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Evaluating the impact of nano‑silica on characteristics of self‑compacting geopolymer concrete with waste tire steel fiber

Althoey Fadi, Zaid Osama, Alsharari Fahad, Yosri Ahmed. M., Isleem Haytham F.

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e48, 2023

EN

The demand for cement-free concrete is increasing worldwide to make the construction industry closer to being sustainable. The current research’s main objective was to develop self-compacting fiber-reinforced geopolymer concrete using waste/recycled materials. Steel wire from an old discarded tire was cut to make steel fibers. Wheat straw ash, an agricultural waste material, was utilized as the primary binder, and alkali-activated solutions were used as the precursors. Further, nano-silica (NS) was added from 0.5 to 3.0%, and waste tire steel fibers (WTSF) were added from 1 to 3.5% by binder content in different mixes. To evaluate the characteristics of different concrete, tests were performed, such as compressive, split tensile, and flexural strength for mechanical properties and sorptivity, rapid chloride penetration (RCP), and drying shrinkage tests for durability properties. It was noted that at 2.5% NS and 3.0% WTSF, the strength increases as 71.5, 6.5, and 8.2 MPa strength was achieved at 90 days for compressive, split tensile and flexural strength. For the RCP test, all samples were categorized as “low” in electrical conductance, micro-strains for drying shrinkage all came in an acceptable range for all samples, and sorptivity values were higher in earlier curing phases than in later phases of concrete. To understand the phase analysis of concrete, x-ray diffraction (XRD) analysis was performed, and it was revealed that the M5 mix (2.5% NS + 3.0% WTSF) had the highest peaks of C-S-H, N-A-S-H, and C-A-S-H, which demonstrates the densified microstructure of concrete with addition of nano-silica.

2

Laboratory experiments for crude oil removal from water surface using hydrophobic nano-silica as sorbent

Knapik E., Stopa J.

AGH Drilling, Oil, Gas

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2014

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Vol. 31, no. 2

281--289

EN

Nanomaterials have a great potential for the possible oil spill cleanup due to their unique wettability characteristics and large surface area. This work reports investigations on oil sorption behavior of a commercially available hydrophobic nano-silica when tested with a light paraffinic crude oil and a heavy aromatic crude oil. Sorption experiments were carried out in batch sorption system under static and dynamic conditions. Influence of mass of sorbent, sorption time, temperature and pH value of water on sorption capacity were tested and compared to find an optimal operational conditions for adsorption process. Nanopowder exhibited high selectivity for absorbing oil from water; a removal efficiency found by gravimetric method was high as 96% to 99%. The sorption capacity inereases with the inerease of sorption time and mass of sorbent. Nano-silica powder was found to be effective sorbent material as compared to widely used synthetic fibers

3

Wpływ nanometrycznych proszków ceramicznych na proces termicznej konwersji paku węglowego do węgla

Mikociak D., Socha A., Błażewicz S., Łabojko G.

Karbo

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2013

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Nr 3

209--216

PL

W pracy przedstawiono wyniki badań wpływu nanometrycznych proszków ceramicznych na proces pirolizy paku węglowego i jego dalszej obróbki termicznej do 2000°C. Do modyfikacji paku wykorzystano montmorylonit (MTT) i krzemionkę w ilości do 10 % wagowych. Badania wykazały, że wprowadzenie nanoproszku ceramicznego w ilości do 5 % wagowych nie zmienia istotnie mechanizmu rozkładu termicznego paku w niskich temperaturach. Wpływ nanocząstek zaznacza się wyraźnie w wyższych temperaturach obróbki. Przy małej koncentracji nanododatku obserwuje się obniżenie rozmiarów krystalitów w pozostałości węglowej po karbonizacji do 1000°C. Jednocześnie odległości międzygrafenowe d002 ulegają zmniejszeniu, w porównaniu do próbek węglowych nie zawierających dodatku ceramicznego, co wskazuje na porządkowanie struktury węgla w trakcie obróbki termicznej po karbonizacji paku. W próbkach węglowych zawierających nanokrzemionkę powyżej 1000°C zachodzi proces karboredukcji, który prowadzi do utworzenia węglika krzemu. W próbach ogrzewanych do 2000°C, oprócz węglika krzemu występuje także krystobalit. W temperaturze 2000°C w obecności 0,5 % zawartości MTT tworzą się dwie formy węgla różniące się parametrami strukturalnymi. Przy wyższych koncentracjach nanododatków ceramicznych (powyżej 5%) proces porządkowania struktury węglowej jest hamowany.

EN

The work presents the results of the investigations on the influence of nano-metric ceramic powders on the pyrolysis of coal tar pitch and its subsequent heat treatment up to 2000°C., Montmorillonite (MTT), and silica in an amount up to 10 % by weight, were used to modify the pitch. The studies have shown that the introduction of the ceramic nano-powder up to 5 % does not substantially change the mechanism of thermal decomposition of pitch at low temperatures. The impact of nano-particles is observed at higher processing temperatures. At low concentrations of nano-additives the decrease in the crystallite size of carbon residue after carbonization to 1000°C was observed. At the same time the inter-planar distance d002 between graphene layers is reduced, as compared to the samples without ceramic nano-additives, which indicates that the ordering of the structure of carbon residue in the presence of ceramic nano-particles takes place. In the case of nano-silica during heat treatment of coal tar pitch above 1000°C carboreduction process occurs, which leads to the formation of silicon carbide within carbon matrix. However, after the treatment up to 2000°C cristobalite in the carbon residue was found. Heat treatment of coal tar pitch to 2000°C in the presence of 0,5% of the MTT leads to the formation of two structurally different carbon components. At higher concentrations of ceramic nano-additives (above 5 %) carbon structure ordering process is inhibited.

4

Ocena struktury fazowej i właściwości zmęczeniowych nowych poliestrów multiblokowych modyfikowanych nanometryczną krzemionką

El Fray M., Rybko M.

Przetwórstwo Tworzyw

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2012

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[R.] 18, nr 3

184-188

PL

Praca dotyczy analizy struktury fazowej i oceny właściwości zmęczeniowych nowych elastomerów poliestrowych modyfikowanych nanometryczną krzemionką. Materiały zostały otrzymane metodą dwuetapową: transestryfikacji i polikondensacji w stopie. Nanonapełniacz został wprowadzony in situ w drugim etapie syntezy. Matrycę kompozytów tworzą elastomerowe poliestry zbudowane z segmentów sztywnych (30% wag. PBT - poli(tereftalan butylenu)), oraz segmentów giętkich (70% wag) zawierających, DLA - dimeryzowany kwas tłuszczowy), a jako napełniacz zastosowano krzemionkę o rozmiarze ziaren 16 nm w ilości 0.1-0.3% wag. (Aerosil 130, Evonic, krzemionka hydrofilowa). Stwierdzono, że dodatek nanokrzemionki nie wykazuje wpływu na strukturę fazową, którą badano metodami DSC i DMTA, zaś przy najwyższej zawartości, tj. 0,3%wag. wpływa korzystnie na wytrzymałość zmęczeniową, ocenianą metodą pętli histerezy mechanicznej.

EN

The work presents the analysis of phase structure and evaluation of fatigue properties of new polyester elastomers modified with nano-silica. The materials were obtained by two-step method: transesterification and melt polycondensation. Nanofiller was introduced in situ during the second stage of the synthesis. The matrix of the composites consisted of hard segments (30% wt. PBT - poly(butylene terephthalate)), and soft segments (70 wt.% DLA - dimerized fatty acid). Hydrophilic silica with particle size of 16 nm (Aerosil 130, Evonic) was used as a filler. The filler content in the composites was 0.1-0.3 wt.%. It was found that the addition of nanosilica had no effect on the phase structure, as verified by DSC and DMTA. On the other hand, the materials with highest silica content had best fatigue strength, as assessed by mechanical hysteresis loop method.

5

Effect of nano silica on mechanical properties and durability of normal strength concrete

Gopinath S., Mouli P.C., Murthy A.R., Iyer N.R., Maheswaran S.

Archives of Civil Engineering

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2012

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Vol. 58, nr 4

433-444

EN

Nano technology is an emerging field of interest for civil engineering application. Among the nano materials presently used in concrete, nano-silica possess more pozzolanic nature. It has the capability to react with the free lime during the cement hydration and forms additional C-S-H gel giving strength, impermeability and durability to concrete. Present paper investigates the effects of addition of nano silica in normal strength concrete. Three types of nano-silica in the form of nano suspension having different amount of silica content have been investigated. Mix design has been carried out by using particle packing method. X-Ray diffraction (XRD) analysis has been carried out to find the chemical composition of control concrete and nano modified concrete. Further, experimental investigations have been carried out to characterize the mechanical behaviour in compression, tension and flexure. It has been observed that the addition of nano-silica in normal strength concrete increased the compressive strength and decreased the spilt tensile strength and flexural strength. Also, Rapid chloride permeability test (RCPT) has been conducted to know the chloride permeability of control concrete, nano modified concrete, and nano coated concrete. It has been observed that the chloride permeability is less for nano coated concrete.

6

Plasma-chemical surface engineering of wood

Sokołowska A., Szawłowski J., Frąckowiak I., Rudnicki J., Boruszewski P., Beer P., Olszyna A.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

694-697

EN

Purpose: Wood infiltrated with nano-silica hydrosol forms a “weak”, irregular composite of components bound with hydrogen bonds only. The purpose of this study was to investigate the influence of low-energy ions bombardment on the structure and properties of the surface of this composite. The aim of these investigations was to produce a shallow “buried” layer of a dense wood-ceramic composite on a wood surface . Design/methodology/approach: D.c. glow-discharge in N2/H2 (9:11) atmosphere under a pressure of 4hPa was the source of ions. A beech plate was placed on the cathode. The temperature of wood was 200°C. The material collected from the wood-silica composite surface was investigated with FTIR spectroscopy and SEM observations. The surface energy was determined with the use of contact angle measurements. Findings: The ions influenced silica only. The nano-particles underwent sintering changing its medium size twice and a small I.R. peak of N2 trapped in SiO2 suggest the possibility of silica nitriding. A buried, continual surface layer of sintered silica did not form. The surface energy of the “wood-silica” plate was slightly decreased after plasma treatment. Research limitations/implications: The results proved the possibility of plasma treatment of wood even in a d.c. glow-discharge under low pressure. Silica sintering, a difficult process which in a thermal way has to be carried out at a temperature of 1000°C, taking place in a plasma at a temperature of 200°C showed the very special nature of an influence of ions. Originality/value: The plasma surface treatment of wood in the d.c. glow-discharge (GD) under reduced pressure has not been investigated. There are only publications about glow-dielectric-barrier-discharge (GDBD) at atmospheric pressure applications for wood surface modification. The energy of ions in GDBD is much smaller than that of ions in GD and therefore the application of glow discharge under reduced pressure to wood surface treatment can be more efficient.