Advances in Materials Science and Engineering The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Study on Strength and Microstructure of Cement-Based Materials Containing Combination Mineral Admixtures Tue, 23 Aug 2016 11:25:34 +0000 The compressive strength of complex binders containing two or three blended mineral admixtures in terms of glass powder (GP), limestone powder (LP), and steel slag powder (SP) was determined by a battery solution type compressive testing machine. The morphology and microstructure characteristics of complex binder hydration products were also studied by microscopic analysis methods, such as XRD, TG-DTA, and SEM. The mechanical properties of the cement-based materials were analyzed to reveal the most appropriate mineral admixture type and content. The early sample strength development with GP was very slow, but it rapidly grew at later stages. The micro aggregate effect and pozzolanic reaction mutually occurred in the mineral admixture. In the early stage, the micro aggregate effect reduced paste porosity and the small particles connected with the cement hydration products to enhance its strength. In the later stage, the pozzolanic reaction of some components in the complex powder occurred and consumed part of the calcium hydroxide to form C-S-H gel, thus improving the hydration environment. Also, the produced C-S-H gel made the structure more compact, which improved the structure’s strength. Meijuan Rao, Jianpeng Wei, Zhiyang Gao, Wei Zhou, Qiaoling Li, and Shuhua Liu Copyright © 2016 Meijuan Rao et al. All rights reserved. Investigation on Dynamic Propagation Characteristics of In-Plane Cracks in PVB Laminated Glass Plates Tue, 23 Aug 2016 09:11:11 +0000 Polyvinyl butyral (PVB) laminated glass has been widely used as an important component of mechanical and construction materials. Cracks on PVB laminated glass are rich in impact information, which contribute to its impact resistance design. In this paper, a three-dimensional (3D) numerical simulation model describing PVB laminated glass under impact loading is firstly established and validated qualitatively and quantitatively compared with the corresponding experimental results recorded by the high-speed photography system. In the meantime, the extended finite element method (XFEM) is introduced to analyze the crack propagation mechanism of laminated glass based on dynamic stress intensity factors (DSIFs) and propagations of stress waves. Parametric studies are then carried out to investigate the influence of five critical parameters, that is, plate dimension, crack length, impact energy, glass properties, and PVB properties, on crack propagation characteristics of laminated glass. Results show that the interaction between crack tip and stress waves as well as the propagations of stress waves corresponds to the fluctuations of DSIFs at crack tip. Both the structure and material variables are proven to play a very important role in glass cracking DSIFs and thus govern the crack propagation behavior. Results may provide fundamental explanation to the basic crack propagation mechanism on radial cracks in PVB laminated glass under impact loading conditions, thus to instruct its impact design improvement. Xiaoqing Xu, Bohan Liu, and Yibing Li Copyright © 2016 Xiaoqing Xu et al. All rights reserved. Influence of Grain Boundary on the Fatigue Crack Growth of 7050-T7451 Aluminum Alloy Based on Small Time Scale Method Mon, 22 Aug 2016 16:50:35 +0000 Based on the small time scale method, the influence of grain boundary on the fatigue crack growth of 7050-T7451 has been investigated. The interaction between fatigue crack and grain boundary was investigated by in situ SEM testing. Results showed that the fatigue crack growth will be retarded by grain boundary when the angle between fatigue crack and grain boundary is greater than 90 degrees. Mechanism analysis showed that the fatigue crack tip would not be able to open until the loading reached the 55% of maximum load, and the fatigue crack had been closed completely before the loading was not reduced to the minimum value, which led to the crack growth retardation. When the 7050-T7451 aluminum alloy suffered from fatigue loading with constant amplitude, a behavior of unstable fatigue crack growth could be observed often, and results indicated that the bridge linked mechanism led to the behavior. The grain boundary was prone to fracture during fatigue loading, and it became the best path for the fatigue crack growth. The fatigue crack tip would be connected with fractured grain boundary eventually, which led to the fast crack growth in different loading stage. Weihan Wang, Weifang Zhang, Hongxun Wang, Xiaoliang Fang, and Xiaobei Liang Copyright © 2016 Weihan Wang et al. All rights reserved. Simulation on the Self-Compacting Concrete by an Enhanced Lagrangian Particle Method Sun, 21 Aug 2016 11:00:34 +0000 The industry has embraced self-compacting concrete (SCC) to overcome deficiencies related to consolidation, improve productivity, and enhance safety and quality. Due to the large deformation at the flowing process of SCC, an enhanced Lagrangian particle-based method, Smoothed Particles Hydrodynamics (SPH) method, though first developed to study astrophysics problems, with its exceptional advantages in solving problems involving fragmentation, coalescence, and violent free surface deformation, is developed in this study to simulate the flow of SCC as a non-Newtonian fluid to achieve stable results with satisfactory convergence properties. Navier-Stokes equations and incompressible mass conservation equations are solved as basics. Cross rheological model is used to simulate the shear stress and strain relationship of SCC. Mirror particle method is used for wall boundaries. The improved SPH method is tested by a typical 2D slump flow problem and also applied to L-box test. The capability and results obtained from this method are discussed. Jun Wu, Xuemei Liu, Haihua Xu, and Hongjian Du Copyright © 2016 Jun Wu et al. All rights reserved. Safety Evaluation of a Hybrid Substructure for Offshore Wind Turbine Thu, 18 Aug 2016 16:33:13 +0000 Towers and rotor-nacelles are being enlarged to respond to the need for higher gross generation of the wind turbines. However, the accompanying enlargement of the substructure supporting these larger offshore wind turbines makes it strongly influenced by the effect of wave forces. In the present study, the hybrid substructure is suggested to reduce the wave forces by composing a multicylinder having different radii near free surface and a gravity substructure at the bottom of the multicylinder. In addition, the reaction forces acting on the substructure due to the very large dead load of the offshore wind turbine require very firm foundations. This implies that the dynamic pile-soil interaction has to be fully considered. Therefore, ENSOFT Group V7.0 is used to calculate the stiffness matrices on the pile-soil interaction conditions. These matrices are then used together with the loads at TP (Transition Piece) obtained from GH-Bladed for the structural analysis of the hybrid substructure by ANSYS ASAS. The structural strength and deformation are evaluated to derive an ultimate structural safety of the hybrid substructure for various soil conditions and show that the first few natural frequencies of the substructure are heavily influenced by the wind turbine. Therefore, modal analysis is carried out through GH-Bladed to examine the resonance between the wind turbine and the hybrid substructure. Min-Su Park, Youn-Ju Jeong, Young-Jun You, and Yoon-Koog Hwang Copyright © 2016 Min-Su Park et al. All rights reserved. Performance of Soft Asphalt and Double Otta Seal within First Three Years Thu, 18 Aug 2016 12:08:04 +0000 Gravel roads play an important role in the transport infrastructure. However, their maintenance (especially the control of dustiness using chemical dust suppressants) is expensive. Besides, the condition of gravel roads results in low driving comfort, longer travelling time, faster vehicle amortization, and so forth. Typically, these problems are solved by paving gravel roads with asphalt wearing layer. However, north countries practice had shown pavement structure high susceptibility to frost due to insufficient thickness of frost resistance layer. The construction of thicker frost resistant layer increases road construction cost by 25% and, in most cases, there is no need to increase bearing capacity by increasing total thickness of pavement structure. In 2012 19 gravel roads were constructed using cost effective rehabilitation technologies—soft asphalt and double Otta Seal in Lithuania. This paper focuses on those two technologies’ performance within first three years of constructed roads exploitation. The implemented experimental research consisted of three parts by evaluating constructed roads base layers bearing capacity; pavement roughness; and pavement distresses and defects. As a result, the acceptable performance indicators were determined for both technologies—soft asphalt and double Otta Seal. Also recommendations for construction and exploitation improvement were defined. Audrius Vaitkus, Viktoras Vorobjovas, Faustina Tuminienė, and Judita Gražulytė Copyright © 2016 Audrius Vaitkus et al. All rights reserved. The Effect of the Rolling Direction, Temperature, and Etching Time on the Photochemical Machining of Monel 400 Microchannels Wed, 17 Aug 2016 16:49:43 +0000 The present paper describes the effect of the rolling direction on the quality of microchannels manufactured using photochemical machining (PCM) of Monel 400. Experiments were carried out to fabricate microchannels along and across the rolling direction to investigate the effect of the grain orientation on microchannel etching. The input parameters considered were channel width and rolling direction, whereas the depth of etch was the response parameters. Different channels of widths of 60, 100, 150, 200, and 250 μm were etched. The effects of the etching time and temperature of the etchant solution on the undercut and depth of the microchannels were studied. For good quality microchannels, the effects of spinning time, spinning speed, exposure time, and photoresist film strength were also taken into consideration. Optimized values of the above were used for the experimentation. The results show that the depth of etch of the microchannel increases more along the rolling direction than across the rolling direction. The channel width and depth are significantly affected by the etching time and temperature. The proposed study reports an improvement in the quality of microchannels produced using PCM. Deepakkumar H. Patil and Sadaiah Mudigonda Copyright © 2016 Deepakkumar H. Patil and Sadaiah Mudigonda. All rights reserved. Prediction Intervals for the Failure Time of Prestressed Concrete Beams Wed, 17 Aug 2016 13:54:16 +0000 The aim is the prediction of the failure time of prestressed concrete beams under low cyclic load. Since the experiments last long for low load, accelerated failure tests with higher load are conducted. However, the accelerated tests are expensive so that only few tests are available. To obtain a more precise failure time prediction, the additional information of time points of breakage of tension wires is used. These breakage time points are modeled by a nonlinear birth process. This allows not only point prediction of a critical number of broken tension wires but also prediction intervals which express the uncertainty of the prediction. Sebastian Szugat, Jens Heinrich, Reinhard Maurer, and Christine H. Müller Copyright © 2016 Sebastian Szugat et al. All rights reserved. On the Development of an Al4.8 wt% Cu Alloy Obtained from Recycled Aluminum Cans Designed for Thixoforming Process Wed, 17 Aug 2016 12:47:18 +0000 This work has focused on the development of a new aluminum alloy containing 4.8 wt% of Cu alloy obtained from recycled aluminium cans designed for thixoforming process. After the step of melting and solidification of the alloy in a metallic permanent mold, samples were solution heat treated at 525°C for times ranging from 2 h to 48 h, quenched in water and followed by natural aging. Results have shown the evolution of hardness so from them solubilization solution heat treatment was chosen for 24 h. The best condition for aging was 190°C during 3 h. With this data pieces were thixoforged at 580°C and 615°C corresponding, respectively, to solid fraction () of 0.8 and 0.6. The optimized T6 temper was applied and tensile tests were performed. The mechanical properties obtained are compatible with those obtained for consolidated alloys processed in semisolid state (SS) and after T6 temper hardness increases from 95 HB to 122 HB and the best results were a tensile strength of 324 MPa ± 10 MPa, yield strength of 257 MPa ± 18 MPa, and an elongation of 7.1%  ±  1%. For alloys designed for thixoforming process, these results are in accordance with what was expected whereas globular microstructure, high ductility, and good performance under cyclic conditions are desirable. Ronan Miller Vieira, Gianni Ferreira Alves Moreira, André Itman Filho, and Estéfano Aparecido Vieira Copyright © 2016 Ronan Miller Vieira et al. All rights reserved. Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials Tue, 16 Aug 2016 16:13:48 +0000 In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases. Haoliang Huang and Guang Ye Copyright © 2016 Haoliang Huang and Guang Ye. All rights reserved. Estimation on the Field Application for In-Site Recycling of the Wastes Soil from Preboring Tue, 16 Aug 2016 14:26:51 +0000 The design criteria for a structural foundation with soil cement injected precast piles (SIP) indicate that the cement milk gains a conservatively high compressive strength. In addition, a certain amount of the cement milk is lost to the surrounding soil as a result of the high water-cement ratio. Furthermore, the cost increases since the material needs to be exported to the outside of the construction site to dispose of the waste soil. This study was carried out to develop a new mixing method to replace a portion of the cement milk with site soil and a cement hardener. The applicability of this method was confirmed by examining the basic physical characteristics of the new material by on-site conducting dynamic pile loading and bond capacity tests. The test results indicate that the new filling material reduced the bleeding and reduced the loss of filling material when compared to cement milk, but the compressive strength and the results of the dynamic pile loading and bond capacity tests were lower than those obtained for cement milk. However, the new filling material satisfies the standard criterion for structure design, and the economic benefits of implementing the proposed method, including saving on the amount of cement used and reducing the costs of transporting waste soil, were confirmed. Baek-Joong Kim and Heebok Choi Copyright © 2016 Baek-Joong Kim and Heebok Choi. All rights reserved. Sodium Metasilicate Cemented Analogue Material and Its Mechanical Properties Mon, 15 Aug 2016 09:04:24 +0000 Analogue material with appropriate properties is of great importance to the reliability of geomechanical model test, which is one of the mostly used approaches in field of geotechnical research. In this paper, a new type of analogue material is developed, which is composed of coarse aggregate (quartz sand and/or barite sand), fine aggregate (barite powder), and cementitious material (anhydrous sodium silicate). The components of each raw material are the key influencing factors, which significantly affect the physical and mechanical parameters of analogue materials. In order to establish the relationship between parameters and factors, the material properties including density, Young’s modulus, uniaxial compressive strength, and tensile strength were investigated by a series of orthogonal experiments with hundreds of samples. By orthogonal regression analysis, the regression equations of each parameter were obtained based on experimental data, which can predict the properties of the developed analogue materials according to proportions. The experiments and applications indicate that sodium metasilicate cemented analogue material is a type of low-strength and low-modulus material with designable density, which is insensitive to humidity and temperature and satisfies mechanical scaling criteria for weak rock or soft geological materials. Moreover, the developed material can be easily cast into structures with complex geometry shapes and simulate the deformation and failure processes of prototype rocks. Songlin Yue, Yanyu Qiu, Pengxian Fan, Pin Zhang, and Ning Zhang Copyright © 2016 Songlin Yue et al. All rights reserved. Pneumatic Formwork Systems in Structural Engineering Sun, 14 Aug 2016 13:16:25 +0000 Concrete as a construction material is characterized by high compressive strength, low tensile strength, and good casting ability. In order to fully utilize the potential of this material, the form of load-carrying structures has to be designed according to the stress distribution in the structure. Partially hollow structures, such as hollow beams, or doubly curved structures, such as shells, have favorable characteristics. In hollow structures, material savings are achieved in the individual building components by locally reducing dimensions. Concrete shells, if designed properly, are able to span over large areas by transferring the loads mainly by membrane stresses. The main problem with these structures, however, is the high effort required for producing the complicated formwork. One possibility of reducing this effort is to use a pneumatic formwork. This paper describes different pneumatic formwork systems invented in the past 100 years and presents the latest developments in this area. The many types of possible applications are divided into three categories in order to obtain a clearer overview. Finally, a new construction method, called “Pneumatic Forming of Hardened Concrete (PFHC),” is presented. This method was invented at the TU Vienna and uses the pneumatic formwork in a novel way. Benjamin Kromoser and Patrick Huber Copyright © 2016 Benjamin Kromoser and Patrick Huber. All rights reserved. Sulfur Fixation by Chemically Modified Red Mud Samples Containing Inorganic Additives: A Parametric Study Sun, 14 Aug 2016 09:22:54 +0000 Sulfur retention ability of Bayer red mud from alumina plant was investigated. Bayer red mud modified by fusel salt and waste mother liquor of sodium ferrocyanide as the main sulfur fixation agent and the calcium based natural mineral materials as servicing additives; the experimental results showed the following: (1) Through 10 wt% waste mother liquor of sodium ferrocyanide modifying Bayer red mud, sulfur fixation rate can increase by 13 wt%. (2) Magnesium oxide can obviously improve the sulfur fixation performance of Bayer red mud and up to a maximum sulfur fixation rate of 47 wt% at adding 1 wt% magnesium oxide. (3) Dolomite enhanced the sulfur fixation performances with the sulfur fixation rate of 68 wt% in optimized condition. (4) Vermiculite dust reduced sulfur dioxide during the fixed-sulfur process of modified Bayer red mud, and the desulphurization ration could reach up to a maximum 76 wt% at 950°C. (5) An advanced three-component sulfur fixation agent was investigated, in which the optimized mass ratio of modified Bayer red mud, dolomite, and vermiculite dust was 70 : 28 : 2 in order, and its sulfur fixation efficiency has reached to a maximum 87 wt% under its 20 wt% dosage in the coal. Yang Liu, Yang Li, Feng-shan Zhou, Ying-mo Hu, and Yi-he Zhang Copyright © 2016 Yang Liu et al. All rights reserved. Study on Acoustic Emission Characteristics of a Semirigid Base of Dense Skeleton Type during Complete Uniaxial Compression Tests Sun, 14 Aug 2016 08:39:08 +0000 Acoustic emission testing of semirigid base specimens subjected to uniaxial compression was performed by a mechanical testing machine and AE system to find the AE criterion of the uniaxial compressive failure process of the semirigid base of dense skeleton types. AE counts, cumulative AE energy, and -value were discussed. Results indicated that the AE parameters could reflect the failure process of semirigid bases of dense skeleton types. The failure process mainly underwent three stages that were divided based on AE parameters into initial stage of development, stable growth stage, and unstable stage. The knees of the AE parameter curve were at 25% and 85% of the ultimate load. The variation of the -value could indicate the stress and be a precursor to the failure of the specimens. In general terms, a -value greater than 3.5 indicates that specimens are at the initial stage of development. A -value between 1 and 2 indicates that the specimens are at the stable growth stage. If the -value seems to fluctuate and increase, the specimens are at the unstable stage. Moreover, the AE parameters indicated that attaching sensors to the waist of specimens was superior to that at other locations of a specimen. Shengli Li, Guangming Wu, and Hao Wu Copyright © 2016 Shengli Li et al. All rights reserved. Modeling of Flow Stress of 2026 Al Alloy under Hot Compression Thu, 11 Aug 2016 14:26:50 +0000 In order to investigate the workability and to optimize the hot forming parameters for 2026 Al alloy, hot compression tests were performed in the temperature range of 350~450°C with strain rates of 0.01~10 s−1 and 60% deformation degree on a Gleeble-1500 thermosimulation machine. The true stress-strain curves obtained exhibit that the stress increases dramatically at small strains and then moves forward to a steady state, showing dynamic flow softening. Meanwhile, on the basis of Arrhenius equation, a constitutive equation on the flow stress, temperature, and strain rate was proposed. Yet, the values of the predicated stress from the equation and the true stress differ by as much as 50.10%. Given the intricate impact of precipitation of the second phases on the strength of 2026 Al alloy, the introduction of a revised equation with the reinforcement of temperature was carried out, fitting well with the experiment data at peak stresses. What is more, both pictures obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were compatible with all the inferences. Zheng-bing Xiao, Yuan-chun Huang, and Yu Liu Copyright © 2016 Zheng-bing Xiao et al. All rights reserved. Preparation of Antheraea pernyi Silk Fibroin Microparticles through a Facile Electrospinning Method Thu, 11 Aug 2016 13:01:35 +0000 The goal of this study was to fabricate Antheraea pernyi silk fibroin (ASF) microparticles using electrospinning under mild processing conditions. To improve processability of the ASF solution, poly(ethylene oxide) (PEO) was used to regulate viscosity of ASF solution for electrospinning. It was found that the blend of ASF with PEO could form a bead-on-string structure with well spherical particles. Furthermore, aqueous ethanol and ultrasonic treatments could disrupt the nanofibrillar string structure between particles and ultimately produced water-insoluble ASF particles with submicron scale. Cell viability studies indicated that the ASF microparticles were nontoxic to EA926 cells. Moreover, fluorescent images based on FITC labeling showed that the ASF microparticles were easily uptaken by the cells. Aqueous-based electrospinning provides a potentially useful option for the fabrication of ASF microparticles based on this unique fibrous protein. Xiufang Li, Qiang Zhang, Yanfei Feng, Shuqin Yan, Jing Qu, and Renchuan You Copyright © 2016 Xiufang Li et al. All rights reserved. Interfacial Effects on the Spherulitic Morphology of Isotactic Polystyrene Thin Films on Liquid Substrates Thu, 11 Aug 2016 11:54:24 +0000 The influence of interfaces on the morphology of flat spherulites of isotactic polystyrene (iPS) grown in thin films on liquid substrates was investigated. Amorphous iPS thin films spin-cast from a solution were annealed for cold crystallization on glycerol and silicone oil (nonsolvents for iPS). The number density of grown spherulites was revealed to be higher on the glycerol substrate than on the silicone oil substrate. This implies that the primary nucleation rate of crystallization is greater at the iPS/glycerol interface than at the iPS/silicone oil interface. The results may be consistent with the previous findings that concern the molecular interaction between atactic polystyrene and nonsolvents at the interface. In some cases, holes were formed in the thin films during the cold crystallization due to dewetting, which also significantly affect the spherulite morphology via, for example, transcrystallization. Takashi Sasaki, Masaaki Nakagiri, and Satoshi Irie Copyright © 2016 Takashi Sasaki et al. All rights reserved. Control Parametric Analysis on Improving Park Restoring Force Model and Damage Evaluation of High-Strength Structure Thu, 11 Aug 2016 11:36:32 +0000 In the dynamic time-history analysis of structural elastoplasticity, it is important to develop a universal mathematical model that can describe the force-displacement characteristics for restoring force. By defining three control parameters (stiffness degradation, slip closure , energy degradation ), the Park restoring force mathematical model can simulate various components. In this study, the Park restoring force has been improved by adding two control parameters (energy-based strength degradation and ductility-based strength degradation ). Based on the testing data, the constitutive model is input and 55 numerical models are developed to analyze the effects of various parameters on structural behavior. Conclusion. (1) has determinative effect on structural behavior; the effect of is basically consistent with that of ; has significant effect on shear forces and bending moments; has significant effect on displacements and accelerations; has significant effect on shearing forces, acceleration, and total energy consumptions. (2) Based on the classification of four types of damage level, the recommended values for , , , , and are presented. (3) Based on the testing data of high-strength columns, the recommended values for the five control parameters of the improved Park restoring force model are presented. Huang-bin Lin, Shou-gao Tang, and Cheng Lan Copyright © 2016 Huang-bin Lin et al. All rights reserved. Geopolymers Based on Phosphoric Acid and Illito-Kaolinitic Clay Thu, 11 Aug 2016 06:41:04 +0000 New three-dimensional geopolymer materials based on illito-kaolinitic clay and phosphoric acid were synthesized. The effect of Si/P molar ratio on the geopolymers properties was studied. Raw, calcined clay, and geopolymers structures were investigated using XRD, IR spectroscopy, and SEM. The phosphoric acid-based geopolymers mechanical properties were evaluated by measuring the compressive strength. The Si/P molar ratio was found to increase with the increase of the compressive strength of the obtained geopolymers, which attained a maximum value at Si/P equal to 2.75. Beyond this ratio, the mechanical strength decreases. The XRD patterns of these geopolymers samples have proven that when the Si/P molar ratio decreases, the amorphous phase content increases. Besides, the structural analyses have revealed the presence of aluminum phosphate and Si-O-Al-O-P polymeric structure, whatever the Si/P molar ratio is (between 2.25 and 3.5). The obtained results have confirmed that the presence of the associated minerals such as hematite and quartz in the clay does not prevent the geopolymerization reaction, but the presence of illite mineral seems to have a modest contribution in the geopolymerization. S. Louati, S. Baklouti, and B. Samet Copyright © 2016 S. Louati et al. All rights reserved. Application of Coal Ash to Postmine Land for Prevention of Soil Erosion in Coal Mine in Indonesia: Utilization of Fly Ash and Bottom Ash Wed, 10 Aug 2016 13:58:38 +0000 The increase in the number of coal-fired power plants with the increase in coal production and its consumption has caused the problem of the treatment of a large amount of coal ash in Indonesia. In the past studies, coal ash was applied to postmine land with the aim of improving soil conditions for plant growth; however, heavy rain in the tropical climate may cause soil erosion with the change in soil conditions. This study presents the effects of application of coal ash to postmine land on soil erosion by performing the artificial rainfall test as well as physical testing. The results indicate that the risk of soil erosion can be reduced significantly by applying the coal ash which consists of more than 85% of sand to topsoil in the postmine land at the mixing ratio of over 30%. Additionally, they reveal that not only fine fractions but also microporous structures in coal ash enhance water retention capacity by retaining water in the structure, leading to the prevention of soil erosion. Thus, the risk of soil erosion can be reduced by applying coal ash to topsoil in consideration of soil composition and microporous structure of coal ash. Shinji Matsumoto, Shunta Ogata, Hideki Shimada, Takashi Sasaoka, Ginting J. Kusuma, and Rudy S. Gautama Copyright © 2016 Shinji Matsumoto et al. All rights reserved. Strain Rockbursts Simulated by Low-Strength Brittle Equivalent Materials Wed, 10 Aug 2016 13:57:55 +0000 This paper presents experimental study on rockbursts that occur in deep underground excavations. To begin with, the boundary conditions for excavation in deep underground engineering were analysed and elastic adaptive boundary is an effective way to minimize the boundary effect of geomechanical model test. Then, in order to simulate an elastic adaptive loading boundary, Belleville springs were used to establish this loading boundary. With the aforementioned experimental set-ups and fabrication of similarity models for test, the phenomena of strain mode rockbursts were satisfactorily reproduced in laboratory. The internal stress, strain, and convergences of the openings of the model were instrumented by subtly preembedded sensors and transducers. Test results showed that, with an initial state of high stress from both upper layers’ gravitational effects and in situ stress due to tectonic movements, the excavation brings a dramatic rise in the hoop stress and sharp drop in radial stress, which leads to the splitting failure of rock mass. Finally a rockburst occurred associated with the release of strain energy stored in highly stressed rock mass. In addition, the failure of the surrounding rock demonstrated an obvious hysteresis effect which supplies valuable guide and reference for tunnel support. Not only do these results provide a basis for further comprehensive experiments, but also the data can offer assisting aids for further theoretical study of rockbursts. Lang Li, Mingyang Wang, Pengxian Fan, Haiming Jiang, Yihao Cheng, and Derong Wang Copyright © 2016 Lang Li et al. All rights reserved. Influence of Inertia and Low Active Mineral Admixture on Strength and Microstructure of Cement-Based Materials Wed, 10 Aug 2016 13:41:44 +0000 Cement-based materials were investigated by comparing the strength and microstructure of pastes and mortar containing limestone powder or low quality fly ash. The compressive strength of the mortar at 28 and 90 d was examined whose microstructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis, and differential thermal analysis (TG-DTA). The results indicated that the strength of mortar decreased with increasing mineral admixtures. The limestone powder mainly acted as inert filler and hardly took part in the chemical reaction. Low quality fly ash may accelerate the formation of hydration products in samples with more chemically bonded water. This further resulted in a higher degree of cement hydration and denser microstructure, while the overall heat of hydration was reduced. At the early stage of hydration, low quality fly ash can be considered as an inert material whereas its reactivity at the later stage became high, especially for ground low quality fly ash. Meijuan Rao, Wan Tang, Wei Zhou, Yaning Kong, and Shuhua Liu Copyright © 2016 Meijuan Rao et al. All rights reserved. Impact Response of Quasi-Isotropic Asymmetric Carbon Fabric/Epoxy Laminate Infused with MWCNTs Wed, 10 Aug 2016 11:59:32 +0000 Effect of embedding multiwalled carbon nanotubes (MWCNTs) on low velocity impact response of quasi-isotropic asymmetric laminate of plain woven carbon fabric/epoxy was investigated. Laminates were embedded with 0 wt.%, 2 wt.%, and 5 wt.% MWCNTs to improve impact resistance. Impact in laminates was conducted according to ASTM D7136 standard at an impact energy of 94.14 J corresponding to the impact velocity of 6 m/sec. Energy-time response, force-time response, and pyramidal damage area of laminates doped with varying weight percentage (wt.%) of MWCNTs were quantified and compared with laminate without MWCNTs. Absorbed impact energy increases by 13.53% on doping of 2 wt.% MWCNTs, whereas it decreases by 10.49% on doping 5 wt.% MWCNTs. Damage area is reduced on doping 2 wt.% MWCNTs in laminate. Nand Kishore Singh, Prashant Rawat, and K. K. Singh Copyright © 2016 Nand Kishore Singh et al. All rights reserved. Compressive Behavior and Mechanical Characteristics and Their Application to Stress-Strain Relationship of Steel Fiber-Reinforced Reactive Powder Concrete Tue, 09 Aug 2016 14:17:42 +0000 Although mechanical properties of concrete under uniaxial compression are important to design concrete structure, current design codes or other empirical equations have clear limitation on the prediction of mechanical properties. Various types of fiber-reinforced reactive powder concrete matrix were tested for making more usable and accurate estimation equations for mechanical properties for ultra high strength concrete. Investigated matrix has compressive strength ranged from 30 MPa to 200 MPa. Ultra high strength concrete was made by means of reactive powder concrete. Preventing brittle failure of this type of matrix, steel fibers were used. The volume fraction of steel fiber ranged from 0 to 2%. From the test results, steel fibers significantly increase the ductility, strength and stiffness of ultra high strength matrix. They are quantified with previously conducted researches about material properties of concrete under uniaxial loading. Applicability of estimation equations for mechanical properties of concrete was evaluated with test results of this study. From the evaluation, regression analysis was carried out, and new estimation equations were proposed. And these proposed equations were applied into stress-strain relation which was developed by previous research. Ascending part, which was affected by proposed equations of this study directly, well fitted into experimental results. Baek-Il Bae, Hyun-Ki Choi, Bong-Seop Lee, and Chang-Hoon Bang Copyright © 2016 Baek-Il Bae et al. All rights reserved. The Effect of Synthetic Hydrated Calcium Aluminate Additive on the Hydration Properties of OPC Tue, 09 Aug 2016 10:57:16 +0000 The effect of synthetic CAH (130°C; 8 h; CaO/(SiO2 + Al2O3) = 0.55; Al2O3/(SiO2 + Al2O3) = 0.1, 0.15) with different crystallinity on the hydration kinetics of OPC at early stages of hydration was investigated. Also, the formation mechanism of compounds during OPC hydration was highlighted. It was determined that the synthetic CAH accelerated the initial reaction and shortened the induction period. Also, the second and third exothermic reactions begun earlier, and, during the latter reaction, the higher values of the heat flow were obtained in comparison with pure OPC samples. At later stages of hydration, synthetic CAH affect the OPC hydration as the usual pozzolanic additives; moreover, the larger values of cumulative heat were reached. It should be noted that the nature of synthetic CAH samples accelerated the dissolution of gypsum and stimulates the earliest C3S hydration. Jolanta Doneliene, Anatolijus Eisinas, Kestutis Baltakys, and Agne Bankauskaite Copyright © 2016 Jolanta Doneliene et al. All rights reserved. Relationships between Imperfections and Shear Buckling Resistance in Web Plate with Sectional Damage Caused by Corrosion Mon, 08 Aug 2016 16:22:34 +0000 This study deals with the relationship between imperfections and shear buckling resistance of web plates with sectional damage caused by corrosion. To examine the imperfection effect on the shear buckling resistance of a web plate with sectional damage, a series of nonlinear finite element (FE) analyses were carried out for a web plate with sectional damage, which was assumed as local corrosion damage. For considering imperfections of the web plate in the girder, initial out-of-plane deformation was introduced in the FE analysis model. Using the FE analysis results, the changes in the shear buckling resistance of the web plate with sectional damage were quantitatively examined and summarized according to the aspect ratio, boundary conditions, and height of the damaged section of the web plate. The effects of web imperfections on the shear buckling resistance were evaluated to be little compared to that of the web plate without sectional damage. The shear buckling resistance was shown to significantly change in the high-aspect-ratio web plate. A simple evaluation equation for the shear buckling resistance of a web plate with sectional damage was modified for use in the practical maintenance of a web plate in corrosive environments. Jin-Hee Ahn, Shigenobu Kainuma, Won-Hong Lee, Youn-Ju Jeong, and In-Tae Kim Copyright © 2016 Jin-Hee Ahn et al. All rights reserved. Preparation and Performance of Asphalt Compound Modified with Waste Crumb Rubber and Waste Polyethylene Mon, 08 Aug 2016 14:27:53 +0000 Three kinds of modified asphalt were prepared by adding waste crumb rubber (WCR), waste polyethylene (WPE), and WCR/WPE to base asphalt, respectively. The influence of different doses on the performance of modified asphalt, such as 25°C penetration, softening point, 5°C ductility, and 135°C, 165°C viscosity, was studied, and the modification mechanism of modified asphalt was discussed through the fluorescence microscope. As the waterproofing materials, the waterproofness of WCR/WPE compound modified asphalt was tested. The results show that the WPE modified asphalt has excellent resistance to high temperature and WCR modified asphalt has good low temperature resistance. The resistance to deformation ability of WPE modified asphalt is better than that of the WCR modified asphalt. The 135°C viscosity of compound modified asphalt is better than that of WPE and WCR modified asphalt. In addition, the waterproofness of compound modified asphalt using waterproofing materials is better than that of common waterproofing materials. Yuqiao Yang and Youliang Cheng Copyright © 2016 Yuqiao Yang and Youliang Cheng. All rights reserved. Influence of Freeze-Thaw Damage on the Steel Corrosion and Bond-Slip Behavior in the Reinforced Concrete Mon, 08 Aug 2016 14:06:31 +0000 This paper mainly studies the behavior of steel corrosion in various reinforced concrete under freeze-thaw environment. The influence of thickness of concrete cover is also discussed. Additionally, the bond-slip behavior of the reinforced concrete after suffering the freeze-thaw damage and steel corrosion has also be presented. The results show that the freeze-thaw damage aggravates the steel corrosion in concrete, and the results become more obvious in the concrete after suffering serious freeze-thaw damage. Compared with the ordinary concrete, both air entrained concrete and waterproofing concrete possess better resistance to steel corrosion under the same freeze-thaw environment. Moreover, increasing the thicknesses of concrete cover is also an effective method of improving the resistance to steel corrosion. The bond-slip behavior of reinforced concrete with corroded steel decreases with the increase of freeze-thaw damage, especially for the concrete that suffered high freeze-thaw cycles. Moreover, there exists a good correlation between the parameters of bond-slip and freeze-thaw cycles. The steel corrosion and bond-slip behavior of reinforced concrete should be considered serious under freeze-thaw cycles environment, which significantly impact the durability and safety of concrete structure. Fangzhi Zhu, Zhiming Ma, and Tiejun Zhao Copyright © 2016 Fangzhi Zhu et al. All rights reserved. A Numerical Modelling Approach for Time-Dependent Deformation of Hot Forming Tools under the Creep-Fatigue Regime Mon, 08 Aug 2016 11:43:25 +0000 The present study was aimed at predicting the time-dependent deformation of tools used in hot forming applications subjected to the creep-fatigue regime. An excessive accumulated plastic deformation is configured as one of the three main causes of premature failure of tools in these critical applications and it is accumulated cycle by cycle without evident marks leading to noncompliant products. With the aim of predicting this accumulated deformation, a novel procedure was developed, presented, and applied to the extrusion process as an example. A time-hardening primary creep law was used and novel regression equations for the law’s coefficients were developed to account not only for the induced stress-temperature state but also for the dwell-time value, which is determined by the selected set of process parameters and die design. The procedure was validated against experimental data both on a small-scale extrusion die at different stress, temperature, load states, and for different geometries and on an industrial extrusion die which was discarded due to the excessive plastic deformation after 64 cycles. A numerical-experimental good agreement was achieved. B. Reggiani, L. Donati, and L. Tomesani Copyright © 2016 B. Reggiani et al. All rights reserved.