bluuebunny/crossref_metadata_2025 huggingface dataset:
Control Research of DC Servo System Based on Friction Compensation
Authors: Chai Hua Wei , Zhou Jin Yu , Wang Yi Xin , Tan Heng , Li Zhi Gang
Published: June 2012

In order to realize high precision position tracking control in some dc servo system, aimed at all kinds of uncertainties, a disturbance torque compensation control tactics is put forward. In other words, friction model is approximated online by fuzzy system and identification result is taken as compensation item of control algorithm. Besides, adaptive fuzzy compensation PID algorithm is utilized. Simulation results show that compared with conventinal PID control, this control tactics can enhance dynamic performances and steady-state precision, satisfying performance requests.
Study on Grain Size Characteristics and Strength Test of Gravel in Conglomerate Layer of a Coal Mine
Authors: Wang Xiao Lei , Yan Shun Xi , Zhao Shu Jiang
Published: June 2012

The direct roof of B132 coal seam is conglomerate layer in a coal mine, which is cemented with gravels and sandstones and has brought great difficulty for tunnel supporting. It is necessary to study the grain size and strength characteristics of gravel in conglomerate layer for the mining of B132 coal seam safely and efficiently. The statistics and analysis of grain-size characteristics of gravel was carried out in this paper, including of the quantity and volume percent of gravel. Uniaxial compressive strength of gravel was tested with point load method. The test results show that uniaxial compressive strength of gravel is very high, especially the black gravels, whose compressive strength is commonly above 200 MPa and the highest even can reach more than 300 MPa.
Dewatering Efficiency Comparison between Vacuum Tube Well and Normal Tube Well in Silty Clay Layer
Authors: Li Zhi Guang , Ma Jian , Cao Yong Jian , Xu Bai Qing
Published: June 2012

Vacuum Tube Well Dewatering (VTWD) is one of high efficiency methods to vacuum dewatering in Beijing district in recent years. Water output, surrounding drawdown, and land settlement of vacuum and normal tube well respectively were measured during the process of engineering dewatering at three sites in Beijing subway engineering. The results showed that the water output by VTWD was 1.6 to 2 times than that by Normal Tube Well Dewatering (NTWD) while the land settlement was twice compared to NTWD. It is suggested to consider the carrying capacity of surrounding environment when using VTWD.
Rapid Excavation Research of Half Coal Rock Lane in Liu-Wan Mine
Authors: Yang Ren Shu , Cao Wen Jun , Liu Guo Qing , Bai Xiao Sheng , Guo Dong Ming
Published: June 2012

In order to solve the question of excess or under excavation, poorly forming around the lane, low rate of excavation caused by less drilling, arbitrarily drilling, non-standard charging, unreasonable initiation network in the construction process of half coal rock lane in Liu-wan mine. According to coal and rock conditions at the scene and through theoretical calculations and engineering analogy, made a scientific and rational borehole layout and correct initiation network, strengthened temporary support and changed operation modes. The driving rate of the single circulation was improved from 1.6m to max.2.75m. The utilization rate of the blasting boreholes was improved from 89% to previous 94.7%. The unit consumption of explosives was significantly reduced from the original 1.24kg/m3 minimum to 0.74 kg/m3.Thus the profile shape results would be good and the driving speed could be highly increased. Research results will be the same geological conditions for excavating to provide reference.
Research Status and Prospect of Rock Acoustic Emission Technology
Authors: Zhang Qing , Wang Lei
Published: June 2012

The research status of the rock acoustic emission technology had been discussed from three aspects, as the different status rock study, the processing technology study, the character analyzing technology study. The rock acoustic emission should be combined with the practical engineering, and to create effective rock acoustic emission processing and analyzing technology, to make the rock acoustic technology better adapted to the testing of the practical project.
Analysis of Pile Side Resistance with Pile Lateral Stress Factor
Authors: Zheng Ying Jie , Li Lian Xiang , Li Shu Cai , Dai Xue
Published: June 2012

A pile-soil interface model was established. The model considered the influence of interface lateral stress on the interface mechanics parameters. In this model the ultimate shear stress and the max tangential stiffness in loading process were related with pile lateral stress ratio. The influence of loading model on pile side resistance can be considered in this model. With the model, the interface parameters under pressing down at pile top can be got from those under pushing at pile bottom load. The suggested model was applied to analyze an O-cell pile test case. The analysis results show that the bearing capacity under loading press at pile top is higher than that under pushing at pile bottom, and the increase extent is agree with practical experience. It is also confirmed that the model is applicable and effective.
Study about the Compacted Properties of Completely Weathered Granite Improved Soil
Authors: Wen Yi , Wang Yong He , Xiao Hong Bing , Qu Chang Zi
Published: June 2012

In this paper, through the indoor experiment study of compaction characteristics of completely weathered granite improved soil, analyse the relation of the maximum dry density and the optimum moisture content with lime and cement content, and through the fitting working out the relation curves and fitting formula of the improved soil of the maximum dry density and the optimum moisture content with lime and cement content . Provide reference for similar engineering.
Rock’s Acoustic Emission and Damage Deformation Characteristic in Uniaxial Compression Condition
Authors: Guo Zi Hong , Tao Qian , Liu Bao Xian , Luo Chao , Meng Li , Xu Hai Yang
Published: June 2012

Rock’s uniaxial compression test is completed and the datum is analyzed, then relationship between loading time and AE amplitude, AE counts sum, AE total energy’s released rate come out. Rock’s critical damage is defined which equal result of one minus ratios of residual strength to critical strength. Based on strain equivalence discipline, damage constitutive models related with acoustic emission characteristic are set up. With damage constitutive models established with AE counts sum and AE total energy serving as damage variables respectively and testing datum, the relationship between rock’s damage and stress and strain is described. Then conclusions come out: 1) damage constitutive model with AE counts sum serving as damage variable manifest rock’s damage increasing process and accords with testing result better; 2) theoretical curve is well consistent with testing curve at rock’s peak strength zone.
Study on the Stochastic Law of Gob Stowing Effect
Authors: Guo Li , Xie Bing
Published: June 2012

The cut-and-fill mining is the main content of the technical system of green coal mining. And it is an effective way for solving the environmental problems and mining the coal under buildings, under railway, under water and over confined aquifer. No matter what kind of filling way, the gob stowing cannot achieve ideal filling effect, the filling effect is random in certain scope. Taking a coal mine as an example, with the aid of stochastic finite element method, the three situations of gob stowing were calculated and analyzed to explore the statistical rule of the ground surface settlement and the stability of surrounding rock because of random variation of gob stowing effect.
The Application of Anchor Block in Large Soft Foundation Pit Excavation
Authors: Ma Chi , Liu Guo Nan , Liang Yue Ying
Published: June 2012

Based on pit excavation of Shenzhen Airport Rail transport hub project, combined with anchorage stress characteristics, difficulties was studied and numerical calculation for the envelope structure was undertaken. The successful application of design provides new ideas, improved design methods for super soft soil foundation engineering, which can greatly promote the application and development of anchor block in soft foundation excavation.
ANSYS Simulating Analysis of a 3D High-Temperature Stope Reinforced in Advance with Fully Grouted Cable Bolts
Authors: Zhan Feng Lin , Ye Ping
Published: June 2012

By using ANSYS, 3D high-temperature stope models based on the in-situ experiment of reinforcement with fully grouted cable bolts in the test stope hangingwall of Dongxiang Copper Mine are established and analyzed. Results show that both displacements of ground surface and stope hangingwall are in their allowable scopes. The surrounding rock rising displacement caused by heated rock expansion can partly or fully offset the subsidence displacement caused by gravity. Hangingwall rising displacement occurs if stope temperature is equal to or greater than 100°C. Mining is safe if stope temperature is equal to or less than 500°C. The stope hangingwall anchoring parameters can meet the requirements of surrounding rock stability in the process of extraction.
Initiation Analysis of an Irrigation-Induced Loess Landslide
Authors: Li Hong Jie , Jin Yan Li
Published: June 2012

Underground water level rise because of irrigation has induced a lot of loess landslides in South Jingyang Plateau located in Shanxi Province, PR China. This paper presents a detailed initiation analysis of the landslides through field investigations, a series of GDS triaxial tests composed of isotropically and anisotropically consolidated undrained (ICU/ACU) compression tests and constant-shear-drained (CQD) triaxial tests for undisturbed saturated loess and numerical modeling. The tests show that the contractive failure will cause excess pore water pressure that cannot be dissipated instantly, and will result in the decrease of the shearing resistance. Shear deformation during failure moves the soil toward the critical state rapidly and make the loess completely in liquefactive condition. Therefore, the slope is prone to rapid and long run-out flow slide after failure under the action of gravity because of its high water content.
Numerical Simulation of Fracture Propagation of Heterogeneous Material
Authors: Zhu Ze Qi , Sheng Qian , Fu Xiao Dong
Published: June 2012

For the Three Gorges granite, a finite difference software package FLAC was used to study failure process of heterogeneous rock material. Based on mineral components identification results of the granite and fuzzy clustering method, the actual image date was transformed into the finite difference grid by applying image processing techniques. A convenient and efficient two-dimensional numerical modeling method for heterogeneous geomaterials was presented. Then, failure process of the granite were simulated in uniaxial compression test based on experimental strain soft model, and the stress concentration phenomenon was analyzed. The results show that the numerical modeling method based on digital image processing can be used to calculate the mechanical responses of geomaterials by taking their heterogeneities into considerations.
Stability Evaluation and Safety Monitoring of Pressure in Yichang Phosphorus Mine
Authors: Xiao Yun , Li Xian Fu , Tian Bin , Wang Jia Guo
Published: June 2012

The disasters dynamics and security of phosphate are important problems in Phosphorus ore-deposit mining. So monitoring in unstable, hazardous areas and goaf can effectively focus on the activities of ground pressure. Based on mine-site exploration, engineering test, collection of physical and mechanical parameters for ore, research of geology and mining conditions, the main controlling factors of ground pressure were identified. Combining practical projects, the fuzzy matter-element model of stability evaluation on ground pressure in empty areas was built and analyzed, which showed the good agreement with the evaluation results and measured values. At the same time, based on the stability of underground mining partition, automatic monitoring system of phosphate was constructed, which may provide some useful advices for the safety study of ground pressure in phosphate rock mass.
Experimental Studies on Disintegration Features of Carbon Mudstone
Authors: Li Tao , Fu Hong Yuan , Zhou Gong Ke
Published: June 2012

Carbon Mudstone will have a complicated change in the aspect of physics, chemistry and mechanics behavior when wet. Thus, it is difficult to describe the process in a quantitative standard. In order to find out the effect of testing conditions and water content, there are two different conditions in test drying and original state samples, one is outdoor test and the other is indoor soaking test. What’s more, Fractal Theory is used in the research of Carbon Mudstone. The result shows: A short-lived process of water absorption and weight increment appears in the initial disintegration; Different conditions will result in different destructional forms of samples; The key reason of disintegration is that wetting and drying cycle results in the change of water content; The difference of water content partly affects the process before disintegration, but less affects fractal dimension after disintegration.
Researches on the Relationship between Characteristic Parameters of Surrounding Rock and Structural Parameters of Bolting-Grounting Support Body Based on the Ideal Elastic-Plastic Support Model
Authors: Liu Fu Sheng , Wang Lian Guo , Sun Lei , Dong Gang Gang
Published: June 2012

For the time being the theory about the failure mechanism of the soft rocks, mechanical behavior of bolting-grouting support body in soft rocks has not been fully comprehended. The design of the bolting-grouting support is mostly based on experience and by analogy, and the theoretical analysis results are far more different with the practical engineering. To solve the problem, the researches on the bolting-grouting support mechanism of the soft rocks and the interrelationship between characteristic parameters of the surrounding rocks and structural parameters of bolting-grouting support body are carried out based on the nested models of original surrounding rocks and the bolting-grouting structure. The qualitative and quantitative relationship between characteristic parameters of the surrounding rocks and structural parameters of bolting-grouting support is found out. At the same time, it could also provide beneficial reference to the practical engineering design and construction.
Effect of Staged Excavation on Retaining Structure in Soft Soil Area
Authors: Liu Jie , Xu Xin Guang
Published: June 2012

Based on a deep foundation pit in Tianjin, the authors introduced the retaining structure type, surrounding conditions, and the geological conditions of proposed field. According to the engineering characteristics, the excavation was divided into three typical operating conditions. Based on the monitoring of staged excavation of deep foundation pit, analysis on horizontal displacement, deep soil displacement, column settlement and bracing axial force was carried out. The general rules of the deformation and internal force of retaining structures induced by staged excavation were given, which will provide the references for similar engineering.
Laboratory Model Tests on Dredger Fills by Vacuum Preloading with No Sand Cushion
Authors: Wu Ya Jun , Yang Jian Bo
Published: June 2012

It is difficult to operate on the hydraulic-filled mucky soil foundation which the water content is high, so the vacuum preloading method with no sand cushion is used to deal with the foundation in some areas in China. Although there are still many problems in it’s application, such as, the effective range of the prefabricated vertical drains(PVDs) is small, the surrounding soil is easy to be accumulated and the soil strength increases little. For these problems, a laboratory model test on dredger fills made from the 4th layer of the Shanghai mucky soil by vacuum preloading with no sand cushion is performed. The changes and distributions in the settlement, water contents, permeability, plasticity index and grain composition of the dredger fill are studied in the process of the vacuum preloading. It is found that the water contents and permeability of the soft clay near the PVD (the diameter is about 40 to 50cm) are much lower than the outside, while the content of fine particles, plasticity index and soil strength near the PVD is much higher than the others. The measured data shows that the fine particles gather to a soil column at the center of the PVD under the action of vacuum negative pressure, then the permeability and the grain composition of the soil around the PVD is changed. As a result, soil parameters are not evenly distributed. Finally, some suggestions about how to reduce the non-uniformity are proposed.
Effect of Particle Size on Mechanical and Material Behaviors of Sand under Triaxial Shear
Authors: Lu Ye
Published: June 2012

This study examines the effect of particle size on the behaviors of triaxial sand specimens. In order to investigate the material behaviors (i.e., local void ratios and inter-particle contacts) as well as the mechanical behaviors, three numerical triaxial tests assigned with different particle size ranges were performed. The results showed that the specimen with uniform particle sizes exhibited higher strength, larger local void ratios and more inter-particle contacts than the specimen of wider size ranges.
Slope Stability Analysis by SSR Based on Connectivity of Plastic Zone Failure Criterion
Authors: Xu Guo Zhang , Liang Jin Qiu , Zeng Yi Pei
Published: June 2012

While the elasto-plastic finite element method based on the shear strength reduction(SSR) technique is employed to analyze slope stability, the overall factor of safety computed numerically is，in a certain degree，dependent on the failure criteria used for evaluating critical instability condition of slope. In the present paper, the connectivity of plastic zone criterion is chosen with its close physical meaning to the LEM , and the farther 3D critical slip surface searching procedure is presented. The results of stability analysis of a certain initial quarry slope show that the chosen failure criterion and the 3D critical slip surface searching procedure is reasonable and can be widely applied to slope engineering practice．
Slope Optimization Design Based on Improved Response Surface
Authors: Wang Qiu , Song Zhi Gang , Cao Jing
Published: June 2012

Due to lacking of explicitly analytical model, optimization design of complex slope is often consulted to enumerative algorithm which generally results huge computation efforts. To overcome this problem, a new optimization method based on improved response surface (IRS) is proposed. The IRS, constructed by uniform design (UD) and non-parametric regression (NR), provides a regressed and explicitly analytical model through a few trial computations without prior assumed sliding surface. The optimization process is explained and a slope is optimized to verify the feasibility of the proposed method. The results show that the provided method can optimize a slope with multiple sliding surfaces and provide an optimum result under the safety constraints of the slope. Meanwhile, the introduction of UD and NR to construct the IRS can provide a better regression effect with fewer computational costs.
Limit Equilibrium Method for Expansive Soil Slope with Fissures under Rainfall Condition
Authors: Wang Xiao Lei , Shi San Yuan , Liu Li Bo , Yuan Chang Feng
Published: June 2012

Based on the analysis of influence of fissures and accumulation rainwater at toe of slope under rainfall condition on expansive soil slope, A limit equilibrium method was proposed based on former studies by dividing the slope into fully fissures area A , partially developed fissures area B , accumulation rainwater influence area B′, without fissures area C, and considering the top slope tension crack to reflect influence of fissures on expansive soil slope under rainfall condition. The depths of every layer and strength indexes were determined. The computed results of an engineering example using bishop method showed that the proposed method can not only reflect the characteristics of expansive soil landslide but also evaluate the long-term stability of the slope at ultimate state.
The Study of the Quantity of Wave Speed in Low Strain Integrity Testing of Foundation Pile
Authors: Du Si Yi , Li De Peng , Chen Yi Han
Published: June 2012

the stress wave speed is the necessary condition to make sure pile length and pile defects position in low strain integrity testing of foundation pile with the stress wave echo method. Quantifying the stress wave speed is very difficult, because it is affected by multi- factors. This has been choke point developing test technology of foundation pile. In the paper, some factors influencing the stress wave speed were analyzed according to stress wave theory and experiment results, the quantity relations of the stress wave speed in pile and time and concrete age were made sure. lastly, five brief methods to quantifying the stress wave speed in pile were presented to control pile quality for test engineers according engineering practice.
Research on Engineering Characteristics of Negative Friction Resistance for Large-Diameter Caisson Pile
Authors: Wei Ji Hong , Fu Wei Bin , Shang Zheng , Yue Ling
Published: June 2012

The negative frictional resistance for large-diameter caisson pile is very important to the stability of pile foundation. Lots of engineering projects speak volume for the signal influence of negative frictional resistance on foundation pile. Therefore, it is very necessary to analyze the generation mechanism of the negative frictional resistance on the large-diameter caisson pile and the mechanics characteristics for pile-soil in the coastal under consolidated soil environment. Base on the generation conditions and basic characteristics of negative frictional resistance, the generation conditions and generation mechanisms of negative frictional resistance for large-diameter caisson pile are analyzed on condition of under consolidation for saturated soft clay. Based on the linear softening model for the pile lateral face and hardening model for the tip of the pile, the analytical solution for negative frictional resistance based on the elastic theory was proposed. According to the one-dimensional consolidation theory, the analytical equations are attained when the pile-surrounding soil and pile-end soil is in different conditions. At last, the rationality of analysis process is verified by an engineering case.
Appropriate Geometry Parameters Determination of Anti-Slide Pile with Stochastic Search Algorithms
Authors: Qu Wan Bo , Li Yan
Published: June 2012

Based on the analysis of the main factors which influence the cost of the anti-slide pile, a mathematical model was proposed. In this model, the expenditure of anti-slide pile construction was taken as the objective function, and the constraints covered the strength and stability of anti-slide pile, the strength of the soil mass or rock mass and some other demands. A program was developed for the anti-slide pile geometry sizes determination using stochastic search algorithm. With the aid of this program, appropriate geometry sizes of anti-slide pile with lower cost and enough safety could be automatically found. An example showed that the cost of the anti-slide pile could be decreased in contrust with conventional design method.
Identifying Soil Stratigraphy in Shanghai from Piezocone Soundings
Authors: Wang Jun Peng , Du Ye , Tian Dong
Published: June 2012

This article presents a case history of piezocone penetration test (CPTU) of soft deposit in Shanghai. In Shanghai, stratigraphy for soft deposit is mainly obtained by the laboratory test with borehole samples. The stratigraphy identified by CPTU was developed and improved in recent decades. The analysis is carried out with the field data at test site of Yan’an Road Tunnel in Shanghai. The stratigraphy chart proposed by Robertson (1990) is employed to identify soil layer. The results show that the Robertson charts (1990) is suitable to identify the stratigraphy of the soft deposit in Shanghai. However, there are some discrepancies of the results from Robertson charts (1990) and the norm method. Discussion on the reasons of these discrepancies is conducted.
Research on Deformation Prediction of Foundation Pit Braced by Complicate Soil Nailing
Authors: Xie Pan
Published: June 2012

Compared with current finite element analysis and monitoring techniques, prediction model of deformation of complicate soil nailing bracing for foundation pit based on grey system theory is a short-time method. It exactly exhibits the “less data” characteristics of grey system theory and is satisfied with the urgent requirement of mastering deformation of foundation pit in a short period. In Addition, through theoretical analysis and engineering practical example, the method is proved feasible.
Finite Element Method Utilization of Disturbed State Concept Theory on Seepage or Anisotropy
Authors: Zheng Jian Ye , Hu Zhi Fu
Published: June 2012

Disturbed state concept theory (DSC) utilizes constitutive models to depict material responses. The response is gained by weight-averaging reference responses. DSC also can superpose disturbance factor on reference responses to reach actual response values. Suitable constitutive models give reference responses and DSC revises them to be acceptable outputs. Disturbance factor is independent to constitutive model. On DSC application on seepage problem, combination of DSC and Biot’s consolidation is forwarded by introducing disturbance factor into equilibrium function and extended cam-bridge model provides reference response. On DSC application on anisotropy, anisotropic disturbance factor is applied on to obtain stress anisotropy. Hierarchical single surface model is utilized to provide reference response for further anisotropic revision. Detailed formula derivation for DSC-seepage or for DSC-anisotropy is accomplished. On both applications, the key combination of DSC and other theory depends on the introduction of disturbance factor into equilibrium equation. Outcomes of DSC show readjustment of parameters of disturbance factor guaranties quantity of response descriptions. DSC takes into account of outside effects without changing inside. Existing models and existing methods can be used to describe newly responses.
Investigate on Pore Structure Characteristics of Reactive Powder Concrete after High Temperatures
Authors: Liu Hong Bin , Ju Yang , Tian Kai Pei , Liu Jin Hui , Wang Li , Zhang Qin Gang , Liu Peng
Published: June 2012

The pore structure characteristics of reactive powder concrete (RPC) were investigated by means of the mercury injection method at seven temperature levels, namely, 20°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, respectively. The characteristic parameters such as porosity, pore volume, average pore size and threshold aperture varied with temperatures were analyzed. The results indicate that the porosity, pore volume, threshold aperture and other characteristic parameters of RPC increased with the temperature increasing.
Properties of Epoxy Modified Mortar Used in Caulking
Authors: Lei Da , Liu Yuan Cai , Xia Bing Hua , Wang Ji
Published: June 2012

By this method of adding fly ash of equal amount in the mortar, making analysis including the decreasing water change、7d and 28d compressive strength as well as flexural strength. Results show that exists the optimum proportion of fly ash cement mortar, that is C：F：S：W=220：55：1410：275.On the basis of mixing only 20% fly ash and epoxy resin-polymer, doing analysis about the decreasing water change、7d compressive strength and flexural strength、application property. At the same time, this paper fits the regression equation which using the 7d compressive strength and flexural strength、decreasing water rate as the dependent variables, polymer cement ratio as the independent variable. More important is that the credibility of regression equation is much high.
Hydrothermal Synthesis of Magnesium Hydroxide Sulfate Hydrate Whisker Flame Retardant
Authors: Zhang Jun Ji , Wu Bin , Tao Shuang , Yuan Xiao Man , Zhang Qiong , Gao Hong
Published: June 2012

Magnesium Hydroxide Sulfate Hydrate (MgSO4•5Mg(OH)2•3H2O, MHSH) whiskers were synthesized via the hydrothermal method in a mixed solution of magnesium sulfate (MS) and NH3•H2O . X-ray powder diffraction (XRD) investigations showed that the phase composition changed from Mg(OH)2 to MHSH as the volume ratio of MS / NH3•H2O increasing gradually. Accordingly, SEM images showed that the morphological structures changed from granule dominant to whisker dominant. The morphology of the samples changed from lathy to whisker gradually as the reaction time increasing under the same volume ratio of MS / NH3•H2O and reaction temperature of 180 °C.
Improved Bending Strength and early Crack-Resistance Performance of Engineered Cementitious Composites Reinforced by Hybrid-Fiber
Authors: Wu Ying , Sun Qiao Yao , Li Wei
Published: June 2012

The bending strength and crack-resistance performance of blank concretes are poor, which are not favorable to the sustainable development of infrastructure. Engineered cementitious composite (ECC) is a high performance fiber-reinforced cementitious composite designed with micromechanical principles, which can improve concrete bending performance to prolong service life and to reduce maintenance cost of infrastructure, so there is important significance for sustainable development of infrastructure. In this study, we have experimentally evaluated the effectiveness of bending and crack-resistance performance of concretes reinforced by different kinds of fibers which include UF500 cellulose fiber (UF500), polyvinyl alcohol (PVA) fiber, polypropylene (PP) fiber and hybrid-fiber (PVA and UF500 cellulose fibers), respectively. The bending performance of concrete with different kinds of fibers is better than that of blank concrete. In addition, early crack-resistance performance of hybrid-fibres enhanced samples has been improved as confirmed by the three-point bending test.
Test Research on Elastic Modulus and Poisson’s Ratios of Long Age Recycled Aggregate Concrete
Authors: Li Wei Ning , Zhan Dong Hui , Xu Jin Jun , Zhang Wen , Chen Zong Ping
Published: June 2012

In order to reveal the constitutive behavior of recycled aggregate concrete (RAC) which is related to time effect, 33 prismatic specimens were designed to have uniaxial compression tests. The changing variation of elastic modulus and Poisson’s ratios of RAC specimens which were placed two years in the lab were inspected, and a related correction formula was put forward to describe the elastic modulus. The results show that with the aggregate replacement rate growing, the RAC brittleness was relatively obvious. Since time effect played a great role, the axial compressive strength and elastic modulus were larger than those of normal concrete and the standard age concrete which is calculated. Poisson's ratio did not change significantly and the values were relatively stable, while the higher replacement rate is, the lower values are.
Adsorption Characteristics of Surfactant on Slag in Alkali Activated Slag Cement System
Authors: Liu Xian Feng , Peng Jia Hui , Wei Gui Fang , Yang Chang Hui , Huang Lin Qing
Published: June 2012

Alkali activated slag cement was a new green cementing material with many performances. Whereas, high viscosity and bad workability of the fresh mixture were the matters to embarrass its application. For exploring the special superplasticizer, the adsorption characteristics of surfactant on slag was studied, by UV Vis Absorption Spectrum Method. The results showed, first, the adsorbed amount of cationic surfactant [CH3(CH2)11N(CH3)3]Cl was the highest value among the five surfactants, 12.8 mg/g. Second, the effect of alkali on the adsorbed amount of surfactant was complex. Cationic surfactant had cooperativity with alkali. But, adding water glass, the adsorbed amounts of the surfactants on slag were negative, because it was both colloid property and alkali solution property. Finally, the retarder of YP-3 made the adsorbed amount of ionic surfactant to increase, due to YP-3 contracted electric double layer in the surface of slag.
Research and Applying Evolution of Admixture for High Performance Concrete
Authors: Wang Zheng Jun , Liang Jia Bin
Published: June 2012

With the rapid development of science and technology of concrete, the direction of research is changing from single high strength to high performance (strength and durability).Admixtures can improve concrete workability and improve resistance corrosion, especially it can inhibit alkali-aggregate reaction. Admixtures are paid attention to researchers in this field. In order to realize research and application of high performance concrete for the better, this paper systematically expounds the mineral admixtures and biomass admixtures. Mineral admixtures cost is higher, and it is limited available resources. Biomass admixtures have recycling, sustainable application and other characteristics, so it has the very good application prospects.
The Preparation of N-Compound Coating Based Fe and Appropriate Studies on its Friction Test
Authors: Li Zhen , Zhang Ben Sheng , Gao Zheng
Published: June 2012

N-compound coating based Fe has the feature of effective, rapid and large depth. So it is fit for repairing the metal parts. FeCl2 plating liquid fixed with n- Al2O3 was adopted, in term of given technical process, so the coating can be acquired. Used the coating, glide, rolling, fixed, half fixed friction and frictional pairs tribological characteristics were studied. The conclusion is that under the condition of gliding and half fixed, the bearing capability is very well, breaking in was necessary when the frictional pairs needed to work.
Preparation and Properties of Sulphoaluminate Cementitious Materials with Low Alkalinity
Authors: Yan Xiao Bo , Lu Ling Chao , Gong Chen Chen , Wang Shou De
Published: June 2012

The influence of anhydrite on mechanical property and alkalinity of sulphoaluminate cement clinker was investigated. The alkalinity was examined by mixing powdered samples with a solvent and measuring the pH of the suspension. The hydration mechanism was analysed by XRD analysis. The results indicated that with the increase of anhydrite addition, both the alkalinity and compressive strength decreased. Yeelimite completely converted into ettringite with the dosage of anhydrite reaching to 50% by weight of the paste. With the dosage of 30%, the 7 d pH could be reduced to 10.43 while the 7 d compressive strength was 48 MPa.
Effect of Different Mineral Admixtures on Properties of Sulphoaluminate Cement
Authors: Ma Rui , Cheng Xin , Gong Chen Chen , Wang Shou De , Lu Ling Chao
Published: June 2012

Effects of superfine slag powder, fly ash and ultra-fine CaCO3 on compressive strength of sulphoaluminate cement were investigated. Cement hydration products were analyzed by using scanning electron microscopy (SEM). The results show that different fineness and additions of mineral admixture differ in compressive strength. When the amount of superfine slag powder, fly ash and ultra-fine CaCO3 are added by 10%, 10% and 3% (by weight), the compressive strength of the hardened paste of sulphoaluminate cement is highest, respectively. Meanwhile, it is concluded that the additions of superfine slag powder and ultra-fine CaCO3 facilitates hydration at early ages, while fly ash could accelerate hydration at later ages.
Experimental Study of Design of Mix Proportion of Leaf Concrete
Authors: Jiang De Min , Cui Su Ping
Published: June 2012

This paper makes a study of design of mix proportion of leaf concrete. In the experiment orthogonal design scheme is used to analyze the effect of category of cement, variety and grain size of leaves, variety of superplasticizers, and ratio of water-binder ratio (W/B) on the fluidity (diffusivity index) and the 28-days’ strength of leaf concrete, and had found the primary and secondary order of the influence of the above-mentioned four factors on the index, thus laying a reasonable basis for further development and application of leaves in the field of heat insulating and building materials.
Influence of Nano Materials on the Properties of Epoxy Resin Structural Adhesives
Authors: Sheng Li
Published: June 2012

Nano SiO2 is employed in this research to modify the epoxy resin structural adhesives, and the law how different volumes of nano material influence the tensile and adhesive properties is studied. The experimental results indicate that incorporation of Nano SiO2 improves the tensile and adhesive properties of structural adhesives, yet if its volume fraction exceeds 5%, the modified result is undeniable. Moreover, high-temperature processing of structural adhesives will achieve better properties.
Study on Pavement Performance of Plant-Mix Hot Reclaiming Asphalt Mixture (PHRAM)
Authors: Nie Yi Hua , Liu Ping , Dai Xu , Xu Wang Guo
Published: June 2012

In this study, plant-mix hot reclaiming asphalt mixture can be used to surface and sub surface taking DAC-13I and DAC-20I asphalt mixture with five different RAP contents as 0%, 10%, 20%, 30%, 40%. The fatigue, rutting, water damage and cracking tests in laboratory have been taken to evaluate the road performance, and flexure, rutting, asphalt content tests have been taken on the trial sections to evaluate the practice road performance. The result of tests shows that plant-mix hot reclaiming asphalt mixture should be good service performance as new asphalt mixture when the RAP content is appropriate.
Experimental Study on Compressive Strength of Recycled Aggregate Concrete with Different Replacement Ratios
Authors: Cai Hai Yong , Zhang Min , Dang Ling Bo
Published: June 2012

Compressive strengths of recycled aggregate concrete(RAC) with different recycled aggregates(RA) replacement ratios at 7d, 28d, 60d ages are investigated respectively. Failure process and failure mode of RAC are analyzed, influences on compressive strength with same mix ratio and different RA replacement ratios are analyzed, and the reason is investigated in this paper. The experimental results indicate that compressive strength of recycled concrete at 28d age can reach the standard generally, it is feasible to mix concrete with recycled aggregates, compressive strength with 50% replacement ratio is relatively high.
Insulation and Fireproof Performance of Several New Materials for Exterior Wall
Authors: Yao Jia Wei , Hou Zhao Ming , Yao Yi Shu
Published: June 2012

Exterior insulation is currently promoting a building energy-saving insulation technology. Compared with internal insulation, it is a reasonable technique and has its obvious advantages. However, in the insulation material, thermal insulation effect is better, fireproof performance is often worse. Through analyzing several external wall insulation materials’ insulation and fireproof performance, the article recommends a kind of external wall thermal insulation material with good insulation and fireproof performance, to meet the construction needs.
Effect of Rubber Particles on Fracture Properties and Microstructure of Matrix for PDCC
Authors: Pang Chao Ming , Christopher K.Y. Leung , Sun Wei
Published: June 2012

Non-biodegradable rubber waste from tyres can be employed for the making of pseudo-ductile cementitious composites (PDCC) which requires a matrix of low toughness. In the present study, compressive strength and fracture toughness are measured for cementitious mortar containing small volume of sand, and with or without rubber particles. Also micro-hardness testing, mercury intrusion porosimetry and scanning electron microscopy are performed. According to the test results, the incorporation of 10%~11% rubber particles with average size of 0.4mm or 0.2mm by volume decreases the compressive strength by 40%~60% and the fracture toughness by 10%~40% which makes preparation of PDCC easier. These can be explained by the presence of cracks at the interface between rubber particle and matrix, as well as the increased porosity and specifically the increased content of large capillary pores in the cementitious composites with rubber particles which is considered as solid air-entraining agent. Moreover, there is a more significant increase in the content of capillary pores for composites with small size rubber particles, explaining the lower strength and toughness when these particles are employed.
Application of Phenolic Foam Plate in the Exterior Wall Thermal Insulation
Authors: Yao Jia Wei , Hou Zhao Ming , Yao Yi Shu
Published: June 2012

With the deep reform of national policy of building energy conservation and the increasing requirements of building fire protection, building insulation industry appeared a hitherto unknown development opportunity and challenge. This paper introduces the research and application of phenolic foam plate, modified phenolic foam plate with thermal insulation, fire prevention, environmental protection and other excellent properties, puts forward in the field of building energy conservation should be vigorously promoted the application of phenolic foam.
The Application and Developmental Trend of Exterior Wall External Insulation
Authors: Guo Shu Rong
Published: June 2012

Materials for exterior wall external insulation have various types and the uneven development in different areas. Based on the studies of related works, exterior wall external insulation can be generalized as four series according to the construction technologies, which includes the series of the plug-in insulation materials, the slurry and spray, the concrete sandwich heat insulation, and the energy-saving inorganic insulation materials. Associated with China’s situation, the application features and developmental prospect of main exterior wall external insulation materials in every series have been emphasized, and furthermore, several suggestions have been given to the development of exterior wall external insulation materials in China.
Mechanical Properties of Steel Fibre-Reinforced High Strength Concrete with High early-Age Strength Used in Freezing Shaft Lining
Authors: Song Hai Qing , Zheng Teng Long
Published: June 2012

Plain concrete is susceptible to cracking under aggressive environment such as in freezing shaft. And addition of steel fibres in plain high strength concrete is proved to be effective in cracking resistance and brittleness improvement, etc. This paper presents results of experimental investigation carried out to study the mechanical properties of steel fibre-reinforced concrete having volume fractions of 0.38%, 0.51% and 0.64% for two types of fibres respectively. The results of this study revealed that there is an increase for all the mechanical properties such as compressive strength, split tensile strength, modulus of elasticity and flexural strength. Enhancement for split tensile strength and flexural strength is more evident than compressive strength.
Mechanical Properties of Concretes Containing Super-Fine Mineral Admixtures
Authors: Li Hong Fang , Guo Li , Xia Yi
Published: June 2012

The mechanical properties of concretes containing super fine mineral admixtures such as limestone powder, titanium slag, lithium slag and silica ash have been investigated by compression tests. It was found that 10% limestone powder used in cocncrete is beneficial to compressive strength, it reaches 111Mpa after 28 days curing. The optimum mixing amounts of titanium slag, lithium slag and silica ash are 20%, 10% and 10%, respectively. All their 28d compressive strengths exceed 100MPa, reach super-early and super-high strength concrete level. By introducing mineral admixures into concrete, the cement consumption in concrete can be greatly reduced.
Experimental Research on the Mix Proportion Design of the Cement-Clay Composite Powder Mixed Mortar
Authors: Xue Bin , Cong Xiao Hong , Wang Li Xin , Zhao Fei
Published: June 2012

As a part of the mixed mortar, the admixture is very important in the field of changing the mortar workability and others. In this paper, the clay-composite powder is used as the admixture of the mixed mortar, and the ratio design experimental research is proceeding by adjusting the ratio of the composite powder. A result is obtained by testing and analyzing the performance of the mortar workability, it indicates that clay composite powder can be used directly in the mixed mortar as the admixture, its technical characteristics can meet the requires of design and application, and it is better than the traditional cement-lime mixed mortar in economy, execution, environmental protection and so on.
Experiment and Research on the Influence of Mineral Admixture on Cement-Based Material Performance
Authors: Cong Xiao Hong , Xue Bin , Sun Jing , Sun Xiao Wei
Published: June 2012

Cement mortar as the basic material and the fly ash and silicon fume as the research object, experiment and research were operated through adjusting the admixture replacing dosage and changing the mixture ratio of silica fume and fly ash. By testing the fluidity and strength and data analysis and discussion, some conclusions are drawn from the analysis, such as: fly ash makes the fluidity increasing with the admixture replacing dosage below 30%, and the fluidity declines with the mixture ratio of silica fume and fly ash increasing. 7d compressive strength decreases with the admixture replacing dosage increasing, 7d compressive strength increases slowly with the mix ratio of silica fume and fly ash. With the mix ratio of silica fume and fly ash increasing, 28d compressive strength of mortar also increases, and proper mix ratio of silica fume and fly ash is 1:1.
Lightweight Aggregate Made of Desulfurized Fly Ash and Bottom Ash after Magnetic Separation
Authors: Kim Yoo Taek , Kang Seung Gu , Kim Chang Sam
Published: June 2012

This research provides a comparison of ALAs which was made up of two different raw materials, that is, MDFA and MDBA which were produced from fluidized bed type boiler of power plant and then magnetically separated. ALAs made up of MDFA had too much liquid phase at high temperature; on the other hand, those made up of MDBA showed a black core region as well as good distribution of various sizes of pores inside ALA. Although a good quality of ALA can be made of MDBA only, the optimum composition was obtained under the conditions of MDBA:DS=5:5 and at 1200°C. Nonetheless for its high sintering temperature, MDBA is a prospective recycling material for making lightweight aggregate.
Fatigue Performance of Partially Prestressed RC Beams with HRBF500 Bars
Authors: Li Ke , Wang Xin Ling , Cao Shuang Yin
Published: June 2012

500 MPa level hot-rolled ribbed bars of fine grains (HRBF500) is a successfully developed new-type steel in Chain. The fatigue behavior of partially prestressed reinforced concrete (RC) beams with HRBF500 bars was investigated in fatigue tests of pre-tensioned T-beams. The beams are simply supported with the same overall dimensions, and the main parameter in the study is prestress degree and longitudinal steel ratio. Four beams were constructed and tested under constant-amplitude fatigue loading. All beams are initially cracked before the application of repeated loading. The stress evolution of HRBF500 bars and prestressed strands, the information about crack growth and the deflection developments of test beams were presented. The main factors that affect the fatigue properties of prestressed concrete test beams were fully discussed. Test results indicate that, the prestressed concrete beams reinforced with appropriate amount of HRBF500 bars and reasonable prestressing conﬁgurations can survive 2.5 millions cycles of constant-amplitude fatigue loading using an upper-bound fatigue load producing tensile stress of less than 150 MPa in HRBF500 bars. The results provide important guidance for the fatigue design of prestressed concrete beams with HRBF500 bars.