Advances in Materials Science and Engineering The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Development in Rubber Preparation for Endoscopic Training Simulator Mon, 25 Jul 2016 16:16:49 +0000 Endoscopy is one of the most important procedures in diagnosis and treatment of gastrointestinal tract problems. While endoscopic procedure has tremendous benefits, physicians require considerable practice and time to develop competency. Current endoscopic training process involves cognitive learning and hands-on training under the supervision of an expert gastroenterologist. Previous studies have shown that fellow involvement prolongs procedural time and incurs additional expenses to the institution. Moreover, the patient also experiences more discomfort and injury risk. Introduction of training simulator into the training process could reduce the involvement of the patients and thus reduce the risk. Porcine model is commonly used for training in endoscopy due to the similar tactile response to a human gastrointestinal tract. However, information on elastic behavior of pig or human gastrointestinal tract for the engineering purposes was limited. In this study, the modulus of elasticity and ultimate tensile stress data of the pig stomach and intestines, small and large intestines, were measured and compared with multiple rubber stomach and intestines models. Based on the experimental results and experienced gastroenterologists feedback, the proposed dipped rubber composition can provide a satisfactory tactile feedback and could be used to simulate a human gastrointestinal tract for an endoscopic simulation training model. D. Surangsrirat, A. Tongkratoke, S. Samphanyuth, T. Sununtachaikul, and A. Pramuanjaroenkij Copyright © 2016 D. Surangsrirat et al. All rights reserved. Off-Axial Tensile Properties of Precontraint PVDF Coated Polyester Fabrics under Different Tensile Rates Mon, 25 Jul 2016 13:10:59 +0000 Two types of Precontraint PVDF coated polyester are taken as the research objects. A series of uniaxial tensile tests were carried out to study the tensile performances of the specimens in eleven in-plane directions including 0°, 5°, 15°, 25°, 35°, 45°, 55°, 65°, 75°, 85°, and 90°, and six tensile rates (10 mm/min, 25 mm/min, 50 mm/min, 100 mm/min, 200 mm/min, and 500 mm/min) were also considered. The corresponding failure modes and fracture mechanisms were discussed, and the relationships between tensile strength and strain at break and tensile rate and off-axial angles were obtained. Results show that the Precontraint PVDF coated woven fabrics are typically anisotropic. With off-axial angle increasing, the tensile strength decreases while the strain at break increases. Three failure modes can be observed, including failure of yarns pulled out, yarns fracture, and mixture failure. With tensile rate increasing, the tensile strength increases slightly while the strain at break decreases. The tensile strength and strain at break show good linear relationship with tensile rate’s logarithm. Lanlan Zhang Copyright © 2016 Lanlan Zhang. All rights reserved. Influence of Nano-SiO2 on the Consistency, Setting Time, Early-Age Strength, and Shrinkage of Composite Cement Pastes Mon, 25 Jul 2016 11:28:26 +0000 The study outlined the raw materials and mix proportions to prepare composite cement pastes with the addition of silica-based micro- and nanoparticles. The effects of amorphous nano-SiO2 on the early-age properties, including the consistency, setting time, early-age strength, and chemical and autogenous shrinkages, were investigated. Under the condition of the same dosage of superplasticizer used, the consistency of cement paste with nano-SiO2 is higher than that with silica fume. Significant reductions of the initial and final setting times are observed especially for nano-SiO2 addition groups, and the time difference between the initial and final setting times goes up with the increasing proportions of nano-SiO2. The addition of nano-SiO2 is more helpful to the improvement of early-age strengths of the paste with or without fly ash admixed than silica fume additive for the same mass proportion. Both the chemical and autogenous shrinkages of cement paste develop with the increasing amount of micro- or nanolevel silica particles; however, nano-SiO2 plays a more active role than silica fume in inspiring early-age shrinkage. The physical and chemical mechanisms of nano-SiO2 in cement paste are also discussed. Yu Chen, Yi-fan Deng, and Meng-qiang Li Copyright © 2016 Yu Chen et al. All rights reserved. A New Appliance for Improving the Miniscrew Stability Mon, 25 Jul 2016 10:07:24 +0000 The aim of this study is to present a new appliance called stability leg designed as an additional anchorage providing device for increasing primary stability of orthodontic miniscrew. For this purpose, two finite element models (FEMs) with two different cortical layer thicknesses of 1 mm and 2 mm are considered. In order to achieve the stability analysis, these two main models, namely, Model I and Model II, are divided into subgroups according to stability leg lengths. Two types of forces are considered. (1) First force is a constant force of 1 N which is applied to all two models. (2) Second force is defined in the range of 1–4 N. Each of 1, 2.5, and 4 N of the second force is applied with a position angle ranging from 34° to 44°. Results show that stability of a miniscrew with 5 mm leg increases primary stability of the miniscrew. Nurhat Ozkalayci and Mehmet Yetmez Copyright © 2016 Nurhat Ozkalayci and Mehmet Yetmez. All rights reserved. Measurement of Surface Damage through Boundary Detection: An Approach to Assess Durability of Cementitious Composites under Tannery Wastewater Mon, 25 Jul 2016 10:02:20 +0000 Concrete structures are often subjected to aggressive aqueous environments which consist of several chemical agents that can react with concrete to produce adverse effects. A Central Effluent Treatment Plant consisting of reinforced concrete structures which is being constructed at Savar, Bangladesh, is an example of such a case. The purpose of this treatment facility is to reduce the environmental pollution created by tannery wastewater. However, tannery wastewater consists of several chemicals such as sulfates, chlorides, and ammonium, which, from the literature, are known to generate detrimental effects on concrete. Evaluation of durability of concrete structures in such environments is therefore imperative. This paper highlights a technique of boundary detection developed through image processing performed using MATLAB. Cement mortar cubes were submerged in simulated tannery wastewater and the images of the surface of cubes were taken at several time intervals. In addition, readings for compressive strength and weight were also taken on the same days. In this paper, an attempt is made to correlate the results from image processing with that of strength and weight loss. It was found, within the scope of this study, that the specimens which suffered greater strength and weight loss also underwent greater loss of surface area. Tanvir Manzur, Khaled Mahmood Ehsan, Sinha Lamia Sultana, and Samira Mahmud Copyright © 2016 Tanvir Manzur et al. All rights reserved. Model Tests on the Retaining Walls Constructed from Geobags Filled with Construction Waste Thu, 21 Jul 2016 10:04:08 +0000 Geobag retaining wall using construction waste is a new flexible supporting structure, and the usage of construction waste to fill geobags can facilitate the construction recycling. In this paper, model tests were performed on geobag retaining wall using construction waste. The investigation was concentrated on the slope top settlement, the distribution characteristics of the earth pressures on retaining walls and horizontal wall displacements, and slope failure modes. The results indicated that the ultimate loads that the slope tops with retaining walls could bear were 87.5%~125% higher than that of the slope top without retaining walls. The ultimate loading of strengthened slopes with different slope ratios from 1 : 0.75 to 1 : 0.25 could be reduced by 11.8% to 29.4%. The horizontal displacements of the retaining walls constructed from geobags were distributed in a drum shape, with the greatest horizontal displacements occurring about 1/3~1/2 of the wall height away from the bottom of the wall. As the slope ratio increased, the failure of the slope soil supported by geobag retaining wall using construction waste changed from sliding to sliding-toppling (dominated by sliding) and then to toppling-sliding (dominated by toppling). The range of 1/3~1/2 of wall height is the weak part of the retaining walls, which should be strengthened with certain measures during the process of design and construction. Hua Wen, Jiu-jiang Wu, Jiao-li Zou, Xin Luo, Min Zhang, and Chengzhuang Gu Copyright © 2016 Hua Wen et al. All rights reserved. Mathematical Model of Homogeneous Corrosion of Steel Pipe Pile Foundation for Offshore Wind Turbines and Corrosive Action Thu, 21 Jul 2016 09:16:37 +0000 In this paper, the nonlinear corrosion model under the combined action of the anticorrosion system and corrosive environment is chosen as the mathematical model of homogeneous corrosion of steel pipe pile foundation for the offshore wind turbine. Based on the mathematical model, a three-dimensional finite element model was established for the steel pipe pile foundation of the offshore wind turbine. And the homogeneous corrosion action of the steel pipe piles was calculated, and the reduction rules of the strength and stability of the steel pipe piles for wind turbines under different corrosion patterns are analyzed. According to the calculation results, the mathematical model can be used in the analysis of corrosion for steel pipe pile in the wind turbine. Under the normal operation conditions, the reduction rules of the strength and stability of the steel pipe piles contain three stages: no influence stage, negative exponential decrease stage, and stable stage. But under the extreme load conditions, the effect of corrosion is enormous for the strength and stability of the steel pipe pile. Kui Wang and Ming-jie Zhao Copyright © 2016 Kui Wang and Ming-jie Zhao. All rights reserved. Bias Magnetic Field of Stack Giant Magnetostrictive Actuator: Design, Analysis, and Optimization Wed, 20 Jul 2016 10:51:24 +0000 Many novel applications using giant magnetostrictive actuators (GMA) require their actuators output bidirectional strokes to be large enough to drive the load. In these cases, the sophisticated method to form such a sufficient bias field with minimum power and bulk consumption should be considered in the principal stage of GMA design. This paper concerns the methodology of bias field design for a specific GMA with stack PMs and GMMs (SGMA): both loop and field models for its bias field are established; the optimization method for given SGMA structure is outlined; a prototype is fabricated to verify the theory. Simulation and test results indicate that the bias field could be exerted more easily using SGMA structure; the modeling and optimization methodology for SGMA is valid in practical design. Zhaoshu Yang, Zhongbo He, Dongwei Li, and Ce Rong Copyright © 2016 Zhaoshu Yang et al. All rights reserved. Mechanism Underlying Bonding Water Film Effect on Rheological Parameters Wed, 20 Jul 2016 09:48:12 +0000 From experiments on bonding water of different slurries and the analysis of flow curves, the bilinear fluid model has been improved. The results showed that the rheological parameters correspond to physical processes at different stages of shear strain. As shear rate increases, slurries evolve from high-viscosity Bingham fluids to low-viscosity Bingham fluids. Specific surface area determines the number of edge-to-face arrangements; mineral composition influences the binding strength of each edge-to-face arrangement; and the volume fraction of particles regulates the distance between clay particles and number of edge-to-face arrangements. Yiyan Lv, Wei Zhu, and Tingting Han Copyright © 2016 Yiyan Lv et al. All rights reserved. Experimental and Analytical Investigation Based on 1/2 Scale Model for a Cleanroom Unit Module Consisting of Steel Section and Reinforced Concrete Tue, 19 Jul 2016 12:57:14 +0000 The rapid advances in high tech industries and the increased demand for high precision and reliability of their production environments call for larger structures and higher vertical vibration performance for high technology facilities. Therefore, there is an urgent demand for structural design and vertical vibration evaluation technologies for high tech facility structures. For estimating the microvibration performance for a cleanroom unit module in high technology facilities, this study performs the scale modeling experiment and analytical validation. First, the 1/2 scale model (width 7500 mm, depth 7500 mm, and height 7250 mm) for a cleanroom unit module is manufactured based on a mass-based similitude law which does not require additional mass. The dynamic test using an impact hammer is conducted to obtain the transfer function of 1/2 scale model. The transfer function derived from the test is compared with the analytical results to calibrate the analytical model. It is found that, unlike for static analyses, the stiffness of embedded reinforcement must be considered for estimating microvibration responses. Finally, the similitude law used in this study is validated by comparing the full-scale analytical model and 1/2 scale analytical model for a cleanroom unit module. Sijun Kim and Se Woon Choi Copyright © 2016 Sijun Kim and Se Woon Choi. All rights reserved. Effects of Morphology and Topology on the Effective Stiffness of Chiral Cellular Materials in the Transverse Plane Tue, 19 Jul 2016 12:12:42 +0000 The present study investigates the influence of topology and morphology on the effective stiffness of chiral cellular materials in the transverse plane by means of a homogenization method. For this purpose, finite element models of representative volume elements for regular hexagonal and hexagonal-chiral configurations are used and simulations are conducted to quantify how cell topology—that is, chirality inside the cell—and cell wall slenderness affect the effective stiffness. Closed form solutions for regular hexagonal square and triangular RVEs provided in the literature are then taken as a basis for model validation. The results indicate that there are drastic differences between regular hexagonal and hexagonal-chiral configurations, which can be explained in terms of deformation mechanism transformations between bending and stretching. The investigations also reveal the positive impact of cell wall slenderness on stiffness due to volumetric increase in the cell wall material resisting the deformation. Alp Karakoç and Ertuǧrul Taciroǧlu Copyright © 2016 Alp Karakoç and Ertuǧrul Taciroǧlu. All rights reserved. Emergency Communication and Quick Seismic Damage Investigation Based on Smartphone Tue, 19 Jul 2016 11:55:51 +0000 The communications in the quake-hit area are always cut off from the outside after the earthquake, and the traditional seismic field investigation method calls for immense time to accomplish house-to-house investigation, which goes against timeliness of the emergency rescue. In this paper, an emergency communication and quick seismic damage investigation method based on smartphone is proposed. Towards this, an application, E-Explorer, on iOS platform is initially developed. First, in the emergency communication module, the communication is available by using the Multipeer Connectivity Framework technology even without external network. A series of validation experiments are simulated without external network, and the results prove convincing. This module enhances the possibility of communication and increases the chances for rescue. Second, in the damage investigation module, E-Explorer integrates the functions of questionnaire and picture collection for damage phenomenon recording and image acquisition, following an intensity evaluation method according to seismic index. Last, a website, which provides guidance for rescue workers and collects damage information for quick intensity evaluation, is being built. Ruicong Han, Xuefeng Zhao, Yan Yu, Quanhua Guan, Deli Peng, Mingchu Li, and Jinping Ou Copyright © 2016 Ruicong Han et al. All rights reserved. Damage Simulation of a Random Aggregate Model Induced by Microwave under Different Discontinuous Ratios and Exposure Times Mon, 18 Jul 2016 14:12:57 +0000 A random aggregate algorithmic method and a numerical model for two-phase materials (composed of quartz and plagioclase) with different discontinuous ratios and irradiation times were studied based on the discrete element method using two-dimensional particle flow code (). The results showed that this algorithm can simulate random irregular aggregate shapes. Furthermore, crack initiation and development and the coalescence process of microwave-induced material damage could be predicted using the discrete element method. After analysis of this study, the micro crack originated from the boundary of the high-absorption-phase plagioclase crystal and expanded around the plagioclase, extending into the quartz material. The crack morphology presented a radial network. Yang Tang, Guobin Xu, Chunlai Qu, Liying Sun, and Yu Duan Copyright © 2016 Yang Tang et al. All rights reserved. The Static and Dynamic Mechanical Properties of Magnetorheological Silly Putty Mon, 18 Jul 2016 14:07:27 +0000 A novel magnetorheological material defined as magnetorheological Silly Putty (MRSP) is prepared by dispersing soft magnetic particles into Silly Putty matrix with shear stiffening property. Static mechanical properties including creep and stress relaxation and dynamic rheological properties of MRSPs are tested by rheometer. The experimental results indicate that the external magnetic field exerts significant influence on the creep and relaxation behaviors. Moreover, the storage modulus of MRSPs increases sharply in response to the external stimuli of increasing angular frequency automatically and can be enhanced by external magnetic field. Besides, temperature plays a key role in shear stiffening and magnetorheological effect of MRSPs. Furthermore, considering the obstruction to the particle chains formation induced by Silly Putty matrix, a nonperforative particle aggregated chains model is proposed. The model curve is in consistency with experimental data, which means it can describe magnetoinduced behavior of MRSPs well. Fei Guo, Cheng-bin Du, Guo-jun Yu, and Run-pu Li Copyright © 2016 Fei Guo et al. All rights reserved. Calculation of Constrained Stress in Expansive Mortar with a Composite Creep Model Mon, 18 Jul 2016 09:33:07 +0000 The creep phenomenon of hardening cement paste mixed with an expansive additive was modeled by considering the creep performance of hydration products of cement and expansive additive. A new composite model that is appropriate for particle conditions is proposed by considering the balance of the hydration products of cement and expansive additive and the stress redistribution phenomenon of hydration products newly generated by the progress of hydration. The creep of mortar and concrete mixed with the expansive additive was evaluated using a composite model of the paste and aggregate. Under the assumption that the modeled creep deformation is proportional to the stress and the gel volume of the hydration products, which allows the law of superposition to be applied, the distribution stress was predicted by applying the step-by-step method at each time increment. By predicting the maximum tensile stress applied to an inner steel ring through a creep analysis based on the measured deformation of the inner steel ring, it is possible to predict the stress progression with age to some degree. Hyeonggil Choi and Bongsuk Cho Copyright © 2016 Hyeonggil Choi and Bongsuk Cho. All rights reserved. An Overview of Nanomaterials for Water and Wastewater Treatment Mon, 18 Jul 2016 07:37:07 +0000 Due to the exceptional characteristics which resulted from nanoscale size, such as improved catalysis and adsorption properties as well as high reactivity, nanomaterials have been the subject of active research and development worldwide in recent years. Numerous studies have shown that nanomaterials can effectively remove various pollutants in water and thus have been successfully applied in water and wastewater treatment. In this paper, the most extensively studied nanomaterials, zero-valent metal nanoparticles (Ag, Fe, and Zn), metal oxide nanoparticles (TiO2, ZnO, and iron oxides), carbon nanotubes (CNTs), and nanocomposites are discussed and highlighted in detail. Besides, future aspects of nanomaterials in water and wastewater treatment are discussed. Haijiao Lu, Jingkang Wang, Marco Stoller, Ting Wang, Ying Bao, and Hongxun Hao Copyright © 2016 Haijiao Lu et al. All rights reserved. Effect of Polypropylene and Basalt Fiber on the Behavior of Mortars for Repair Applications Sun, 17 Jul 2016 12:54:27 +0000 The fresh, mechanical, and durability properties of the polypropylene fiber-reinforced mortar (PP FRM) and the basalt fiber-reinforced mortar (BFRM) with various fiber contents were tested in this paper. The test results show that the presence of polypropylene (PP) fiber and basalt fiber (BF) in the mortar reduces the initial slump flow and increases the slump flow loss rate. The bond strength and flexural strength of fiber-reinforced mortar (FRM) are improved, whereas no obvious improvement on the compressive strength has been observed. Compared with the control mortar, the bond strength of PP FRM and BFRM reinforced with 0.6 kg/m3, 1.6 kg/m3, and 2.6 kg/m3 fiber increases by 16.60%–28.80% and 10.60%–21.40%, respectively. Furthermore, FRM shows lower drying shrinkage, superior abrasion resistance, water impermeability, and freeze-thaw resistance compared with the control mortar. The abrasion resistance strength of PP FRM and BFRM is 77.30% and 38.65% more than the control mortar with 2.6 kg/m3 fiber content. Therefore, PP FRM and BFRM are suitable to be utilized as repair materials, especially in repairing hydraulic structures surfaces with excellent bond strength and abrasion resistance. Chaohua Jiang, Shanshan Huang, Yuwen Zhu, Yifeng Lin, and Da Chen Copyright © 2016 Chaohua Jiang et al. All rights reserved. Molding Properties of Inconel 718 Feedstocks Used in Low-Pressure Powder Injection Molding Thu, 14 Jul 2016 14:24:40 +0000 The impact of binders and temperature on the rheological properties of feedstocks used in low-pressure powder injection molding was investigated. Experiments were conducted on different feedstock formulations obtained by mixing Inconel 718 powder with wax-based binder systems. The shear rate sensitivity index and the activation energy were used to study the degree of dependence of shear rate and temperature on the viscosity of the feedstocks. The injection performance of feedstocks was then evaluated using an analytical moldability model. The results indicated that the viscosity profiles of feedstocks depend significantly on the binder constituents, and the secondary binder constituents play an important role in the rheological behavior (pseudoplastic or near-Newtonian) exhibited by the feedstock formulations. Viscosity values as low as 0.06 to 2.9 Pa·s were measured at high shear rates and high temperatures. The results indicate that a feedstock containing a surfactant agent exhibits the best moldability characteristics. Fouad Fareh, Vincent Demers, Nicole R. Demarquette, Sylvain Turenne, and Orlando Scalzo Copyright © 2016 Fouad Fareh et al. All rights reserved. On the Tensile Strength of Granite at High Strain Rates considering the Influence from Preexisting Cracks Thu, 14 Jul 2016 13:40:58 +0000 The dynamic tensile behavior of granite samples, when some preexisting cracks are introduced artificially, is investigated. Spalling tests using a Hopkinson bar are performed and strain rates of ~102 1/s are obtained in both specimen types (with and without initial cracks). This experimental technique is employed being of the same order as strain rates in rock materials during percussive drilling, the application of interest here. The dynamic tensile responses of both sample-sets are compared using the velocity profile measured on the free-end of the sample. Furthermore, an anisotropic damage model based on the concept of obscuration probability describes the response without preexisting cracks. Here, a term of cohesive strength in obscuration zones is added to accurately handle the softening behavior of the material in tension. Results from the spalling tests are used to validate the model prediction of the dynamic tensile strength and also to calibrate the cohesive model parameters. Damaged elements are numerically introduced in the finite element calculations simulating the spalling experiments performed on predamaged samples. The results are compared with the experimental ones. Good agreement is obtained showing that a two-scale approach may constitute a suitable method to simulate numerically the tensile response of predamaged granite. Mahdi Saadati, Pascal Forquin, Kenneth Weddfelt, and Per-Lennart Larsson Copyright © 2016 Mahdi Saadati et al. All rights reserved. Study of Electrical Transport Properties of Thin Films Used as HTL and as Active Layer in Organic Solar Cells, through Impedance Spectroscopy Measurements Wed, 13 Jul 2016 13:32:07 +0000 Impedance spectroscopy (IS) is used for studying the electrical transport properties of thin films used in organic solar cells with structure ITO/HTL/active layer/cathode, where PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid) and CuPC (tetrasulfonated copper-phthalocyanine) were investigated as HTL (hole transport layer) and P3HT:PCBM (poly-3-hexylthiophene:phenyl-C61-butyric acid methyl ester) blends prepared from mesitylene and chlorobenzene based solutions were studied as active layer and Ag and Al were used as cathode. The study allowed determining the influence of the type of solvent used for the preparation of the active layer as well as the speed at which the solvents are removed on the carriers mobility. The effect of exposing the layer of P3HT to the air on its mobility was also studied. It was established that samples of P3HT and P3HT:PCBM prepared using mesitylene as a solvent have mobility values significantly higher than those prepared from chlorobenzene which is the solvent most frequently used. It was also determined that the mobility of carriers in P3HT films strongly decreases when this sample is exposed to air. In addition, it was found that the electrical properties of P3HT:PCBM thin films can be improved by removing the solvent slowly which is achieved by increasing the pressure inside the system of spin-coating during the film growth. Camilo A. Otalora, Andres F. Loaiza, and Gerardo Gordillo Copyright © 2016 Camilo A. Otalora et al. All rights reserved. Using Recycled Glass and Zeolite in Concrete Pavement to Mitigate Heat Island and Reduce Thermal Cracks Wed, 13 Jul 2016 13:03:12 +0000 Urban heat island (UHI) effect is built environmental issue related to pavements. It is desired to reduce pavement high surface temperature in summer to mitigate UHI effect. High surface temperature also affects slab temperature difference (the top surface temperature minus the bottom surface temperature of the slab). The increased slab temperature difference induces a high possibility of cracking in concrete roads. The prime aim of this study was to reduce the slab surface temperature by using recycled glass as a fine aggregate and zeolite as cement in concrete. Recycled glass was used to replace fine aggregate in proportions of 10%, 20%, and 30% by total weight of aggregate. Zeolite replaced Portland cement in proportions of 10% and 30% for three different proportions of recycled glass concrete mixtures. Optimum proportions were determined by examining mechanical properties of samples and alkali-silica reactions. It was noticed that using recycled glass and zeolite together in concrete reduces pavement surface temperature and temperature gradient in summer. Erhan Burak Pancar Copyright © 2016 Erhan Burak Pancar. All rights reserved. Influence of MgO and Hybrid Fiber on the Bonding Strength between Reactive Powder Concrete and Old Concrete Wed, 13 Jul 2016 11:17:32 +0000 The reactive powder concrete (RPC) was used as concrete repair material in this paper. The influence of steel fiber, steel fiber + MgO, and steel fiber + MgO + polypropylene fiber (PPF) on the mechanical properties of RPC repair materials and the splitting tensile strength between RPC and old concrete was studied. Influences of steel fiber, MgO, and PPF on the splitting tensile strength were further examined by using scanning electronic microscopy (SEM) and drying shrinkage test. Results indicated that the compressive and flexural strength was improved with the increasing of steel fiber volume fraction. However, the bonding strength showed a trend from rise to decline with the increasing of steel fiber volume fraction. Although MgO caused mechanical performance degradation of RPC, it improved bonding strength between RPC and existing concrete. The influence of PPF on the mechanical properties of RPC was not obvious, whereas it further improved bonding strength by significantly reducing the early age shrinkage of RPC. Finally, the relationship of drying shrinkage and splitting tensile strength was studied, and the equation between the splitting tensile strength relative index and logarithm of drying shrinkage was obtained by function fitting. Mo Jinchuan, Ou Zhongwen, and Wang Yahui Copyright © 2016 Mo Jinchuan et al. All rights reserved. The Effects of High Alkaline Fly Ash on Strength Behaviour of a Cohesive Soil Wed, 13 Jul 2016 09:40:00 +0000 Contemporarily, there are 16 coal-burning thermal power plants currently operating in Turkey. This number is expected to rise to 46 in the future. Annually, about 15 million tons of fly ash are removed from the existing thermal power plants in Turkey, but a small proportion of it, 2%, is recyclable. Turkey’s plants are fired by lignite, producing Class C fly ash containing a high percentage of lime. Sulfate and alkali levels are also higher in Class C fly ashes. Therefore, fly ash is, commonly, unsuitable as an additive in cement or concrete in Turkey. In this study, highly alkaline fly ash obtained from the Yeniköy thermal power plants is combined with soil samples in different proportions (5%, 10%, 15%, 20%, and 25%) and changes in the geomechanical properties of Ankara clay were investigated. The effect of curing time on the physicomechanical properties of the fly ash mixed soil samples was also analyzed. The soil classification of Ankara clay changed from CH to MH due to fly ash additives. Free swelling index values showed a decrease of 92.6%. Direct shear tests on the cohesion value of Ankara clay have shown increases by multiples of 15.85 and 3.01 in internal friction angle values. The California bearing ratio has seen a more drastic increase in value (68.7 times for 25% fly ash mix). A. Binal Copyright © 2016 A. Binal. All rights reserved. Reexamination In Vitro and In Situ of an Antibacterially Modified Experimental Dental Resin Composite with Molecular Methods: A Pilot Study Wed, 13 Jul 2016 06:55:38 +0000 Purpose. To introduce additional methods to detect and to quantify single pathogens in the complex biofilm formation on an antibacterial dental material. Materials and Methods. A conventional (ST) and an antibacterial dental composite (B) were manufactured. In vitro: specimens were incubated with a mixture of early colonizers. Bacterial adhesion was analyzed by TaqMan PCR after 8/24 h. In situ: TaqMan PCR and 16S rRNA Next Generation Sequencing (NGS) were performed. Results. In vitro: after 8 h incubation, B was covered by 58.6% of the bacterial amount that was attached to ST. After 24 h, the amount of attached bacteria to ST remained constant on ST only slightly lower on B. In situ: after 8 h the amount of adhering A. viscosus and S. mitis was prominent on ST and reduced on B. NGS revealed that S. sanguinis, S. parasanguinis, and Gemella sanguinis were the mainly attached species with S. sanguinis dominant on ST and S. parasanguinis and G. sanguinis dominant on B. Conclusions. Initial biofilm formation was altered by B. A shift between actinomycetes and streptococci was observed in situ. TaqMan PCR and 16S rRNA NGS revealed comparable results in situ and demonstrated the usefulness of NGS to characterize complex bacterial communities. Birgit Henrich, Ilka Hermann, Mara Di Giulio, Karl Köhrer, René Deenen, Sugi Sivalingam, Ulrike Peters, Thomas Beikler, Ralf Janda, and Stefan Rüttermann Copyright © 2016 Birgit Henrich et al. All rights reserved. Frost Durability and Strength of Concrete Prepared with Crushed Sand of Different Characteristics Sun, 10 Jul 2016 10:27:41 +0000 The influences of fines content, methylene blue (MB) value, and lithology of crushed sand (CS) on frost durability and strength of concrete were investigated, and the frost durability and strength of crushed sand concrete (CSC) and river sand concrete (RSC) were compared. The results show that inclusion of fines improves CSC compressive strength and reduces frost durability of C30 CSC when fines content reaches 10%, whereas it has little negative influence on frost durability of C60 CSC. Increasing MB value does not negatively affect compressive strength of C30 CSC but decreases compressive strength of C60 CSC and frost durability of CSC, and the reduction is more pronounced when MB value exceeds 1.0. Lithology has no prominent influence on frost durability and compressive strength of CSC within the lithologies (dolomite, limestone, granite, basalt, and quartz) studied. Though compressive strength of CSC is a little higher than RSC under equal water to cement ratio, frost durability of CSC is no better than RSC especially for C30 CSC, and air-entraining agent is suggested for enhancing frost durability of C30 CSC exposed to freezing environment. Ming-kai Zhou, Zhan-ao Liu, and Xiao Chen Copyright © 2016 Ming-kai Zhou et al. All rights reserved. Effect of Al on Microstructure and Properties of Hot-Rolled 2205 Dual Stainless Steel Tue, 05 Jul 2016 08:52:26 +0000 The microstructure, mechanical properties, oxidation, and corrosion resistance of 2205 stainless steels without and with Al in a range of 0.5 to 2.5 wt.% were investigated in this paper. The results showed that the matrix phase transformed from austenite to ferrite. The volume fraction of the ferrite in the steels decreased at first and then increased and was the lowest in the steel with 0.5 wt.% Al. Most of the Al was dissolved in the ferrite and austenite phases in the steels. The ultimate tensile strength and elongation rate of the steels increased at first and then decreased with the increasing Al content, with the highest values in the steel with 0.5 wt.% Al. The yield strength of the steels slightly increased from 544 to 607 MPa due to the addition of Al. The oxidation rates of the steels with Al were much lower than that of the steel without Al, and the rate of the steel with 1.5 wt.% Al was the lowest, approximately 10 times lower than that of the steel without Al. The corrosion rates of the steels with 0.5 and 1.0 wt.% Al were slightly higher than that of the alloy without Al. In general, the steel with 1 wt.% Al had optimal properties. Qian Meng, Peiqing La, Liang Yao, Peng Zhang, Yupeng Wei, and Xin Guo Copyright © 2016 Qian Meng et al. All rights reserved. Modelling Thermal Shock in Functionally Graded Plates with Finite Element Method Mon, 04 Jul 2016 11:24:43 +0000 Thermomechanical behavior and crack propagation in a functionally graded metal/ceramic plate undergoing thermal shock are analyzed by using the finite element method. A two-dimensional plane strain functionally graded finite element has been developed within the ABAQUS software environment for this purpose. An actual material gradation has been accomplished by sampling material quantities directly at the Gauss points of the element via programming appropriate user-defined subroutines. The virtual crack closure technique is used to model a crack growth under thermal loading. Contact possible between crack lips during the crack advance is taken into account in thermomechanical simulations as well. The paper shows that the presented finite element model can be applied to provide an insight into the thermomechanical respond and failure of the metal/ceramic plate. Vyacheslav N. Burlayenko Copyright © 2016 Vyacheslav N. Burlayenko. All rights reserved. Water Vapor Diffusion and Adsorption of Sandstones: Influence of Rock Texture and Composition Mon, 04 Jul 2016 09:12:04 +0000 The term sandstone is used for wide range of rocks containing quartz clasts which can be cemented by secondary precipitated quartz or calcite; moreover the space between clasts can be filled by matrix. These facts result in existence of numerous rocks having highly various properties. Sandstones have been used as construction materials due to their good accessibility and workability. Since most of sandstones are porous, water vapor can penetrate through sandstone constructions. The rate of water vapor diffusion, as well as the vapor sorption isotherm, was determined for range of sandstone types. The diffusion resistance factor was found to be dependent on the total porosity of sandstone but the sorption behavior was strongly influenced by nature of the particular sandstone; the specific surface area of stone and presence of clay matrix are determining its sorption isotherm. The published data enable estimating (i) diffusion resistance factor of a sandstone via knowledge of its total porosity and (ii) the sorption isotherm via knowledge of the stone’s nature and specific surface area. This approach can significantly reduce the time necessary to acquire vapor-related properties of a sandstone. Martin Keppert, Jaromír Žumár, Monika Čáchová, Dana Koňáková, Petr Svora, Zbyšek Pavlík, Eva Vejmelková, and Robert Černý Copyright © 2016 Martin Keppert et al. All rights reserved. Investigation of Mechanical and Wear Properties of LM24/Silicate/Fly Ash Hybrid Composite Using Vortex Technique Mon, 04 Jul 2016 08:42:19 +0000 This work has investigated to find the influence of silicate on the wear behavior of LM 24/4 wt.% fly ash hybrid composite. The investigation reveals the effectiveness of incorporation of silicate in the composite for gaining wear reduction. Silicate particles with fly ash materials were incorporated into aluminum alloy matrix to accomplish reduction in wear resistance and improve the mechanical properties. The LM24/silicate/fly ash hybrid composite was prepared with 4 wt.% fly ash particles with 4, 8, 12, 16, 20, and 24 wt.% of silicate using vortex technique. Tribological properties were evaluated under different load (15, 30, 45, 60, and 75 N); sliding velocity (0.75, 1.5, 2.25, and 3 m/sec) condition using pin on disc apparatus and mechanical properties like density, hardness, impact strength, and tensile strength of composites were investigated. In addition, the machining of the aluminum hybrid composite was studied using Taguchi L9 orthogonal array with analysis of variance. The properties of the hybrid composites containing 24 wt.% silicates exhibit the superior wear resistance and mechanical properties. B. R. Senthil Kumar, M. Thiagarajan, and K. Chandrasekaran Copyright © 2016 B. R. Senthil Kumar et al. All rights reserved. Nondestructive Inspection of Thin Basalt Fiber Reinforced Composites Using Combined Terahertz Imaging and Infrared Thermography Sun, 03 Jul 2016 10:53:39 +0000 The inspection of thin basalt fiber reinforced composite materials was carried out using two nondestructive methods: terahertz time domain imaging and infrared thermography. In order to combine the information about the defects arising in examined materials the inspection results were parametrized. In order to acquire more information content, new approximation based features are proposed. Then, a knowledge extraction based multivariate analysis of preselected features’ vector was carried out. Finally, in order to integrate features distributions of representing different dynamic level of information, a multiresolution wavelet based data fusion algorithm was applied. The results are presented and discussed. Przemyslaw Lopato, Grzegorz Psuj, and Barbara Szymanik Copyright © 2016 Przemyslaw Lopato et al. All rights reserved.