Showing papers on "Compressive strength published in 2016"
14 Jun 2016-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the nano-, micro-, and macro-scale mechanical properties of selective laser melting (SLM) AlSi10Mg were examined and correlated to the generated microstructure.
Abstract: Selective laser melting (SLM) of aluminium is of research interest because of its potential benefits to high value manufacturing applications in the aerospace and automotive industries. In order to demonstrate the credibility of SLM Al parts, their mechanical properties need to be studied. In this paper, the nano-, micro-, and macro-scale mechanical properties of SLM AlSi10Mg were examined. In addition, the effect of a conventional T6-like heat treatment was investigated and correlated to the generated microstructure. Nanoindentation showed uniform hardness within the SLM material. Significant spatial variation was observed after heat treatment due to phase transformation. It was found that the SLM material's micro-hardness exceeded its die-cast counterpart. Heat treatment softened the material, reducing micro-hardness from 125±1 HV to 100±1 HV. An ultimate tensile strength (333 MPa), surpassing that of the die cast counterpart was achieved, which was slightly reduced by heat treatment (12%) alongside a significant gain in strain-to-failure (~threefold). Significantly high compressive yield strength was recorded for the as-built material with the ability to withstand high compressive strains. The SLM characteristic microstructure yielded enhanced strength under loading, outperforming cast material. The use of a T6-like heat treatment procedure also modified the properties of the material to yield a potentially attractive compromise between the material's strength and ductility making it more suitable for a wider range of applications and opening up further opportunities for the additive manufacturing process and alloy combination.
447 citations
TL;DR: In this paper, the effects of three shaped steel fibers (straight, corrugated, and hooked-end) with different fiber contents by volume on mechanical properties of ultra high performance concrete (UHPC) were investigated.
443 citations
TL;DR: In this article, the differences in the microstructure, defects and mechanical behavior of porous structures from a β-type Ti 24Nb 4Zr 8Sn manufactured by electron beam melting (EBM) and selective laser melting (SLM) were investigated and correlated to the compressive mechanical and fatigue properties.
404 citations
TL;DR: In this article, the authors present the process of crack healing phenomenon in concrete by microbial activity of bacteria, Bacillus subtilis, which is introduced in concrete via direct incorporation, and thorough various carrier compounds namely light weight aggregate and graphite nano platelets.
375 citations
TL;DR: In this article, the authors present a comprehensive review of the mechanism of crack formation and propagation, compressive strength, modulus of elasticity, stress-strain behavior, tensile strength (TS), flexural strength, drying shrinkage, creep, electrical resistance, and chloride migration resistance of high performance fiber reinforced concrete.
Abstract: In recent years, an emerging technology termed, “High-Performance Fiber-Reinforced Concrete (HPFRC)” has become popular in the construction industry. The materials used in HPFRC depend on the desired characteristics and the availability of suitable local economic alternative materials. Concrete is a common building material, generally weak in tension, often ridden with cracks due to plastic and drying shrinkage. The introduction of short discrete fibers into the concrete can be used to counteract and prevent the propagation of cracks. Despite an increase in interest to use HPFRC in concrete structures, some doubts still remain regarding the effect of fibers on the properties of concrete. This paper presents the most comprehensive review to date on the mechanical, physical, and durability-related features of concrete. Specifically, this literature review aims to provide a comprehensive review of the mechanism of crack formation and propagation, compressive strength, modulus of elasticity, stress–strain behavior, tensile strength (TS), flexural strength, drying shrinkage, creep, electrical resistance, and chloride migration resistance of HPFRC. In general, the addition of fibers in high-performance concrete has been proven to improve the mechanical properties of concrete, particularly the TS, flexural strength, and ductility performance. Furthermore, incorporation of fibers in concrete results in reductions in the shrinkage and creep deformations of concrete. However, it has been shown that fibers may also have negative effects on some properties of concrete, such as the workability, which get reduced with the addition of steel fibers. The addition of fibers, particularly steel fibers, due to their conductivity leads to a significant reduction in the electrical resistivity of the concrete, and it also results in some reduction in the chloride penetration resistance of the concrete.
350 citations
TL;DR: In this article, the results of an experimental investigation to comparatively study the depth of chloride penetration, resistance to acid attack and macrocell corrosion of rubberized concrete and control mix concrete were presented.
300 citations
TL;DR: In this paper, the formation of disordered solid solution in the hexagonal close-packed (hcp) structure in the GdHoLaTbY alloy and its mechanical properties were investigated.
297 citations
TL;DR: In this paper, the authors introduced a new rapid, relevant and reliable (R 3 ) test to predict the pozzolanic activity of calcined clays with kaolinite contents ranging from 0 to 95%.
296 citations
TL;DR: In this article, a shot-peening (SP) process was used to induce grain refinements through creating severe plastic deformation at the outer surface layers to improve the physical and mechanical properties of 17-4 stainless steel components produced by DMLS.
285 citations
TL;DR: A novel hexagonal architecture for a glass-ceramic scaffold is designed to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa, which is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater for ceramic and glass scaffolds at similar porosity.
Abstract: A challenge in regenerating large bone defects under load is to create scaffolds with large and interconnected pores while providing a compressive strength comparable to cortical bone (100–150 MPa). Here we design a novel hexagonal architecture for a glass-ceramic scaffold to fabricate an anisotropic, highly porous three dimensional scaffolds with a compressive strength of 110 MPa. Scaffolds with hexagonal design demonstrated a high fatigue resistance (1,000,000 cycles at 1–10 MPa compressive cyclic load), failure reliability and flexural strength (30 MPa) compared with those for conventional architecture. The obtained strength is 150 times greater than values reported for polymeric and composite scaffolds and 5 times greater than reported values for ceramic and glass scaffolds at similar porosity. These scaffolds open avenues for treatment of load bearing bone defects in orthopaedic, dental and maxillofacial applications.
270 citations
TL;DR: In this paper, the contribution of expanded polystyrene (EPS) particles on fire resistance, thermal conductivity and compressive strength of foamed concrete has been investigated for densities ranging from 1200 to 150 kg/m3 with an EPS volume range of 0 −82.22% and water-cement ratio of 0.33.
TL;DR: In this article, the effect of incorporating recycled aggregates, sourced from processed construction and demolition waste, on the modulus of elasticity of concrete is identified, based on the identification, appraisal, selection and synthesis of the evidence of 121 publications published over a period of 43 years from 1973 to 2015.
TL;DR: In this paper, the authors studied the thermal effect on physical and mechanical properties of rock, such as mass, density, porosity, P-wave velocity, compressive strength, peak strain, elastic modulus, and acoustic emission of rock.
TL;DR: In this paper, the effects of different factors on the strength, reaction rate, hydration products and microstructure were examined; these factors include the activator dosage, FA/slag ratio, and curing regime.
TL;DR: In this paper, the effect of coir fibres for use as reinforcement materials for polymer and cementitious composites was investigated, and the results showed that the treatment improved the tensile and flexural properties of composites.
TL;DR: In this paper, a systematic experimental investigation is carried out on concrete with rubber fibers (obtained by grinding waste rubber tyres) as partial replacement of fine aggregates, to evaluate the compressive strength, density, water permeability, static modulus of elasticity, dynamic modulus, and chloride diffusion.
TL;DR: In this article, a holistic review of current research on the mechanical properties of alkali-activated concretes including research on its compressive strength, tensile strength, elastic modulus, Poisson's ratio, stress-strain relationship under uniaxial compression, fracture properties, bond mechanism with steel reinforcement, dynamic mechanical properties, and high-temperature performance.
TL;DR: In this article, the AA6351-AlN composites were characterized using scanning electron microscope (SEM) and x-ray diffraction (XRD) and the mechanical properties such as micro-hardness, compression strength, flexural strength and tensile strength of the proposed composite have been studied.
Abstract: In the present investigation, AA6351 aluminum alloy matrix composites reinforced with various percentages of AlN particles were fabricated by stir casting technique. The percentage of AlN was varied from 0 to 20% in a step of 4%. The prepared AA6351-AlN composites were characterized using scanning electron microscope (SEM) and x-ray diffraction (XRD). The mechanical properties such as micro-hardness, compression strength, flexural strength, and tensile strength of the proposed composite have been studied. X-ray diffraction patterns confirm the presence of AlN particles in the composites. SEM analysis reveals the homogeneous distribution of AlN particles in the AA6351 matrix. The mechanical properties of the composite were found to be noticeably higher than that of the plain matrix alloy due to augmented particle content. The produced composites exhibit superior mechanical properties when compared with unreinforced matrix alloy. Fracture surface analysis of tensile specimens show the ductile–brittle nature of failure in the composites.
TL;DR: In this paper, the effect of adding different types of fibers on the microstructure and the mechanical behavior of cementitious composites, in particular on UHPC, was investigated by using a uni-axial compression test which combines the gas permeability and the acoustic emission (AE) measurement.
Abstract: This study investigates the effect of adding different types of fibers on the microstructure and the mechanical behavior of cementitious composites, in particular on UHPC. These fibers were distinguished mainly by their differing nature (steel, mineral and synthetic), their dimensions (macroscopic or microscopic), and their mechanical properties. The microstructure of the specimens was examined by using SEM observation and by measuring the porosity, the intrinsic permeability and the P-wave velocity. The mechanical behavior under loading has been studied using a uni-axial compression test which combines the gas permeability and the acoustic emission (AE) measurement. This work focuses on the cracking process under mechanical loading. The experimental results show that the fiber has a relatively slight influence on the compressive strength and elastic modulus of concrete, except for the steel fiber which improves the strength because of its intrinsic rigidity. However, The addition of fiber significantly reduces the lateral strain at peak loading and increases the threshold of initial cracking (σk-ci) and that of unstable cracking (σk-pi). Therefore, the fibers clearly restrain the cracking process in concrete under the mechanic loading.
TL;DR: In this article, the authors reviewed the terminologies commonly used to quantify the amount of water stored in rocks and reviewed the water-weakening effects on rock strengths, particularly focusing on uniaxial compressive strength and modulus, as well as tensile strength, under quasi-static loading and dynamic loading.
Abstract: Reduction in strength and stiffness in rocks attributed to an increase in water content has been extensively researched on a large variety of rock types over the past decades. Due to the considerable variations of texture and lithology, the extent of water-weakening effect is highly varied among different rock types, spanning from nearly negligible in quartzite to 90 % of uniaxial compressive strength reduction in shale. Readers, however, often face difficulties in comparing the data published in different sources due to the discrepancy of experimental procedures of obtaining the water saturation state and how the raw laboratory data is interpreted. In view of this, the present paper first reviews the terminologies commonly used to quantify the amount of water stored in rocks. The second part of the paper reviews the water-weakening effects on rock strengths, particularly focusing on uniaxial compressive strength and modulus, as well as tensile strength, under quasi-static loading and dynamic loading. The correlation relationships established among various parameters, including porosity, density and fabric of rocks, and external factors such as strain rate, surface tension and dielectric constant of the saturating liquid, absorption percentage and suction pressure, are reviewed and presented toward the end of the paper.
TL;DR: In this paper, the effect of colloidal nanosilica on the properties of High Performance Concrete with copper slag as fine aggregate at a constant replacement level of 40% was investigated.
TL;DR: In this paper, the compressive strength of the examined mixes was found to be in the range of 40-50 MPa for 40% and 50% ground granulated blast furnace slag replacement mixtures respectively.
TL;DR: In this paper, a mix design methodology for GPC with the main focus on achieving better compressive strength in an economical way for different alkaline solutions to binder proportions was proposed.
TL;DR: In this paper, the compressive strength of High Performance Concrete containing nano silica and copper slag as partial cement and fine aggregate replacement respectively was determined using MRA and ANN models.
TL;DR: In this paper, three different data-driven models, i.e., Artificial Neural Network (ANN), Adaptive Neuro-Fuzzy Inference System (ANFIS), and Multiple Linear Regression (MLR), were used to predict the 28-day compressive strength of recycled aggregate concrete (RAC).
Abstract: Compressive strength of concrete, recognized as one of the most significant mechanical properties of concrete, is identified as one of the most essential factors for the quality assurance of concrete. In the current study, three different data-driven models, i.e., Artificial Neural Network (ANN), Adaptive Neuro-Fuzzy Inference System (ANFIS), and Multiple Linear Regression (MLR) were used to predict the 28 days compressive strength of recycled aggregate concrete (RAC). Recycled aggregate is the current need of the hour owing to its environmental pleasant aspect of re-using the wastes due to construction. 14 different input parameters, including both dimensional and non-dimensional parameters, were used in this study for predicting the 28 days compressive strength of concrete. The present study concluded that estimation of 28 days compressive strength of recycled aggregate concrete was performed better by ANN and ANFIS in comparison to MLR. In other words, comparing the test step of all the three models, it can be concluded that the MLR model is better to be utilized for preliminary mix design of concrete, and ANN and ANFIS models are suggested to be used in the mix design optimization and in the case of higher accuracy necessities. In addition, the performance of data-driven models with and without the non-dimensional parameters is explored. It was observed that the data-driven models show better accuracy when the non-dimensional parameters were used as additional input parameters. Furthermore, the effect of each non-dimensional parameter on the performance of each data-driven model is investigated. Finally, the effect of number of input parameters on 28 days compressive strength of concrete is examined.
TL;DR: In this paper, fly ash based geopolymer concretes with different percentages of silica fume were made by using NaOH/sodium silicate and cured in an oven at 100°C.
TL;DR: In this article, the suitability of scrap tire rubber as a partial substitute for natural fine aggregate in high strength cement concrete was analyzed using Scanning Electron Microscopy (SEM).
TL;DR: SEM result presents that the addition of GO obviously improves the porous structures of aerogel, which is beneficial for the enhancement of strength-toughness and adsorbability.
TL;DR: In this paper, the effects of RCA on the measured mechanical and durability properties of geopolymer concrete containing recycled coarse aggregate (RCA) are presented. But the correlation between the compressive strength and the sorptivity is not that strong.
Abstract: This paper presents mechanical and durability properties of geopolymer concrete containing recycled coarse aggregate (RCA). The RCA is sourced from local construction and demolition (C&D) waste in Perth, Australia. The RCA is used as a partial replacement of natural coarse aggregate (NCA) in geopolymer concrete at 15%, 30% and 50% by wt. which corresponds to series two, three and four, respectively, while the geopolymer concrete containing 100% NCA is control and is considered as the first series. Class F fly ash is used as the source material for the geopolymer and 8 M sodium hydroxide and sodium silicate alkali activators are used to synthesise the fly ash geopolymer in this study. In all four series a constant alkali activator to fly ash ratio is used. Compressive strength, indirect tensile strength and elastic modulus of above geopolymer concrete are measured at 7 and 28 days, while sorptivity, immersed water absorption and volume of permeable voids of above geopolymer concrete are measured at 28 days. Relevant Australian standards are used to measure all the above properties except the sorptivity which is measured according to ASTM standard. Results show that the compressive strength, indirect tensile strength and elastic modulus of geopolymer concrete decrease with an increase in RCA contents, which is also true for both 7 and 28 days. Excellent correlations of compressive strength with indirect tensile strength and elastic modulus are also observed in geopolymer concrete containing RCA. Existing empirical models for cement concrete and geopolymer concrete containing NCA underestimate and overestimate the indirect tensile strength and elastic modulus, respectively of geopolymer concrete containing RCA. The measured durability properties such as sorptivity, water absorption and volume of permeable voids of geopolymer concrete were also adversely affected by the incorporation of RCA and these properties increase with an increase in RCA contents. The effects of RCA on the measured mechanical and durability properties of geopolymer concrete follow similar trend in cement concrete. Very good correlations of compressive strength with volume of permeable voids and water absorption of geopolymer concrete containing RCA are also observed, while the correlation between the compressive strength and the sorptivity is not that strong.
TL;DR: In this article, a novel approach that adding thermally expandable microspheres into matrix and combining FDM process with thermal treatment was proposed to tackle the problem of significant voids between deposition lines.