Showing papers on "Compressive strength published in 2002"
TL;DR: In this article, the properties of FDM parts fabricated by the FDM 1650 were analyzed using a Design of Experiment (DOE) approach, such as raster orientation, air gap, bead width, color and model temperature.
Abstract: Rapid Prototyping (RP) technologies provide the ability to fabricate initial prototypes from various model materials. Stratasys Fused Deposition Modeling (FDM) is a typical RP process that can fabricate prototypes out of ABS plastic. To predict the mechanical behavior of FDM parts, it is critical to understand the material properties of the raw FDM process material, and the effect that FDM build parameters have on anisotropic material properties. This paper characterizes the properties of ABS parts fabricated by the FDM 1650. Using a Design of Experiment (DOE) approach, the process parameters of FDM, such as raster orientation, air gap, bead width, color, and model temperature were examined. Tensile strengths and compressive strengths of directionally fabricated specimens were measured and compared with injection molded FDM ABS P400 material. For the FDM parts made with a 0.003 inch overlap between roads, the typical tensile strength ranged between 65 and 72 percent of the strength of injection molded ABS P400. The compressive strength ranged from 80 to 90 percent of the injection molded FDM ABS. Several build rules for designing FDM parts were formulated based on experimental results.
1,886 citations
TL;DR: In this paper, fly ash, a waste product of the electricity and petrochemical industries, was investigated as a basic ingredient of a new geopolymeric material, which can best be viewed as consisting of a polymeric Si-O-Al framework.
590 citations
TL;DR: A model for compressive stress generation during thin film growth is presented in which the driving force is an increase in the surface chemical potential caused by the deposition of atoms from the vapor.
Abstract: We present a model for compressive stress generation during thin film growth in which the driving force is an increase in the surface chemical potential caused by the deposition of atoms from the vapor. The increase in surface chemical potential induces atoms to flow into the grain boundary, creating a compressive stress in the film. We develop kinetic equations to describe the stress evolution and dependence on growth parameters. The model is used to explain measurements of relaxation when growth is terminated and the dependence of the steady-state stress on growth rate.
415 citations
TL;DR: In this paper, two geopolymer systems were prepared by alkali activation of fly ash and kaolin at room temperature with alkaline silicate solutions, and the strength and durability of the resultant products were examined by comparing the compressive strengths, Fourier transform transmission infrared spectroscopy (FTIR) spectra, X-ray diffraction (XRD) diffractograms and scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS) analysis at different ages.
396 citations
TL;DR: ACI Structural Journal, V. 99, No. 4, July-August 2002 as discussed by the authors, was reviewed under Institute publication policies, and a discussion was published in the May-June 2003 ACI structural journal if received by January 1, 2003.
Abstract: ACI Structural Journal/July-August 2002 ACI Structural Journal, V. 99, No. 4, July-August 2002. MS No. 01-402 received November 27, 2001, and reviewed under Institute publication policies. Copyright © 2002, American Concrete Institute. All rights reserved, including the making of copies unless permission is obtained from the copyright proprietors. Pertinent discussion will be published in the May-June 2003 ACI Structural Journal if received by January 1, 2003. ACI STRUCTURAL JOURNAL TECHNICAL PAPER
365 citations
TL;DR: In this paper, the concept of an efficiency factor is applied as a measure of the relative performance of supplementary cementing materials (SCM) compared with Portland cement, and a mix design strategy to fulfil any requirements for concrete strength and service lifetime was developed and it enables concrete performance to be accurately predicted.
362 citations
TL;DR: In this article, three industrial materials, i.e., fly ash, kaolinite and albite, are selected to investigate various combinations. And the results show that when appropriate reaction parameters are used, the three component system gives geopolymers possessing the highest compressive strength and the lowest probability of cracking.
360 citations
TL;DR: In this paper, the authors investigated the possibility of using recycled aggregates from different sources in Hong Kong, as the replacement of both coarse and fine natural aggregates in molded bricks and blocks.
348 citations
TL;DR: In this paper, the tensile strength of technical fiber bundles was found to depend strongly on the clamping length of the fiber bundles, and the failure behavior of elementary flax fibres under compression can be described as similar to the failure behaviour of a stranded wire.
Abstract: Mechanical properties of standard decorticated and hand isolated flax bast fibres were determined in tension as well as in compression. The tensile strength of technical fibre bundles was found to depend strongly on the clamping length. The tensile strength of elementary flax fibres was found to range between 1500 MPa and 1800 MPa, depending on the isolation procedure. The compressive strength of elementary flax fibres as measured with a loop test lies around 1200 MPa. However, the compressive strength can be lowered severely by the decortication process. The standard decortication process induces kink bands in the fibres. These kink bands are found to contain cracks bridged by microfibrils. The failure behaviour of elementary flax fibres under compression can be described as similar to the failure behaviour of a stranded wire.
343 citations
TL;DR: In this article, the main parameters studied were evolution of compressive strength, products of degradation, and microstructural changes of AAS concrete in a sulfate environment, and two tests were used to determine resistance to sulfate attack, which involved immersion in 5% magnesium sulfate and 5% sodium sulfate solutions.
339 citations
TL;DR: In this article, the authors investigated the relationship between porosity and compressive strength and presented mathematical models that have been developed to describe this relationship and concluded that the equation derived by Hoff could effectively be used to predict the compressive strengths of foamed concrete mixtures containing high percentages of ash.
TL;DR: Many theoretical and experimental studies have been carried out on fiber-reinforced plastic (FRP)-confined circular concrete specimens, leading to a variety of models for predicting their axial com...
Abstract: Many theoretical and experimental studies have been carried out on fiber-reinforced plastic (FRP)-confined circular concrete specimens, leading to a variety of models for predicting their axial com...
TL;DR: Grinding of Y-TZP needs to be optimized to achieve the CAD/CAM manufacture of all-ceramic restorations with improved strength and reliability.
Abstract: Yttria-stabilized zirconia ceramics is a high-performance material with excellent biocompatibility and mechanical properties, which suggest its suitability for posterior fixed partial dentures. The hypothesis under examination is that the strength and reliability of Y-TZP zirconia ceramics are affected by the inner surface grinding of crowns, and vary with the grinding parameter. Flexural strength, surface roughness, and fracture toughness were determined on samples machined by face and peripheral grinding with varied feed velocities and cutting depths. Results have been compared with those on lapped samples. Analysis of variance and Weibull parameter were used for statistical analysis. It was found that inner surface grinding significantly reduces the strength and reliability of Y-TZP zirconia compared with the lapped control sample. Co-analysis of flexural strength, Weibull parameter, and fracture toughness showed counteracting effects of surface compressive stress and grinding-introduced surface flaws. In conclusion, grinding of Y-TZP needs to be optimized to achieve the CAD/CAM manufacture of all-ceramic restorations with improved strength and reliability.
TL;DR: In this paper, a split Hopkinson tension bar was modified for the dynamic tensile stress-strain behavior of the low-strength and low-mechanical-impedance specimens.
TL;DR: In this paper, the effects of inorganic salt addition towards the setting and rheological characteristics of the early pastes of fly ash-based concrete cements were examined using compressive strength, Fourier transform infrared spectroscopy (FTIR) and X-ray diffractograms.
TL;DR: In this article, the authors present a new approach to design concrete mixtures based upon a set of models relating composition and engineering properties of concrete, to be implemented into software, linked with a material database.
TL;DR: In this paper, a model was developed to predict the buckling of platelets in reinforced materials under compressive loading, and a critical strain above which platelet buckling, and hence a reduction in the compressive modulus relative to the tensile modulus, would be expected to occur.
TL;DR: Sfer et al. as mentioned in this paper proposed a method to solve the problem by using the Sfer algorithm, which can be found at the Facultad de Ciencias Exactas and Tecnologia; Argentina
Abstract: Fil: Sfer, Domingo. Universidad Nacional de Tucuman. Facultad de Ciencias Exactas y Tecnologia; Argentina
TL;DR: In this paper, the buckling mechanism of reinforcing bars was investigated using fine element microanalysis using fiber technique and it was found that reinforcing bars under inelastic axial compression exhibit later deformation defined as buckling due to the geometrical nolinearity.
Abstract: Finite element microanalysis using fiber technique was carried out to study the buckling mechanism of reinforcing bars. It was found that reinforcing bars under inelastic axial compression exhibit later deformation defined as buckling due to the geometrical nolinearity. Further investigation revealed that the postbuckling average compressive stress is less than the local stress corresponding to the same strain due to the different striffness for loading and unloading fibers in the laterally deformed section. It was clarified that the average compressive stress-strain relationship including the softening in the postbuckling range can be completely described in terms of the product of square root of yield strength and the slenderness ration of the reinforcing bar. Moreover, a unique relationship between the average stress and average strain of reinforcing bars including the effect of buckling is established through various parametric analyses. The comparison of the analytical results and proposed model with some experimental results showed good agreement, thus verifying the reliability of the microanalysis and proposed computational model.
TL;DR: In this article, a series of experiments were conducted to investigate the effectiveness of fiber inclusion in the improvement of mechanical performance of concrete with regard to concrete type and specimen size, and the experimental findings indicate that the low volume of fibre has little effect on compressive strength but improve remarkably splitting tensile strength, flexural strength and toughness.
TL;DR: In this article, a fuzzy triangular chart for the prediction of uniaxial compressive strength of the Ankara agglomerates from their petrographical composition is suggested.
TL;DR: In this paper, the effects of binder type, binder proportion and tailings properties on compressive strength development of paste backfill during the course of curing time were investigated.
TL;DR: In this paper, the Schmidt hammer has been used worldwide as an index test for a quick rock strength and deformability characterisation due to its rapidity and easiness in execution, simplicity, portability, low cost and nondestructiveness.
TL;DR: In this paper, a parametric study was carried out to identify the specific effects of each type of cement, namely, Portland cement, gypsum, and calcite, on the engineering behavior of calcareous soil under triaxial loading.
Abstract: There is little information in the geotechnical literature regarding the influence of the type of cement on the engineering behavior of cemented soils. This paper explores the mechanical behavior of a calcareous soil under triaxial loading after treatment with different types of cement, namely Portland cement, gypsum, and calcite. To identify the specific effects of each cement type a parametric study was undertaken, where factors such as density and unconfined compressive strength were maintained constant for each cementing agent. Samples of the cemented soil were examined under optical and electron microscopy to understand the bond mechanism created by each cement. Results from triaxial testing have shown that, despite having the same unconfined compressive strength and density, the effective stress paths and postyield response are significantly different, mainly because of the different volumetric response upon shearing. Samples prepared using Portland cement showed ductile yield and strong dilation afterwards; calcite and gypsum-cemented samples exhibited brittle yield, generally followed by contractive behavior. The paper discusses the results and explains the reasons behind the differences in the mechanical response.
TL;DR: In this article, the effect of crushed sand on high-strength concrete has been analyzed using three different types of crushed sands (granite, limestone and dolomite) with similar grading.
TL;DR: In this paper, the behavior of concrete-filled tube columns under seismic loads was studied by testing six columns which were subjected to a constant axial load in addition to a cyclic lateral load.
TL;DR: In this article, the ash-portland cement mixture has been evaluated with respect to setting time, workability and compressive strength with a pozzolanic index value of 75.9%.
Abstract: Sawdust is a waste product from the timber industry. Research work carried out on the ash derived from the sawdust has confirmed its pozzolanic properties with a pozzolanic index value of 75.9%. This material compares favourably with fly ash and wastes from the oil palm industry. The only difference noticed is in the low content of Al 2 O 3 (4.09%) and Fe 2 O 3 (2.26%). Concrete mixes have been proportioned to have various percentages of cement replacement with sawdust ash (SDA) ranging from 0% to 30% by mass. Performance of the ash–portland cement mixture has been evaluated with respect to setting time, workability and compressive strength. From the results obtained, 10% replacement of cement with SDA shows good performance giving the desired workability and strength.
TL;DR: In this paper, the usability of Basic Oxygen Process (BOP) slags of Kardemir Iron and Steel Plant, Karabuk, Turkey as an additive into cement was investigated.
TL;DR: This study investigates whether compaction significantly alters the specific surface area and pore-size distribution of CPC prepared according to the method of Brown and Chow, which resulted in an increase in the wet compressive strength.
Abstract: Hydroxyapatite (HA) calcium phosphate cements (CPCs) are attractive materials for orthopedic applications because they can be molded into shape during implantation. However their low strength and brittle nature limits their potential applications to principally non-load-bearing applications. Little if any use has been made of the HA cement systems as manufacturing routes for preset HA bone grafts, which although not moldable pastes, are resorbable, unlike HA sintered ceramic. It is known that the strength of cements can be increased beyond that attainable from slurry systems by compaction, and this study investigates whether compaction significantly alters the specific surface area and pore-size distribution of CPC prepared according to the method of Brown and Chow. Compaction pressures of between 18 and 106 MPa were used to decrease the porosity from 50 to 31%, which resulted in an increase in the wet compressive strength from 4 to 37 MPa. The Weibull modulus was found to increase as porosity decreased; in addition the amount of porosity larger than the reactant particle size increased as porosity decreased. It is proposed that this was caused by a combination of voids created by the aqueous solvent used in fabrication and shrinkage that occurs on reaction. The specific surface area was unchanged by compaction.
TL;DR: In this article, binary and ternary blended cementitious systems based on ordinary Portland cement (OPC), pulverised fuel ash (PFA), and silica fume (SF) were investigated.