bluuebunny/crossref_metadata_2025 huggingface dataset:
Durability Design of Concrete Structures in Severe Environments
Authors: Xu Lin
Published: October 2014

Concrete has a high performance corrosion resistance, with the choice of the thickness of the active alkali aggregate,grain shape structured,well-graded,small porosity. Superfine cement with mineral powder instead of 30% to 50%, mineral superfine powder participate hydration, solve concrete interface structure Ca (OH) 2 enrichment and directional crystallization problems, improve the coagulation. The internal structure of the soil, improving the strength and density of concrete. Meanwhile ultra-fine powder mixed with minerals, reducing the C3A content in the powder and the concrete in the late ettringite hazards greatly. Improve the corrosion resistance of concrete, with also improve the internal structure of concrete and the strength of concrete, compactness and corrosion resistance. Composite type superplasticizer, reducing water consumption unilateral concrete, air-entraining agent is added to improve the density of concrete, the concrete has good impermeability and frost resistance. On the use of ordinary portland cement, it gets high performance, by the ratio test, developed the corrosion and frost resistance of concrete for the chloride, sulfate alone or jointly under the action of the environment concrete structures in corrosive environments, such as coastal areas, inland lakes, underground sewage or chemical zones, there are concrete structure durability requirements, with good economic and promotional value.
Study on High Performance Concrete at High Temperatures in the past 10 Years
Authors: Xiao Jian Zhuang , Xu Shi Ying , Hou Yi Zhao
Published: October 2014

High performance concrete (hereafter, HPC) is well known by its high compressive strength, strong resistance to deformation and excellent durability. Whereas, HPC is prone to spall when exposed to high temperatures and it probably results in sharp reduction of the fire resistance and loading capacity of HPC elements and structures. This paper presents a summary of research achievements on fire-resistance behavior of HPC in the past 10 years including the mechanical behavior degradation, analysis of spalling mechanism, effect of various types of fiber and other factors influencing the post-fire properties of HPC material as well as structural behavior of HPC elements. Studies on micro-structure of HPC have been carried out, which will help build a more sophisticated recognition of its performance under high temperatures. In spite of the large number of research results, more improvement on HPC material and HPC structures are still needed because of the devastating consequences caused by strength degradation or spalling-to-collapse. Thus in this paper a new idea of HPC-composite structures is proposed, expected to decrease the probability of spalling.
Researcher Progress of Steel Slag Cascade Utilization in Building Materials
Authors: Meng Gang , Zhang Kai Feng , Zhao Shi Ran , Ouyang Meng Xue , Li Xiang
Published: October 2014

This paper studied the cascade use of industrial waste slag as the cementitious material, the fine aggregate and the coarse aggregate, assisted by XRD, SEM and other microscopic test methods. The results that the system had the best volume stability when the steel slag addition of 40%. When the cement mortar prepared by 10% steel slag fine aggregate, and mixed with 20% steel slag powder and 20% blast furnace slag powder, the mortar construction performance and shrink resistant performance is excellent. On the basis of concrete double mixing 25% steel slag aggregate and 30% steel slag powder, compound mixing 20% blast furnace slag powder, the durable properties of concrete are also excellent.
Development and Application of High Performance Green Hybrid Fiber-Reinforced Concrete (HP-G-HyFRC) for Sustainable and Energy-Efficient Buildings
Authors: Hay Rotana , Ostertag Claudia
Published: October 2014

The synergy of hybrid fibers allows for an enhanced concrete composite performance at a lower fiber volume fraction as compared to other types of fiber-reinforced concrete. This paper outlines the development process and properties of a new concrete composite termed high-performance green hybrid fiber-reinforced concrete (HP-G-HyFRC). Steel and polyvinyl alcohol (PVA) fibers were used as discontinuous reinforcement of the composite. Up to 60% of cement by mass was replaced by industrial wastes comprising slag and fly ash. At water-binder ratio of 0.25 and with the presence of coarse aggregates, careful proportioning of the mix constituents allows for a composite that is highly flowable. At a combined fiber volume fraction of only 1.65%, the composite also exhibits a deflection hardening behavior which is known to be beneficial for both serviceability and durability of structures. The composite was proposed to be used in an innovative double skin façade (DSF) system consisting of 30 mm air gap in between two thin HP-G-HyFRC skins with no main reinforcing rebars. It was shown that the DSF system alone allows for about 7.6% reduction of cooling energy in buildings.
Autogenous Shrinkage of HPC and Ways to Mitigate it
Authors: van Breugel Klaas , van Tuan Nguyen
Published: October 2014

Autogenous shrinkage strains may cause cracking of brittle cement-based systems. The lower the water/cement ratio of a mixture, the higher the autogenous shrinkage and the higher the probability of cracking. Cracking increases the probability of ingress of aggressive substances into the concrete, jeopardizing the durability of the material. Low water/cement ratios, however, result in a dense microstructure, which is one of the desired features of high performance concrete because of the assumed increase in durability. This results in a kind of dilemma: the high density of low water/cement ratio concretes is desired, but the increased risk of (micro) cracking of these mixtures, of course, not. This dilemma is discussed in this contribution. The search for ways to get out of this dilemma starts with understanding the mechanisms of autogenous shrinkage. It is shown that autogenous shrinkage is not only an issue in low water/cement ratio mixtures. In normal strength concretes, with w/c ratios between 0.40 – 0.50, autogenous shrinkage can make out a substantial part of the total strain. Ways to mitigate autogenous shrinkage of mixtures with water/binder ratios ranging from 0.18 to 0.50 are discussed. Finally brief comments are made on autogenous shrinkage values prescribed in current design codes.
Relationship between Defects of Recycled Aggregate and Mechanical Properties of Recycled Aggregate Concrete
Authors: Peng Gai Fei , Zhang Jiu Feng
Published: October 2014

This paper presents an experimental research on the influence of defects of recycled coarse aggregate on mechanical properties of recycled aggregate concrete (RAC). Concretes at two water/binder ratios (0.255 and 0.586) were broken into recycled aggregate (RA). A type of thermal treatment, i.e. heating to target temperature 620 °C, which was maintained for 3 hr, was employed to remove mortar from gravel in RA. Tests were conducted on RA and natural aggregate to measure their water absorption and crushing values, and on RAC and natural aggregate concrete (NAC) to measure compressive strength, tensile splitting strength, and fracture energy. The experimental results revealed that both gravel damage and mortar attached can significantly influence the water absorption and crushing value of RA, as well as strength and fracture energy of RAC. The mechanical properties RAC were obviously lower than those of NAC at an identical mix proportion. Moreover the removal of mortar caused additional change in mechanical properties of RA, which might be a decrease in mechanical properties in the case of low water/binder ratio, but might be an increase in mechanical properties in the case of high water/binder ratio. As to RAC at a low water/binder ratio, gravel damage was a main factor governing the decrease in fracture energy, which means a decrease in cracking resistance of hardened RAC, whereas the mortar attached had only a slight influence on fracture energy. However, as to RAC at a high water/binder ratio, mortar attached could significantly cause a greater decrease in cracking resistance of RAC than that caused by gravel damage.
The Effect of Concrete Containing Recycled Concrete Aggregate and Crushed Clay Bricks on Slab under Dynamic Loading
Authors: Yazdi Mohammad Ali , Motaghi Saeid , Yang Jian
Published: October 2014

This paper investigates a set of nonlinear numerical studies slab subjected to blast loading. A three-dimensional finite element model is developed using ABAQUS by emphasizing on using concrete with recycled concrete aggregate and crushed clay bricks (RCA and CCB) to promote the strength of slab against blast loading. Different charge weights of 0.2–0.55 kg equivalent weight of TNT at a 0.4 m standoff above the slabs were considered as variables in order to evaluate damage levels and define the relations among these variables with respect to the residual strength of slab after blast. The maximum deflection and spalling ratio of the specimens were verified with the experimental data. The results corroborate that using recycled concrete aggregate and crushed clay bricks improve the strength of slabs against blast loading. In addition, the best fraction of this type of materials has been illustrated.
Experimental Study on Mix Design of Chloride Resistant Cementitious Spacers
Authors: Huang Chen , Guo Wen Ying , Yang Yi Bo , Zhao Hui , Li Zhen Jie , Li Jian Kuan , Bao Jian Yong , Wang Heng Chang
Published: October 2014

Chloride resistant HPC and protective cover are two basic measurements to improve the durability of concrete in chloride environment. Though it provides crucial cover for concrete to resist chloride ions, spacer has limited chloride resistant ability, which is overlooked by past researchers. Cementitious spacers are easy access for chloride ions to penetrate into concrete resulting in reduction of structural durability. To improve cementitious spacers’ performance, a systematic study was conducted. Test results showed that there was major difference between mortar and concrete in terms of chloride coulomb electric flux but minor difference in terms of chloride ion diffusion coefficient, which implied using chloride ion diffusion coefficient as spacer’s durability indicator was preferable; parameters of mix design had a similar influence on mortar and concrete and, with the same mixing parameters, the strength and chloride resistant ability of mortar were weaker than concrete’s; it was feasible to develop the mix design of chloride resistant cementitious spacers based on concrete’s design method with certain adjustments, such as using stricter mix proportion, adding small-size coarse aggregate, lowering water-binder ratio and optimizing the binder proportion, to achieve higher strength and durability.
Impact of Air Entrainment on the Microstructure and Mechanical Performance of High Performance Mortar
Authors: Dils Jeroen , Boel Veerle , de Schutter Geert
Published: October 2014

High performance self-compacting mortar has the ability to push out air bubbles under its own weight. Consequently, the resistance against freeze-thaw cycles with or without deicing salts can decrease due to the total air content reduction. In order to assure the necessary expansion zones1,2 air entraining agents (AEA) are commonly used to increase the amount of stable air bubbles. Depending on the mixture, the workability and rheology decrease or increase by the entrained air bubbles3. This will depend on the ratio between the surface tension and the shear stress applied during the test. If the latter can overcome the first, the bubbles will deform and increase the fluidity of the mixture. Besides the influence on the durability and the fresh concrete, air entraining agents also alter the pore structure and the mechanical performance of the mortar. The effect of AEA on these properties is the subject of this paper. The pore structure is examined on two different levels. On the one hand, mercury intrusion porosimetry is used to investigate the capillary porosity, ranging from 10 nm to 10 μm. On the other hand air void analysis and fluorescence microscopy is performed to evaluate the larger air bubbles ranging from 0.1 mm to 1 mm4. Both techniques showed an overlap in their measuring range. Consequently it was possible to compare the techniques critically. Similar as in literature, mercury intrusion porosimetry underestimates the amount of larger air bubbles in mortar, due to its measuring principle5. Furthermore, the bubbles with a diameter of 80 μm increase significantly by the addition of AEA. This confirms the average air bubble size often used in literature to explain the influence of AEA on the workability and rheology3. The influence of air entraining agent on the mechanical performance was tested by the compressive and bending tensile strength. In conclusion, a good balance is necessary between the air content necessary for a proper freeze-thaw resistance without changing the mechanical performance drastically.
Research on Hydration Reaction of Slag-Cement Material System
Authors: Wang Qing , Ding Zhao Yang , Wang Ning , Jiang Wei , Wu Tao Jun
Published: October 2014

The influence of slag dosage on the hydration kinetics of slag-cement composite cementing material system is studied. The results show that the exothermic rate of hydration decreases as the slag dosage increases or the temperature of hydration decreases. The non-evaporable water content increases at first and then decreases with the increasing of slag dosage, and reaches the maximum as slag dosage is 30%. The compressive strength decreases as slag dosage increases, the increasing rate of which is evidently before 28 days, after that it is flat or become slow. It can be seen from SEM (scanning electron microscope), in the system of slag dosage below 30%, the gel-like structures bind with crystals which make the system very compact.
Mix Optimization for Precast Concrete Members in Building Industrialization
Authors: Li Jing , Zhang Jun , Hou Zhao Rong , Wu Sheng Wei
Published: October 2014

The traditional mix proportion for concrete used in building field could not meet the requirements for industrialization production any more, and the optimization needs developing to obtain an ideal mix proportion for precast concrete with high early strength and good workability, as well as economy. To achieve the high early strength, Low-Alkalinity Sulphoaluminate Cement was selected, accompanied by Ordinary Portland Cement. The properties of other materials, namely aggregates (medium sand and gravel) and admixtures (polycarboxylate-based superplasticizer and sodium sulfate), were determined through literature review. The parameters of materials, such as the fineness modulus, mud-content of aggregates and cement strength, were determined. Besides, the range of water-cement ratio, admixture content and the ratio of two kinds of cements etc. in a total of 13 preliminary concrete mixes are analyzed. With further analysis, the four dominant factors were chosen, that is, water-cement ratio, cement content, superplasticizer content and sand ratio, leading to a series of orthogonal experiments with 3 levels of each factor. By analysis of test result data and consideration of cost, the optimized mix for precast concrete in building industrialization was carried out, of which the compressive strength in 10 hours reached the required strength and other properties reasonable.
Effect of Slag on the Rheological and Strength Properties of Self-Compacting Concrete
Authors: Sethy Kaliprasanna , Pasla Dinakar , Sahoo Umesh C.
Published: October 2014

This study deals mainly deals with the rheological and strength properties of self-compacting concrete (SCC) incorporating high volume replacements of slag. Plastic viscosity and yield stress were evaluated using ICAR rheometer. The effect of high range water reducing admixture (HRWR) dosage, the time to reach 500 mm diameter (T50), the final slump flow, V-funnel flow times and L-box blocking ratio were also investigated and studied in this research program. The results show that the plastic viscosity decreases with the increase of the percentage of slag and the yield stress was nearly zero for all the replacements studied. The compressive strengths determined for the SCCs demonstrate that high strength SCC of more than 100 MPa can be realized by using slag appropriately.
The Application of New Type Melt-Spinning PVA Fiber in ECC
Authors: Yang Zhi Qian , Xu De Gen , Liu Jian Zhong , Li Lin , Zhou Hua Xin , Cui Gong
Published: October 2014

This article prepared a new type PVA fiber with large diameter by plasticizing melt spinning method, which instead of traditional wet-spinning or gel-spinning method. The mechanical properties and microstructure of fiber were characterized by tensile instrument respectively and SEM. Then, the PVA fiber was used in cementitious composites after surface sizing. The test result shown that: the melt-spinning PVA fiber could achieve stress-strain hardening in ECC system, and appeared multi-cracking phenomenon, the flexural deflection and strength is not worse than the Japan Kurary PVA fiber. Finally, the PVA has an advantage in price.
Study on Mechanical Properties and Impermeability of Rubber Concrete
Authors: Zheng Xiu Hua , Zhang Xu , Zhan Shi Zuo
Published: October 2014

The effects of the size and volumetric content of rubber powder on properties of concrete, including flexural strength, compressive strength and permeability, were studied in this paper. Two different particle sizes (20 meshand 60 mesh) of rubber powder were chosen to replace the sand with volume content of sand as5%, 10%, 15%, 20%, 25%, 30% respectively. The results showed that both flexural and compressive strength of concrete, especially compressive strength, decreased with the increase of rubber content. Moreover, the smaller the particle of rubber powder, the greaterer the strength of the concrete, which was not obvious as effect of rubber powder content on the strength of concrete. The impermeability of concrete increased with the increase of rubber powder content. The electric flux of concrete with 30% rubber powder reduced to about 900 C, which was only 1/5 of that with 5%. At the same content, smaller rubber particle has positiveeffects on the impermeability of concrete. Keywords: rubber concrete,rubber powder, compressive strength,flexural strength, permeability performance.
Property Optimization of Inorganic Silicon Aluminum Polymer Based on Quadratic Regression and Orthogonal Design
Authors: Ma Xiao , Rao Qiu Hua
Published: October 2014

Because of the dosage of metakaolin and ash fly had a big impact on the performance optimization of inorganic silicon aluminum polymer, using of metakaolin and ash fly can optimize the pore structure and hydration products of inorganic silicon aluminum polymer paste, how to determine the dosage of metakaolin and ash fly of inorganic silicon aluminum polymer reasonably and directly has become a problem in this research needed to be resolved instantly at hand. The current study investigated the relationship between the amounts of metakaolin and fly ash added and the compressive strength of the inorganic silicon aluminum polymer paste, and then established relevant mathematical model using a quadratic regression quadrature combination design. Previous studies have shown that the addition of 13.56% metakaolin and 3% fly ash would be the optimal plan, and that 57.4 MPa would be the maximum value of the compressive strength of the cement paste of inorganic silicon aluminum polymer that could be obtained. Keywords: Inorganic silicon aluminum polymer; Property Optimization; Quadratic Regression and Orthogonal Design
Experimental Study on Mechanical Properties of Epoxy Resin Concrete
Authors: Liu Ke Fei , Li Yu Zhi
Published: October 2014

This paper presents an investigation on the mechanical properties of epoxy resin concrete (ERC for short) and its contrast test to cement concrete under the same conditions. It was observed that the strength formation time of ERC is very short and it has higher early strength, the strength formation of ERC has close relationship with temperature. It was found that under the same load, the deformation of ERC is larger than that of cement concrete, namely the toughness of ERC is superior to cement concrete.
Micromechanical Damage Constitutive Model of Leached Concrete
Authors: Qian Chun Xiang , Huang Bei , He Zhi Hai
Published: October 2014

This paper deal with concrete behavior under chemical and mechanical degradation. Experimental investigations were described where the effects of the calcium leaching process of concrete on its mechanical properties were highlight. The compressive strength and the stress-strain relationship of leached concrete with different leaching degradations were investigated experimental. As leaching grew, a loss of stiffness and of strength were observed and an obviously decrease of peak strain was noted. Then the micromechanical damage constitutive model of the leached concrete was proposed. The proposed model was applied to simulate typical laboratory tests. And it was shown that the proposed model was able to describe the main features of mechanical behavior of concrete in sound and leaching degraded states. And the parameters in the proposed model can be got by testing the pH value of pore solution, which it is easier to measure from the existing concrete.
PFC2D Numerical Simulation Study of Interfaces Characteristics for Prestressed Anchor Cable under Cyclic Loading
Authors: Feng Jian Xiang , Zhang Si Feng , Du Jin Sheng
Published: October 2014

Abstract: Affected by various external factors, the tensile force of prestressed anchorage structures presents loop and fluctuation characteristics in practical engineerings, which will cause severe impact on the inner anchoring section of the prestressed anchorage structures. On this base, PFC2D discrete element program was established for numerical simulation analysis of microscopic physical and mechanical changing characteristics of stress, porosity, angle, etc. of different interfaces locations for prestressed anchor cable under cyclic loading. The results showed that: at locations of the front-middle, the grouting body near interfaces were divided into tensile stress area of the inside part and compressive stress area of the outside part, and two locations of y-direction stress concentration were located at the two end of inner anchoring section; The interfaces had the feature of progressive failure and the characteristic of shear stress peak shifting; While loading finish, particles at different locations of interfaces basically generated clockwise rotation angle, but at two locations of y-direction stress concentration, the particles rotation angle, which was very small at the other locations, was very large; At y-direction tension and compression stress boundary, the particles spinning direction showed instability characteristic and the ultimate rotation angle was small.
Quality Evaluation of Air Entraining Agent Based on Air Void Parameters of Fresh Concrete
Authors: Yang Lu , Xie Yong Jiang , Li Hua Jian
Published: October 2014

In order to evaluate the quality of air entraining agent quickly and effectively. Air void parameters of fresh concrete with different air entraining agents were studied by Air Void Analyzer (AVA). The spacing factor and durability index of hardened concrete were tested and the relationship between the surface tension of air entraining agent and frost resistance of concrete was compared. The results showed that, the quality of air entraining agent can be evaluated quickly and effectively by diameter distribution of air bubbles in fresh concrete and spacing factor of fresh concrete. AEA2 introduced much more big air bubbles into concrete which is bad for the frost resistance of concrete. The quality of AEA2 was the worst, so the durability index of hardened concrete was 58.7%. Quality of air entraining agent cannot be characterized by properties of air entraining agent, but air entraining ability can be characterized by surface tension of air entraining agent. Keywords: air entraining agent (AEA), air void parameter, fresh concrete
Relationship between Methylene Blue Value of Manufactured Sand and Mortar Properties
Authors: Liu Zhan Ao , Zhou Ming Kai , Yao Chu Kang
Published: October 2014

Methylene blue value (MBV) is an effective index for detecting harmful clay in manufactured sand (MS) and it’s of great importance for quality control of MS concrete. In order to verify relationship between MBV and concrete properties and feasibility of using MBV to confine clay harmfulness, influences of MBV on fresh and hardened mortar properties were investigated under constant flow by means of adjusting water and water reducer content, respectively. The results indicate that water and water reducer demand and drying shrinkage increase while frost resistance decreases with increasing MBV. Meanwhile, compressive strength and permeability resistance decrease significantly with increasing MBV when water content is increased and they are not greatly negatively affected when W/C is held constant. Certain relationships can be established between MBV and mortar properties and adverse effect of clay is relatively limited when MBV is within 1.0g/kg.
Cable-Stayed Footbridge with UHPC Segmental Deck
Authors: Kalny Milan , Kvasnička Vaclav , Komanec Jan , Vitek Jan L. , Broz Robert , Koukolik Petr
Published: October 2014

Ongoing research and development of ultra-high performance concrete (UHPC) in the Czech Republic has been utilized in design and implementation of light-weight segmental deck of the cable-stayed footbridge over the Labe River in Celakovice with main span of 156 m. Detailing, design issues, construction method and efficiency of using UHPC on this large span lightweight bridge is described in the paper. The superstructure of the Celakovice footbridge was completed in the December 2013 and the bridge was opened for the public in April 2014. Main advantages of this project is not only low maintenance and reasonable life cycle cost but also favourable tender price which was achieved by the contractor Metrostav a.s. due to combination of high-strength modern materials steel and UHPC.
Reinforcement to Induce Ductile Behavior in an Ultra High Performance Fiber Reinforced Concrete Beam
Authors: Han Sang Mook , Wu Xiang Guo
Published: October 2014

The purpose of this study was to reduce production costs for UHPFRC members by using a bundle of longitudinal reinforcement bars as a substitute for steel fiber. Experiments on the ductile behavior of Ultra High Performance Concrete (UHPC) rectangular beams with a combination of steel fiber and longitudinal reinforcement bars were performed.The volume fractions of steel fiber were 0%, 0.7%, 1%, 1.5%, 2%, and the reinforcement ratios of longitudinal reinforcement bars that promoted ductile behavior were 0.0036, 0.016, 0.029 and 0.036.Fifteen UHPC beams were made with the combination of these test factors. Both the steel fiber and the longitudinal reinforcement bars had the effect of induciing ductile behavior for UHPC structural members. The load-deflection relationship, the concrete stress variation and the crack pattern indicated the usefulness of the bundle of longitudinal bars that have a small diameter with close arrangement.
Effect of Nano-Silica Particles on the Fresh Properties of UHPC
Authors: Zhang Qian Qian , Liu Jian Zhong , Lin Wei
Published: October 2014

Nanotechnology is being used in UHPC for achieving more dense structural packing and better physical and mechanical properties. In this paper, nanosilica particles (0-1wt %) by cement were incorporated in cement pastes and mortars with water-binder ratio of 0.2, and their effect on fresh properties was addressed. The fresh properties of mixtures were investigated by spread, rheology and cohesiveness. In addition, effect of nanosilica on cement hydration was also investigated. The results show that significant increase of yield stress, viscosity and cohesiveness is observed with nanosilica above 0.005 wt% by cement, but nanosilica with content below 0.005% presents an improvement of workability especially with content of 0.002%. Moreover, the addition of nanosilica in cement pastes obviously accelerates the early cement hydration rate, but does not increase the cumulative heat evolution.
Mechanical Properties and Durability of Ultra-High Performance Concrete Incorporating Coarse Aggregate
Authors: Yang Juan , Peng Gai Fei , Gao Yu Xin , Zhang Hui
Published: October 2014

Ultra-high performance concrete (UHPC) incorporating coarse aggregate was prepared with common raw materials. Fresh concrete had excellent good workability with slump of 265 mm and slump spread of 673 mm. Compressive strength of UHPC at 56 d reached 150 MPa. However, UHPC exhibited high brittleness in terms of spalling failure which occurred during compression loading.The ratio of splitting tensile strength to compressive strength of about 1/18 and the ratio of flexural strength to compressive strength of about 1/14 at 56 d were also associated with the brittleness of UHPC in this research. Mineral admixtures and fluidity of fresh concrete influenced compressive strength of UHPC significantly. Moreover, UHPC had excellent permeation-related durability but considerable shrinkage. Autogenous shrinkage of UHPC was less than half of free shrinkage, for which the reason is unknown and needs further research.
Fabrication of Aluminum Superhydrophobic Surface with Facile Chemical Etching Method
Authors: Huang Zhen , Li Yu Feng , Jin Pu , Hu Meng Shan , He Bo , Gao Nai Kui , Zhang Hao , Jin Hai Yun
Published: October 2014

Superhydrophobic surfaces have attracted much interest for its potential applications. In this study, the superhydrophobic aluminum surfaces were fabricated by method of chemical etching. Aluminum surfaces were firstly chemically etched by hydrochloric acid, and modified with stearic acid. The relationship between the etching time and the surface hydrophobicity was investigated. The contact angle and the sliding angle were tested, the results showed that with increasing etching time, the contact angle experienced a rise and then decrease, while the sliding angle dropped first and then started to climb. A maximum value of 152 degrees for the contact angle and a minimum value of 3 degrees for the sliding angle were obtained with etching time of 1 minute. The results indicated an ideal superhydrophobic property of the aluminum surfaces.
Production and Characterization of Recycled SUS 439L Powders by Gas Atomization Process
Authors: Kim Jin Chun , Jo Jae Young , Shin Min Kyun , Lim Jae Hyun
Published: October 2014

A Gas atomization process is well known method to produce spherical metallic powders. In this paper, we produced spherical stainless (SUS) 439L powders using the gas atomization process. The SUS 439L alloy powders were prepared with the SUS 439L scraps which come from after mechanical machining (press and cutting) processes. The as-prepared gas atomized powders were observed by visual identification method. Internal microstructure of the powers was observed by optical microscopy. Size and size distribution and shape of the powders were observed by field emission scanning electron microscope and laser partial size analyzer. Phase of the powers was analyzed by X-ray diffraction. Full densified samples were produced by conventional sintering and spark plasma sintering processes. Mechanical properties of the sintered samples were measured by Vickers hardness tester.
Effect of the Alkali-Activation on the Mechanical Property of Geopolymer Composite
Authors: Son Yeong Geum , Lee Woo Keun
Published: October 2014

In this work, pastes were prepared from slag and MSWI bottom ash by geopolymer technique. And its physical property was evaluated with mixing ratio of sodium silicate and potassium silicate. The amounts of leaching products, such as silica, alumina and calcium ions were changed for mixing ratio of raw materials. The compressive strength was increased with the increment of leaching amount of silica, alumina and calcium ions.
Preparation and Thermal-Physical Properties of Three Dimensional Bicontinuous SiC/Cu-Si Composite
Authors: Zhang Kuo , Xia Hong Yan , Wang Bo , Shi Zhong Qi , Zhang Xiang Zhao , Liu Gui Wu , Qiao Guan Jun
Published: October 2014

A three dimensional (3D) SiC/Cu-Si composite with bicontinuous structure was fabricated by spontaneous infiltration method, using porous recrystallized SiC ceramic with porosity of 37% as 3D network reinforcement and Cu alloy (Cu-18Si) as matrix. The phase composition, microstructure, and thermo-physical properties of the as-prepared 3D-SiC/Cu-Si composite were investigated. The experimental results showed that the Cu-18Si alloy could fully penetrate into the porous SiC ceramic at 1600 °C for 2 h spontaneously. SiC and Cu15Si4 phases were identified in the as-prepared composites. The interfacial bond between SiC and Cu-Si alloy was tightly and no severe interfacial reaction was observed. The thermal conductivity and coefficient of thermal expansion of the as-prepared 3D-SiC/Cu-Si composite were changed from 89.8 to 55 W·m-1·K-1 and 7.512 to 9.64×10-6 °C-1 with the temperature increased from room temperature to 500 °C, respectively.
Research on Preparation Technology for Machinable Ceramics
Authors: Zhang Hao , Xu Yan , Jin Hai Yun , Qiao Guan Jun
Published: October 2014

In this paper, the compact SiO2-B2O3-Al2O3-MgO-F machinable ceramics were prepared through melt-cast and sintering method. The phase composition and microstructure of the ceramics were analyzed and observed using XRD and SEM, and the relationship between processing and microstructure were discussed. The results showed that, after the heat treatment, the main phase of the ceramics changed from fluorophlogopite (mica like) to fluoramphibole (rod like). When the crystallization temperature at 950°C, the nuclei growth rate of the mica glass-ceramics was higher. Meanwhile, a small quantity of forsterite (Mg2SiO4) was also crystallized out in the process. The best heat treatment process was nucleated at 630°C for 2h and crystallized at 950°C for 2h.
The Photocatalytic Degradation of Methomyl over TiO2 Nanopowder Prepared by the Low Temperature Solvothermal Route
Authors: Pookmanee Pusit , Phiwchai Isara , Yoriya Sorachon , Puntharod Ratchadaporn , Sangsrichan Supaporn , Kittikul Jiraporn , Phanichphant Sukon
Published: October 2014

Titanium dioxide (TiO2) nanopowder was prepared by the low temperature solvothermal route with starting chemicals containing titanium isopropoxide, ammonium hydroxide, nitric acid and ethanol in a PTFE–lined autoclave. The final pH of the mixed solution was 1 and treated at 100 °C for 2–6 h. The white precipitated was filtered and dried in an oven at 80 °C for 24 h. The phase transition was characterized by X–ray diffractometer (XRD). Single phase anatase structure was obtained without calcination step. The morphology and particle size of TiO2 nanopowder was investigated by scanning electron microscope (SEM). The average of TiO2 nanopowder size was 80–120 nm. The average particle size increased with temperature and time increased. The photocatalytic degradation of methomyl in natural water was studied by high performance liquid chromatograph (HPLC). The percentage of methomyl was decreased in the presence of 34, 23 and 24 over TiO2 nanopowder prepared by the low temperature solvothermal route at 100 °C for 2, 4 and 6 h, respectively.
Control of Indoor Suspended Microorganisms by UV and Photocatalytic Disinfection
Authors: Yoon Young H. , Nam Sook H. , Joo Jin Chul , Ahn Ho Sang , Hwang Tae M. , Park Jae Ro
Published: October 2014

This study presents the results of removal of Bacillus subtilis sp. and irradiated by UVA(3 μW/cm2) with three types of photo-catalysts (TiO2, ZnO, ZnO/laponite ball) to improve indoor air quality. The results showed that B.subtilis sp. was removed up to over 80% after 2 hours of reaction with all the photo-catalysts used and UVA irradiation. The B.subtilis sp. removal rate increased to more than 30 % when used both UVA and photo-catalysts, compared to that with only UVA control. Among the catalysts, ZnO/Laponite composite ball was found to have similar sterilization capacity to TiO2. Further study needs to figure out the optimum intensity of UVA and catalysts dosage to effectively disinfect and destroy the other microorganisms commonly found in indoor air environment.
Influencing Factors on Chest Compression in Moving Ambulance
Authors: Roh Sang Gyun , Lee Jae Gook , Kim Jee Hee
Published: October 2014

The High quality cardiopulmonary resuscitation (CPR), defibrillation, and drug administration have influence on the return of spontaneous circulation (ROSC) in cardiac arrest victim. In out-of-hospital environment, the influencing factors of quality of CPR include manpower, fatigue of the rescuers, space limitation of the ambulance, chest compression and ventilation within moving ambulance, CPR experience of the emergency medical technicians, and transport distance. The purpose of the study is to investigate the ventilation and chest compression within moving ambulance. The subjects were 763 firefighters in Gyeonggido. Male accounted for 87.8%. Emergency medical technician 1 (EMT-1) was 29.9%. and EMT-2 was 70.1%. One handed chest compression accounted for 14.0% and two handed chest compression accounted for 86.0%. Chest compression only accounted for 71.3% and the compression to ventilation ratio of 30:2 was performed in 28.7%. EMT-1 was more skillful than EMT-2, but there was no statistical significance between the compression to ventilation ratio of 30:2 CPR, chest compression only, one handed compression and two handed compression.
Influence of Top Slag on the Plasticity of CaO-SiO2-Al2O3 Inclusions in 42CrMoA Crankshaft Steel
Authors: Ju Jian Tao , Yang Sen , Guo Yan Ping , She Yuan , Zhang Zhao Hui
Published: October 2014

In order to control the plasticity of CaO-SiO2-Al2O3 system inclusions so as to reduce the harm to the quality of 42CrMoA crankshaft steel, the target controlling ranges of CaO-SiO2-Al2O3 inclusions is put forward. On the basis, influence of CaO-SiO2-Al2O3 and CaO-SiO2-Al2O3-MgO system top slag on the content of calcium and aluminum in molten steel is contrasted. Theoretical research results show that, calcium activity should be controlled in the range of (90~3300)×10-10, oxygen activity should be below 7×10-6, the mass percent of calcium should be controlled more than 75ppm. And CaO-SiO2-Al2O3-MgO should be a good choice to obtain the plastic inclusions of CaO-SiO2-Al2O3.
Finite Element Simulation and Experimental Study on Internal Fracture of Railway Sleeper Screw during Cross Wedge Rolling Process
Authors: van Hai Dinh , Thi Hong Hue Dang
Published: October 2014

The internal defects in cross wedge rolling process are a big issue restricting the widely use of the technology in industry. Although internal failures in cross wedge rolling have been investigated by several authors, the internal defect generation and effective parameters are still not completely clear. In this study, the internal fracture of 1045 steel railway sleeper crew during cross wedge rolling were investigated numerically by using Johnson-Cook fracture model. Based on analyzing the relationship between stress and strain in the deformed area, the mechanisms of internal fracture of sleeper screw during cross wedge rolling process was explained and made clear. The simulation results are in reasonable agreement with experimental results conducted at the same conditions.
Simulation Analysis of HPDC Process with Automobile Part by CAE
Authors: Kwon Hong Kyu , Lee Boong Joo
Published: October 2014

In present casting industries, product development paradigm is shifting from traditional trial-and-error to proof-of-concept based on CAE-enabled simulation. In the new production development paradigm, CAE simulation plays an important role because it models the entire casting process and reveals the dynamic behavior of the casting system in working conditions. In this research, Computer Aided Engineering (CAE) simulation was performed by using the simulation software (AnyCasting) in order to optimize casting design of an automobile part (Upper Oil Pan) which is well known and complicated to achieve a good casting layout. The simulation results were analyzed and compared carefully in order to apply them into the production die-casting mold. During the filling process, internal porosities caused by air entrapments were predicted and reduced remarkably by the modification of the gate system and the configuration of overflow. With the solidification analysis, internal porosities caused by the solidification shrinkage were also predicted.
Effects of Nano-Porous Materials and Inert Gas on Sound Proof Properties of Double Layer Acryl Plate
Authors: Park Hyun Chul , Lee Ju Haeng , Kim Il Ho , Sajjad Muhammad , Ahn Kwang Ho , Kim Kwang Soo
Published: October 2014

The purpose of this study was to investigate the sound proof properties of the double layer acryl plates with various packing materials inside. The acryl plates were filled with vacuum pressure ranged from-20 to-80 kPa, fumed silica as nanoporous materials, and HCFC (hydrochloro-fluorocarbon) as inert gas. The sound pressure level passed though panels was measured to compare soundproof performance. All other panel showed better performance from 500-1000 Hz than air layer panel. For the vacuum layer panel, panel with-80 kPa showed the best performance among other vacuum layer panel throughout all range of frequency. It is found that the more nanomaterial filled in panel, the lower sound proof performance. When it comes to panel filled with inert gas, the sound proof performance improved when it has greater pressure of gas.
Characteristics of Pollutants Removal by Carbonized Porous Media Made from Sewage Sludge
Authors: Yoo Yeong Seok , Jo Jun Ho , Seo Gyu Tae
Published: October 2014

In this study, carbonized porous media was manufactured using sewage sludge and analyzed for pollutants removal characteristics. Sewage sludge produced by activated sludge sewage treatment contained much organics to be carbonized, so it was mixed with other mixtures, extruded and formed in ∅ 5~10 mm ball shape, and sintered at 900°C and 1 hour in furnace for carbonization under N2 purge. The characteristics of the porous media was BET 35 m2/g and average pore size 39.3Å, pore volume 0.0092 cm3/g, Iodine number 45.9 and bulk density 0.91 cm3/g. Experiments were performed for SS, phosphate, nitrate and heavy metals (Cu, Zn). Its removal characteristics of SS and fertilizer components were compared with gravel’s used in filtration and its heavy metals removal was characterized by derivation of its adsorption equilibrium equations. In result, the carbonized porous media could be utilized as massive adsorption media for pollutant removal or fertilizer adsorption in fields of roof planting or non-point source pollutants control.
Carbapenem-Resistant Enterobacteriaceae: Occult Threat in the Intensive Care Unit
Authors: Zurawski Ranae M.
Published: October 2014

Carbapenem-resistant Enterobacteriaceae are a group of virulent, drug-resistant gram-negative bacteria that are increasingly the cause of infection. Such infections are associated with a high morbidity and mortality and increased health care costs. Management of these infections requires recognition of patients at risk for multidrug-resistant microbial colonization and infections, identification of the causative organism, and rapid, appropriate treatment. Lack of awareness of proper isolation of patients harboring these organisms and delay in prescribing antibiotics such as tigecycline and polymyxins contribute to the spread of infection in intensive care units. Surveillance and infection control measures are paramount in preventing outbreaks of infection caused by carbapenem-resistant Enterobacteriaceae. Critical care nurses are in a vital position to monitor patients at risk for such infections and to promote infection prevention measures.
Predictive surficial geology derived from LANDSAT 7, Marian River, NTS 85-N, Northwest Territories
Authors: Ednie M , Kerr D E , Olthof I , Wolfe S A , Eagles S
Published: October 2014

Surficial geology maps provide important geoscience information for geological reconstructions, mineral exploration and development, and land use planning. In this study, remote predictive mapping was used to derive a predictive surficial geology map for Marian
River NTS 85N, which straddles the Slave, the Bear-Slave and the Interior Platform geological provinces. The predictive map was generated using radiometrically balanced LANDSAT 7 imagery (collected in 2001) and knowledge from airphoto interpretations, fire history, elevation models, field
observations and legacy datasets. This Open File contains graphical and digital geo-referenced versions of the predictive maps. A printable version of the predictive surficial geology map is provided in pdf format (map scale 1:125 000).
Computational Methods for CLIP-Seq Data Processing
Authors: Reyes-Herrera Paula H. , Ficarra Elisa
Published: October 2014

RNA-binding proteins (RBPs) are at the core of post-transcriptional regulation and thus of gene expression control at the RNA level. One of the principal challenges in the field of gene expression regulation is to understand RBPs mechanism of action. As a result of recent evolution of experimental techniques, it is now possible to obtain the RNA regions recognized by RBPs on a transcriptome-wide scale. In fact, CLIP-seq protocols use the joint action of CLIP, crosslinking immunoprecipitation, and high-throughput sequencing to recover the transcriptome-wide set of interaction regions for a particular protein. Nevertheless, computational methods are necessary to process CLIP-seq experimental data and are a key to advancement in the understanding of gene regulatory mechanisms. Considering the importance of computational methods in this area, we present a review of the current status of computational approaches used and proposed for CLIP-seq data.
Double Hit Lymphoma – a Case of Unusual Response after Sequential Aggressive Chemotherapy and Review of the Literature
Authors: Cheema Faisal N. , Agloria Maliha , Koshy Nebu , Hildebrandt Gerhard C.
Published: October 2014

Lymphomas with recurrent chromosomal breakpoints activating multiple oncogenes, including MYC, BCL2, and BCL6 are often referred to as “Dual Hit” or “Double Hit” lymphomas (DHL). In the updated classification for malignant lymphomas by the World Health Organization (WHO), the novel category of “B-cell lymphoma unclassifiable with features intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt's lymphoma (BL)” was proposed in an attempt to create a (temporary) container for aggressive mature B-cell lymphomas that should not be diagnosed as either BL or DLBCL. DHL make up an important part of this novel WHO category, the other part representing heterogeneous cases of aggressive B-cell lymphoma that have features of BL. DHL are highly aggressive lymphomas with generally poor response to first line and salvage treatment. Limited data is available to guide therapeutic decisions, and despite aggressive measures including high dose (HD) chemotherapy followed by autologous hematopoietic cell transplantation (AHCT), outcome is unsatisfyingly poor. Herein, we report a case of a patient with DHL and review the relevant literature.