Application of waste rubber to reduce the settlement of road embankment

Tafreshi, S.N. Moghaddas,Norouzi, A.H. Techno-Press 2015 Geomechanics & engineering Vol.9 No.2

In this paper, a series of repeated load tests were carried out on a 150 mm diameter plate simulative of vehicle passes, to demonstrate the benefits of soil-rubber shred mixture in decreasing the soil surface settlement of road embankment. The results show that the efficiency of rubber reinforcement is significantly a function of the rubber content, thickness of rubber-soil mixture and soil cap thickness over the mixture. Minimum surface settlement is provided by 2.5% of rubber in rubber-soil mixture, the thickness of mixture layer and soil cap of 0.5 times the loading surface diameter, giving values of 0.32-0.68 times those obtained in the unreinforced system for low and high values of amplitude of repeated load. In this installation, in contrast with unreinforced bed that shows unstable response, the rate of enhancement in settlement decreases significantly as the number of loading cycles increase and system behaves resiliently without undergoing plastic deformation. The findings encourage the use of rubber shreds obtained from non-reusable tires as a viable material in road works.

Cyclic loading response of footing on multilayered rubber-soil mixtures

Tafreshi, S.N. Moghaddas,Darabi, N. Joz,Dawson, A.R. Techno-Press 2018 Geomechanics & engineering Vol.14 No.2

This paper presents a set of results of plate load tests that imposed incremental cyclic loading to a sandy soil bed containing multiple layers of granulated rubber-soil mixture (RSM) at large model scale. Loading and unloading cycles were applied with amplitudes incrementally increasing from 140 to 700 kPa in five steps. A thickness of the RSM layer of approximately 0.4 times the footing diameter was found to deliver the minimum total and residual settlements, irrespective of the level of applied cyclic load. Both the total and residual settlements decrease with increase in the number of RSM layers, regardless of the level of applied cyclic load, but the rate of reduction in both settlements reduces with increase in the number of RSM layers. When the thickness of the RSM layer is smaller, or larger, settlements increase and, at large thicknesses may even exceed those of untreated soil. Layers of the RSM reduced the vertical stress transferred through the foundation depth by distributing the load over a wider area. With the inclusion of RSM layers, the coefficient of elastic uniform compression decreases by a factor of around 3-4. A softer response was obtained when more RSM layers were included beneath the footing damping capacity improves appreciably when the sand bed incorporates RSM layers. Numerical modeling using "FLAC-3D" confirms that multiple RSM layers will improve the performance of a foundation under heavy loading.

Improvement of pavement foundation response with multi-layers of geocell reinforcement: Cyclic plate load test

Khalaj, Omid,Tafreshi, Seyed Naser Moghaddas,Mask, Bohuslav,Dawson, Andrew R. Techno-Press 2015 Geomechanics & engineering Vol.9 No.3

Comprehensive results from cyclic plate loading at a diameter of 300 mm supported by layers of geocell are presented. The plate load tests were performed in a test pit measuring $2000{\times}2000mm$ in plane and 700 mm in depth. To simulate half and full traffic loadings, fifteen loading and unloading cycles were applied to the loading plate with amplitudes of 400 and 800 kPa. The optimum embedded depth of the first layer of geocell beneath the loading plate and the optimum vertical spacing of geocell layers, based on plate settlement, are both approximately 0.2 times loading plate diameter. The results show that installation of the geocell layers in the foundation bed, increase the resilient behavior in addition to reduction of accumulated plastic and total settlement of pavement system. Efficiency of geocell reinforcement was decreased by increasing the number of the geocell layers for all applied stress levels and number of cycles of applied loading. The results of the testing reveal the ability of the multiple layers of geocell reinforcement to 'shakedown' to a fully resilient behavior after a period of plastic settlement except when there is little or no reinforcement and the applied cyclic pressure are large. When shakedown response is observed, then both the accumulated plastic settlement prior to a steady-state response being obtained and the resilient settlements thereafter are reduced. The use of four layers of geocell respectively decreases the total and residual plastic settlements about 53% and 63% and increases the resilient settlement 145% compared with the unreinforced case. The inclusion of the geocell layers also reduces the vertical stress transferred down through the pavement by distributing the load over a wider area. For example, at the end of the load cycle of the applied pressure of 800 kPa, the transferred pressure at the depth of 510 mm is reduced about 21.4%, 43.9%, 56.1% for the reinforced bases with one, two, and three layers of geocell, respectively, compared to the stress in the unreinforced bed.

Damage studies on irradiated tungsten by helium ions in a plasma focus device

Seyyedhabashy, Mir mohammadreza,Tafreshi, Mohammad Amirhamzeh,bidabadi, Babak Shirani,Shafiei, Sepideh,Nasiri, Ali Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.4

Damage of tungsten due to helium ions of a PF device was studied. The tungsten was analyzed by SEM and AFM after irradiation. SEM revealed fine bubbles of helium atoms with diameters of a few nanometers, which join and form larger bubbles and blisters on the surface of tungsten. This observation confirmed the results of molecular dynamics simulation. SEM analysis after etching of the irradiated surface indicated cavities with depth range of 35-85 nm. The average fluence of helium ion of the PF device was calculated about 5.2 × 10¹⁵ cm^-2 per shot, using Lee code. Energy spectrum of helium ions was estimated using a Thomson parabola spectrometer as a function of dN/dE ∝ E^-2.8 in the energy range of 10-200 keV. The characteristics of helium ion beam was imported to SRIM code. SRIM revealed that the maximum DPA and maximum helium concentration occur in the depth range of 20-50 nm. SRIM also showed that at depth of 30 nm, all of the tungsten atoms are displaced after 20 shots, while at depth of higher than 85 nm the destruction is insignificant. There is a close match between SRIM results and the measured depths of cavities in SEM images of tungsten after etching.

Analysis of the superplasticizer demand using computer simulation

Heirati, Arian,Zandi, Yousef,Tafreshi, Shahriar Tavousi,Behruyan, Manuchehr Techno-Press 2021 Advances in nano research Vol.11 No.5

The merits of self-consolidating concrete (SCC) such as high deformability, excellent resistance to segregation, and usability without applying vibration is highly common. To gain an environment-friendly approach or improving SCC properties, cement in SCC can be partially replaced with other materials. However, identifying the most effective parameters on the Superplasticizer demand (SP demand) of SSC would not be easy after the replacement. The main aim of this study is to identify the most influencing approaches on SP demand prediction. Hence, five different approaches in SP demand prediction, including Jring test, V funnel test, Ubox test, 3-min slump value, and 50-min slump value have been considered. Then, different models of an artificial intelligence approach are developed and the most influential one in an accurate SP demand prediction was determined. In comparison with other methods, it was indicated that in estimating the SP demand, V-funnel can be a better technique because of producing the lowest RMSE.

Two-stage cracking catalyst of amorphous silica-alumina on Y zeolite for enhanced product selectivity and suppressed coking

Mahdi Davoodpour,Reza Tafreshi,Abbas Ali Khodadadi,Yadolla Mortazavi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.3

A novel bilayer catalyst composed of amorphous silica-alumina (ASA) layer coated on Y zeolite layer is proposed as a fluid catalytic cracking (FCC) catalyst to cause two-stage reactions of pre-cracking and deep-cracking. The bilayer catalyst (Y/ASA) is compared with the usual mixed one (ASA+Y), in catalytic cracking of a feed composed of 1,3,5-triisopropylbenzene and naphthalene. The two catalyst representations were prepared by applying layers of Y zeolite and ASA or both on inert monolith supports. Catalytic cracking experiments were carried out at 300, 350 and 400 oC. Compared to Y+ASA, Y/ASA yielded about 33% and 46% more benzene and toluene, respectively, and 18% less coke in the catalytic cracking at 350 oC. The coke of Y/ASA was less refractory than that of Y+ASA as burnt at lower temperatures, while emitting less carbon monoxide in regeneration. Y/ASA configuration shows promising features as FCC catalysts for increased bottoms cracking and suppressed coking.

Theoretical Study of the Resveratrol Adsorption on B12N12 and Mg-Decoration B12N12 Fullerenes

Sheikhi Masoome,Azarakhshi Fatemeh,Tafreshi Elnaz Sarabadani,Kaviani Sadegh,Shahab Siyamak,Ahmadianarog Mahin 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.6

The adsorption of Resveratrol (RSV) drug on surfaces of the pure B12N12 and Mg-decoration B12N12 fullerenes at physiological PH was studied using density functional theory and time-dependent density functional theory methods at the B3PW91/6-31+G* level at T = 298.15 K and 1 atm in the solvent (water) with a dielectric constant of 78.4. The adsorption energy (Eads) of RSV on two fullerenes have investigated through hydroxyl (-OH) groups. The adsorption effect of the RSV on the bond lengths, electronic properties, UV spectra, and excited states of B12N12 and Mg-B12N12 is detected. Natural bond orbital analysis shows a charge transfer between the RSV and two fullerenes. The electron location function (ELF) and localized orbital locator (LOL) values show that interaction between reactive atoms of RSV (O atoms) and B atom of B12N12 are an electrostatic and partially covalent character. The study interaction of RSV with the B12N12 and Mg-decoration B12N12 can be used in the field of drug delivery and adsorption on metal surfaces.

Optimization of the Double Reduced Beam Section (DRBS) Connection

Saeed Asil Gharebaghi,Reza Fami Tafreshi,Nader Fanaie,Omid Sepasgozar Sarkhosh 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.4

The double reduced beam section (DRBS) connection is a newly developed steel moment connection. In this paper, the chaotic particle swarm optimization technique was utilized to optimize this connection for the best seismic performance. The resulting optimum DRBS connection shapes showed up to 39% better energy dissipation and up to respectively 50% and 55% lower rupture index ( RI ) and equivalent plastic strain ( PEEQ ) at the beam-column interface, compared to the conventional RBS connection. Also, the optimum design parameters determined in this paper led to up to a 28% increase in the objective function (energy dissipation) and up to respectively 36% and 38% decreases in the RI and PEEQ with respect to the original DRBS connection, indicating noticeable seismic performance enhancements. The results indicated that changing the size of the beam and column sections does not lead to any signifi cant change in the optimal shape of the beam fl ange cut or the seismic performance of the connection.

Visible-light-driven super-active Sn and GO single- and Sn/Cu Co-doped nanophotocatalysts for phenol degradation: Thin-film printability, thermal stability, and cytotoxicity assay

Atasheh Soleimani-Gorgani,Jamal Al-Sabahi,Sepideh Akbaripoor Tafreshi Nejad,Maryam Heydari,Mohammed Al-Abri,Arash Namaeighasemi 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-

Sn- and graphene oxide (GO) single-doped and Sn/Cu co-doped titanium dioxide (TiO2) nanoparticleswere synthesized as printed-layer nano-photocatalysts for degradation of phenol under visible-light. The doped TiO2 nanoparticles (Sn-doped-TiO2, Cu/Sn-doped-TiO2, and GO-doped-TiO2) were synthesizedvia sol–gel method and calcinated at a temperature of 450 C. X-ray diffraction (XRD), UV–Visible DRSanalysis, Raman analyses, and Energy-dispersive X-ray spectroscopy (EDXS) were utilized to evaluatethe crystalline structure and photocatalytic activities of doped-TiO2 nanoparticles. Different screenprintingpastes were separately formulated with 26% w/w doped-TiO2 nanoparticles (Paste1-to-Paste3)for printing onto microscope glass slides. Photocatalytic printed film was sustainable filter for unusedsuspension of nanoparticles in wastewater. The printed pasts were sintered at varying temperatures(100–500 C), then three-layer printed nanoparticles sintered at 500 C examined for photocatalysis. Photocatalytic activity of single-layer-printed GO-doped-TiO2 nanoparticles was extraordinary (80%degradation of 10 ppm phenol solution). Hydroquinone, catechol, benzoquinone and acetic acid wereobserved to be produced at different concentrations over different time intervals as a result of phenoldegradation for single-layer-printed GO-doped-TiO2 nanoparticles sintered at 500 C. Bandgap of GOdoped-TiO2nanoparticles was 2 eV, meaningfully lower than anatase TiO2 (3.2 eV). The cytotoxicity assayapplied for normal and cancer cells demonstrated cytocompatibility besides photodegradability. Thisnovel process is a targeted, clean, cost-effective and on-demand approach, taking a big step towarddecontamination of the environmental pollution.

A microlagal-based carbonaceous sensor for enzymatic determination of glucose in blood serum

Seyed Mostafa Jafari,Saeed Masoum,Seyed Ali Hosseini Tafreshi 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.101 No.-

In the present work, Chlorella vulgaris, a well-known microalga was used as a carbonic precursor, tosynthesis the water-soluble carbon dots (CDs) via hydrothermal method. To improve the properties,acidic carbon dots (ACDs) were also synthesized via ultrasoncation of microalgal biomass after acidichydrolysis (using diluted acidic solution). The aqueous solution of ACDs was used as a sensor for glucosedetermination based on glucose oxidase enzyme (GOx) reaction and fluorescence quenching of ACDs inthe presence of Fe3+ ions under the optimized conditions. The linear range of glucose in the blood serumwas measured from a range of 5 mM to 500 mM with a limit of detection (LOD) 2.84 mM. Additionally, thehydrogen peroxide, as the conventional reactive oxygen species (ROS) was determined based on theFenton reaction. The linear range of H2O2 was obtained from 10 mM to 200 mM with LOD of 975 nM. Inall of these applications, fluorescence quenching of ACDs was followed according to photo-inducedelectron transfer (PET) mechanism in the presence of generated Fe3+ ions by Fenton reaction.