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Materials, Volume 9, Issue 5 (May 2016)

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Cover Story (view full-size image) The Gibson–Ashby relation for porous materials has been used for over 20 years to infer the elastic [...] Read more.
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Open AccessArticle Phase Changes of Monosulfoaluminate in NaCl Aqueous Solution
Materials 2016, 9(5), 401; https://doi.org/10.3390/ma9050401
Received: 4 May 2016 / Revised: 16 May 2016 / Accepted: 16 May 2016 / Published: 21 May 2016
Cited by 6 | PDF Full-text (2608 KB) | HTML Full-text | XML Full-text
Abstract
Monosulfoaluminate (Ca4Al2(SO4)(OH)12∙6H2O) plays an important role in anion binding in Portland cement by exchanging its original interlayer ions (SO42− and OH) with chloride ions. In this study, scanning transmission
[...] Read more.
Monosulfoaluminate (Ca4Al2(SO4)(OH)12∙6H2O) plays an important role in anion binding in Portland cement by exchanging its original interlayer ions (SO42− and OH) with chloride ions. In this study, scanning transmission X-ray microscope (STXM), X-ray absorption near edge structure (XANES) spectroscopy, and X-ray diffraction (XRD) were used to investigate the phase change of monosulfoaluminate due to its interaction with chloride ions. Pure monosulfoaluminate was synthesized and its powder samples were suspended in 0, 0.1, 1, 3, and 5 M NaCl solutions for seven days. At low chloride concentrations, a partial dissolution of monosulfoaluminate formed ettringite, while, with increasing chloride content, the dissolution process was suppressed. As the NaCl concentration increased, the dominant mechanism of the phase change became ion exchange, resulting in direct phase transformation from monosulfoaluminate to Kuzel’s salt or Friedel’s salt. The phase assemblages of the NaCl-reacted samples were explored using thermodynamic calculations and least-square linear combination (LC) fitting of measured XANES spectra. A comprehensive description of the phase change and its dominant mechanism are discussed. Full article
(This article belongs to the Section Advanced Composites)
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Open AccessArticle Water Uptake Behavior and Young Modulus Prediction of Composites Based on Treated Sisal Fibers and Poly(Lactic Acid)
Materials 2016, 9(5), 400; https://doi.org/10.3390/ma9050400
Received: 19 February 2016 / Revised: 11 May 2016 / Accepted: 17 May 2016 / Published: 21 May 2016
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Abstract
The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed
[...] Read more.
The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed the water absorption of fibers only for a short time of period. No significant differences were observed in water uptake profiles of composites based on fibers with different surface treatments. After water uptake period, tensile strength and Young modulus values of sisal fiber/poly(lactic acid) (PLA) composites were decreased. On the other hand, composites based on NaOH + silane treated fibers showed the lowest diffusion coefficient values, suggesting that this treatment seemed to be the most effective treatment to reduce water diffusion rate into the composites. Finally, Young modulus values of composites, before water uptake period, were predicted using different micromechanical models and were compared with experimental data. Full article
(This article belongs to the Special Issue Advances in Functionalization of Lignocellulosic Materials)
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Open AccessArticle Experimental and Numerical Evaluation of the Mechanical Behavior of Strongly Anisotropic Light-Weight Metallic Fiber Structures under Static and Dynamic Compressive Loading
Materials 2016, 9(5), 398; https://doi.org/10.3390/ma9050398
Received: 2 February 2016 / Revised: 11 May 2016 / Accepted: 13 May 2016 / Published: 21 May 2016
Cited by 3 | PDF Full-text (23863 KB) | HTML Full-text | XML Full-text
Abstract
Rigid metallic fiber structures made from a variety of different metals and alloys have been investigated mainly with regard to their functional properties such as heat transfer, pressure drop, or filtration characteristics. With the recent advent of aluminum and magnesium-based fiber structures, the
[...] Read more.
Rigid metallic fiber structures made from a variety of different metals and alloys have been investigated mainly with regard to their functional properties such as heat transfer, pressure drop, or filtration characteristics. With the recent advent of aluminum and magnesium-based fiber structures, the application of such structures in light-weight crash absorbers has become conceivable. The present paper therefore elucidates the mechanical behavior of rigid sintered fiber structures under quasi-static and dynamic loading. Special attention is paid to the strongly anisotropic properties observed for different directions of loading in relation to the main fiber orientation. Basically, the structures show an orthotropic behavior; however, a finite thickness of the fiber slabs results in moderate deviations from a purely orthotropic behavior. The morphology of the tested specimens is examined by computed tomography, and experimental results for different directions of loading as well as different relative densities are presented. Numerical calculations were carried out using real structural data derived from the computed tomography data. Depending on the direction of loading, the fiber structures show a distinctively different deformation behavior both experimentally and numerically. Based on these results, the prevalent modes of deformation are discussed and a first comparison with an established polymer foam and an assessment of the applicability of aluminum fiber structures in crash protection devices is attempted. Full article
(This article belongs to the Special Issue Metal Foams: Synthesis, Characterization and Applications)
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Open AccessArticle Titanium Carbide Nanofibers-Reinforced Aluminum Compacts, a New Strategy to Enhance Mechanical Properties
Materials 2016, 9(5), 399; https://doi.org/10.3390/ma9050399
Received: 8 March 2016 / Revised: 11 May 2016 / Accepted: 18 May 2016 / Published: 20 May 2016
Cited by 3 | PDF Full-text (11759 KB) | HTML Full-text | XML Full-text
Abstract
TiC nanofibers reinforced Al matrix composites were produced by High Frequency Induction Heat Sintering (HFIHS).The titanium carbide nanofibers with an average diameter of 90 nm are first prepared by electrospinning technique and high temperature calcination process. A composite solution containing polyacrylonitrile and titanium
[...] Read more.
TiC nanofibers reinforced Al matrix composites were produced by High Frequency Induction Heat Sintering (HFIHS).The titanium carbide nanofibers with an average diameter of 90 nm are first prepared by electrospinning technique and high temperature calcination process. A composite solution containing polyacrylonitrile and titanium isopropoxide is first electrospun into the nanofibers, which are subsequently stabilized and then calcined to produce the desired TiC nanofibers. The X-ray diffraction pattern and transmission electron microscopy results show that the main phase of the as-synthesized nanofibers is titanium carbide. The TiC nanofibers is then mixed with the aluminum powders and introduced into high frequency induction heat sintering (HFIHS) to produce composites of TiC nanofibers reinforced aluminum matrix. The potential application of the TiC nanofibers reinforced aluminum matrix composites was systematically investigated. 99.5% relative density and around 85 HV (833 MPa) Vickers hardness of the Al reinforced with 5 wt % TiC nanofiber has been obtained. Furthermore, the sample of Al contains 5 wt % TiC, has the highest value of compression and yield strength of about 415 and 350 MPa, respectively. The ductility of the Al/5 wt % TiC showed increasing with increasing the TiC contents. Full article
(This article belongs to the Section Advanced Composites)
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Open AccessArticle Gold Nanoparticle-Mediated Delivery of Molecules into Primary Human Gingival Fibroblasts Using ns-Laser Pulses: A Pilot Study
Materials 2016, 9(5), 397; https://doi.org/10.3390/ma9050397
Received: 24 March 2016 / Revised: 4 May 2016 / Accepted: 16 May 2016 / Published: 20 May 2016
Cited by 2 | PDF Full-text (4769 KB) | HTML Full-text | XML Full-text
Abstract
Interaction of gold nanoparticles (AuNPs) in the vicinity of cells’ membrane with a pulsed laser (λ = 532 nm, τ = 1 ns) leads to perforation of the cell membrane, thereby allowing extracellular molecules to diffuse into the cell. The objective of this
[...] Read more.
Interaction of gold nanoparticles (AuNPs) in the vicinity of cells’ membrane with a pulsed laser (λ = 532 nm, τ = 1 ns) leads to perforation of the cell membrane, thereby allowing extracellular molecules to diffuse into the cell. The objective of this study was to develop an experimental setting to deliver molecules into primary human gingival fibroblasts (pHFIB-G) by using ns-laser pulses interacting with AuNPs (study group). To compare the parameters required for manipulation of pHFIB-G with those needed for cell lines, a canine pleomorphic adenoma cell line (ZMTH3) was used (control group). Non-laser-treated cells incubated with AuNPs and the delivery molecules served as negative control. Laser irradiation (up to 35 mJ/cm2) resulted in a significant proportion of manipulated fibroblasts (up to 85%, compared to non-irradiated cells: p < 0.05), while cell viability (97%) was not reduced significantly. pHFIB-G were perforated as efficiently as ZMTH3. No significant decrease of metabolic cell activity was observed up to 72 h after laser treatment. The fibroblasts took up dextrans with molecular weights up to 500 kDa. Interaction of AuNPs and a pulsed laser beam yields a spatially selective technique for manipulation of even primary cells such as pHFIB-G in high throughput. Full article
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Open AccessArticle Modeling of Compressive Strength for Self-Consolidating High-Strength Concrete Incorporating Palm Oil Fuel Ash
Materials 2016, 9(5), 396; https://doi.org/10.3390/ma9050396
Received: 13 March 2016 / Revised: 4 May 2016 / Accepted: 12 May 2016 / Published: 20 May 2016
Cited by 5 | PDF Full-text (704 KB) | HTML Full-text | XML Full-text
Abstract
Modeling is a very useful method for the performance prediction of concrete. Most of the models available in literature are related to the compressive strength because it is a major mechanical property used in concrete design. Many attempts were taken to develop suitable
[...] Read more.
Modeling is a very useful method for the performance prediction of concrete. Most of the models available in literature are related to the compressive strength because it is a major mechanical property used in concrete design. Many attempts were taken to develop suitable mathematical models for the prediction of compressive strength of different concretes, but not for self-consolidating high-strength concrete (SCHSC) containing palm oil fuel ash (POFA). The present study has used artificial neural networks (ANN) to predict the compressive strength of SCHSC incorporating POFA. The ANN model has been developed and validated in this research using the mix proportioning and experimental strength data of 20 different SCHSC mixes. Seventy percent (70%) of the data were used to carry out the training of the ANN model. The remaining 30% of the data were used for testing the model. The training of the ANN model was stopped when the root mean square error (RMSE) and the percentage of good patterns was 0.001 and ≈100%, respectively. The predicted compressive strength values obtained from the trained ANN model were much closer to the experimental values of compressive strength. The coefficient of determination (R2) for the relationship between the predicted and experimental compressive strengths was 0.9486, which shows the higher degree of accuracy of the network pattern. Furthermore, the predicted compressive strength was found very close to the experimental compressive strength during the testing process of the ANN model. The absolute and percentage relative errors in the testing process were significantly low with a mean value of 1.74 MPa and 3.13%, respectively, which indicated that the compressive strength of SCHSC including POFA can be efficiently predicted by the ANN. Full article
(This article belongs to the Section Advanced Composites)
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Open AccessArticle Effect of Na3PO4 on the Hydration Process of Alkali-Activated Blast Furnace Slag
Materials 2016, 9(5), 395; https://doi.org/10.3390/ma9050395
Received: 13 April 2016 / Revised: 6 May 2016 / Accepted: 17 May 2016 / Published: 20 May 2016
Cited by 6 | PDF Full-text (1852 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, the utilization of different non-traditional cements and composites has been increasing. Alkali-activated cementitious materials, especially those based on the alkali activation of blast furnace slag, have considerable potential for utilization in the building industry. However, alkali-slag cements exhibit very rapid
[...] Read more.
In recent years, the utilization of different non-traditional cements and composites has been increasing. Alkali-activated cementitious materials, especially those based on the alkali activation of blast furnace slag, have considerable potential for utilization in the building industry. However, alkali-slag cements exhibit very rapid setting times, which are too short in some circumstances, and these materials cannot be used for some applications. Therefore, it is necessary to find a suitable retarding admixture. It was shown that the sodium phosphate additive has a strong effect on the heat evolution during alkali activation and effectively retards the hydration reaction of alkali-activated blast furnace slag. The aim of the work is the suggestion of a reaction mechanism of retardation mainly based on Raman and X‑ray photoelectron spectroscopy. Full article
(This article belongs to the Special Issue Advances in Geopolymers and Alkali-Activated Materials)
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Open AccessArticle Insulation Cork Boards—Environmental Life Cycle Assessment of an Organic Construction Material
Materials 2016, 9(5), 394; https://doi.org/10.3390/ma9050394
Received: 25 February 2016 / Revised: 6 May 2016 / Accepted: 13 May 2016 / Published: 20 May 2016
Cited by 4 | PDF Full-text (1354 KB) | HTML Full-text | XML Full-text
Abstract
Envelope insulation is a relevant technical solution to cut energy consumption and reduce environmental impacts in buildings. Insulation Cork Boards (ICB) are a natural thermal insulation material whose production promotes the recycling of agricultural waste. The aim of this paper is to determine
[...] Read more.
Envelope insulation is a relevant technical solution to cut energy consumption and reduce environmental impacts in buildings. Insulation Cork Boards (ICB) are a natural thermal insulation material whose production promotes the recycling of agricultural waste. The aim of this paper is to determine and evaluate the environmental impacts of the production, use, and end-of-life processing of ICB. A “cradle-to-cradle” environmental Life Cycle Assessment (LCA) was performed according to International LCA standards and the European standards on the environmental evaluation of buildings. These results were based on site-specific data and resulted from a consistent methodology, fully described in the paper for each life cycle stage: Cork oak tree growth, ICB production, and end-of-life processing-modeling of the carbon flows (i.e., uptakes and emissions), including sensitivity analysis of this procedure; at the production stage—the modeling of energy processes and a sensitivity analysis of the allocation procedures; during building operation—the expected service life of ICB; an analysis concerning the need to consider the thermal diffusivity of ICB in the comparison of the performance of insulation materials. This paper presents the up-to-date “cradle-to-cradle” environmental performance of ICB for the environmental categories and life-cycle stages defined in European standards. Full article
(This article belongs to the Section Biomaterials)
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Open AccessArticle Contrastive Numerical Investigations on Thermo-Structural Behaviors in Mass Concrete with Various Cements
Materials 2016, 9(5), 378; https://doi.org/10.3390/ma9050378
Received: 23 March 2016 / Revised: 11 May 2016 / Accepted: 12 May 2016 / Published: 20 May 2016
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Abstract
This work is a contrastive investigation of numerical simulations to improve the comprehension of thermo-structural coupled phenomena of mass concrete structures during construction. The finite element (FE) analysis of thermo-structural behaviors is used to investigate the applicability of supersulfated cement (SSC) in mass
[...] Read more.
This work is a contrastive investigation of numerical simulations to improve the comprehension of thermo-structural coupled phenomena of mass concrete structures during construction. The finite element (FE) analysis of thermo-structural behaviors is used to investigate the applicability of supersulfated cement (SSC) in mass concrete structures. A multi-scale framework based on a homogenization scheme is adopted in the parameter studies to describe the nonlinear concrete behaviors. Based on the experimental data of hydration heat evolution rate and quantity of SSC and fly ash Portland cement, the hydration properties of various cements are studied. Simulations are run on a concrete dam section with a conventional method and a chemo-thermo-mechanical coupled method. The results show that SSC is more suitable for mass concrete structures from the standpoint of temperature control and crack prevention. Full article
(This article belongs to the Section Structure Analysis and Characterization)
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Open AccessArticle Investigation on Polylactide (PLA)/Poly(butylene adipate-co-terephthalate) (PBAT)/Bark Flour of Plane Tree (PF) Eco-Composites
Materials 2016, 9(5), 393; https://doi.org/10.3390/ma9050393
Received: 4 April 2016 / Revised: 13 May 2016 / Accepted: 16 May 2016 / Published: 19 May 2016
Cited by 2 | PDF Full-text (8316 KB) | HTML Full-text | XML Full-text
Abstract
Polylactide (PLA)/poly(butylene adipate-co-terephthalate) (PBAT)/bark flour of plane tree (PF) eco-composites were prepared via melt blending. The morphologies, mechanical properties, crystal structures and melting and crystallization behaviors of the eco-composites were investigated by means of scanning electron microscopy (SEM), mechanical tests, polarized light microscopy
[...] Read more.
Polylactide (PLA)/poly(butylene adipate-co-terephthalate) (PBAT)/bark flour of plane tree (PF) eco-composites were prepared via melt blending. The morphologies, mechanical properties, crystal structures and melting and crystallization behaviors of the eco-composites were investigated by means of scanning electron microscopy (SEM), mechanical tests, polarized light microscopy (PLM), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC), respectively. It is shown that the interfacial adhesion between PLA matrix and PF is weak and the mechanical properties of PLA/PF eco-composites are poor. The titanate treatment improves the adhesion between the matrix and the filler and enhances the stiffness of the eco-composites. The toughness is improved by PBAT and ductile fractured surfaces can be found. The spherulitic size of PLA is decreased by the addition of PF. The α crystalline form of PLA remains in the composites. Compared with PF, T-PF (PF treated by a titanate coupling agent) and PBAT have negative effects on the crystallization of PLA. Full article
(This article belongs to the Special Issue Polymer Blends and Compatibilization) Printed Edition available
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Open AccessArticle Optimising Ambient Setting Bayer Derived Fly Ash Geopolymers
Materials 2016, 9(5), 392; https://doi.org/10.3390/ma9050392
Received: 11 April 2016 / Revised: 5 May 2016 / Accepted: 11 May 2016 / Published: 19 May 2016
Cited by 1 | PDF Full-text (2156 KB) | HTML Full-text | XML Full-text
Abstract
The Bayer process utilises high concentrations of caustic and elevated temperature to liberate alumina from bauxite, for the production of aluminium and other chemicals. Within Australia, this process results in 40 million tonnes of mineral residues (Red mud) each year. Over the same
[...] Read more.
The Bayer process utilises high concentrations of caustic and elevated temperature to liberate alumina from bauxite, for the production of aluminium and other chemicals. Within Australia, this process results in 40 million tonnes of mineral residues (Red mud) each year. Over the same period, the energy production sector will produce 14 million tonnes of coal combustion products (Fly ash). Both industrial residues require impoundment storage, yet combining some of these components can produce geopolymers, an alternative to cement. Geopolymers derived from Bayer liquor and fly ash have been made successfully with a compressive strength in excess of 40 MPa after oven curing. However, any product from these industries would require large volume applications with robust operational conditions to maximise utilisation. To facilitate potential unconfined large-scale production, Bayer derived fly ash geopolymers have been optimised to achieve ambient curing. Fly ash from two different power stations have been successfully trialled showing the versatility of the Bayer liquor-ash combination for making geopolymers. Full article
(This article belongs to the Special Issue Advances in Geopolymers and Alkali-Activated Materials)
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Open AccessArticle The Structure and Mechanical Properties of High-Strength Bulk Ultrafine-Grained Cobalt Prepared Using High-Energy Ball Milling in Combination with Spark Plasma Sintering
Materials 2016, 9(5), 391; https://doi.org/10.3390/ma9050391
Received: 8 March 2016 / Revised: 29 April 2016 / Accepted: 13 May 2016 / Published: 19 May 2016
Cited by 5 | PDF Full-text (2874 KB) | HTML Full-text | XML Full-text
Abstract
In this study, bulk ultrafine-grained and micro-crystalline cobalt was prepared using a combination of high-energy ball milling and subsequent spark plasma sintering. The average grain sizes of the ultrafine-grained and micro-crystalline materials were 200 nm and 1 μm, respectively. Mechanical properties such as
[...] Read more.
In this study, bulk ultrafine-grained and micro-crystalline cobalt was prepared using a combination of high-energy ball milling and subsequent spark plasma sintering. The average grain sizes of the ultrafine-grained and micro-crystalline materials were 200 nm and 1 μm, respectively. Mechanical properties such as the compressive yield strength, the ultimate compressive strength, the maximum compressive deformation and the Vickers hardness were studied and compared with those of a coarse-grained as-cast cobalt reference sample. The bulk ultrafine-grained sample showed an ultra-high compressive yield strength that was greater than 1 GPa, which is discussed with respect to the preparation technique and a structural investigation. Full article
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Open AccessArticle Influence of Hybridizing Flax and Hemp-Agave Fibers with Glass Fiber as Reinforcement in a Polyurethane Composite
Materials 2016, 9(5), 390; https://doi.org/10.3390/ma9050390
Received: 31 March 2016 / Revised: 6 May 2016 / Accepted: 13 May 2016 / Published: 19 May 2016
Cited by 1 | PDF Full-text (8324 KB) | HTML Full-text | XML Full-text
Abstract
In this study, six combinations of flax, hemp, and glass fiber were investigated for a hybrid reinforcement system in a polyurethane (PU) composite. The natural fibers were combined with glass fibers in a PU composite in order to achieve a better mechanical reinforcement
[...] Read more.
In this study, six combinations of flax, hemp, and glass fiber were investigated for a hybrid reinforcement system in a polyurethane (PU) composite. The natural fibers were combined with glass fibers in a PU composite in order to achieve a better mechanical reinforcement in the composite material. The effect of fiber hybridization in PU composites was evaluated through physical and mechanical properties such as water absorption (WA), specific gravity (SG), coefficient of linear thermal expansion (CLTE), flexural and compression properties, and hardness. The mechanical properties of hybridized samples showed mixed trends compared to the unhybridized samples, but hybridization with glass fiber reduced water absorption by 37% and 43% for flax and hemp-agave PU composites respectively. Full article
(This article belongs to the Special Issue Bio- and Natural-Fiber Composites)
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Open AccessFeature PaperArticle Determination of Specific Heat Capacity on Composite Shape-Stabilized Phase Change Materials and Asphalt Mixtures by Heat Exchange System
Materials 2016, 9(5), 389; https://doi.org/10.3390/ma9050389
Received: 9 March 2016 / Revised: 6 May 2016 / Accepted: 16 May 2016 / Published: 19 May 2016
Cited by 3 | PDF Full-text (2539 KB) | HTML Full-text | XML Full-text
Abstract
Previous research has shown that composite shape-stabilized phase change material (CPCM) has a remarkable capacity for thermal storage and stabilization, and it can be directly applied to highway construction without leakage. However, recent studies on temperature changing behaviors of CPCM and asphalt mixture
[...] Read more.
Previous research has shown that composite shape-stabilized phase change material (CPCM) has a remarkable capacity for thermal storage and stabilization, and it can be directly applied to highway construction without leakage. However, recent studies on temperature changing behaviors of CPCM and asphalt mixture cannot intuitively reflect the thermoregulation mechanism and efficiency of CPCM on asphalt mixture. The objective of this paper is to determine the specific heat capacity of CPCM and asphalt mixtures mixed with CPCM using the heat exchange system and the data acquisition system. Studies have shown that the temperature-rise curve of 5 °C CPCM has an obvious temperature plateau, while an asphalt mixture mixed with 5 °C CPCM does not; with increasing temperature, the specific heat capacities of both 5 °C CPCM and asphalt mixture first increase and then decrease, while the variation rate of 5 °C CPCM is larger than that of the asphalt mixture, and the maximum specific heat capacity of 5 °C CPCM appears around the initial phase change temperature. It is concluded that the temperature intervals of 5 °C CPCM are −18 °C–7 °C, 7 °C–25 °C and 25 °C–44 °C, respectively, and that of the asphalt mixture are −18 °C~10 °C, −10 °C~5 °C and 5 °C~28 °C. A low dosage of 5 °C CPCM has little influence on the specific heat capacity of asphalt mixture. Finally, the functions of specific heat capacities and temperature for CPCM and asphalt mixture mixed with CPCM were recommended by the sectional regression method. Full article
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Open AccessCommunication Evaluation of Microstructure and Transport Properties of Deteriorated Cementitious Materials from Their X-ray Computed Tomography (CT) Images
Materials 2016, 9(5), 388; https://doi.org/10.3390/ma9050388
Received: 14 February 2016 / Revised: 10 May 2016 / Accepted: 11 May 2016 / Published: 19 May 2016
Cited by 7 | PDF Full-text (5197 KB) | HTML Full-text | XML Full-text
Abstract
Pore structure, tortuosity and permeability are considered key properties of porous materials such as cement pastes to understand their long-term durability performance. Three-dimensional image analysis techniques were used in this study to quantify pore size, effective porosity, tortuosity, and permeability from the X-ray
[...] Read more.
Pore structure, tortuosity and permeability are considered key properties of porous materials such as cement pastes to understand their long-term durability performance. Three-dimensional image analysis techniques were used in this study to quantify pore size, effective porosity, tortuosity, and permeability from the X-ray computed tomography (CT) images of deteriorated pastes that were subjected to accelerated leaching test. X-ray microtomography is a noninvasive three-dimensional (3D) imaging technique which has been recently gaining attention for material characterization. Coupled with 3D image analysis, the digitized pore can be extracted and computational simulation can be applied to the pore network to measure relevant microstructure and transport properties. At a spatial resolution of 0.50 μm, the effective porosity (ψe) was found to be in the range of 0.04 to 0.33. The characteristic pore size (d) using a local thickness algorithm was found to be in the range of 3 to 7 μm. The geometric tortuosity (τg) based on a 3D random walk simulation in the percolating pore space was found to be in the range of 2.00 to 7.45. The water permeability values (K) using US NIST Permeability Stokes Solver range from an order of magnitudes of 10−14 to 10−17 m2. Indications suggest that as effective porosity increases, the geometric tortuosity increases and the permeability decreases. Correlation among these microstructure and transport parameters is also presented in this study. Full article
(This article belongs to the Special Issue Image Analysis and Processing for Cement-based Materials)
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