1946-1950. 

Asbtract ( 46 )   PDF (1283KB) ( 55 )  

Related Articles | Metrics

The effects of different basalt fiber content on the sulfate resistance of concrete were studied by testing the corrosion resistance coefficient of strength, the mass-change rate and volume expansion ratio of concrete.Meanwhile, the impermeability and pore structure of the concrete with different basalt fiber content were studied.The results show that the incorporation of 0.1%-0.5%basalt fiber can reduce the total pore volume, reduce the content of harmful large pores and more hazardous holes and optimize pore structure.Therefore, the sulfate resistance and impermeability of concrete were improved to different extents.Meanwhile, the sulfate resistance and impermeability of concrete with 0.3% fiber content are best.

Evaluation Standard for Anti-rutting Performance of Asphalt Pavement Based on Cylindrical Core Sample

ZHANG Ke;ZHANG Zheng-qi;LUO Yao-fei

2018, 37(6):  1951-1959. 

Asbtract ( 41 )   PDF (1273KB) ( 36 )  

Related Articles | Metrics

To evaluate the anti-rutting performance of asphalt pavement, it is necessary to set up the evaluation standard of rutting resistance for asphalt pavement.Firstly, the rutting tests based on plate specimen and Superpave Gyratory Compactor ( SGC) specimen were carried out, and the conversion formula of dynamic stability of two kind specimens was established.Secondly, the asphalt mixture was taken from construction site to shape plate specimen, and the cylindrical core sample in the corresponding position were also drilled.The dynamic stability of two kind specimens was used to modify the conversion formula.Again, the rutting test results of core samples with different thickness were selected to complete the thickness correction for conversion formula.Finally, combined with the dynamic stability technical requirements of asphalt mixture in current specifications, the anti-rutting performance evaluation standard of asphalt pavement based on core samples was established.The results show that when the thickness of modified asphalt pavement core sample is 4 cm, 5 cm or 6 cm, the dynamic stability should not be less than 2800 time/mm, 2400 time/mm and 2250 time/mm at 70 ℃ respectively. For raw asphalt pavement, the dynamic stability at 60 ℃ should not be less than 3450 time/mm and 3200 time/mm respectively when the thickness of core sample is 5 cm or 6 cm.

Mix Proportion Design of Pervious Concrete Based on Compressible Packing Model

CHEN Jin-dong;WANG Wu-xiang;ZHANG Lei-lei;LIAO Li-ping;WANG Ai-jun

2018, 37(6):  1960-1965. 

Asbtract ( 45 )   PDF (1420KB) ( 50 )  

Related Articles | Metrics

Based on the compressible packing model and the total porosity was taken as the main mix proportion design parameter, a mix proportion design method of pervious concrete considering the influence of molding process and aggregate gradation was proposed.In this method, the graded aggregates with high dry packing density were selected based on the compressible packing model, the relationship between the packing density of the aggregates in pervious concrete and its dry packing density was established by introducing a scale factor λwhich reflected the influence of the molding method, then the aggregate mass per unit volume of pervious concrete was determined; and the paste volume and cement mass were calculated according to the aggregate mass and water-cement ratio.the pervious concrete has been formulated according to this method to validate it, the results demonstrate that the gap between the measured total porosity and the design total porosity is very small, which indicates that this method achieves the design object, and the strength variation tendency against the volumetric fraction of fine aggregates is similar to that of aggregate's dry packing density, but not the higher the dry packing density the higher the strength, the strength is also affected by the aggregates size.

Effect of Adipic Acid on Properties of Cement Paste Mixed with Limestone Powder

WU Yong-hua;ZHANG Lu-lu;CHEN Chang;ZHANG Kai-feng;JIA Lin;CHENG Hao;YU Hao

2018, 37(6):  1966-1969. 

Asbtract ( 38 )   PDF (1672KB) ( 39 )  

Related Articles | Metrics

In order to investigate the effect of adipic acid in the cement paste with limestone powder, the influence of adipic acid on the fluidity, strength, hydration heat and chemical bonding water of cement paste with limestone powder was studied.X-ray diffraction and scanning electron microscopy were used to analyze the mechanism.The results show that adipic acid improved the fluidity, compressive strength at curing age of 3 d, the early hydration temperature, the early hydration of combined water of cement paste.And calcium carboaluminate hydrates is more generated in the mortar for 3 d hydration time, which results to a more compact structure of hydration products.

Experimental Study about Preparation of Sintered Square Brick by Using Vanadium Tailings

LI Liang

2018, 37(6):  1970-1973. 

Asbtract ( 36 )   PDF (1087KB) ( 32 )  

Related Articles | Metrics

The sintered square brick was prepared by the semi dry forming method using the vanadium tailing slag as the main raw material.The physical index of sintered square brick with vanadium tailings can be optimized, and the properties of brick can be improved by adding Guangxi white mud, ferrosilicon ash, fly ash and A12O3 powder.By means of the condition test, the influence of the proportioning of white mud in Guangxi, fly ash, silicon iron ash and Al2O3 powder on the compressive strength and water absorption of the sintered wide-field brick is studied at room temperature.The conditional test shows that the allocation of Guangxi white mud is about 20%, and the amount of ferrosilicon ash control is less than 5%.It is more suitable to control the amount of fly ash in 6%, and the amount of Al2O3 powder is less than 6%.The brick's compressive strength is above 28 MPa and the water absorption can be reduced to about 10%at room temperature.

Study on the Properties of Fiber Reinforced Micro-expansion Wet Joint Concrete

YANG Xiao-ming;WANG Ai-guo;LIU Kai-wei;JING Yan;SUN Dao-sheng

2018, 37(6):  1974-1978. 

Asbtract ( 54 )   PDF (1673KB) ( 33 )  

Related Articles | Metrics

The effects of steel fiber, MgO-type expansive agent ( MEA) and their composite on the performance of wet joint concrete were studied.The interface structure between steel fiber and matrix in concrete was observed by stereoscopic microscope, and the pore structure of mortar in concrete was measured by mercury pressure method.The results show that the incorporation of MEA is favorable for compensating the shrinkage of concrete.With the increase of steel fiber content, the expansion rate of expansive concrete is decreasing.Steel fiber and MEA composite can effectively improve the volume deformation of concrete.The synergistic effect of steel fiber and MEA improves the micro-structure of concrete, increases the density of matrix and between steel fiber and matrix, and enhances the bonding force of the matrix to steel fiber, which is more conducive to improving the mechanical and permeability of wet joint concrete.

Acid Rain Attack Damage Progress of Concrete in Freezing-thawing Environment

WANG Kai;XIAO Yong;LIN Jing;REN Liang

2018, 37(6):  1979-1982. 

Asbtract ( 52 )   PDF (1366KB) ( 33 )  

Related Articles | Metrics

Based on measuring the damage deterioration curves of the relative surface elastic modulus and relative dynamic elastic modulus of concretes, the influence of freezing-thawing cycles on the damage progress of concretes to acid rain attack were investigated.The results show that freezing-thawing cycles shorten the performance of concrete at the initial stage of acid rain corrosion so that it advanced into the damage reduction stage, and accelerate the damage progress of acid rain attack on concretes.And the damage rate of acid rain to concrete increases with the increases of freezing-thawing cycles and acid rain acidity.Microscopic studies demonstrate that this is due to that the frost heave stress caused by freezing-thawing cycles can accelerate acid rain corrosion products to quickly fall away from concrete surface and increase new internal cracks of concretes, and prompts the expansion of the existing micro cracks until link up, so that provides fast channel for acid rain erosion media into concretes.

Influence of Internal Curing by Pre-wetted Cement Particles on the Early-aged Autogenous Shrinkage and Compressive Strength of Concrete

WANG Yu-xuan;CHEN Pei-yuan;XU Ying;SHEN Peng-hui;ZHANG Dong-lei;SHI Yu-hang

2018, 37(6):  1983-1988. 

Asbtract ( 33 )   PDF (1624KB) ( 33 )  

Related Articles | Metrics

Cement paste particles with different particle size and water-cement ratio were prepared as internal curing ( IC) material of concrete with low water-cement ratio.Three kinds of concrete was designed based on the optimum IC water to cement ratio, which sand is replaced by equal volume with the same size of cement paste particles with different water-cement ratio of 0.6, 0.7 and 0.8.Influence of cement paste particles with different water-cement ratio on the early-age autogenous shrinkage, compressive strength and microstructure of concrete was investigated.The results show that the water absorption rate of particles is positively correlated with the water-cement ratio and negatively correlated with particle size.Pre-wetted cement particles can significantly reduce the early-age autogenous shrinkage of concrete, and the autogenous shrinkage decreases with the increase of the water-cement ratio of particles.However, the mixing of pre-wetted particles will reduce the compressive strength of concrete, the compressive strength of concrete decreases with the increase of water-cement ratio of particles, the water-cement ratio of the IC particles should be optimized in the application.As the IC material of concrete, Cement paste particles can improve the pore structure of micro-interface, increase the compactness of the interface and reduce the autogenous shrinkage of concrete in the early-age.

Testing for Non-metallic Ceramic Materials Based on Air-coupling Ultrasonic Wave

XIE Ji-li;GAO Jun-guo

2018, 37(6):  1989-1994. 

Asbtract ( 42 )   PDF (1275KB) ( 45 )  

Related Articles | Metrics

Aiming at the problem of air-coupling ultrasonic testing for non-metallic ceramic materials, the mathematic model and the finite element model of air-coupled ultrasonic detection of non-metallic materials was established.Air-coupled ultrasonic propagation dispersion curve and received signals obtained from some node was simulated by the method of Matlab software and ANSYS finite element software, and the propagation characteristics of air-coupled ultrasonic wave in non-metallic ceramic materials were studied.The results show that wave of A0, S0 and SH0 modes in the S3N4 ceramic material as the frequency is less than 2 MHz· mm.When the frequency is larger than 2 MHz· mm, the kinds of wave model is more in the medium.As the distance of wave propagation increase, the received signal amplitude of the A0 modal and the S0 modal is smaller, and the amplitude of A0 modal is larger than amplitude of the S0 modal, so it should stimulate the A0 modal of air coupled ultrasonic for testing and evaluating non-metallic ceramic materials.

Experimental Study on Cementing Material of Sand-based Permeable Concrete Pavement Brick

CAI Run-ze;MAN Du-la;CHEN Si-han

2018, 37(6):  1995-2001. 

Asbtract ( 37 )   PDF (2227KB) ( 54 )  

Related Articles | Metrics

The influences of self-developed admixture with different contents, water-cement ratio, aggregate gradation and ash-aggregate ratio on the strength and water permeability of sand-based permeable concrete pavement bricks were studied, and test the water retention, frost resistance, wear resistance, resistance to sulfate attack and dry-wet cycles performance of the specimen through the indoor test.Firstly, compare the self-developed admixture Ⅰ with three kinds of admixtures of the same type through the mortar test and choose the best.The results show that the admixture Ⅰ ( 28 d ) has compressive strength of 59.2 MPa and bending strength of 9.3 MPa, which is better than the same type of admixture; the optimal amount of admixture Ⅰ with sand-based permeable concrete pavement is 5% of cement mass.The strength is 35.6 MPa, the water permeability coefficient is 3.5×10 -2cm/s, and it has good water retention, frost resistance, wear resistance and resistance to sulfate attack and dry-wet cycles.

Effect of Alkali Concentration and Modulus of Alkaline Activator on the Compressive Properties and Hydration Products of Alkali Activated Slag Cementitious Materials

MA Qian-min;HUANG Li-ping;NIU Zhi-liang;GUO Rong-xin;YAN Feng;LIN Zhi-wei;DU Hai-yun

2018, 37(6):  2002-2007. 

Asbtract ( 204 )   PDF (1221KB) ( 97 )  

Related Articles | Metrics

Granulated blast furnace slag was activated by using water glass (sodium hydroxide was added in to adjust modulus) to prepare alkali activated slag paste specimens.Effect of alkali concentrations of 4%, 6% and 8% and moduli of 0.75, 1.00, 1.50 and 2.00 of the activator on the compressive properties and hydration products of alkali activated slag was studied by using compressive strength test, X-ray diffraction (XRD) and thermal analysis (TG-DSC) techniques.The results show that when a lower modulus was used, such as 0.75 and 1.00, compressive strength of alkali activated slag decreased with the increase of alkali concentration.While when the modulus used was higher, such as 1.50 and 2.00, the specimens could obtain the maximum compressive strength when alkali concentration was 6%.Under same alkali concentration, modulus of 1.50 could make the specimens get the maximum compressive strength.The main hydration products of alkali activated slag was C-S-H gels, certain amount of C-A-S-H gels was also formed simultaneously.Besides, small amount of gismondine (CaAl2Si2O8· 4H2O) was also detected in the system.Hydrotalcite (Mg6Al2(OH)6CO3· 4H2O) was found in some of the mixes. Larger amount of C-S-H gels was formed in the alkali activated slag system with higher alkali concentration.Use of higher modulus, such as 1.50 and 2.00, was beneficial for the formation of C-S-H gels in the system.When a lower alkali concentration/modulus was used, the C-S-H gels in alkali activated slag was more crystalline.Compared to the degree of crystallinity, amount of C-S-H gels was more influenced on the compressive strength of such system.

Strength and Damage Model Analysis of Pure Tailings Cemented Filling Body with Different Water Content

NIE Ya-lin;WANG Xiao-jun;HUANG Guang-li;LI Shi-chao;FENG Xiao;CAO Shi-rong

2018, 37(6):  2008-2013. 

Asbtract ( 42 )   PDF (1114KB) ( 26 )  

Related Articles | Metrics

A full tailing cemented filling body made of metal mine tailing and cement is taken as the research object, the strength test of the specimens with different moisture contents filling body in the process of deformation and failure was carried out by uniaxial compression and using RMT-150C hydraulic servo control system and sensor acquisition system.The test results show that: the samples with completely dry state have the highest strength, and the different moisture contents have obvious influence on the strength of the filling body.The higher the water content, the lower the uniaxial compressive strength.In the elastic phase, water has a great influence on the elastic modulus of the filler sample, the brittleness in the dry state is larger, the slope of the curve is larger, and water softens obviously. Intergranular cohesion and friction are reduced by the action of water.The quantitative relationship between uniaxial compressive strength and moisture content shows a polynomial decrease.Different water content filling bodies have different damage characteristics, the damage development of the dry filling body is inhibited by water, but the damage development of the aqueous filling body is promoted by the increase of the water content.

Experimental Study of Double-K Fracture Parameters Using Arch Specimensin Concrete

DING Shao-qiang;QING Long-bang;CAO Guo-rui

2018, 37(6):  2014-2018. 

Asbtract ( 44 )   PDF (1429KB) ( 34 )  

Related Articles | Metrics

Through the arch three-point bending beam experiment of concrete, double-K fracture parameters were calculated by the experimental curve, then the influence of different seam height ratios on double-K fracture parameters was studied.Based on the digital image correlation ( DIC) method, the field strain information of the crack propagation direction of concrete was obtained, and the process of fracture propagation was studied.The results show that Pini/Pmax value was between 0.60 and 0.85.The double-K fracture parameters were not related to the initial seam-height ratio of the specimen, and they could describe the fracture characteristics of arch specimens.Compared with the preload phase of peak load, the crack propagation speed increased significantly after the peak load.

Corrosion Test of Fly Ash Cement Soil with Fulvic Acid

CAO Jing;SUN Cheng-jiao;GAO Yue;BAI Shu-ting

2018, 37(6):  2019-2024. 

Asbtract ( 60 )   PDF (1934KB) ( 40 )  

Related Articles | Metrics

Studying the durability of cement soil in corrosive environment is of great significance to the safety of building structure.Fly ash, as an important admixture of civil engineering materials, can reduce the amount of cement used and can improve the workability of cement soil mixing, is widely used in practical engineering.In order to study the corrosion of cement soil mixed with fly ash in humic acid environment, according to the environment of peat ( soil) in Kunming, this paper simulated the corrosive environment by using laboratory tests, and mixed pure fly ash with fly ash of cement soil immersed in fulvic acid environment, through the immersion process apparent changes in two groups of samples, acid consumption and corrosion softening depth comparison of pure cement and fly ash mixed cement soil in the fulvic acid environment corrosion in the changing conditions.The results show that cement-soil mixed with fly ash deteriorates more seriously in the fulvic acid environment.Considering the long-term safety of building structure, cement-soil structures in humic acid environment should not be mixed with fly ash.

Experimental Study on Chloride Ion Permeability of Steel-plastic Fiber Lightweight Aggregate Concrete

NIU Jian-gang;WANG Xiao-peng

2018, 37(6):  2025-2029. 

Asbtract ( 39 )   PDF (2013KB) ( 42 )  

Related Articles | Metrics

The chloride ion permeability of steel-plastic fiber lightweight aggregate concrete was studied by rapid chloride ion transport coefficient method.The amount of steel-plastic fiber, the type of ceramsite and the time of pre-wetting time of ceramsite were investigated.The research results show that the diffusion coefficient of steel-plastic fiber lightweight aggregate concrete decreases with the increases of fiber content, and the diffusion coefficient is the lowest when the content is 9 km/m3.Compared with fly ash ceramsite, steel-plastic fiber lightweight aggregate concrete that is made the shale ceramsite has lower diffusion coefficient.The pre-wetting time of ceramsite has little effect on the chloride ion diffusion coefficient of steel-plastic fiber lightweight aggregate concrete.However, the diffusion coefficient in the lightweight aggregate concrete increases with the increases of the pre-wetting time.

Preparation and Application of Vanadate Glass-ceramic Sealing Material

LI Ming-yue;TIAN Zhi-yun;SHAO Jing;ZHANG Hong-bo;ZOU Xiang-yu;SU Chun-hui

2018, 37(6):  2030-2034. 

Asbtract ( 33 )   PDF (1389KB) ( 26 )  

Related Articles | Metrics

The glass ceramics containing Ba3( VO4)2 were prepared by melting quenching method.The influence of heat treatment on the crystallization, thermal properties and mechanical properties of the samples were studied.The results indicate that the best heat treatment of the glass ceramics containing Ba3(VO4)2 samples: crystallization temperature of is 540 ℃,for 2 h; Under heat treatment conditions, the glass ceramics are better than glass for transition temperature, temperature Tg, softening temperature Tf, thermal expansion coefficient and hardness .The coefficient of thermal expansion is 17.81 × 10 -6℃-1, which is similar to the thermal expansion coefficient of copper metal(17.7×10 -6℃-1).It can be sealed directly with copper to replace traditional lead sealing material.

Synthesis and Performance Study of Self-repairing Microcapsules for Micro-cracks of Oil-well Cement Matrix

ZHANG Chun-mei;CHENG Xiao-wei;YANG Yong-sheng;GUO Xiao-yang;CHEN Zu-wei

2018, 37(6):  2035-2041. 

Asbtract ( 46 )   PDF (1830KB) ( 35 )  

Related Articles | Metrics

A new type of self-repairing microcapsules (with epoxy resin as the core and urea formaldehyde resin as the wall) for micro-cracks of oil-well cement matrix.The particle size distribution, surface topography, chemical composition and thermal stability of the microcapsules were analyzed by the Laser particle size analyzer, scanning electron microscopy ( SEM ), infrared spectroscopy ( FT-IR ) and differential thermal gravimetric analyzer ( TG/DTA) respectively.After preparation, microcapsules were added into cement paste, and the compressive strength and strength recovery rate of oil-well cement matrix were tested to evaluate the self-repairing effect of microcapsule.The results show that the average particle size is about 36.08 μm, the surface of microcapsules is rough and its thermal stability is good.In addition, the addition of microcapsules can improve the compressive strength of cement matrix by increasing the strength recovery rate ηof cement matrix (after repairing) to 2-3 times co MPared to that of pure cement matrix.When the content of microcapsule is 1.5wt%, the samples have the most excellent mechanical properties than the others.

Experimental Study on the Cracking of Concrete about the High Speed Railway in Big Temperature Difference Area of Gobi

HU Rui-peng;ZHANG Rong-ling;WANG Meng-shi;GUO Hai-zhen;LI Hua;LOU Xu-yu

2018, 37(6):  2042-2047. 

Asbtract ( 40 )   PDF (2599KB) ( 41 )  

Related Articles | Metrics

In view of the early crack and other durability problems of concrete slab of ballast bed after the construction of LanXin second-line ballastless track, 1:1 full-scale model tests in laboratory simulation. Using artificial climate simulation box to simulate the great temperature difference in Northwest China, the cracking mechanism of ballastless track slab of ballastless track is studied from the aspects of distribution, variation and deformation of early hydration heat field, establishing the relationship between the temperature field of concrete hydration temperature and the atmospheric temperature environment in Northwest China.At the same time, the temperature field of hydration heat is simulated by finite element software, and the calculated results are compared with the indoor test results.The results show that: The large temperature difference and abominable environment are the main causes of the cracking of the bed slab.The temperature field and the environmental temperature change periodically.Closer to the surface of bed plate, the larger temperature gradient is, the more likely to create cracks.

Key Performance and Application of Ultra High Performance Concrete in Bridge Expansion Joint

REN Liang;LIANG Ming-yuan;WANG Kai;HE Yu;ZHAO Guo-gang

2018, 37(6):  2048-2052. 

Asbtract ( 81 )   PDF (2307KB) ( 39 )  

Related Articles | Metrics

Based on the theory of hybrid fibers, an improved ultra high performance concrete ( UHPC) is proposed after the optimization of different hybrid fibers, including PVA fiber or polypropylene ( PP) fiber and steel fiber, which realizes the curing under the normal temperature.The application of the proposed UHPC used in the repair of the transition of the bridge expansion joint is discussed.The research results show that the hybrid fiber reinforced UHPC has high strength and good crack resistance when the addition of the PP fiber is 20 kg/m3.The flexural strength and compressive strength of UHPC samples can amount to 13.6 MPa and 40.9 MPa when the curing time is 2 d, respectively, and 51.3 MPa and 138.5 MPa when the curing time is 28 d, respectively.The phenomenon of the shrinkage crack isn't clear during the shrinkage slab test.Engineering practice indicates that the proposed UHPC used in the repair of bridge expansion joint can not only satisfy the service performance, but also quickly restore the traffic, which has broad application prospects

Volumetric Determination of Sulfur Trioxide in Gypsum

NIU Gai-ling

2018, 37(6):  2053-2056. 

Asbtract ( 79 )   PDF (981KB) ( 70 )  

Related Articles | Metrics

The gravimetric method is a classical method for the determination of sulfur trioxide ( SO3) in gypsum, and it has high accuracy and wide range of application.However, it is not suitablefor a large number of testing tasks and field test due to the low efficiency.In this study, the sulfate ion was precipitated with excess solution of barium chloride, and then the remaining barium chloride solution was titrated by EDTA instantly.In this way, the content of SO3 was obtained indirectly.Compared with the gravimetric method, the absolute error of the volumetric method is less than 1%, and the relative error can be kept below 0.5%.Therefore, this method can enhance the determination speed of SO3 in gypsum without the interference of other factors.The developed method is simple and reliable, and provides an ideal method for determinationof SO3 in Gypsum .

Degradation Research of Guar Gum by the Green Oxidant K2FeO4

HAN Hong-jing;YANG Yuan-lin;WANG Bao-hui

2018, 37(6):  2057-2061. 

Asbtract ( 45 )   PDF (1482KB) ( 31 )  

Related Articles | Metrics

Hydroxypropyl guar gum ( HPG) is widely used as a thickening agent in fracturing fluids, which is difficult to degrade in natural environment after being flowed back to the ground and has caused great harm to the environment.The investigation of green and effective method to treat the flowback fluid has become the hot and difficult issues.This we used the green oxidant K2FeO4 to degrade the simulation solution of flowback fluid in the laboratory (the mass concentration was 0.3‰ of HPG solution).The results show that the optimal reaction conditions is as below: When the usage of K2FeO4 is 0.5 g/L, the reaction temperature is 30 ℃, the reaction pH is 12.0, the viscosity degradation of HPG is reached 89. 27%, and the COD degradation is reached at 36.27% at the same time, the degradation products of oxidation agents are ferric ions without toxic and pollution.

Experimental Research on Performance of C30 Concrete with Aggregate of High Titanium Heavy Slag in Xichang City

QIAN Bo;HU Jian-chun;QI Ming-qiang;ZHENG Fa-ping;ZHAO Jie

2018, 37(6):  2062-2066. 

Asbtract ( 28 )   PDF (1294KB) ( 27 )  

Related Articles | Metrics

In accordance with relevant standards, experimental research was carried out respectively to verify the feasibility of pumping concrete of industrial and civil construction engineering, which concrete prepared by aggregate of high titanium heavy slag ( HTHS aggregate) in Xichang City.According to natural aggregate concrete and HTHS aggregate concrete of C30, comparative experimental research contained mix proportion design of concrete, mixing performance, mechanical performance, long-term performance and durability.Experimental research shows that it can significantly increase concrete performance that pre-wetting time of HTHS aggregate is 12 h; HTHS aggregate in Xichang City can be used instead of natural aggregate to prepare pumping concrete, which mixing performance, mechanical performance, long-term performance and durability, structure performance met relevant standard requirements.

Breakdown Characteristics and Junction Termination Structural Parameters of Power Semiconductor Devices

XU Jian-li;XIA Ting-ting

2018, 37(6):  2067-2072. 

Asbtract ( 56 )   PDF (1599KB) ( 42 )  

Related Articles | Metrics

According to the characteristics of junction terminal structure of power semiconductor devices (Such as BJT, VDMOSFET, etc) .And then the influences of junction terminal high concentration diffusion region junction depth and three different junction terminal protection structure ( junction terminal extension structure, floating field limit ring structure and the junction terminal etching structure ) parameters on the breakdown characteristic of device are analyzed comprehensively and systematically by using TCAD semiconductor device simulation software.The simulation results show that the junction terminal high concentration diffusion region, when the surface concentration is a fixed value, with the increase of diffusion region junction depth, the change characteristics of device breakdown voltage present first increases and then decreases.And the cylindrical junction at the edge of the area junction local electric field concentration is the dominating factor for decreasing the breakdown voltage.For three different junction terminal protection structure, can effectively reduce the cylindrical junction edge electric field intensity, the reverse breakdown characteristics significantly improved.Comparing three junction terminal protection structure, junction edge etching structure is works best at improvement of reverse breakdown characteristic.

Preparation and Property of White Carbon Black-zinc Inorganic Antibacterial Agent

CHEN Ying;DING Hao;SUN Si-jia

2018, 37(6):  2073-2078. 

Asbtract ( 48 )   PDF (1848KB) ( 49 )  

Related Articles | Metrics

The antibacterial precursor was prepared by loading Zn2+ on the white carbon black ( WCB) substrate through water bath heating and stirring, and then the white carbon black-zinc inorganic antibacterial agent ( WCB-Zn) was obtained after the calcination of antibacterial precursor, meanwhile, the antibacterial coating was added to the coating to prepare the antibacterial coating.The preparation conditions including the concentration of Zn2 +, solid content of WCB, pH value, and calcination temperature and time were investigated and optimized.Moreover, the properties of inorganic antibacterial agent and antibacterial coating were also tested and characterized.The results show that both the WCB-Zn and antibacterial coating show good antibacterial properties.The minimal inhibitory concentration (MIC)of WCB-Zn on E.coil and S.aureus is 19 mg/mL and 6 mg/mL respectively, and the bacteriostatic rate of antibacterial coating with 8wt% WCB-Zn added against E.coil and S.aureus is 90.48% and 98.77%respectively.

Inhibiting Effect of Flint Powder on Expansion of ASR

BAI Guang;ZHANG Hui;YANG Fei;WU Jian-hua

2018, 37(6):  2079-2082. 

Asbtract ( 50 )   PDF (1899KB) ( 26 )  

Related Articles | Metrics

The influence of adding different fineness and proportion flint powder on expansion of Alkali-Silica Reaction (ASR) in mortar samples were investigated by comparing the expansion rate in different ages, SEM images and energy spectrum analysis (EDS) of the samples.Adding appropriate amount flint powder with different fineness can effectively inhibit the expansibility of the specimens caused by ASR. SEM images and the results of EDS show that the amount of alkali silicate gel around flint aggregates decrease when adding appropriate flint powder.It proved that flint powder have the potential to inhibit ASR.And the reactive flint powder decrease Ca/Si mole ratio, which increases Na ions fixation capacity of CSH, and improves the inhibition of ASR.The results can provide some reference for inhibiting the ASR reaction measures when using latent alkali active aggregates.

Experimental Investigation on Influence of Cement Content on Concrete Performance

XIAO Wei;DING Cheng-ping;XIE Xu-jian

2018, 37(6):  2083-2087. 

Asbtract ( 72 )   PDF (1062KB) ( 43 )  

Related Articles | Metrics

To explore the regularity of cement content on concrete performance.Strength, deformability, frost resistance and anti-chemical erosion of concrete were analyzed systematically by experiments with using the same kinds of water binder ratio of a benchmark for the 250 kg/m3, an increase of 50 kg/m3 of 5 different cement content.The results show that under the condition of the same water cement ratio, the frost resistance and anti-chemical erosion of concrete increased with the increase of cement content, but it decreased slightly when the amount of cement content was more than 350 kg/m3; And it has the best performance-price ratio for the strength, deformability, frost resistance and anti-chemical erosion of concrete when cement contents reached around 350 kg/m3.