Advances in Materials Science and Engineering The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Dynamic Behaviours of a Single Soft Rock-Socketed Shaft Subjected to Axial Cyclic Loading Sun, 25 Sep 2016 14:18:15 +0000 The soft rock was simulated by cement, plaster, sand, water, and concrete hardening accelerator in this paper. Meanwhile, uniaxial compressive strength tests and triaxial compression tests were conducted to study the mechanical properties of simulated soft rock samples. Model tests on a single pile socketed in simulated soft rock under axial cyclic loading were conducted by using a device which combined test apparatus with a GCTS dynamic triaxial system. Test results show that the optimal mix ratio is cement : plaster : medium sand : water : concrete hardening accelerator = 4.5% : 5.0% : 84.71% : 4.75% : 1.04%. The static load ratio (SLR), cyclic load ratio (CLR), and the number of cycles affect the accumulated deformation and cyclic secant modulus of the pile head. The accumulated deformation increases with increasing numbers of cycles. However, the cyclic secant modulus of pile head increases and then decreases with the growth in the number of cycles and finally remains stable after 50 cycles. According to the test results, the development of accumulated settlement was analysed. Finally, an empirical formula for accumulated settlement, considering the effects of the number of cycles, the static load ratio, the cyclic load ratio, and the uniaxial compressive strength, is proposed which can be used for feasibility studies or preliminary design of pile foundations on soft rock subjected to traffic loading. Ben-jiao Zhang, Bin Huang, Can Mei, Xu-dong Fu, Gang Luo, and Zhi-jun Yang Copyright © 2016 Ben-jiao Zhang et al. All rights reserved. Experimental Field Tests and Finite Element Analyses for Rock Cracking Using the Expansion of Vermiculite Materials Sun, 25 Sep 2016 12:31:57 +0000 In the previous research, laboratory tests were performed in order to measure the expansion of vermiculite upon heating and to convert it into expansion pressure. Based on these test results, this study mainly focuses on experimental field tests conducted to verify that expansion pressure obtained by heating vermiculite materials is enough to break massive and hard granite rock with an intention to excavate the tunnel. Hexahedral granite specimens with a circular hole perforated in the center were constructed for the experimental tests. The circular holes were filled with vermiculite plus thermal conduction and then heated using the cartridge heater. As a result, all of hexahedral granite specimens had cracks in the surface after 700-second thermal heating and were finally spilt into two pieces completely. The specimen of larger size only requires more heating time and expansion pressure. The material properties of granite rocks, which were obtained from the experimental tests, were utilized to produce finite element models used for numerical analyses. The analysis results show good agreement with the experimental results in terms of initial cracking, propagation direction, and expansion pressure. Chi-hyung Ahn and Jong Wan Hu Copyright © 2016 Chi-hyung Ahn and Jong Wan Hu. All rights reserved. New Mechanism on Synergistic Effect of Nitrite and Triethanolamine Addition on the Corrosion of Ductile Cast Iron Sun, 25 Sep 2016 09:05:18 +0000 In general, we compared the different inhibition mechanisms of organic inhibitor with that of anodic inhibitor. When triethanolamine or nitrite was added separately to tap water for inhibiting the corrosion of ductile cast iron, large amounts of inhibitor were needed. This is because the corrosion inhibitors had to overcome the galvanic corrosion that occurs between graphite and matrix. In this work, we investigated the corrosion of ductile cast iron in tap water with/without inhibitors. The corrosion rate was measured using chemical immersion test and electrochemical methods, including anodic polarization test. The inhibited surface was analyzed using EPMA and XPS. Test solutions were analyzed by performing FT-IR measurement. When triethanolamine and nitrite coexisted in tap water, synergistic effect built up, and the inhibition effect was ca. 30 times more effective than witnessed with single addition. This work focused on the synergistic effect brought about by nitrite and triethanolamine and its novel mechanism was also proposed. K. T. Kim, H. Y. Chang, B. T. Lim, H. B. Park, and Y. S. Kim Copyright © 2016 K. T. Kim et al. All rights reserved. Influence of Compacting Rate on the Properties of Compressed Earth Blocks Thu, 22 Sep 2016 14:17:43 +0000 Compaction of blocks contributes significantly to the strength properties of compressed earth blocks. This paper investigates the influence of compacting rates on the properties of compressed earth blocks. Experiments were conducted to determine the density, compressive strength, splitting tensile strength, and erosion properties of compressed earth blocks produced with different rates of compacting speed. The study concludes that although the low rate of compaction achieved slightly better performance characteristics, there is no statistically significant difference between the soil blocks produced with low compacting rate and high compacting rate. The study demonstrates that there is not much influence on the properties of compressed earth blocks produced with low and high compacting rates. It was further found that there are strong linear correlations between the compressive strength test and density, and density and the erosion. However, a weak linear correlation was found between tensile strength and compressive strength, and tensile strength and density. Humphrey Danso Copyright © 2016 Humphrey Danso. All rights reserved. Ordered Mesoporous Carbons as Novel and Efficient Adsorbent for Dye Removal from Aqueous Solution Thu, 22 Sep 2016 11:30:05 +0000 Ordered mesoporous carbons (OMCs) were successfully synthesized by using hard template and soft template methods. These materials were characterized by XRD, TEM, and N2 adsorption-desorption Brunauer-Emmett-Teller (BET). From the obtained results, it is revealed that the obtained OMCs samples showed high surface area (>1000 m2/g) with high pore volume, mainly mesopore volume (1.2–2.4 cm3/g). Moreover, OMCs samples had similar structure of the SBA-15 silica and exhibited high MB adsorption capacity with of 398 mgg−1 for OMCs synthesis with hard template and 476 mgg−1 for OMCs synthesis with soft template, respectively. From kinetics investigation, it is confirmed that MB adsorption from aqueous solution obeys the pseudo-second-order kinetic equation. Phuong T. Dang, Hoa T. H. Nguyen, Canh D. Dao, Giang H. Le, Quang K. Nguyen, Kien T. Nguyen, Hoa T. K. Tran, Tuyen V. Nguyen, and Tuan A. Vu Copyright © 2016 Phuong T. Dang et al. All rights reserved. Complexing Agents on Carbon Content and Lithium Storage Capacity of LiFePO4/C Cathode Synthesized via Sol-Gel Approach Thu, 22 Sep 2016 10:47:23 +0000 Olivine-structured LiFePO4 faces its intrinsic challenges in terms of poor electrical conductivity and lithium-ion diffusion capability for application to lithium-ion batteries. Cost-effective sol-gel approach is advantageous to in situ synthesize carbon-coated LiFePO4 (LiFePO4/C) which can not only improve electronic conductivity but also constrain particle size to nanometer scale. In this study, the key parameter is focused on the choice and amount of chelating agents in this synthesis route. It was found that stability of complexing compounds has significant impacts on the carbon contents and electrochemical properties of the products. At the favorable choice of precursors, composition, and synthesis conditions, nanocrystalline LiFePO4/C materials with appropriate amount of carbon coating were successfully obtained. A reversible capacity of 162 mAh/g was achieved at 0.2 rate, in addition to good discharge rate capability. C. Guan and H. Huang Copyright © 2016 C. Guan and H. Huang. All rights reserved. Shear Behavior of Frozen Rock-Soil Mixture Thu, 22 Sep 2016 05:50:49 +0000 Mechanical behavior of frozen rock-soil mixture was investigated through direct shear test based on remolded specimens. The peak shear strength of rock-soil mixture increases greatly when it is fully frozen. The shear process goes through four stages including compaction, elastic deformation, plastic yield, and failure. The specimen has slight compaction in vertical direction at the beginning of shear test; then it changes to dilatancy. The temperature and ice content have vital important effect on the shear behavior of frozen rock-soil mixture. Results indicated that the peak shear strength of rock-soil mixture increases with temperature decreasing when temperature ranges from −1°C to −16°C. But the curve has clear inflexion at −5°C. When temperature is higher than this degree, the peak shear strength increases sharply with temperature decreasing. Otherwise, the rise of the peak shear strength with the decrease of temperature becomes gentle. The shear strength of rock-soil mixture goes up first and then down with ice content increasing at −5°C for samples with initial water contents varying from 9% to 14%. The shear strength reaches its peak value at initial water content ranging between 10% and 12% by weight. Changqing Qi, Liuyang Li, Jihong Wei, and Jin Liu Copyright © 2016 Changqing Qi et al. All rights reserved. Experimental and Theoretical Study of Sandwich Panels with Steel Facesheets and GFRP Core Wed, 21 Sep 2016 06:49:41 +0000 This study presented a new form of composite sandwich panels, with steel plates as facesheets and bonded glass fiber-reinforced polymer (GFRP) pultruded hollow square tubes as core. In this novel panel, GFRP and steel were optimally combined to obtain high bending stiffness, strength, and good ductility. Four-point bending test was implemented to analyze the distribution of the stress, strain, mid-span deflection, and the ultimate failure mode. A section transformation method was used to evaluate the stress and the mid-span deflection of the sandwich panels. The theoretical values, experimental results, and FEM simulation values are compared and appeared to be in good agreement. The influence of thickness of steel facesheet on mid-span deflection and stress was simulated. The results showed that the mid-span deflection and stress decreased and the decent speed was getting smaller as the thickness of steel facesheet increases. A most effective thickness of steel facesheet was advised. Hai Fang, Huiyuan Shi, Yue Wang, Yujun Qi, and Weiqing Liu Copyright © 2016 Hai Fang et al. All rights reserved. Shear Stress-Relative Slip Relationship at Concrete Interfaces Tue, 20 Sep 2016 16:44:22 +0000 This study develops a simple and rational shear stress-relative slip model of concrete interfaces with monolithic castings or smooth construction joints. In developing the model, the initial shear cracking stress and relative slip amount at peak stress were formulated from a nonlinear regression analysis using test data for push-off specimens. The shear friction strength was determined from the generalized equations on the basis of the upper-bound theorem of concrete plasticity. Then, a parametric fitting analysis was performed to derive equations for the key parameters determining the shapes of the ascending and descending branches of the shear stress-relative slip curve. The comparisons of predictions and measurements obtained from push-off tests confirmed that the proposed model provides superior accuracy in predicting the shear stress-relative slip relationship of interfacial shear planes. This was evidenced by the lower normalized root mean square error than those in Xu et al.’s model and the CEB-FIB model, which have many limitations in terms of the roughness of the substrate surface along an interface and the magnitude of equivalent normal stress. Keun-Hyeok Yang Copyright © 2016 Keun-Hyeok Yang. All rights reserved. Application of Generalized Fractional Thermoelasticity Theory with Two Relaxation Times to an Electromagnetothermoelastic Thick Plate Tue, 20 Sep 2016 16:43:59 +0000 The fractional mathematical model of Maxwell’s equations in an electromagnetic field and the fractional generalized thermoelastic theory associated with two relaxation times are applied to a 1D problem for a thick plate. Laplace transform is used. The solution in Laplace transform domain has been obtained using a direct method and its inversion is calculated numerically using a method based on Fourier series expansion technique. Finally, the effects of the two fractional parameters (thermo and magneto) on variable fields distributions are made. Numerical results are represented graphically. A. M. Abd El-Latief Copyright © 2016 A. M. Abd El-Latief. All rights reserved. Inverse Strategies for Identifying the Parameters of Constitutive Laws of Metal Sheets Tue, 20 Sep 2016 16:43:22 +0000 This article is a review regarding recently developed inverse strategies coupled with finite element simulations for the identification of the parameters of constitutive laws that describe the plastic behaviour of metal sheets. It highlights that the identification procedure is dictated by the loading conditions, the geometry of the sample, the type of experimental results selected for the analysis, the cost function, and optimization algorithm used. Also, the type of constitutive law (isotropic and/or kinematic hardening laws and/or anisotropic yield criterion), whose parameters are intended to be identified, affects the whole identification procedure. P. A. Prates, A. F. G. Pereira, N. A. Sakharova, M. C. Oliveira, and J. V. Fernandes Copyright © 2016 P. A. Prates et al. All rights reserved. Research on the Selection Strategy of Green Building Parts Supplier Based on the Catastrophe Theory and Kent Index Method Tue, 20 Sep 2016 13:00:58 +0000 At present, the green building and housing industrialization are two mainstream directions in the real estate industry. The production of green building parts which combines green building and housing industrialization, two concepts, is to be vigorously developed. The key of quality assurance in the assembly project is choosing reliable and proper green building parts suppliers. This paper analyzes the inherent requirements of the green building, combined with the characteristics of the housing industrialization, and puts forward an evaluation index system of supplier selection for green building parts, which includes product index, enterprise index, green development index, and cooperation ability index. To reduce the influence of subjective factors, the improved method which merges Kent index method and catastrophe theory is applied to the green building parts supplier selection and evaluation. This paper takes the selection of the unit bathroom suppliers as an example, uses the improved model to calculate and analyze the data of each supplier, and finally selects the optimal supplier. With combination of the Kent index and the catastrophe theory, the result shows that it can effectively reduce the subjectivity of the evaluation and provide a basis for the selection of the green building parts suppliers. Zhenhua Luo, Jian He, Haize Pan, and Yiluan Yang Copyright © 2016 Zhenhua Luo et al. All rights reserved. Oxygen Defect-Mediated Magnetism in Fe-C Codoped TiO2 Tue, 20 Sep 2016 12:51:52 +0000 The magnetic properties of the C doped and C-Fe codoped TiO2 films fabricated by sol-gel and spin coating have been investigated combining experiments and first-principles calculations. All the samples exhibit the anatase crystal phase and the room temperature ferromagnetism. The values of the saturation magnetizations are in the order of Fe-C codoped TiO2 > Fe-C codoped TiO2 (annealed in O2) > C doped TiO2 > C doped TiO2 (annealed in O2). The calculated net moment values are in the order of Fe-C codoped TiO2 > C doped TiO2 with oxygen vacancies existing, in accord with the experimental results. The hybridization of Fe 3d, C 2p, and O 2p (nearest to the Fe defect) led to the spin split of Fe 3d, C 2p, and O 2p which contributed to the ferromagnetism. Zhaorui Zou, Zhongpo Zhou, Haiying Wang, and Meng Du Copyright © 2016 Zhaorui Zou et al. All rights reserved. Development and Performance Assessment of the High-Performance Shrinkage Reducing Agent for Concrete Mon, 19 Sep 2016 10:04:30 +0000 To develop a high-performance shrinkage reducing agent, this study investigated several shrinkage reducing materials and supplements for those materials. Fluidity and air content were satisfactory for the various shrinkage reducing materials. The decrease in viscosity was the lowest for glycol-based materials. The decrease in drying shrinkage was most prominent for mixtures containing glycol-based materials. In particular, mixtures containing G2 achieved a 40% decrease in the amount of drying shrinkage. Most shrinkage reducing materials had weaker level of compressive strength than that of the plain mixture. When 3% triethanolamine was used for early strength improvement, the strength was enhanced by 158% compared to that of the plain mixture on day 1; enhancement values were 135% on day 7 and 113% on day 28. To assess the performance of the developed high-performance shrinkage reducing agent and to determine the optimal amount, 2.0% shrinkage reducing agent was set as 40% of the value of the plain mixture. While the effect was more prominent at higher amounts, to prevent deterioration of the compressive strength and the other physical properties, the recommended amount is less than 2.0%. Hyung Sub Han, Jong Kyu Kim, and Yong Wook Jung Copyright © 2016 Hyung Sub Han et al. All rights reserved. Experimental and Numerical Investigations of Fretting Fatigue Behavior for Steel Q235 Single-Lap Bolted Joints Mon, 19 Sep 2016 09:39:48 +0000 This work aims to investigate the fretting fatigue life and failure mode of steel Q235B plates in single-lap bolted joints. Ten specimens were prepared and tested to fit the S-N curve. SEM (scanning electron microscope) was then employed to observe fatigue crack surfaces and identify crack initiation, crack propagation, and transient fracture zones. Moreover, a FEM model was established to simulate the stress and displacement fields. The normal contact stress, tangential contact stress, and relative slipping displacement at the critical fretting zone were used to calculate FFD values and assess fretting fatigue crack initiation sites, which were in good agreement with SEM observations. Experimental results confirmed the fretting fatigue failure mode for these specimens. It was found that the crack initiation resulted from wear regions at the contact surfaces between plates, and fretting fatigue cracks occurred at a certain distance away from hole edges. The proposed FFD- relationship is an alternative approach to evaluate fretting fatigue life of steel plates in bolted joints. Yazhou Xu, Zhen Sun, and Yuqing Zhang Copyright © 2016 Yazhou Xu et al. All rights reserved. Structural and Compositional Characterization of Fungus-Derived Pyrolytic Carbon Architectures Sun, 18 Sep 2016 14:25:04 +0000 Three distinctive pyrolytic carbon structures, derived from three specific tissues of Agaricus bisporus mushroom, were studied and characterized. The three structures discovered within the stalk, cap, and cap skin tissues were found to contain unique microarchitectures, which were preserved upon anoxic carbonization. Experiments also revealed the formation of salt pockets and deposits within each microarchitecture, leading to a potential natural hard-template method for porous carbon structures. Brennan Campbell, Robert Ionescu, Cengiz S. Ozkan, and Mihrimah Ozkan Copyright © 2016 Brennan Campbell et al. All rights reserved. Pilot Study for Investigating the Cyclic Response of the Recentering Bridge Bearing System Combined with the Friction Damper Sun, 18 Sep 2016 13:57:13 +0000 The bridge bearing is one of the component members which provide resting supports between piers and decks. The bridge bearing is intended to control longitudinal movement caused by traffic flow and thermal expansion, thereby reducing stress concentration. In high seismicity area, the bridge bearing has been utilized as the base isolation system to mitigate acceleration transferred from the ground. Although the existing bridge bearing installed between superstructure and substructure provides extra flexibility to the base of the entire structure, considerable permanent deformation occurs due to lack of recentering capacity after earthquake. It is required to spend extra cost for repairing impaired parts. The bridge bearings integrated with superelastic shape memory alloy (SMA) devices used for upgrading the recentering effect into the friction damper are proposed in this study. The refined finite element (FE) analyses are introduced to reproduce the response of such new structures under cyclic loading condition. The bridge bearing systems that maintain uniform recentering capability are designed with various friction coefficients so as to examine energy dissipation and residual deformation through FE analyses. After observing FE analysis results, optimal design for the recentering bridge bearing system will be proposed to take advantage of energy dissipation and self-centering capacity. Jong Wan Hu and Yong-il Cho Copyright © 2016 Jong Wan Hu and Yong-il Cho. All rights reserved. Structural Dynamics and Stability of Composite Structures Thu, 15 Sep 2016 08:54:23 +0000 Sung-Cheon Han, Ireneusz Kreja, Guillermo Rus, and Gilson R. Lomboy Copyright © 2016 Sung-Cheon Han et al. All rights reserved. Experimental Investigation and FE Analysis on Constitutive Relationship of High Strength Aluminum Alloy under Cyclic Loading Thu, 15 Sep 2016 07:33:28 +0000 Experiments of 17 high strength aluminum alloy (7A04) specimens were conducted to investigate the constitutive relationship under cyclic loading. The monotonic behavior and hysteretic behavior were focused on and the fracture surface was observed by scanning electron microscope (SEM) to investigate the microfailure modes. Based on Ramberg-Osgood model, stress-strain skeleton curves under cyclic loading were fitted. Parameters of combined hardening model including isotropic hardening and kinematic hardening were calibrated from test data according to Chaboche model. The cyclic tests were simulated in finite element software ABAQUS. The test results show that 7A04 aluminum alloy has obvious nonlinearity and ultra-high strength which is over 600 MPa, however, with relatively poor ductility. In the cyclic loading tests, 7A04 aluminum alloy showed cyclic hardening behavior and when the compressive strain was larger than 1%, the stiffness degradation and strength degradation occurred. The simulated curves derived by FE model fitted well with experimental curves which indicates that the parameters of this combined model can be used in accurate calculation of 7A04 high strength aluminum structures under cyclic loading. Yuanqing Wang and Zhongxing Wang Copyright © 2016 Yuanqing Wang and Zhongxing Wang. All rights reserved. Influence of Vanadium and Boron Additions on the Microstructure, Fracture Toughness, and Abrasion Resistance of Martensite-Carbide Composite Cast Steel Thu, 15 Sep 2016 07:33:02 +0000 High chromium cast steel alloys are being used extensively in many industrial services where dry or wet abrasion resistance is required. Such steel castings are demanded for cement, stoneware pipes, and earth moving industries. In this research, five steel heats were prepared in 100 kg and one-ton medium frequency induction furnaces and then sand cast in both Y-block and final impact arm spare parts, respectively. Vanadium (0.5–2.5%) and boron (120–150 ppm) were added to the 18Cr-1.9C-0.5Mo steel heats to examine their effects on the steel microstructure, mechanical properties especially impact, fracture toughness and abrasion resistance. Changes in the phase transformation after heat treatment were examined using inverted, SEM-EDX microscopy; however, the abrasion resistance was measured in dry basis using the real tonnage of crushed and milled stoneware clay to less than 0.1 mm size distribution. Waleed Elghazaly, R. Rashad, Sayed Elmohr, and Saied Elghazaly Copyright © 2016 Waleed Elghazaly et al. All rights reserved. Compositional Changes for Reduction of Polymerisation-Induced Shrinkage in Holographic Photopolymers Thu, 08 Sep 2016 18:09:30 +0000 Polymerisation-induced shrinkage is one of the main reasons why many photopolymer materials are not used for certain applications including holographic optical elements and holographic data storage. Here, two compositional changes for the reduction of shrinkage in an acrylamide-based photopolymer are reported. A holographic interferometric technique was used to study changes in the dynamics of the shrinkage processes occurring in the modified photopolymer during holographic recording in real time. Firstly, the effect of the replacement of the acrylamide monomer in the photopolymer composition with a larger monomer molecule, diacetone acrylamide, on polymerisation-induced shrinkage has been studied. A reduction in relative shrinkage of 10–15% is obtained using this compositional change. The second method tested for shrinkage reduction involved the incorporation of BEA-type zeolite nanoparticles in the acrylamide-based photopolymer. A reduction in relative shrinkage of 13% was observed for acrylamide photopolymer layers doped with 2.5% wt. BEA zeolites in comparison to the undoped photopolymer. D. Cody, M. Moothanchery, E. Mihaylova, V. Toal, S. Mintova, and I. Naydenova Copyright © 2016 D. Cody et al. All rights reserved. The Measurement of P-, S-, and R-Wave Velocities to Evaluate the Condition of Reinforced and Prestressed Concrete Slabs Thu, 08 Sep 2016 13:41:48 +0000 The traditional P-wave ultrasonic measurement has been used for the condition assessment of general reinforced concrete structures for a long time, but the effects of prestressing applied to concrete structures such as long-span buildings and bridges on ultrasonic pulse velocity have not been studied clearly. Therefore, this study analyzed the statistical distribution of P-wave ultrasonic pulse velocities in reinforced and prestressed concrete slabs of 3000 × 3000 mm with a thickness of 250 mm. In addition, we measured S- and R-waves to identify experimental consistency by statistical analysis using the Kolmogorov-Smirnov goodness-of-fit test. The experimental results show that the P-, S-, and R-wave velocities increased slightly (2-3%) when prestressing was applied. As expected, the S- and R-wave measurements show better statistical reliability and potential for in situ evaluation than the P-wave because they are less sensitive to confinement and boundary conditions. The experimental results in this study can be used when assessing the condition of prestressed concrete structures through the velocities of elastic waves. Young Hak Lee and Taekeun Oh Copyright © 2016 Young Hak Lee and Taekeun Oh. All rights reserved. Stress Analysis of CFG Pile Composite Foundation in Consolidating Saturated Mine Tailings Dam Thu, 08 Sep 2016 12:35:05 +0000 Cement fly-ash gravel (CFG) pile is a widely used ground reinforcement technique. This paper aims to address the mechanical characteristics of CFG composite foundation in consolidating saturated mine tailings (MTs) dam. The field static load tests were employed to explore the bearing capacity of the CFG composite foundation, and finite element (FE) models in three dimensions validated through comparison with experimental results were used to discuss the pile-soil stress distribution and pile-soil stress ratio of the CFG composite foundation. The results indicate that the distribution of earth pressure and pile stress is relatively homogeneous and stable over depth and load, while the development of CFG composite foundation bearing capacity is insufficient, in which the developed bearing capacity of CFG piles is less than 50% of its characteristic value. Additionally, compared with the laboratory model test results, the pile-soil stress ratio decreases with the increasing of the load in FEM results proved to better conform to the actual engineering conditions. Furthermore, the deformation modulus and thickness of cushion exert significant influence on pile-soil stress ratio and integral bearing capacity of CFG composite foundation. Jinxing Lai, Houquan Liu, Junling Qiu, Haobo Fan, Qian Zhang, Zhinan Hu, and Junbao Wang Copyright © 2016 Jinxing Lai et al. All rights reserved. Diagnostics of Corrosion on a Real Bridge Structure Wed, 07 Sep 2016 12:53:18 +0000 Real bridge structures are affected by environmental conditions. The environmental loads in time cause the degradation of concrete and reinforcement. The diagnostics of real state of existing bridges are very important due to actual degradation and corrosion. In the frame of research activities of Department of Structures and Bridges, Civil Engineering Faculty, University of Žilina, the real bridge structure was observed for a few years. It is girder reinforced concrete bridge near town of Žilina in Slovakia. The results of diagnostics which focused on reinforcement corrosion are presented. The paper deals with reinforcement corrosion and its influence on the moment resistance of the existing concrete structures. Peter Koteš, Miroslav Brodňan, and František Bahleda Copyright © 2016 Peter Koteš et al. All rights reserved. Thermodynamic Stability of Ettringite Formed by Hydration of Ye’elimite Clinker Wed, 07 Sep 2016 12:31:49 +0000 In order to save limited natural resources by utilising industrial by-products, this paper focuses on an entirely new application of fluidized bed combustion fly ash (FBCFA) into Portland composite cements. It is not currently used because undesirable ettringite, 3CaO·Al2O3·3CaSO4·32H2O, is formed during the hydration of FBCFA. Although the stability of ettringite has been the subject of much research, the solution is not yet fully clear. Ettringite is generally considered to be stable up to a temperature of 110°C; however, some investigators claimed that ettringite may already decompose at even ambient temperatures. To prove these statements, ettringite was prepared by the hydration of ye’elimite, 3CaO·3Al2O3·CaSO4, and the system stored at laboratory temperature in two environments: in laboratory settings and in an environment of saturated water vapour. The mineralogical composition of ettringite was long term (up to 160 days of hydration) and was analysed by X-ray diffraction (XRD) and differential thermal analysis (DTA). The hydration of ye’elimite is a relatively complex process. Only approximately 30% of ettringite was formed under laboratory conditions that appeared to gradually convert into metaettringite. Within an environment of saturated water vapour, we observed the conversion of ettringite into monosulfate. Original ye’elimite was indicated as the dominant phase of both storages. Marcela Fridrichová, Karel Dvořák, Dominik Gazdič, Jana Mokrá, and Karel Kulísek Copyright © 2016 Marcela Fridrichová et al. All rights reserved. An Experimental Study on the Water-Induced Strength Reduction in Zigong Argillaceous Siltstone with Different Degree of Weathering Mon, 05 Sep 2016 16:21:38 +0000 The water-softening property of soft rocks is a key problem in geotechnical engineering. A typical red-bed soft rock (the Zigong argillaceous siltstones) with different weathering degree is selected as an example to study the water-softening property and the influence of degree of weathering. A series of mechanical and microstructure tests are carried out to analyze the weathering characteristics and mechanism of the Zigong argillaceous siltstones. The results of mechanical experiments reveal that the water content and the weathering degree of rock specimens both have a weakening effect on the compressive and shear strengths. According to the results of present microstructure tests, the mechanical properties of the Zigong argillaceous siltstones are closely correlated with their physical properties, including internal microstructure and material composition for highly weathered rocks or moderately weathered rocks (in both natural and saturation conditions). Finally, experimental results indicate that the changes of microstructure and internal materials are two main factors that influence rock strength parameters after contacting with water and that these properties reflect the rock weathering degree. In a word, when red-bed soft rocks are encountered in geotechnical engineering, special attention should be paid to presence of water. Yu-chuan Yang, Jia-wen Zhou, Fu-gang Xu, and Hui-ge Xing Copyright © 2016 Yu-chuan Yang et al. All rights reserved. Micro Fine Sized Palm Oil Fuel Ash Produced Using a Wind Tunnel Production System Mon, 05 Sep 2016 13:24:15 +0000 Micro fine sized palm oil fuel ash (POFA) is a new supplementary cementitious material that can increase the strength, durability, and workability of concrete. However, production of this material incurs high cost and is not practical for the construction industry. This paper investigates a simple methodology of producing micro fine sized POFA by means of a laboratory scale wind tunnel system. The raw POFA obtained from an oil palm factory is first calcined to remove carbon residue and then grinded in Los Angeles abrasion machine. The grinded POFA is then blown in the fabricated wind tunnel system for separation into different ranges of particle sizes. The physical, morphological, and chemical properties of the micro fine sized POFA were then investigated using Laser Particle Size Analyser (PSA), nitrogen sorption, and Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX). A total of 32.1% micro fine sized POFA were collected from each sample blown, with the size range of 1–10 micrometers. The devised laboratory scale of wind tunnel production system is successful in producing micro fine sized POFA and, with modifications, this system is envisaged applicable to be used to commercialize micro fine sized POFA production for the construction industry. R. Ahmadi, N. Zainudin, I. Ismail, M. A. Mannan, and A. S. Z. Abidin Copyright © 2016 R. Ahmadi et al. All rights reserved. Crack Risk Evaluation of Early Age Concrete Based on the Distributed Optical Fiber Temperature Sensing Thu, 01 Sep 2016 13:43:35 +0000 Cracks often appear in concrete arch dams, due to the thermal stress and low tensile strength of early age concrete. There are three commonly used temperature controlling measures: controlling the casting temperature, burying cooling pipe, and protecting the surface. However, because of the difficulty to obtain accurate temperature and thermal stress field of the concrete, the rationality and economy of these measures are not assessed validly before and after construction. In this paper, a crack risk evaluation system for early age concrete is established, including distributed optical fiber temperature sensing (DTS), prediction of temperature and stress fields, and crack risk evaluation. Based on the DTS temperature data, the back-analysis method is applied to retrieve the thermal parameters of concrete. Then, the temperature and thermal stress of early age concrete are predicted using the reversed thermal parameters, as well as the laboratory test parameters. Finally, under the proposed cracking risk evaluation principle, the cracking risk level of each concrete block is given; the preliminary and later temperature controlling measures were recommended, respectively. The application of the proposed system in Xiluodu super high arch dam shows that this system works effectively for preventing cracks of early age concrete. Nannan Shi, Yanyu Chen, and Zhenbao Li Copyright © 2016 Nannan Shi et al. All rights reserved. Effect of Hot Deformation Temperature on Texture Formation Regularity of CGO Silicon Steel under High Deformation Rate Wed, 31 Aug 2016 16:25:17 +0000 The influence of hot deformation temperature on microstructure and texture of CGO silicon steel under the condition of a high deformation rate (100 ) was studied by SEM and EBSD techniques. The results indicate that the typical microstructures at room temperature consist of ferrite and pearlite under different hot deformation temperatures. The higher deformation temperature is beneficial to obtain a more uniform recrystallization microstructure and lower pearlite content. Cubic texture and rotated cubic texture are dominant texture components in the tested steels, and texture in γ fiber is also strong, the intensity of which is higher than that of texture. Goss texture is weak. With the rising of the hot deformation temperature, texture decreases firstly and then increases at 1100°C. When the hot deformation temperature raises from 800°C to 900°C, texture shows an increasing trend, while texture content is stable. When the temperature further increases to 1100°C and 1150°C, and textures are slightly weakened. Zhi-chao Li, Ning Dang, and Zhen-li Mi Copyright © 2016 Zhi-chao Li et al. All rights reserved. Durability of Steel Fibres Reinforcement Concrete Beams in Chloride Environment Combined with Inhibitor Wed, 31 Aug 2016 11:15:39 +0000 This paper presented the effect of the combination of an inhibitor and steel fibre reinforced concrete (SFRC) for concrete structures in chloride environments. Twelve beams were cast and tested to study their flexural behavior. The morphology of steel surfaces using the inhibitor after observing the scanning electron microscope showed a low layer of corrosion products. The steel surface immersed in the inhibitor free solution was seen to have been subject to chloride ions attacks as shown in this study. The interest to the field of the present study is the relatively higher durability of the performance when using the inhibitor. Crack width and crack spacing for beams under the same load showed that the use of SFRC with the inhibitor for concrete structures in chloride environments must have transferred tension across cracks that led to reducing crack spacing without any chloride ions attack. AbdelMonem Masmoudi and Jamel Bouaziz Copyright © 2016 AbdelMonem Masmoudi and Jamel Bouaziz. All rights reserved.