•Assessment of mechanical and durability properties of rubber ash/fiber concrete.•Addition of rubber fibers in concrete mix increases flexural strength.•Reduction in elastic modulus indicates higher ...flexibility of rubber concrete.•Concrete containing rubber fibers is better in term of abrasion resistance.•Micro-structural study shows weak interfacial bonding.
Now a day’s natural sand is becoming scarcer and costlier due to its non-availability. Waste rubber tire as fine aggregates can be an economical and sustainable alternative to river sand. In this study attempt has been made to utilize waste rubber tire as partial replacement of fine aggregate in the form of rubber ash and rubber ash with rubber fibers (combined form) with three w/c ratios. Workability, compressive strength, flexural strength, density, water absorption, abrasion resistance, carbonation depth, static modulus of elasticity, dynamic modulus of elasticity and chloride ion penetration of rubber ash concrete and modified concrete (10% rubber ash and varied percentage of rubber fibers) have been obtained. Micro-structural study using XRD, EDAX and SEM has also been carried out in this work. It has been shown that flexural strength of rubber ash concrete decreases with the increase of percentage of rubber ash whereas flexural strength of modified concrete is increased with the increase of the percentage of rubber fibers content. The abrasion resistance, carbonation depth, modulus of elasticity and chloride ion penetration of rubber ash concrete and modified concrete were also affected by addition of rubber ash and rubber fibers in concrete.
The special mechanical properties of nanoparticles allow for novel applications in many fields, e.g., surface engineering, tribology and nanomanufacturing/nanofabrication. In this review, the basic ...physics of the relevant interfacial forces to nanoparticles and the main measuring techniques are briefly introduced first. Then, the theories and important results of the mechanical properties between nanoparticles or the nanoparticles acting on a surface, e.g., hardness, elastic modulus, adhesion and friction, as well as movement laws are surveyed. Afterwards, several of the main applications of nanoparticles as a result of their special mechanical properties, including lubricant additives, nanoparticles in nanomanufacturing and nanoparticle reinforced composite coating, are introduced. A brief summary and the future outlook are also given in the final part.
This paper provides an overview of the early-age properties of concrete, from a materials science and concrete engineering perspective. The aim of this manuscript is to contribute to gap analysis and ...to improve the strategy for evaluation methods of the risk of cracking in mass concrete. Strength, elastic modulus, and volumetric stability at early ages are discussed.
Out-of-plane deformation patterns, such as buckling, wrinkling, scrolling, and folding, formed by multilayer van der Waals materials have recently seen a surge of interest. One crucial parameter ...governing these deformations is bending rigidity, on which significant controversy still exists despite extensive research for more than a decade. Here, we report direct measurements of bending rigidity of multilayer graphene, molybdenum disulfide (MoS2), and hexagonal boron nitride (hBN) based on pressurized bubbles. By controlling the sample thickness and bubbling deflection, we observe platelike responses of the multilayers and extract both their Young's modulus and bending rigidity following a nonlinear plate theory. The measured Young's moduli show good agreement with those reported in the literature (Egraphene>EhBN>EMoS2), but the bending rigidity follows an opposite trend, Dgraphene<DhBN<DMoS2 for multilayers with comparable thickness, in contrast to the classical plate theory, which is attributed to the interlayer shear effect in the van der Waals materials.
Hydrogels of conducting polymers, particularly poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), provide a promising electrical interface with biological tissues for sensing and ...stimulation, owing to their favorable electrical and mechanical properties. While existing methods mostly blend PEDOT:PSS with other compositions such as non-conductive polymers, the blending can compromise resultant hydrogels' mechanical and/or electrical properties. Here, we show that designing interconnected networks of PEDOT:PSS nanofibrils via a simple method can yield high-performance pure PEDOT:PSS hydrogels. The method involves mixing volatile additive dimethyl sulfoxide (DMSO) into aqueous PEDOT:PSS solutions followed by controlled dry-annealing and rehydration. The resultant hydrogels exhibit a set of properties highly desirable for bioelectronic applications, including high electrical conductivity (~20 S cm
in PBS, ~40 S cm
in deionized water), high stretchability (> 35% strain), low Young's modulus (~2 MPa), superior mechanical, electrical and electrochemical stability, and tunable isotropic/anisotropic swelling in wet physiological environments.
The dynamic modulus of elasticity (
), specified by ultrasonic pulse velocity measurements, is often used, especially for concrete built into construction, to estimate the static modulus of ...elasticity (
). However, the most commonly used Equations for such estimations do not take into account the influence of concrete moisture. The aim of this paper was to establish this influence for two series of structural lightweight aggregate concrete (LWAC) varying in their strength (40.2 and 54.3 MPa) and density (1690 and 1780 kg/m
). The effect of LWAC moisture content turned out to be much more pronounced in the case of dynamic modulus measurements than for static ones. The achieved results indicate that the moisture content of the concrete should be taken into consideration in modulus measurements as well as in Equations estimating
on the basis of
specified by the ultrasonic pulse velocity method. The static modulus of LWACs was lower on average by 11 and 24% in relation to dynamic modulus, respectively when measured in air-dried and water-saturated conditions. The influence of LWAC moisture content on the relationship between specified static and dynamic moduli was not affected by the type of tested lightweight concrete.
•The successful fabrication of FG-GPLRC is reported.•Micromechanics models to predict effective mechanical properties of GPLRC are reviewed.•A comprehensive review on the mechanical analyses of ...FG-GPLRC structures is presented.•Key technical challenges are identified and future research directions are discussed.
Owing to their superior mechanical properties, e.g. exceptionally high Young’s modulus, high strength, large specific surface area, and good thermal conductivity, graphene and its derivatives such as graphene platelets (GPLs) are excellent reinforcing nanofillers for composite materials. The most recently developed functionally graded graphene platelets reinforced composite (FG-GPLRC) where GPLs are non-uniformly dispersed with more GPLs in the area where they are most needed to achieve significantly improved mechanical performance has opened up a new avenue for the development of next generation structural forms with an excellent combination of high stiffness, light weight and multi-functionality. Research activities in this emerging area have been rapidly increasing since it was first proposed in 2017. The present paper (i) briefly reviews the mechanical properties of graphene and graphene composites; (ii) summarizes the characteristics of functionally graded materials (FGM) and reports the fabrication of FG-GPLRC; (iii) discusses the existing micromechanics models for the prediction of effective mechanical properties of GPLRC; (iv) presents a comprehensive review on the mechanical analyses of FG-GPLRC structures; and (v) discuss the key technical challenges and future research directions.
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