Showing papers on "Compressive strength published in 2003"
TL;DR: In this article, the authors investigated the fracture behavior of a Zr59Cu20Al10Ni8Ti3 bulk metallic glass under compressive and tensile deformation, and found that the fracture is mainly localized on one major shear band and the compressive fracture angle between the stress axis and the fracture plane is 43degrees.
808 citations
TL;DR: In this article, the authors examined the application of split Hopkinson pressure bar (SHPB) to determine the dynamic strength of concrete-like materials whose compressive strength is hydrostatic-stress-dependent and showed that the apparent dynamic strength enhancement beyond the strain-rate of 102 s−1 is strongly influenced by the hydrostatic stress effect due to the lateral inertia confinement in a SHPB test.
541 citations
TL;DR: In this article, the influence of recycled aggregate on interfacial transition zone (ITZ), strength, chloride penetration, and carbonation of concrete is examined, and a double-mixing method is proposed to improve the strength, penetration depth, and resistance to carbonation.
Abstract: This study is conducted (1) to examine the influence of recycled aggregate on interfacial transition zone (ITZ), strength, chloride penetration, and carbonation of concrete, and (2) to propose a method for improving strength, chloride penetration, and carbonation resistances of concrete using recycled aggregates Five types of recycled aggregate, and four levels of water-binder ratio are used in this study The recycled aggregate concrete is evaluated according to compressive strength, tensile strength, chloride penetration depth, and carbonation depth The characteristics of ITZs in recycled aggregate concrete are also measured and used to explain the influence of recycled aggregate on the mentioned properties Additionally, the double-mixing method for improving strength, chloride penetration, and carbonation resistances of recycled aggregate concrete is evaluated in this study
513 citations
TL;DR: In this paper, a simple design-oriented stress-strain model for FRP-confined concrete in rectangular columns is presented, which is an extension of a recent design-driven model developed for concrete uniformly-constructed with FRP based on test results of circular concrete specimens.
Abstract: The behavior of fiber reinforced polymer (FRP)-confined concrete in circular columns has been extensively studied, but much less is known about concrete in FRP-confined rectangular columns in which the concrete is nonuniformly confined and the effectiveness of confinement is much reduced. This paper presents a simple design-oriented stress-strain model for FRP-confined concrete in rectangular columns. To this end, existing theoretical models are first reviewed. A database of existing test results collected by the authors is next presented, which is then augmented by a new set of results from tests conducted by the authors. The augmented test database is next employed to assess the existing theoretical models. Finally, a stress-strain model is presented, which is an extension of a recent design-oriented stress-strain model developed for concrete uniformly-confined with FRP based on test results of circular concrete specimens. The proposed stress-strain model is shown to provide satisfactory predictions of ...
510 citations
TL;DR: In this paper, a pervious concrete pavement material used for roadway is introduced, which consists of a surface layer and a base layer, and compressive strength of the composite can reach 50 MPa and the flexural strength 6 MPa.
484 citations
TL;DR: Atomistic simulations are used to study a surface-stress-induced phase transformation in gold nanowires and show how the emergence of the transformation is controlled by wire size, initial orientation, boundary conditions, temperature and initial cross-sectional shape.
Abstract: Several researchers have demonstrated, through experiments and analysis, that the structure and properties of nanometre-scale materials can be quite different to those of bulk materials due to the effect of surfaces. Here we use atomistic simulations to study a surface-stress-induced phase transformation in gold nanowires. The emergence of the transformation is controlled by wire size, initial orientation, boundary conditions, temperature and initial cross-sectional shape. For a initial crystal orientation and wire cross-sectional area below 4 nm(2), surface stresses alone cause gold nanowires to transform from a face-centred-cubic structure to a body-centred-tetragonal structure. The transformation occurs roughly when the compressive stress caused by tensile surface-stress components in the length direction exceeds the compressive stress required to transform bulk gold to its higher energy metastable crystal structure.
479 citations
TL;DR: In this article, the authors investigated the durability of AAS concrete in acid environments and found that it had a high resistance in acid environment, superior to OPC concrete of similar grade.
460 citations
TL;DR: In this paper, three types of hybrid composites were constructed using fiber combinations of polypropylene (PP) and carbon, carbon and steel, and steel and PP fibers at the same volume fraction (0.5%) in terms of compressive, splitting tensile, and flexural properties.
460 citations
TL;DR: In this article, the mechanical properties of ice and snow are reviewed and the strength and fracture toughness of snow are compared to those of ice, and the fracture-initiating flaw sizes in snow appear to correlate to the snow cell size.
Abstract: The mechanical properties of ice and snow are reviewed. The tensile strength of ice varies from 0.7–3.1 MPa and the compressive strength varies from 5–25 MPa over the temperature range −10°C to −20°C. The ice compressive strength increases with decreasing temperature and increasing strain rate, but ice tensile strength is relatively insensitive to these variables. The tensile strength of ice decreases with increasing ice grain size. The strength of ice decreases with increasing volume, and the estimated Weibull modulus is 5. The fracture toughness of ice is in the range of 50–150 kPa m1/2 and the fracture-initiating flaw size is similar to the grain size. Ice-soil composite mixtures are both stronger and tougher than ice alone. Snow is a open cellular form of ice. Both the strength and fracture toughness of snow are substantially lower than those of ice. Fracture-initiating flaw sizes in snow appear to correlate to the snow cell size.
420 citations
TL;DR: In this article, the compressive strength for concrete mixtures was calculated in MPa per kg of Portland cement and the results showed that the pozzolanic and physical effects have increased as the mineral addition increased in the mixture.
Abstract: Pozzolans play an important role when added to Portland cement because they usually increase the mechanical strength and durability of concrete structures. The most important effects in the cementitious paste microstructure are changes in pore structure produced by the reduction in the grain size caused by the pozzolanic reactions pozzolanic effect (PE) and the obstruction of pores and voids by the action of the finer grains (physical or filler effect). Few published investigations quantify these two effects. Twelve concrete mixtures were tested in this study: one with Portland cement (control), nine mixtures with 12.5%, 25% and 50% of replacement of cement by fly ash, rice husk ash and limestone filler; two with (12.5+12.5)% and (25+25)% of fly ash and rice husk ash. All the mixtures were prepared with water/binder ratios of 0.35, 0.50, and 0.65. The compressive strength for the samples was calculated in MPa per kg of cement. The remaining contents of calcium hydroxide and combined water were also tested. The results show that the pozzolanic and physical effects have increased as the mineral addition increased in the mixture, being higher after 91 days than after 28 days. When the results for the same strength values are compared (35 and 65 MPa), it was observed that the filler effect (FE) increased more than the pozzolanic effect. The PE was stronger in the binary and ternary mixtures prepared with rice husk ash in proportions of 25% or higher.
417 citations
TL;DR: In this paper, the compressive strength of amorphous aluminosilicate polymers produced by sodium silicate activation of metakaolinite were studied, with particular reference to chemical optimisation of the Compressive strength according to the relative concentrations of Si, Al and Na in the polymer.
Abstract: High strength cements can be synthesised by alkali activation of materials rich in Al2O3 and SiO2. In this study, amorphous aluminosilicate polymers produced by sodium silicate activation of metakaolinite were studied, with particular reference to chemical optimisation of the compressive strength according to the relative concentrations of Si, Al and Na in the polymer. The sodium silicate was manufactured from silica fume and sodium hydroxide. The compressive strengths of polymers with Si∶Al molar ratios of 1.0–3.0 and Na∶Al molar ratios of 0.5–2.0 were considered. The polymers were cured at 75 °C for 24 h and their compressive strengths measured after aging for 7 days. The strength was found to depend systematically on the relative amounts of Si, Al and Na, with the maximum being 64 ± 3 MPa for an Si∶Al∶Na molar ratio of 2.5∶1∶1.3. X-Ray diffraction/scattering data indicate qualitatively that the bonding network in the amorphous aluminosilicate alters systematically with composition.
TL;DR: In this paper, the effect of limestone filler on the degree of hydration, the volume of hydrating products, and the optimal replacement of limestone filling in cement pastes at different w/cm ratios (0.25-0.50) were investigated by using a quadratic statistical model.
TL;DR: In this article, the effect of the fiber reinforcement content on the shear strength was investigated and the results of the tests indicated that peak shear and initial stiffness of the sand were not affected significantly by fiber reinforcement.
TL;DR: In this paper, the effect of technological variables on pore structure and mechanical properties of lime-based mortars was discussed, including the influence of curing time, binder-aggregate (B/Ag) ratio, aggregate attributes and porosity.
TL;DR: This study shows that I-PreConS using ANN is very efficient for predicting the compressive strength development of concrete.
TL;DR: In this paper, the effect of change in the internal radius of cenospheres was investigated for flatwise (specimen aspect ratio of 0.5) compressive properties of syntactic foams.
Abstract: The present work is aimed at characterizing syntactic foams for flatwise (specimen aspect ratio of 0.5) properties and investigating the effect of change in the internal radius of cenospheres. The density and mechanical properties of the syntactic foam can be changed while keeping cenosphere volume fraction and particle–matrix interfacial area the same by using cenospheres of same outer radius but different inner radius. Five types of cenospheres, with the same mean outer radius but a different internal radius, have been selected for the fabrication of syntactic foams. ASTM C 365-94, a standard for the flatwise compressive properties of sandwich cores, is followed in the present work. The results obtained in the study are compared with the results of edgewise (specimen aspect ratio of 2) compressive properties evaluated in earlier work. Results show an increase in compressive strength and modulus with decrease in internal radius of cenospheres. The peak compressive strength and modulus were measured to be higher for the specimens tested in flatwise orientation compared to that in edgewise orientation. Varying only one parameter, the internal radius of cenospheres, helped in understanding the role of cenospheres and matrix resin in deformation and fracture process of syntactic foams.
TL;DR: In this paper, expanded polystyrene (EPS) beads were used as lightweight aggregate both in concretes and mortars containing silica fume as a supplementary cementitious material.
TL;DR: In this paper, the authors investigated the contribution of limestone filler (LF) and granulated blast-furnace slag (BFS) to the hydration degree of ternary blended cements.
Abstract: The benefits of limestone filler (LF) and granulated blast-furnace slag (BFS) as partial replacement of portland cement are well established. However, both supplementary materials have certain shortfalls. LF addition to portland cement causes an increase of hydration at early ages inducing a high early strength, but it can reduce the later strength due to the dilution effect. On the other hand, BFS contributes to hydration after seven days improving the strength at medium and later ages. Mortar prisms in which portland cement was replaced by up to 20% LF and 35% BFS were tested at 1, 3, 7, 28 and 90 days. Results show that the contribution of LF to hydration degree of portland cement at 1 and 3 days increases the early strength of blended cements containing about 5–15% LF and 0–20% BFS. The later hydration of BFS is very effective in producing ternary blended cements with similar or higher compressive strength than portland cement at 28 and 90 days. Additionally, a statistical analysis is presented for the optimal strength estimation considering different proportions of LF and BFS at a given age. The use of ternary blended cements (PC–LF–BFS) provides economic and environmental advantages by reducing portland cement production and CO2 emission, whilst also improving the early and the later compressive strength.
TL;DR: In this article, the influence of transverse anisotropy on strength and deformational responses of four schistose rocks obtained from the foundation of two underground powerhouse sites in the Himalayas has been critically examined.
TL;DR: The effect of polypropylene and steel fibers on high strength lightweight aggregate concrete is investigated in this paper, where Sintered fly ash aggregates were used in the lightweight concrete; the fines were partially replaced by fly ash.
Abstract: The effect of polypropylene and steel fibers on high strength lightweight aggregate concrete is investigated. Sintered fly ash aggregates were used in the lightweight concrete; the fines were partially replaced by fly ash. The effects on compressive strength, indirect tensile strength, modulus of rupture, modulus of elasticity, stress–strain relationship and compression toughness are reported. Compared to plain sintered fly ash lightweight aggregate concrete, polypropylene fiber addition at 0.56% by volume of the concrete, caused a 90% increase in the indirect tensile strength and a 20% increase in the modulus of rupture. Polypropylene fiber addition did not significantly affect the other mechanical properties that were investigated. Steel fibers at 1.7% by volume of the concrete caused an increase in the indirect tensile strength by about 118% and an increase in the modulus of rupture by about 80%. Steel fiber reinforcement also caused a small decrease in the modulus of elasticity and changed the shape of the stress–strain relationship to become more curvilinear. A large increase in the compression toughness was recorded. This indicated a significant gain in ductility when steel fiber reinforcement is used.
TL;DR: The experimental results demonstrate that oyster-shells can be resources of pure calcareous materials and effective in replacement of sand, indicating promising reusable construction materials.
TL;DR: In this paper, the results of an experimental investigation carried out to evaluate the mechanical properties of concrete mixtures in which fine aggregate (sand) was partially replaced with Class F fly ash by weight.
TL;DR: In this paper, the effect of four types of coarse aggregates, namely calcareous, dolomitic, quartzitic limestone, and steel slag, on the compressive and tensile strength, and elastic modulus of high strength concrete was evaluated.
TL;DR: In this article, the effect of bending at room temperature on the microstructure of amorphous Al 90 Fe 5 Gd 5 was investigated using both conventional and high-resolution transmission electron microscopy (HRTEM).
TL;DR: In this paper, the physical and mechanical properties of Portland cement (PC) containing metakaolin (MK) or combination of MK and slag and the compatibility between such materials and superplasticizers were investigated.
TL;DR: In this article, the penetration rate of percussive blast hole drill was measured in eight rock types at an open pit mine and three motorway sites and the penetration rates were correlated with the rock properties, including uniaxial compressive strength, Brazilian tensile strength, point load strength and Schmidt hammer value.
TL;DR: In this article, two post-weld treatments, UIT and shot peening, are involved in the present study, and the experimental conditions and the results of these stress measurements are presented.
TL;DR: In this article, the authors investigated the effect of mineral admixture and curing condition on the sorptivity of concrete and showed that the effect is very sensitive to the curing condition.
TL;DR: In this article, the failure mechanism at the spot weld is tensile (shear) mode at the materials level, and stress distribution is assumed and related to the far field load for the lapshear and cross tension test samples.
Abstract: Strength tests were performed to reveal the failure mechanisms of spot weld in lap-shear and cross tension test samples. It is shown the while the lap-shear (cross tension) sample is subjected to shear (normal) load at the structural level the failure mechanism at the spot weld is tensile (shear) mode at the materials level. Based on the observed failure mechanism, stress distribution is assumed and related to the far field load for the lapshear and cross tension test samples. It appears that the failure load of the cross tension sample is 74 percent of the lap-shear sample based on the classical von Mises failure theory. The theoretical model is further extended to the mixed normal/shear loading condition. Data from strength tests as well as finite element numerical method are used to validate the model. Finally, the utility of the model in accessing the failure strength of spot welds is discussed. @DOI: 10.1115/1.1555648#
TL;DR: In this paper, the authors compared tensile, compressive and interlaminar shear properties of different carbon reinforcement/polyamide composites obtained by interfacial polymerization and hot compression molding techniques.