Advances in Materials Science and Engineering The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Experimental Study on a Self-Centering Earthquake-Resistant Masonry Pier with a Structural Concrete Column Thu, 25 May 2017 07:10:34 +0000 This paper proposes a slotting construction strategy to avoid shear behavior of multistory masonry buildings. The aspect ratio of masonry piers increases via slotting between spandrels and piers, so that the limit state of piers under an earthquake may be altered from shear to rocking. Rocking piers with a structural concrete column (SCC) form a self-centering earthquake-resistant system. The in-plane lateral rocking behavior of masonry piers subjected to an axial force is predicted, and an experimental study is conducted on two full-scale masonry piers with an SCC, which consist of a slotting pier and an original pier. Meanwhile, a comparison of the rocking modes of masonry piers with an SCC and without an SCC was conducted in the paper. Experimental verification indicates that the slotting strategy achieves a change of failure modes from shear to rocking, and this resistant system with an SCC incorporates the self-centering and high energy dissipation properties. For the slotting pier, a lateral story drift ratio of 2.5% and a high displacement ductility of approximately 9.7 are obtained in the test, although the lateral strength decreased by 22.3% after slotting. The predicted lateral strength of the rocking pier with an SCC has a margin of error of 5.3%. Lijun Niu and Wenfang Zhang Copyright © 2017 Lijun Niu and Wenfang Zhang. All rights reserved. Correlation between the Compressive, Tensile Strength of Old Concrete under Marine Environment and Prediction of Long-Term Strength Thu, 25 May 2017 00:00:00 +0000 Compressive strength and tensile strength are important mechanical properties of concrete. The long-term strength of concrete under real service environment is an important parameter when evaluating existing buildings, which should also be properly considered in structural design. In this study, the relationship between compressive and splitting tensile strength of old concrete existing for long period under marine environment was investigated. At a deserted harbour, concrete cores samples were drilled by pairs in site. For each pair of samples, the two cores were drilled from the adjacent location and conducted to compressive, splitting tensile test, respectively. 48 compressive and splitting tensile strengths were finally obtained. From the test results, tensile strength presents general uptrend with compressive strength, and the two parameters are well positively correlated. Exponential model generally recommended by building codes or literatures is still capable of describing the relationship between compressive and tensile strength of old deteriorated concrete, when function parameters are properly determined. Based on statistical theory and the experimental result of this study, a method for predicting long-term tensile strength of concrete is developed and an example is given, which may provide a potential way to estimate long-term concrete strength under real marine environment. Weilai Yao, Shiyong Jiang, Wei Fei, and Tao Cai Copyright © 2017 Weilai Yao et al. All rights reserved. Study on Fracture Initiation and Propagation in a Brazilian Disc with a Preexisting Crack by Digital Image Correlation Method Wed, 24 May 2017 10:32:52 +0000 The effect of a preexisting crack with different inclination angles and lengths on mechanical properties, fracture initiation, and propagation in a Brazilian disc was investigated in this paper. In the experiment, digital image correlation (DIC) method was employed to record the deformation in the specimen. Different failure patterns, depending on inclination angles and lengths of the preexisting crack, were observed. The fracture initiation position deviates from the tips of the preexisting crack with the inclination angle increasing from 0° to 72° at an interval of 18° per increment. Secondary cracks are more likely to occur in the Brazilian disc with a more inclined and longer preexisting crack. A finite-discrete element combined method ELFEN was used in the numerical investigation to simulate the failure process. This investigation shows that there are good correlations between the experimental and numerical results. Digital image correlation is a good method to obtain the quantitive full-field strain distribution and to observe the strain evolution process in a jointed rock. Lin Luo, Xibing Li, Jiadong Qiu, and Quanqi Zhu Copyright © 2017 Lin Luo et al. All rights reserved. Temperature Effects on the Friction and Wear Behaviors of SiCp/A356 Composite against Semimetallic Materials Wed, 24 May 2017 08:07:08 +0000 Due to the low density and high temperature resistance, the SiCp/A356 composites have great potential for weight reduction and braking performance using the brake disc used in trains and automobiles. But the friction coefficient and braking performance are not stable in the braking process because of temperature rising. In this paper, friction and wear behaviors of SiCp/A356 composite against semimetallic materials were investigated in a ring-on-disc configuration in the temperature range of 30°C to 300°C. Experiments were conducted at a constant sliding speed of 1.4 m/s and an applied load of 200 N. Worn surface, subsurface, and wear debris were also examined by using SEM and EDS techniques. The third body films (TBFs) lubricated wear transferred to the third body abrasive wear above 200°C, which was a transition temperature. The friction coefficient decreased and weight of semimetallic materials increased with the increase of temperature and the temperature had almost no effect on the weight loss of composites. The dominant wear mechanism of the composites was microploughing and slight adhesion below 200°C, while being controlled by cutting grooves, severe adhesion, and delamination above the 200°C. Like Pan, Jianmin Han, Zhiyong Yang, Jialin Wang, Xiang Li, Zhiqiang Li, and Weijing Li Copyright © 2017 Like Pan et al. All rights reserved. Experimental Investigation on the Material Removal of the Ultrasonic Vibration Assisted Abrasive Water Jet Machining Ceramics Wed, 24 May 2017 00:00:00 +0000 The ultrasonic vibration activated in the abrasive water jet nozzle is used to enhance the capability of the abrasive water jet machinery. The experiment devices of the ultrasonic vibration assisted abrasive water jet are established; they are composed of the ultrasonic vibration producing device, the abrasive supplying device, the abrasive water jet nozzle, the water jet intensifier pump, and so on. And the effect of process parameters such as the vibration amplitude, the system working pressure, the stand-off, and the abrasive diameter on the ceramics material removal is studied. The experimental result indicates that the depth and the volume removal are increased when the ultrasonic vibration is added on abrasive water jet. With the increase of vibration amplitude, the depth and the volume of material removal are also increased. The other parameters of the ultrasonic vibration assisted abrasive water jet also have an important role in the improvement of ceramic material erosion efficiency. Tao Wang, Rongguo Hou, and Zhe Lv Copyright © 2017 Tao Wang et al. All rights reserved. Experimental and Numerical Evaluation of the Ablation Process of Carbon/Carbon Composites Using High Velocity Oxygen Fuel System Wed, 24 May 2017 00:00:00 +0000 The ablation process of carbon/carbon (C/C) composites was tested under hypersonic flowing propane flame. The microstructures of C/C composites were characterized and the numerical analysis was performed. Two typical ablation morphologies of the carbon fibers, which are drum-like and needle-like shapes, were observed depending on the alignments of fibers to the flame directions. Temperature fields in the composites were analyzed using finite element method, and the mechanisms that govern the formation of different ablation behaviors were elucidated. For paralleled fiber bundles, the highest temperature situates in the middle parts underlying the ablation pits, where the drum-like shape is formed. For perpendicular fiber bundles, the highest temperature appears at the turning point between the transverse section and the surface of fiber, which leads to the gradual ablation from the fiber surface toward the axis, and eventually the formation of the needle-like shape. Xueling Fan, Peng Jiang, Biao Li, Xiaochao Jin, and Yong Zhao Copyright © 2017 Xueling Fan et al. All rights reserved. Corrosion and Strength Behaviors in Prestressed Tendon under Various Tensile Stress and Impressed Current Conditions Tue, 23 May 2017 06:32:42 +0000 Corrosion occurs more rapidly under high tensile stress and this leads to several problems like degradation of serviceability and structural performance in PSC (prestressed concrete) structures. In this paper, impressed current method, so-called ICM, was applied to tendons under tensile loadings of 0.0, 20.0, 40.0, and 60.0% of ultimate load. With induction of 20 volts for 24 hours to tendon under tensile stress, loading was induced to failure and the ultimate load was evaluated with varying corrosion behaviors. The changing mechanical behaviors in the same corrosive conditions were evaluated under different initial prestressing levels. With increasing initial prestressing load, corrosion occurred more rapidly and corrosion amount also increased linearly. The ultimate load accordingly decreased with increasing initial prestressing and corrosion amount. The relationships between prestressing levels and corrosion behaviors were quantitatively obtained through regression analysis. The measured current during applied voltage and the related corrosion amounts were also dealt with in this work. Bang-Yeon Lee, K. T. Koh, M. A. Ismail, H. S. Ryu, and S. J. Kwon Copyright © 2017 Bang-Yeon Lee et al. All rights reserved. Thermomechanical Properties of Jute/Bamboo Cellulose Composite and Its Hybrid Composites: The Effects of Treatment and Fiber Loading Tue, 23 May 2017 00:00:00 +0000 Jute cellulose composite (JCC), bamboo cellulose composite (BCC), untreated hybrid jute-bamboo fiber composite (UJBC), and jute-bamboo cellulose hybrid biocomposite (JBCC) were fabricated. All cellulose hybrid composites were fabricated with chemical treated jute-bamboo cellulose fiber at 1 : 1 weight ratio and low-density polyethylene (LDPE). The effect of chemical treatment and fiber loading on the thermal, mechanical, and morphological properties of composites was investigated. Treated jute and bamboo cellulose were characterized by Fourier transform infrared spectroscopy (FTIR) to confirm the effectiveness of treatment. All composites were characterized by tensile testing, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Additionally, surface morphology and water absorption test was reported. The FTIR results revealed that jute and bamboo cellulose prepared are identical to commercial cellulose. The tensile strength and Young’s modulus of composites are optimum at 10 weight percentage (wt%) fibers loading. All cellulose composites showed high onset decomposition temperature. At 10 wt% fiber loading, JBCC shows highest activation energy followed by BCC and JCC. Significant reduction in crystallinity index was shown by BCC which reduced by 14%. JBCC shows the lowest water absorption up to 43 times lower compared to UJBC. The significant improved mechanical and morphological properties of treated cellulose hybrid composites are further supported by SEM images. Fui Kiew Liew, Sinin Hamdan, Md. Rezaur Rahman, and Mohamad Rusop Copyright © 2017 Fui Kiew Liew et al. All rights reserved. Design and Performance of Anticracking Asphalt-Treated Base Mon, 22 May 2017 08:58:09 +0000 To enhance the crack resistance of asphalt-treated base (ATB), a type of gapped and semiopened gradation ATB mixture, GSOG, was designed. Its design method was proposed based on the volume design method and performance tests. Firstly, several gradations were designed preliminarily in which middle particle sizes of coarse aggregates were partially or completely gapped according to the gradation specification. Secondly, their voids in coarse aggregates (VCA) were determined through dry rod compaction test on coarse aggregates, and then their theoretical voids were calculated. Gradations whose theoretical voids met the requirements were selected to fabricate specimens with Superpave Gyratory Compactor, and their voids were determined using vacuum sealing method and submerged weight in water method. Finally, gradations whose voids meet requirements were selected to fabricate different types of specimens for various performance tests, and the optimal gradation can be selected comprehensively considering their performances, especially focusing on their crack resistance. According to this gradation design method, the gradation of GSOG-25 was designed, and its performances, including high-temperature stability, water stability, fatigue, and antireflection crack resistance, were measured and compared to ordinary ATB-25. The results demonstrate that the performance of GSOG-25 is much better than that of ordinary ATB-25, especially in anticracking capacity. Xiaoge Tian, Haifeng Han, Qisen Zhang, Xinwei Li, and Ye Li Copyright © 2017 Xiaoge Tian et al. All rights reserved. Experimental Analysis on Shrinkage and Swelling in Ordinary Concrete Mon, 22 May 2017 00:00:00 +0000 The paper deals with the experimental determination of shrinkage development during concrete ageing. Three concrete mixtures were made. They differed in the amount of cement in the fresh mixture, 300, 350, and 400 kg/m3. In order to determine the influence of plasticiser on the progress of volume changes, another three concrete mixtures were prepared with plasticiser in the amount of 0.25% by cement mass. Measurements were performed with the goal of observing the influence of cement and plasticiser content on the overall development of volume changes in the concrete. Changes in length and mass losses of the concrete during ageing were measured simultaneously. The continuous measurement of concrete mass losses caused by drying of the specimen’s surface proved useful during the interpretation of results obtained from the concrete shrinkage measurement. During the first 24 hours of ageing, all the concrete mixtures exhibited swelling. Its magnitude and progress were influenced by cement, water, and plasticiser content. However, a loss of mass caused by water evaporation from the surface of the specimens was also recorded in this stage. The measured progress of shrinkage corresponded well to the progress of mass loss. Barbara Kucharczyková, Petr Daněk, Dalibor Kocáb, and Petr Misák Copyright © 2017 Barbara Kucharczyková et al. All rights reserved. Effects of Diatomite and SBS on Freeze-Thaw Resistance of Crumb Rubber Modified Asphalt Mixture Sun, 21 May 2017 09:57:38 +0000 Asphalt mixture is susceptible to moisture damage under the effect of freeze-thaw (F-T) cycles. In this paper, crumb rubber (CR) was used to modify stone mastic asphalt (SMA) and the effects of diatomite and styrene butadiene styrene (SBS) on antifreezing performances of crumb rubber modified SMA (CRSMA) were investigated. Regression analysis and modified grey model (MGM) were used to construct the prediction models for properties of modified mixtures. CRSMA, CR and diatomite modified SMA (CRDSMA), and CR and SBS modified SMA (CRSSMA) were prepared in laboratory, respectively. Process of F-T cycles was designed. Air void, indirect tensile strength (ITS), and indirect tensile stiffness modulus (ITSM) were measured to evaluate the antifreezing performances of CRSMA, CRDSMA, and CRSSMA. Results indicate that air voids increase with the increasing of F-T cycles. ITS and ITSM all decrease with the increasing of F-T cycles. The addition of diatomite and SBS can reduce the air void and improve the ITS and ITSM of CRSMA. CRSSMA presents the lowest air void, highest tensile strength, and largest stiffness modulus, which reveals that CRSSMA has the best F-T resistance among three different kinds of mixtures. Moreover, MGM (1, 2) models present more favorable accuracy in prediction of air void and ITS compared with regression ones. Haibin Wei, Ziqi Li, and Yubo Jiao Copyright © 2017 Haibin Wei et al. All rights reserved. Laboratory Performance Evaluation of High Modulus Asphalt Concrete Modified with Different Additives Sun, 21 May 2017 08:57:33 +0000 The objective of this study is to evaluate comprehensive performance of high modulus asphalt concrete (HMAC) and propose common values for establishing evaluation system. Three gradations with different modifiers were conducted to study the high and low temperature performance, shearing behavior, and water stability. The laboratory tests for HMAC included static and dynamic modulus tests, rutting test, uniaxial penetration test, bending test, and immersion Marshall test. Dynamic modulus test results showed that modifier can improve the static modulus and the improvements were remarkable at higher temperature. Moreover, modulus of HMAC-20 was better than those of HMAC-16 and HMAC-25. The results of performance test indicated that HMAC has good performance to resist high temperature rutting, and the resistances of the HMAC-20 and HMAC-25 against rutting were better than that of HMAC-16. Then, the common values of dynamic stability were recommended. Furthermore, common values of HMAC performance were established based on pavement performance tests. Peng Li, Mulian Zheng, Fei Wang, Fa Che, Hongyin Li, Qinglei Ma, and Yonghong Wang Copyright © 2017 Peng Li et al. All rights reserved. Investigation of the Characteristic Properties of Glacial Acetic Acid-Catalyzed Carbon Xerogels and Their Electrochemical Performance for Use as Electrode Materials in Electrical Double-Layer Capacitors Sun, 21 May 2017 00:00:00 +0000 Glacial acetic acid was used as a catalyst in the preparation process of carbon xerogels from the condensation of resorcinol and formaldehyde for shortening significantly the gelation time. The effect of the resorcinol/catalyst ratio over a large range of 2 to 500, the solvent exchange manner with acetone, and the pyrolysis temperature of 700 to 1000°C on the characteristic properties of the carbon xerogels were investigated. A resorcinol/catalyst ratio of 2 and a pyrolysis temperature at 800°C were found to be the optimal condition for the preparation of carbon xerogels with a well-balanced porosity between micro- and mesopores, high surface area (577.62 m2g−1), and large pore volume (0.97 cm3g−1), which are appropriate for use as electrode materials in an electrical double-layer capacitor. The carbon xerogel electrodes that were prepared under these optimal conditions exhibited a good electrochemical performance with the highest specific capacitance of 169 Fg−1 in 6 M KOH electrolyte at a scan rate of 5 mVs−1 from cyclic voltammetry. Nguyen Khanh Nguyen Quach, Wein-Duo Yang, Zen-Ja Chung, Hoai Lam Tran, and Rui Liu Copyright © 2017 Nguyen Khanh Nguyen Quach et al. All rights reserved. Experimental Investigation of Laws during Deformation of Circular Roadway in 10° Inclined Layered Rock Thu, 18 May 2017 09:46:19 +0000 In order to analyze the deformation characteristics and mechanisms caused by high tectonic stress in gentle dip strata, a physical modeling with circular tunnel was designed. The model was constructed by the so-called “Physically Finite Elemental Slab Assemblage (PFESA)” to bring about the structural effect of the deep strata. The gravity was fixed while the lateral pressure increased step by step to mimic high tectonic stress. In order to observe the displacement in different area, the sketches of monitoring points and frame in the model surface were drawn down through video pictures in different periods and to be compared. For the sake of analyzing the deformation and failure mechanism of layers, rock structural mechanics models were set up for the left side and right side in the same stratum, respectively. For verifying the experimental phenomenon and its mechanism, infrared images were utilized based on the temperature variation mechanisms of material. Through systematic study, this paper enriches the research methods of model test and can provide a certain reference for practical engineering of similar conditions. Xiaoming Sun, Qiang Han, Yingqi Zhang, Xin Liu, and Weili Gong Copyright © 2017 Xiaoming Sun et al. All rights reserved. Preparation and Performance of a New-Type Alkali-Free Liquid Accelerator for Shotcrete Wed, 17 May 2017 06:21:33 +0000 A new type of alkali-free liquid accelerator for shotcrete was prepared. Specifically, the setting time and strength and shrinkage performance of two kinds of Portland cement with the accelerator were fully investigated. Moreover, the accelerating mechanism of alkali-free liquid accelerator and the hydration process of the shotcrete with accelerator were explored. Results show that alkali-free liquid accelerator significantly shortened the setting time of cement paste, where the initial setting time of cement paste with 8 wt% of the accelerator was about 3 min and the final setting time was about 7 min. Compressive strength at 1 day of cement mortar with the accelerator could reach 23.4 MPa, which increased by 36.2% compared to the strength of cement mortar without the accelerator, and the retention rate of 28-day compressive strength reached 110%. In addition, the accelerator still shows a good accelerating effect under low temperature conditions. However, the shrinkage rate of the concrete increased with the amount of the accelerator. 5~8% content of accelerator is recommended for shotcrete in practice. XRD and SEM test results showed that the alkali-free liquid accelerator promoted the formation of ettringite crystals due to the increase of Al3+ and concentration. Yanping Sheng, Bin Xue, Haibin Li, Yunyan Qiao, Huaxin Chen, Jianhong Fang, and Anhua Xu Copyright © 2017 Yanping Sheng et al. All rights reserved. Flow Characteristics and Grain Size Distribution of Granular Gangue Mineral by Compaction Treatment Wed, 17 May 2017 00:00:00 +0000 A test system for water flow in granular gangue mineral was designed to study the flow characteristics by compaction treatment. With the increase of the compaction displacement, the porosity decreases and void in granular gangue becomes less. The main reason causing initial porosity decrease is that the void of larger size is filled with small particles. Permeability tends to decrease and non-Darcy flow factor increases under the compaction treatment. The change trend of flow characteristics shows twists and turns, which indicate that flow characteristics of granular gangue mineral are related to compaction level, grain size distribution, crushing, and fracture structure. During compaction, larger particles are crushed, which in turn causes the weight of smaller particles to increase, and water flow induces fine particles to migrate (weight loss); meanwhile, a sample with more weight of size (0–2.5 mm) has a higher amount of weight loss. Water seepage will cause the decrease of some chemical components, where SiO2 decreased the highest in these components; the components decreased are more likely locked at fragments rather than the defect of the minerals. The variation of the chemical components has an opposite trend when compared with permeability. Ran Yuan, Dan Ma, and Hongwei Zhang Copyright © 2017 Ran Yuan et al. All rights reserved. Aging Properties of Polyvinylidenefluoride-Coated Polyesters Used in Tensioned Membrane Structure: Effect of Loading Protocol and Environment Wed, 17 May 2017 00:00:00 +0000 This paper presents the degradation behaviors of polyvinylidenefluoride- (PVDF-) coated polyesters used in tensioned membrane structure by artificial accelerated tests, in which the effects of environment factors and loading conditions are studied. Results show that the degradation ratio of main mechanical parameters (tensile strength, tear strength, and elastic modulus) is related to the aging depth of substrate and coating. The degradation of weather resistance can be considered as the accumulation of environment and loads. The ultraviolet radiation and the temperature mainly affect the mechanical properties of yarns, while the preloading before aging tests can change the crimp degrees and decrease the coating thickness. The effect of loads should not be ignored in the weather resistance analysis of PVDF-coated polyesters. A simplified method composed of cyclic tests and stress-relaxation tests is suggested to study the long-term weather resistance of PVDF-coated polyesters. It can provide a theoretical reference for the proposal of resistance partial factor in the design of tensioned membrane structure. Yingying Zhang and Mingyue Zhang Copyright © 2017 Yingying Zhang and Mingyue Zhang. All rights reserved. Effect of Rare Earth Metals, Sr, and Ti Addition on the Microstructural Characterization of A413.1 Alloy Tue, 16 May 2017 09:11:35 +0000 The present work was performed on A413.1 alloy containing 0.2–1.5 wt% rare earth metals (lanthanum or cerium), 0.05–0.15% Ti, and 0–0.02 wt% Sr. These elements were either added individually or combined. Thermal analysis, image analysis, and electron probe microanalysis were the main techniques employed in the present study. The results show that the use of the depression in the eutectic temperature as a function of alloy modification cannot be applied in the case when the alloy is treated with rare earth metals. Increasing the concentration of RE increases the solidification zone especially in Sr-modified alloys leading to poor feeding ability. This observation is more prominent in the case of Ce addition. Depending upon the amount of added Ti, two RE based intermetallics can be formed: (i) a white phase, mainly platelet-like (approximately 2.5 μm thick), that is rich in RE, Si, Cu, and Al and (ii) a second phase made up of mainly grey sludge particles (star-like) branching in different directions. The grey phase is rich in Ti with some RE (almost 20% of that in the white phase) with traces of Si and Cu. There is a strong interaction between RE and Sr leading to a reduction in the efficiency of Sr as a eutectic Si modifier causing particle demodification. M. G. Mahmoud, A. M. Samuel, H. W. Doty, S. Valtierra, and F. H. Samuel Copyright © 2017 M. G. Mahmoud et al. All rights reserved. Analysis and Alternate Selection of Nanopowder Modifiers to Improve a Special Protective Coating System Tue, 16 May 2017 00:00:00 +0000 This paper presents a practical approach for rational choice of silica nanopowders as modifiers to control and improve the performance of protective coating systems operating in harsh environmental conditions. The approach is based on the multiparameter analysis of nanoparticle reactivity of similar silica synthesized by using chemical and physical methods. The analysis indicates distinct adsorption centers due to the differences in the particles formation; the features of the formation and adsorption mechanisms lead to higher diffusion capacity of the nanoparticles, synthesized by physical methods, into a paint material and finally result in stronger chemical bonds between the system elements. The approach allows reducing the consumption of paint materials by 30% or more, at least 2-3 times increasing of the coating adhesion and hence the system life. Validity of the approach is illustrated through the data obtained from comparative modeling, factory testing, and practical use of modified systems. S. P. Bardakhanov, V. N. Goverdovskiy, C.-M. Lee, O. C. Lee, and V. T. Lygdenov Copyright © 2017 S. P. Bardakhanov et al. All rights reserved. Exploring Polymer-Modified Concrete and Cementitious Coating with High-Durability for Roadside Structures in Xinjiang, China Sun, 14 May 2017 00:00:00 +0000 The concrete roadside structures in Xinjiang, China, such as roadside barriers, bridge rails, and drainage holes, are severely damaged by the coupled effect of seasonal freeze-thaw cycles and deicer salts. To solve the corrosion problems of roadside structures, polymer-modified concrete was recommended for the future construction of roadside structures and polymer-modified cementitious coating was suggested for the protection of the current corroded ones. In this study, air-entraining agent and carboxylated styrene-butadiene latex were added for concrete modification and the corresponding performance tests were conducted. In addition, the performances of six types of readily available coating materials, including the acrylic latex modified cementitious coating designed in this study, were tested in freeze-thaw condition with the presence of chloride ions. The results show that 0.013% of the air-entraining agent and 10% of the carboxylated styrene-butadiene latex were appropriate dosage rates for the modification of Portland cement concrete, in terms of the improvement of the freeze-thaw resistance, compressive strength, and chloride impermeability. For the protection of the current corroded roadside structures, the acrylic-modified cementitious coating material demonstrated a good performance and the field monitoring confirmed that the coating is suitable for the protection of the roadside structures in Xinjiang. Yinchuan Guo, Aiqin Shen, and Xiaohui Sun Copyright © 2017 Yinchuan Guo et al. All rights reserved. Influence of Curing Time on the Drying Shrinkage of Concretes with Different Binders and Water-to-Binder Ratios Thu, 11 May 2017 07:19:42 +0000 Plain cement concrete, ground granulated blast furnace slag (GGBS) concrete, and fly ash concrete were designed. Three wet curing periods were employed, which were 2, 5, and 8 days. The drying shrinkage values of the concretes were measured within 1 year after wet curing. The results show that the increasing rate of the drying shrinkage of concrete containing a mineral admixture at late age is higher than that of plain cement concrete regardless of the wet curing time. With the reduction of wet curing time, the increment of total drying shrinkage of concrete decreases with the decrease of the W/B ratio. The negative effects on the drying shrinkage of fly ash concrete due to the reduction of the wet curing time are much more obvious than those of GGBS concrete and plain cement concrete. Superfine ground granulated blast furnace slag (SGGBS) can reduce the drying shrinkage of GGBS concrete and fly ash concrete when the wet curing time is insufficient. Jun Yang, Qiang Wang, and Yuqi Zhou Copyright © 2017 Jun Yang et al. All rights reserved. Experimental Investigation of Isothermal Section of the B-Cr-Fe Phase Diagram at 1353 K Thu, 11 May 2017 00:00:00 +0000 The isothermal section of the B-Cr-Fe ternary system was studied experimentally at 1353 K. X-ray diffraction and scanning electron microscopy equipped with EDX analyzer were used for determination of phase equilibria and composition of the coexisting phases in the B-Cr-Fe model alloys after long-term annealing (1500–2205 h). Two iron borides FeB and Fe2B, six chromium borides Cr2B, Cr5B3, CrB, Cr3B4, CrB2, and CrB4 and also iron and chromium solid solutions (α(Fe,Cr), α(Cr,Fe), γ(Fe,Cr)) and β-rhombohedral B were observed in the alloys. High solubilities of the third element in binary borides and no ternary phase were found. Based on the experimental results, isothermal section of the B-Cr-Fe system at 1353 K was determined. Viera Homolová and Lucia Čiripová Copyright © 2017 Viera Homolová and Lucia Čiripová. All rights reserved. Nonlinear Dynamic Analysis of Macrofiber Composites Laminated Shells Tue, 09 May 2017 00:00:00 +0000 This work presents the nonlinear dynamical analysis of a multilayer piezoelectric macrofiber composite (MFC) laminated shell. The effects of transverse excitations and piezoelectric properties on the dynamic stability of the structure are studied. Firstly, the nonlinear dynamic models of the MFC laminated shell are established. Based on known selected geometrical and material properties of its constituents, the electric field of MFC is presented. The vibration mode-shape functions are obtained according to the boundary conditions, and then the Galerkin method is employed to transform partial differential equations into two nonlinear ordinary differential equations. Next, the effects of the transverse excitations on the nonlinear vibration of MFC laminated shells are analyzed in numerical simulation and moderating effects of piezoelectric coefficients on the stability of the system are also presented here. Bifurcation diagram, two-dimensional and three-dimensional phase portraits, waveforms phases, and Poincare diagrams are shown to find different kinds of periodic and chaotic motions of MFC shells. The results indicate that piezoelectric parameters have strong effects on the vibration control of the MFC laminated shell. Xiangying Guo, Dameng Liu, Wei Zhang, Lin Sun, and Shuping Chen Copyright © 2017 Xiangying Guo et al. All rights reserved. Formation of Flower-Like Crystals of Tris(8-hydroxyquinoline)aluminum from 8-Hydroxyquinoline on Anodic Porous Alumina Sun, 07 May 2017 07:25:22 +0000 The treatment of anodic porous alumina (APA) plates in heated water containing 8-hydroxyquinoline (HQ) produces crystalline tris(8-hydroxyquinoline)aluminum (Alq3) microbelts about 5–10 μm wide and 5–20 μm long. These microbelts were found to aggregate to form flower-like structures on the surface. X-ray diffraction studies indicated that the Alq3 microbelts are composed of an α-phase having a meridional structure. The Alq3 microbelts exhibited green photoluminescence with a peak at around 520 nm. Scanning electron microscope images and energy dispersive X-ray spectra showed that this reaction is induced at the APA surface by the reaction between the HQ and amorphous Al2O3 species. Shohei Yamaguchi, Tomohiro Iida, and Kazunori Matsui Copyright © 2017 Shohei Yamaguchi et al. All rights reserved. Water Content Influence on Properties of Red-Layers in Guangzhou Metro Line, China Thu, 04 May 2017 00:00:00 +0000 In order to reveal water content influence on shear strength, swelling, and creep properties of red-layers in Guangzhou Metro, Southern China, the typical red-layers rock and soil specimens were experimentally studied by direct shear test, UU triaxial test, swelling test, and creep test, and the measured data were analyzed. The results showed that soil internal friction angle exponentially decreased with the water content increase and cohesion in accordance with the Gaussian function firstly increased and then decreased with the increase of water content. Expansion rate significantly decreased with the initial water content increase. The red sandstone had very strong isotropic expansion and disintegration properties. The mechanism of water content effect on red-layers properties was water induced microstructures and mineral compositions change which caused the macro physical and mechanical characteristics degradation. The results should provide the reference for further research for water induced damage mechanism or creep damage control of red-layers in engineering practice. Jifeng Liu and Huizhi Zhang Copyright © 2017 Jifeng Liu and Huizhi Zhang. All rights reserved. Experimental Research on Longitudinal Steel Bar Bond Properties in Modified Recycled Aggregate Concrete Beam-Column Interior Joint under Cyclic Loading Wed, 03 May 2017 00:00:00 +0000 Three recycled aggregate concrete (RAC) beam-column interior-joint specimens (including two modified recycled aggregate concrete interior joints with replacement of fly ash ratio of 15%) were tested under cyclic loading in order to study the bond behavior of the longitudinal steel bar at RAC joint. The tests obtained load-strain hysteresis curves of longitudinal bars. The relative bond strength of longitudinal bar in characteristic stages was calculated. The test results indicated that the longitudinal steel bar in RAC joint is able to supply a stable bond stress both in the full crack stage and in the ultimate stage, meaning that the requirements of stress transferring and displacement coordinating between RAC and reinforcements can be satisfied. The larger the diameter of steel bar, the more serious the bond strength degradation. The RAC with fly ash can improve the interface compactness and bond strength of recycled aggregate in full crack stage. When beam-column interface of concrete compression zone reaches ultimate strain, the compressive stress of the longitudinal reinforcement cannot be exerted. The bond stress of the steel bar cannot realize the pull and compressive stress conversion in the length of the core area of the joint owing to the stress hysteresis of the compression rebars. Jia-Li Fu, Bing-Kang Liu, and Jun-Wei Ma Copyright © 2017 Jia-Li Fu et al. All rights reserved. Surface Organic Modification of TiO2 Powder and Relevant Characterization Tue, 02 May 2017 08:37:51 +0000 Surface organic modification was conducted to TiO2 with modifiers to improve the dispersity and comparability of pigment TiO2 in application system by adjusting particle surface characteristics. Then, modification effects were characterized according to the changes in wetting contact angle and activation index of TiO2 before and after modification. Moreover, the modification mechanisms of sodium stearate and sodium oleate were studied by analyzing the characteristics of TiO2 surface functional groups in modification system and effects of modifiers. The results showed that, after being wet-processed with sodium stearate and sodium oleate, TiO2 could turn from surface hydrophilic to inductive hydrophobic with controllable degree. The wetting contact angle of modified TiO2 increased from 7° to 125.6° and 121.3°, respectively. The dispersity of TiO2 in organic medium was stronger than that in inorganic medium. The modifiers formed absorption with chemical property on TiO2 particle surface, so the inductive hydrophobicity of surface was stable. Hong Zhou, Sijia Sun, and Hao Ding Copyright © 2017 Hong Zhou et al. All rights reserved. Determination of the Peak and Residual Shear Strengths of the Sandwich Material in Slopes Sun, 30 Apr 2017 10:09:00 +0000 The mudded weak interlayer is a geotechnical sandwich material exhibiting strain softening behavior, which plays an important part in the slope stability. The present work primarily focuses on the shear strength of the mudded weak interlayer in rock slopes. To determine the peak and residual shear strengths of the mudded weak interlayers, the particle flow code (PFC) is used to simulate the failure behavior during the direct shear tests. Laboratory investigations including uniaxial compression test, SEM, and 3D deformation measurement are employed to calibrate the essential micro parameters of the mudded weak interlayer during the simulation process in PFC. The numerical model is built based on these parameters and both the peak and residual shear strengths can be predicted from the model. The prediction results show that the peak and residual internal friction angle are 19.36° and 14.61°, while the peak and residual cohesion are 22.33 kPa and 2.73 kPa, respectively. Moreover, to validate the obtained peak and residual strengths, the results are compared with literature data. The peak and residual shear strengths of the mudded weak interlayer can serve as an important benchmark to evaluate the stability of side slopes and provide guiding suggestions for their reinforcement. Qijun Hu, Qijie Cai, Leping He, Xiaoqiang Yang, Tao Ye, and Rendan Shi Copyright © 2017 Qijun Hu et al. All rights reserved. Shot Peening Effect on Fatigue Crack Repaired Weldments Sun, 30 Apr 2017 08:06:26 +0000 Fracture mechanics calculations are required to validate the safety level defined in design codes to prevent a fatigue failure. The periodic inspection-assessment cycle can lead to the implementation of a fatigue crack repair by crack removal. To improve the fatigue performance of the crack repair, residual compressive stresses induced by peening can be considered. This paper is in relation to the peening effect estimation on stress intensity factors in fatigue crack repaired weldments, since the stress intensity factor is a key parameter in fracture mechanics calculations. A set of T-butt specimens were experimentally fatigue tested and crack propagation data was gathered for the calculation of stress intensity factors. The experiments were designed to estimate the residual compressive stress depth layer and its effect on crack propagation inhibition. Experimental estimation of the peening effect on stress intensity factors in fatigue crack repaired weldments was validated by comparison against an analytical weight function solution. Experimental stress intensity factors determined from a set of fatigue tested T-butt specimens allowed estimating preliminarily that peening has a limited effect on fatigue crack propagation inhibition for edge repaired T-butt weldments subjected to bending loading. J. Efrain Rodriguez-Sanchez, Alejandro Rodriguez-Castellanos, and Faustino Perez-Guerrero Copyright © 2017 J. Efrain Rodriguez-Sanchez et al. All rights reserved. A Parameter Sensitivity Analysis of the Effect of Rebar Corrosion on the Stress Field in the Surrounding Concrete Sun, 30 Apr 2017 07:28:06 +0000 Rebar corrosion results in a change in the stress field in the surrounding concrete, which in turn accelerates the deterioration of the concrete structure. In addition to the protective layer, the compressive stress under which concrete is prestressed also affects the effect of corrosion-induced rebar expansion on the stress field in the concrete. The present study simulates the effect of corrosion-induced rebar expansion on the stress field in the concrete using the finite element method (FEM) by applying a virtual radial displacement to the product of corrosion-induced rebar expansion. Based on an analysis of the effect of multiple rebars on the stress field in ordinary concrete, stress distribution in the protective layer of the concrete is determined. Afterward, the locations where there is damage to the surface concrete caused by rebar corrosion are determined. After verifying the feasibility of the FEM analysis, the effect of corrosion-induced ordinary rebar expansion in a typical prestressed concrete segment is determined by analyzing the characteristics of corrosion-induced rebar expansion occurring in various prestressed concrete specimens. Fangyuan Li and Wenya Ye Copyright © 2017 Fangyuan Li and Wenya Ye. All rights reserved.