Enhancement of the durability characteristics of concrete nanocomposite pipes with modified graphite nanoplatelets (original) (raw)
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Structural performance of dry-cast concrete nanocomposite pipes
Materials and Structures, 2013
Benefits of relatively low-cost graphite nanoplatelets, used alone or in combination with (micro-scale) polyvinyl alcohol (PVA) fibers, towards enhancement of the structural performance of concrete pipes were evaluated through industrial-scale production and experimental evaluation of concrete pipes. A total of ten pipes were manufactured via the dry-cast method using a zero-slump concrete of normal strength. Three-edge bearing tests were performed in order to evaluate the structural performance of pipes with nano-and/or micro-scale discrete reinforcement. Laboratory tests were also conducted on the compressive, flexural, impact and abrasion performances of dry-cast concrete materials produced at industrial scale with different reinforcement systems. Graphite nanoplatelets were surface-treated in order to improve their dispersion and interfacial interactions in concrete. Experimental results indicated that surfacetreated graphite nanomaterials (used alone or in combination with PVA fibers) significantly benefited the structural performance and failure mechanisms of reinforced concrete pipes.
Surface-Modified Graphite Nanoplatelets To Enhance Cement Sheath Durability
SPE Drilling & Completion, 2020
Summary We propose a novel cement additive made of graphite nanoplatelets (GNPs) for improved hydraulic isolation and durability of oil and gas wells. The primary role of the cement sheath, which is zonal isolation, can be significantly affected by the permeability of set cement (hardened cement slurry). On one hand, it is the inherent microstructural defects of cement, including pores and microcracks, that results in the intrinsic permeability of cement, and on the other hand, cracking, micro-annuli, or other flow paths developed through the disturbed cement by connecting the pre-existing microstructural defects determine the equivalent permeability of set cement. The purpose of this research is containing or at least minimizing the intrinsic and developed flow paths through the cementitious matrix with the help of surface-modified GNPs. GNPs possess high surface area to volume ratios. In this study, we focus on the effect of surface-modified GNPs on the overall mechanical properti...
Enhancement of the Concrete Durability with Hybrid Nano Materials
Sustainability
The importance of the incorporation of nanomaterials in concrete has emerged as a promising research interest due to the outstanding functionalized properties of the materials at that size level. This study aims to investigate the engineering and durability properties of concrete incorporated with hybrid nanomaterials. In this study, the influence of carbon nanotube (CNT) on microstructure, mechanical, and corrosion characteristics of nano-clay-based (NC) concrete has been evaluated. The cement was replaced with CNT at different percentages of 0.01%, 0.02%, and 0.04% by weight, while NC was replaced at a constant percentage of 5%. A scanning electron microscope (SEM) was used to examine the microstructural characterization of the samples. To investigate the influence of carbon nanotubes in the fresh properties, slump and air content tests were carried out. The compressive strength, tensile strength, flexural strength, and bond strength of the hardened concrete was evaluated accordin...
Assessing the Durability of Blended Concrete with Some Nanomaterials
Until the late 1930s, there was no research on the durability of concrete. The first discussion for the concrete deterioration and durability was the second symposium at Stockholm in 1938. After this period, several conferences were held with many reports and papers being presented on durability and deterioration of concrete structures[1]. The history repeats itself again where, studying the impact of Nanomaterials on concrete durability through researches and studies has not been achieved yet as required, although these material had been used in some places for more than 20 years. where ,most of this studies which interested in investigating the durability issue deal with cement paste and cement mortar and a few of them deal with concrete in some properties. From this point of view, this research come to compensate the shortage of this issue by studying the effect of using the nanosilica and nanoclay and hybrid from both of them on some durability properties of concrete produced with the three materials as a partial replacement of cement at three ratios for each one. The experimental program of this study consists of nine blended concrete mixtures (three nanomaterials and three ratios of replacement for each one) besides to the control mixture. Each mix had a number of specimens sufficient to study the following durability properties of the blended concrete :-Resistance to exposure to aggressive media at 3 , 6 , 12 month.-The water permeability.-Resistance of the elevated temperature at 400 o C and 600 o C .-The compressive strength at 7 , 28 ,56 day. The material characteristics , the procedures of specimens preparation , the tests set up ,and the test results and discussion are described in detail. Results of experimental work showed that; Nanomaterials are efficient in improving the concrete durability in most of measured properties with different levels of improvement according to the type of the nanomaterial and the ratio of replacement. Optimum replacement ratios are proposed for each type of the nanomaterials. Also, results yielded that nanoclay is more effective than the nanosilica and hybrid nanosilica-nanoclay in enhancing the durability properties of concrete.
Surface-modified graphite nanomaterials for improved reinforcement efficiency in cementitious paste
Graphite nanomaterials can play multi-faceted roles towards enhancing the mechanical, physical and functional attributes of cementitious materials. Graphite nanoplatelets and carbon nanofibers, when compared with carbon nanotubes, offer desired mechanical and physical characteristics at reduced cost. However thorough dispersion of nanomaterials in the cementitious matrix is critical for effective use of their distinct geometric and engineering properties towards development of higher-performance cementitious nanocomposites. The dispersion and interfacial interaction of nanomaterials in the aqueous medium of cementitious matrix can benefit from proper surface treatment of nanomaterials. The surface modification techniques employed in this study emphasize introduction of hydrophilic groups on graphite nanomaterials to facilitate their dispersion in aqueous media. These include: (i) polymer wrapping of oxidized carbon nanofiber; and (ii) covalent attachment of functional groups. The effects of these surface modifications on the performance characteristics of cementitious nanocomposite were evaluated. It was found that wrapping of oxidized graphite nanomaterials with PAA, at polymer-to-nanofiber weight ratio of 10%, was particularly beneficial. With the addition of 0.13 wt.% (0.81 vol.%) of nanomaterials (with respect to anhydrous cementitious materials), up to 73% gain in the flexural strength of cementitious matrix was realized. Test results also indicated that oxidized of graphite nanoplatelets markedly lowered (by up to 50%) the moisture sorptivity.
Ceramics International, 2021
The impact of graphite nanoplatelets (GNPs) on the physical and mechanical properties of cementitious nanocomposites was investigated. A market-available premixed mortar was modified with 0.01% by weight of cement of commercial GNPs characterized by two distinctively different aspect ratios. The rheological behavior of the GNP-modified fresh admixtures was thoroughly evaluated. Hardened cementitious nanocomposites were investigated in terms of density, microstructure (Scanning Electron Microscopy, SEM and micro-Computed Tomography, μ-CT), mechanical properties (three-point bending and compression tests), and physical properties (electrochemical impedance spectroscopy, EIS and thermal conductivity measurements). At 28 days, all GNP-modified mortars showed about 12% increased density. Mortars reinforced with high aspect ratio GNPs exhibited the highest compressive and flexural strength: about 14% and 4% improvements compared to control sample, respectively. Conversely, low aspect ratio GNPs led to cementitious nanocomposites characterized by 36% decreased electrical resistivity combined with 60% increased thermal conductivity with respect to the control sample.
Composites Part B-engineering, 2016
A comprehensive investigation into the mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC), considering various influential factors, is imperative in order to obtain fundamental information for its practical utilization. Therefore, this paper reviewed the early-age strength (or setting) development and mechanical properties of hardened UHPFRC. In connection with the latter, the effects of the curing conditions, coarse aggregate, mineral admixtures, fiber properties, specimen size, and strain-rate on the mechanical performance of UHPFRC were specifically investigated. It was obvious that (1) heat treatment accelerates the hydration process, leading to higher strength; (2) a portion of the silica fume can be replaced by fly ash, slag, and rice husk ash in mechanical perspective; (3) the use of deformed (hooked and twisted) or long straight steel fibers improves the mechanical properties at a static rate; and (4) high rate loading provides a noticeable increase in the mechanical properties. Alternatively, there are some disagreements between the results from various 'size effect' tests and the effectiveness of using twisted steel fibers at static and high rate loadings. Further research to reduce the production cost of UHPFRC is also addressed in an attempt to make its widespread use more practical.
Feasibility of Nano Graphene Oxide Powder With Concrete -A Review
Engineered nano materials exist in three principal shapes, namely 0D nanoparticle, 1D nano fiber and 2D nano sheet. The application of 0D nanoparticle and 1D nano fiber, such as nano silica and carbon nanotubes (CNTs). The discovery of 2D nano sheet known as graphene oxide (GO) provides an extra dimension to interact with cement and concrete matrix and has yet to gain widespread attention. Also highlighted herein are the effect of incorporating nano materials in low dosages to the fabrication, workability, hydration, microstructure, and mechanical properties of cement-based composites. Starting from graphite powder we performed a chemical oxidation using sulfuric acid (H2SO4), sodium nitrate (NaNO3) and potassium permanganate (KMnO4) following the Hummer's method. The graphene oxide sludge has been washed several times and then sonicated to ensure the complete exfoliation of the platelets. The unique features of the two-dimensional GO such as its rough surface and functional group have a favorable influence on the mechanical behavior of cement. Introducing small quantities of GOaslittleas 0.1wt% ,0.13wt%, 0.15wt%, 0.17wt%, 0.20wt%, 0.23wt%, 0.25wt%, 0.27wt%, 0.30wt% to measuring compressive strength, flexural strength, workability, durability, permeability of mix design of concrete M40, M5O (standard concrete) and M60 (high strength concrete).