română DORINEL TĂLPEANU, LAURA ELENA GEAMBAZU, ALINA IULIA DUMITRU, FLORENTINA CLICINSCHI, VIOLETA TSAKIRIS, ANDREI CUCOȘ, VIRGIL MARINESCU
Abstract
The main objectives of this work are represented by both the development of hydroxyapatite (HAP) and the technique of casting it into plaster forms order to develop of ceramic structures with complex shapes for applications in neurosurgery. The tested models were made from ceramic powders based on HAP and, shaped by the casting technique in plaster molds. In order for the process of casting ceramic suspensions to be more efficient, specific techniques were performed such as: rheological curves of shear stress variation depending on the speed gradient and the dependence of the viscosity of the HAP suspensions on the speed gradient. Experimental models of cranial prostheses were developed in the form of a skull cap with an average thickness of ~3.5 mm, rods with a diameter of 5 mm, length of 50 mm. The samples were sintered at temperatures of 1275˚C and 1350˚C, for 2 hours. The variation of density and porosity with sintering temperature were determined by Archimedes method and the mechanical properties were investigated by bending and compression tests. The average values for the bending strength, for the two obtained models, are in the range of 32.64-36.68 MPa and for the compression strength they range from 44.54 to 50.10 MPa. Furthermore, the obtained samples were characterized by scanning electron microscopy (SEM) and the X-ray diffraction data for the HAP powder were confirmed by FT-IR spectra and thermogravimetric measurements. In order to establish the biocompatibile character, a first set of bacteriological and sterility determinations was performed. The novelty of this work consists in the fact that both the rheological characteristics have been optimized (ceramic suspensions with a solid phase content of min. 60%) as well as the technique of casting ceramic suspensions in plaster molds through ultrasonic and degassing processes/deaeration, obtaining shaped products with a raw density of min. 50% of roth.
Keywords
hydroxyapatite, biomaterials, casting in plaster forms, viscosity curves
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Year
2023
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Issue
53 (1)
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Pages
3-12
ALEXANDRU BURCEA, TALAAT GABRIEL REZK-GAVRILĂ, EDWIN SEVER BECHIR BOGDAN CONSTANTIN COSTĂCHEL, LAURENȚA LELIA MIHAI
Abstract
A cervical abrasion lesion is represented by a concave surface, situated at the gum line area. The aim of this study was to compare the efficiency of three composite resins used for the rehabilitation of cervical abrasions. Cervical abrasion lesions were rehabilitated with Estelite Asterıa - Tokuyama, GrandioSO x-tra Bulk Fill - Voco, and Tetric EvoCeram Bulk Fill - Ivoclar Vivadent) composite resins. 111 abrasion cervical lesions were restored with the three aesthetic dental composites in the assessed patients (26). The assessments were realized at 6 days after the insertion of the restoration material (baseline), and then 6, 12 and 18 months after, according to the modified USPHS criteria regarding the colour stability, anatomical contour, surface texture, marginal adaptation and integrity, marginal discoloration, apparition of secondary caries, postoperative sensitivity, and retention of the restoration. The restored teeth with abrasion lesions were distributed in three groups divided by the used restorative material: group G1 (EA, abrasion lesions restored with Estelite Asterıa composite), group G2 (GSOx, restoration with GrandioSO x-tra Bulk Fill composite), and group G3 (TEC, restoration made with Tetric EvoCeram Bulk Fill composite). The comparative study was a split-mouth study. All three restorative dental materials presented good clinical results after 18 months, in all studied criterion, without significant differences.
Keywords
dental non-carious cervical abrasion, direct restorations, composites, modified USPHS criteria
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Year
2023
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Issue
53 (1)
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Pages
13-22
HADEL OBAIDI, AHLAM ABDUL-RHEEM FARHAN, TAHA H. ABOOD AL-SAADI
Abstract
Since concrete is a consistently reliable building material, its importance to all nations economies cannot be overstated. However, the cement and concrete industries continue to generate massive amounts of waste which results in the emission of carbon dioxide which is one of the environmental issues. Therefore, reducing the amount of cement is important by partially replacing one of the waste materials. In this research; two municipal materials were used as alternatives for cement. It is considered available in quantities with appropriate price as compared to other mineral materials. In addition, this research was interest given to assess the strengths and durable behaviour of concrete production with these addition materials. The amount of metakaolin used is (1-15) wt% and alum (1-5) wt% of cement. The central composite design (CCD) method was used in conjunction with the response surface method to design concrete mixtures for this research and to analyse the results obtained from laboratory tests. An empirical model was given for compressive strength, bulk density and splitting tensile strength. All concrete specimens were cured after 7 and 28 days. The best results were found when metakaolin was used between (1-3) wt% and alum sludge between (1.6-3) wt% as mixed materials to produce concrete and as a partial replacement of cement.
Keywords
Metakaolin; Alum sludge; Concrete; Minitab software; Compressive strength; Splitting tensile strength; Durability
RASIM CEM SAKA, SERKAN SUBASI, MUHAMMED MARASLI
Abstract
The technical term GRC (glass fiber reinforced concrete) is widely used in the precast industry. This type of concrete, which is obtained by mixing cement, sand, glass fibers and some chemicals, is very durable. Compared to conventional concretes, high compressive, flexural and impact strength is the preferred choice for building facade coatings. In this paper, the usability of sepiolite as a pozzolan in glass fiber reinforced concrete and its effects on mechanical and physical properties were investigated. GRC samples were produced by adding 3% glass fiber by volume to substituted mixtures. Crude and calcined sepiolites were replaced with cement at 5%, 10%, 15% and 20% by weight. Compressive strength, flexural strength, impact strength and abrasion resistance of produced GRC samples were determined. As a result, It was observed that as sepiolite ratio increased, mechanical and physical properties of samples decreased in early and later ages, and crude sepiolite substituted samples had lower mechanical strength than the calcined sepiolite substituted samples.
Keywords
Glass fiber, GRC, Sepiolite, Calcination
Insights on the mechanisms of seawater-mixing calcium silicate slag-based alkali-activated materials
DI SHI, JIAYUAN YE, WENSHENG ZHANG, WEIGUO SHEN
Abstract
In order to get a full understanding of the mechanisms of seawater-mixing alkali-activated materials, calcium silicate slag (CSS)-based alkali-activated materials (AAMs) with various content of Cl- were synthesized, and then the effect of Cl- on the properties, products, hydration heat evolution, microstructure of AAMs, as well as the characteristics of alkaline solution were investigated. The results showed that the Cl- introduced in the form of solid NaCl significantly decreased the mechanical properties of CSS-based AAMs in the range higher than 1 wt%. This properties degradation can be attributed to the hydration inhibitions caused by the dissolution of solid NaCl and the interaction between NaCl and sodium silicate solution, as well as the formation of non-cementitious sodalite other than C(N)-A-S-H gels. Despite this, the findings of this study provided further evidence for the application potentialities of seawater in AAMs as mixing water due to the limited content of Cl- in seawater.
Keywords
calcium silicate slag; alkali-activated materials; Cl-; interaction; seawater-mixing
AYED KADA, BENADOUDA MOURAD, BENMOKRETAR KARIM, KERDAL DJAMEL EDDINE
Abstract
This study aims at evaluating the durability of self-compacting sand concrete (SCSC) based on pozzolan, brought from the north-western town of Beni-Saf (Algeria), with respect to the diffusion of chloride ions. The influence of the addition of a large amount of natural pozzolana on the diffusion of chloride ions in SCSC samples was studied in the first part of this paper. The compressive strengths of several SCSC samples, which were formulated with different percentages of natural pozzolana, were then compared with those of standard self-compacting concrete (SCC) and vibrated concrete (VC) in the second part. The experimental tests carried out on these formulations indicated that self-compacting sand concrete (SCSC) exhibits better mechanical behavior and also only a small number of chloride ions can penetrate in it as compared to other types of concrete. This study also showed that the partial substitution of cement in the SCSC by natural pozzolana from Beni-Saf improves its resistance to the diffusion of chloride ions.
Keywords
Self-compacting sand concrete; Natural pozzolana; Mechanical strength; Durability; Diffusion of chloride ions; Porosity; Capillarity
ECEM DOGAN, MUSTAFA SENGOR, OGUZHAN GUNDUZ, CEM BULENT USTUNDAG
Abstract
This study aims to obtain nanoparticles by electrospinning method using xanthan gum (XG) and gelatine (GEL) polymers. For the development of these nanoparticles, ten different groups were produced. In some groups, nanofiber was obtained instead of particles. The nanofiber formation was determined in the 10 wt% GEL, 12 wt% GEL, 3 wt% XG, 8 wt% GEL + 3 wt% XG. 12 wt% GEL + 0.1 wt% XG groups. 4 wt% GEL + 1 wt% XG and 8 wt% GEL + 3 wt% XG groups showed nanoparticles structure. To assess the nanofibers chemical properties, Fourier transform infrared spectroscopy (FTIR) were used. Scanning electron microscopy (SEM) was used to characterize mechanical and morphological properties. Physical properties and swelling behaviours were examined to analyse the samples. As a result of the swelling test, 3 wt% XG was degraded, 10 wt% and 12 wt% gelatin groups started to degrade after the fourth day. Our work deduced that GEL/XG nanoparticles could use for carrier purposes. Also, this study was beneficial in finding the right ratios in the production of nanoparticles and nanofibers from the XG/GEL mixture by electrospinning. In addition, proper electrospinning parameters in nanofiber and nanoparticles production are also important results of the study and will be further used in developing composite nanostructures with regenerative or drug release capability.
Keywords
gelatin; xanthan gum; electrospinning; particle; fiber
Keywords
Experimental, behavior, polystyrene, light backfill, polyglass, uni-axial, reinforcement.
CONSTANTIN C. BUNGAU, TUDOR BUNGAU, MARCELA FLORINA PRADA, IOANA FRANCESCA PRADA, RADU DUMITRU MOLERIU
Abstract
Green buildings (GBs) aim to improve the characteristic performance of buildings throughout their entire life cycle, to conserve resources and increase the comfort of residents. The theme of GBs is very specific to the field of construction. However, a relevant, current analysis of the specialized literature in the field, to evaluate the scientific impact and citations, is missing. This study aims to identify and analyze already published scientific papers. In this context, the Scopus database was comprehensively explored. Therefore, the records and citations of the 8612 identified manuscripts were imported into VOSviewer to perform this bibliometric analysis. Most of the manuscripts were published after 2010. The publications were mainly focused on terminology characteristics of sustainable development (i.e. sustainability, GBs, construction). The publication share increased every year. The main contributors to this area are the United States of America, China, Italy, and the United Kingdom. The most prolific journals were Energy and Buildings, Sustainability, Building and Environment and Journal of Cleaner Production. Temporal analysis of citation patterns revealed an intense growth of scientific interest, focusing especially on green/sustainable buildings especially in the recent period. Romania is only at the beginning of approaching this topic, the first work being published only in 2003 and oscillations in the publication tendency being observed.
Keywords
Green buildings; sustainability; constructions; energy performance; bibliometric analysis
ANDREEA IONIŢĂ (AFILIPOAEI), ZINA VULUGA, FLORIN OANCEA, GEORGE-MIHAIL TEODORESCU, RALUCA AUGUSTA GABOR, CRISTIAN ANDI NICOLAE, MĂLINA DEȘLIU-AVRAM, JENICA PACEAGIU
Abstract
In the present work, composites based on recycled polypropylene (PPr) and 30% treated and untreated lignocellulosic waste were prepared. The recycled polypropylene comes from recovered surgical masks used during the COVID-19 pandemic, from which the elastic band and the metal strip have been removed. The lignocellulosic waste used as a reinforcing agent consisted of the depleted substrate from the culture of Pleurotus ostreatus fungi, being a sawdust enriched in chitin pellets of corn cobs treated with borhot from the brewing of beer. The composites with 30% of treated/untreated sawdust were obtained in dynamical conditions by melt processing. The effects of sawdust, both treated and untreated, on tensile properties (strength and modulus of elasticity), dynamic-mechanical properties (storage/loss modulus and loss factor), thermal conductivity and thermal stability were studied. The results showed improved thermal and mechanical properties of bio-composite materials based on recycled polypropylene from used face masks and sawdust, which can be used as construction materials.
Keywords
face mask, lignocellulosic agricultural waste, PP recycled, thermal insulation properties
G. VIGNESH KUMAR, S. UDHAYAKUMAR
Abstract
Increasing threads of the global warming and issues in disposals in municipal solid waste without compromising the mechanical properties the existing composite materials requires some additional materials. The traditional glass fiber, basalt fiber and epoxy based hybrid composite material is accommodate with bio waste tamarind seed polysaccharides and cashew nut frictional dust with different mesh with that the mechanical properties are improved based on the results of tensile, impact and flexural tests. The biodegradable test confirms the biodegradation of the fabricated samples with frictional dust.
Keywords
Frictional Dust, Hybrid biocomposite, biodegradation, tensile property, Tamarind seed polysaccharides
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Year
2023
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Issue
53 (2)
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Pages
103-110
.FLORENTINA MARILENA CLICINSCHI, DORINEL TĂLPEANU, ALINA IULIA DUMITRU, VIOLETA TSAKIRIS, GABRIELA BEATRICE SBÂRCEA, DELIA PĂTROI, MARINESCU VIRGIL EMANUEL
Abstract
The aim of the work is to obtain through the spark plasma sintering (SPS) technique, ceramic composite materials based on Si3N4 and SiC, with different sintering additions (Al2O3 and Y2O3) with improved mechanical properties. The spark plasma sintering process was carried out in vacuum at a pressure of 50 MPa, at temperatures between 1600-1800°C and a maximum sintering time of 5 minutes. In order to put in evidence the structural and morphological behavior of the obtained composites at different sintering temperature that lead to their improved mechanical properties, they were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Physical-mechanical characteristics (apparent density, apparent porosity and Vickers hardness) were determined for all sintered samples. Structural analysis by X-ray diffraction, revealed the formation of two major phases α and β-Si3N4, with an increase of their crystallographic transformation from one phase to another (α→β) with the increasing of the sintering temperature. Si3N4 and SiC based ceramic composites sintered at 1800°C and with a 5wt.% Y2O3 content, showed a good correlation of physical-mechanical and structural characteristics, having a relative density of 93% of the theoretical density, Vickers hardness values of 18.39 GPa and bending strength of 336 MPa.
Keywords
Spark Plasma Sintering,Si3N4, SiC, ceramic composites, X-ray diffraction, scanning electron microscopy
OLURANTI ABIOLA , TEMITAYO OGEDENGBE, ADEKOLA OKE
Abstract
Ceramic is an engineering material that has endeared itself to many sectors especially the building services sector where it is used for floor tiles. Machining is a necessary finishing operation after casting and other forming operations. A very important machining operation performed on ceramic materials such as tiles is grinding to pave way for easy installation, aesthetics and safety. This work investigates the elemental and chemical composition of the raw materials used in the production of the ceramic tiles under investigation and study the effect of different grinding procedures on some mechanical properties of the ceramic tiles. The tiles were ground at two different grinding speeds and two different levels (continuous and intermittent at 2 seconds intervals). Breaking strength, flexural strength, hardness, and surface roughness before and after grinding were analyzed using the Signal-to-Noise (S/N) ratio. The result revealed that the elements and their respective oxides present in the raw materials were able to give strength, rigidity and support to the ceramic article. Also, grinding was found to affect the mechanical properties of the ceramic tile samples as the breaking strength and flexural strength reduces from 339.77 N for the control sample to as low as 273.30 N and 16.40 N/mm2 respectively.
Keywords
ceramic tiles, grinding, breaking strength, flexural strength, hardness
IULIANA PAUN, CRISTINA ILEANA COVALIU- MIERLA, EUGENIU VASILE
Abstract
Benzalkonium chlorides are among the active ingredients of the products with biocidal properties used for disinfection of hands and surfaces. After use, a large part of benzalkonium chlorides end up in the wastewater from the treatment plants where they can cause imbalances of the biological treatment step by destroying the bacteria in the activated sludge. Having bactericidal properties, these pollutants are unlikely to be removed by conventional wastewater treatment techniques. In this paper we present an unconventional method for wastewater treatment using TiO2 nanomaterial with a particle size of 10 nm having the photocatalytic activity for degrading two components of benzalkonium chloride, namely tetradecyldimethyl benzyl ammonium chloride (C14-BAC) and hexadecyldimethylbenzyl ammonium chloride (C16-BAC) from wastewater. The concentration of the two compounds was analyzed using a high-performance liquid chromatograph equipped with a diode array detector (HPLC-DAD). The wastewater treatment yield was 100 %, and the half-life was for C14-BAC of 7.56 h and for C16-BAC of 10.67 h.
Keywords
benzalkonium chloride, nanomaterial, TiO2 powder, wastewater treatment
SUTHANKUMAR N, THANKA JEBARSAN V, PHANI MANOJ AV
Abstract
The development of unique and high volume cement replacement concrete with enhanced strength and durability properties is attempted in the present study. In this paper, fresh and hardened state properties of concrete containing wollastonite and limesludge are used as cement replacements to attain a unique composition and several experiments such as determination of compressive strength, flexural strength, split tensile strength, water absorption, sorptivity, ultrasonic pulse velocity, charge passed, alkali silica reaction, scanning electron microscope studies coupled with EDX analysis (Energy Dispersive X-Ray Analysis) were performed. The results show that the size of mineral additions has a pre-dominant role on the reduction of ASR expansion. Among all the ternary blended mixes, the mix containing wollastonite at 15% with 5% LS showed increased strength and durability at all ages. This paper also emphasized the measurement of electrical resistivity behaviour of the series of wollastonite-limesludge mixes thereby showing enhanced bulk resistance of the concrete mixes
Keywords
wollastonite, lime sludge, durability, mechanical strength, microstructure
ALI OSAT AKBARI MOGHADDAM, ALI DELNAVAZ , SEYED AMIRHOSSEIN HASHEMI , SEYED HOOMAN GHASEMI
Abstract
The purpose of this paper is to provide a model for predicting the corrosion process in concrete. This model is defined based on the simultaneous infiltration of chloride ions and the phenomenon of carbonation of concrete under certain environmental conditions. For this purpose, the simultaneous effect of chloride ion diffusion and carbonation phenomenon was studied using experiments on the fabricated samples. For this reason, in the first case, the samples are exposed to carbon dioxide once and then to chloride ions. In the latter case, only samples under the influence of chloride infiltration are examined. To make the samples, which include 9 mixing designs, three water-to-cement ratios of 0.35, 0.4 and 0.5 and three percent of 0%, 7% and 10% silica fume have been used. In this study, accelerated chloride ion (RCPT) penetration, capillary adsorption, pressurized water penetration and compressive strength tests of concrete were performed on the samples. Also in control and carbonate samples, the results of long-term experiments including chloride ion penetration and determination of chloride ion profile and determination of chloride ion diffusion coefficient have been investigated. The results of permeability tests show that carbonation has a direct effect on reducing the flow rate in the chloride ion permeation test and also reducing the capillary adsorption coefficient in the water capillary adsorption test. While increasing the ratio of water to cementations materials, the effect of carbonation on reducing the flow rate and also the capillary absorption coefficient of water increases, it should be noted that increasing the percentage of soot silica reduces this effect. Using linear fitting models on the results of long-term experiments, the amount of changes in chloride ion diffusion coefficient due to carbonation of concrete and determination of chloride ion concentration in concrete is presented.
Keywords
Carbonation, Chloride diffusion coefficient, Concrete, Porosity, Silica fume
SABINA SCRIPCĂ, MARINELA BĂRBUȚĂ
Abstract
The main purpose of this study is to investigate the impact of microsilica and fly ash as cement replacements on the modulus of elasticity of concrete and microconcrete, as well as the effect of metal and polypropylene fibres in this context. Different concrete and microconcrete mixtures were designed with 5% and 10% microsilica or fly ash as cement replacements, with and without metal or polypropylene fibres. The modulus of elasticity was determined through compression tests, and the results were analyzed to evaluate the effects of the additives and fibres on the modulus of elasticity compared to traditional concrete.According to the results obtained, it was found that microsilica and fly ash as cement replacements can improve the modulus of elasticity of microconcrete in most cases, while in the case of concrete, only a few exceptions with a higher modulus of elasticity were recorded. Comparing the values of the modulus of elasticity from the two data sets, it can be observed that the modulus of elasticity values of the fly ash/microsilica-based microconcrete are up to 27.03% higher than those of the fly ash/microsilica-based concrete. The general trend observed is that replacing a higher proportion of cement with microsilica and fly ash can lead to a decrease in the modulus of elasticity of concrete/microconcrete. Regarding fibers, they did not significantly influence the modulus of elasticity of microconcrete and concrete with fly ash or microsilica, except for metal fibers, which had a more pronounced effect in some cases. At the same time, it is important to note that the addition of polypropylene fibers had a negative effect in certain situations. With regard to strength class, the majority of concretes were classified as C12/15 strength class.It is essential to highlight the benefits of replacing cement with fly ash or microsilica in terms of reducing costs and carbon dioxide emissions associated with cement production. Therefore, using these additives brings multiple environmental advantages and, at the same time, maintains or even improves the properties of concrete.
Keywords
Concrete, fly ash, microconcrete, microsilica, moduls of elasticity, fibers
DENG CHEN , LI-WU MO, AI-GUO WANG, KAI-WEI LIU, TAO YANG, SHI-PING ZHANG, FEI SONG
Abstract
This work focuses on the sulfate resistance performances of Portland cement (PC) incorporating different amounts (0~60 wt%) of dolomite powder (DM) pre-cured at different temperatures (20 °C and 60 °C). The results show that the PC-DM samples pre-cured at 20 °C for 28 d and then eroded by sulfate solution for 180 d exhibit the worse appearances and higher expansion values than the reference PC sample. On the opposite, the sulfate resistance performances of the PC-DM samples pre-cured at 60 °C are better than those of the PC sample. Furthermore, with the increase of the DM content, the sulfate resistance properties get better and better. The degradation of the pore structure may act as a major factor for the poor sulfate resistance of the PC-DM samples pre-cured at 20 °C. However, for the PC-DM samples pre-cured at 60 °C, the poor pore structure does not increase the risk of sulfate erosion. This is mainly due to that the formation of hydrotalcite (Ht) results in the decomposition of monosulfate, and SO42- may also be bound firmly by Ht in the PC-DM samples, thus contributing to the excellent sulfate resistance. Additionally, brucite can be identified in the PC-DM samples pre-cured at 60 °C, especially with high DM dosages (≥40 wt%).
Keywords
dolomite powder; sulfate attack; pore structure; hydrotalcite
SERGII KROVIAKOV , LUBOV SHESTAKOVA
Abstract
Influence of basalt fiber and air-entraining admixture on the properties of rigid concrete pavement was investigated. Concretes without fiber and with 0.50, 0.75 and 1.0 kg/m3 fiber were produced. The amount of air-entraining admixture varied from 0 to 0.15% of the cement mass. Due to dispersed reinforcement, the compressive strength of concrete increased by 13-24%, and the tensile strength increased by 21-29%. The use of air-entraining admixture did not affect the tensile strength of concrete, but reduced compressive strength by 2-21%. Concrete without dispersed reinforcement and air-entraining admixture has a frost resistance F200. The use of basalt fiber increases the frost resistance of concrete up to F300. When using 0.05% air-entraining admixture, the frost resistance of concrete decreases, but when using 0.15% admixture, the frost resistance of concrete without fiber increases from F200 to F300. The air-entraining admixture does not affect the abrasion resistance of concrete, and the dispersed reinforcement reduces the abrasion resistance by 14-15%, which contributes to the increase in the durability of the pavement. The use of dispersed reinforcement and complex modification with polycarboxylate type superplasticizer and air-entraining admixture made it possible to obtain concrete for rigid concrete pavement with high durability and the required strength.
Keywords
rigid concrete pavement, basalt fiber, air-entraining admixture, durability, strength, frost resistance
NISHANT A NAIR, VISWANATHAN T S
Abstract
This article aims to produce sustainable and durable mortar with help of wollastonite admixing with Pozzolan portland cement with and without nano-silica. Wollastonite was chosen for its flexural capacity and nano-silica for refining the pore matrix and improving the overall properties of the mortar matrix. At 3, 7, and 28 days, eight different mix proportions were investigated. The ease with which water moves through the mortar medium and also porosity parameters were used as durability indicators. Mechanical properties tested were compressive strength, flexural strength, and dynamic modulus of elasticity. Correlations of mechanical properties were found using a graphical method. X-Ray Diffraction (XRD) and Fourier Transform infra-red (FT-IR) spectroscopy were employed to characterize the samples taken from the fractured specimens. Pore radius was calculated with the help of sorptivity and permeable porosity values. In terms of mechanical and durability properties, wollastonite replacement at 10% and nano-silica replacement at 6% were found to be optimum.
Keywords
Wollastonite, nano-silica, sorptivity, porosity, pore radius
MUSA AYRAN, ZEKIYE AKDAG, SONGUL ULAG, OGUZHAN GUNDUZ
Abstract
Diabetic wounds pose a significant challenge in clinical settings, primarily due to uncontrolled blood sugar levels and compromised immune systems observed in diabetes mellitus. Curcumin (CUR), a well-known anti-inflammatory and antioxidant agent, has shown potential for wound regeneration. However, its limited bioavailability and stability necessitate the development of a novel scaffold to overcome these limitations. In this study, we investigated the wound-healing properties of extracted CUR from Curcuma longa rhizomes and their combination with organic polymers by developing and evaluating a biomimetic composite 3D scaffold specifically designed for diabetic wounds. Incorporating CUR and Ethyl cellulose (EC) nanoparticles onto Alginate and Chitosan (SA/CS) scaffolds was achieved through the electrospraying method, resulting in an average particle size of 784±35.1 nm for CUR/EC nanoparticles. The interaction between different concentrations of CUR1 and CUR3 (1mg/1ml and 3mg/1ml) with EC on scaffolds was analyzed using FTIR spectroscopy, providing insights into the chemical composition of the scaffolds. The structural properties of the scaffolds and nanoparticles were examined to assess their morphological characteristics. Furthermore, the swelling and degradation behaviors of the scaffolds were investigated under in vitro conditions. The release profile of CUR was determined, and cytotoxicity testing was performed on the L929 cell line using an MTT assay to evaluate the biocompatibility of CUR/EC-coated scaffolds, as indicated by viable and proliferating cells in vitro study. In addition, the potential of CUR/EC-coated scaffolds to support tissue regeneration was evaluated using a DAPI staining assay and scanning electron microscopy (SEM).
Keywords
alginate, chitosan, curcumin, electrospraying, wound healing, 3D printing
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Year
2023
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Issue
53 (3)
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Pages
189-204
MIHAI-ALEXANDRU EFTIMIE, CARMEN-CRISTINA UDREA, MIHAELA-ALINA MELINESCU, ANA-VIOLETA FILIP
Abstract
Borosilicate glasses that possess UV transmission can be used in materials that facilitate the disinfection or inactivation of bacteria using UV light. Three compositions were elaborated in the low alkali domain of borosilicate glasses through the classical melt-quenching technique at temperatures up to 1680 °C. The analysis of the samples was performed using thermal expansion, hydrolytic stability, density, UV-Vis transmission, Raman spectroscopy, and X-ray diffraction. The hydrolytic stability of the analysed samples showed that they are chemically stable. From the thermal expansion it was observed that the processed samples had low expansion coefficients. Regarding the UV-Vis transmittance, glasses have acceptable transmittances in the ultraviolet region down to 260 nm. Raman spectroscopy was used to identify the glass network bonds and the presence of nonbridging oxygen ions in the processed glass samples by the presence of specific high-frequency peaks in the spectrum. XRD analysis also showed that the borosilicate glass samples did not crystallize.
Keywords
borosilicate glass, UV-Vis transmission, germicidal applications
ANDRADA-ELENA ALECU, STEFANIA-ANDREEA GIRJOABA, MIHAELA BEREGOI, MIHAELA BACALUM, MINA RAILEANU, SORIN-ION JINGA, CRISTINA BUSUIOC
Abstract
In this work, polyvinylidene fluoride (PVDF) fibres loaded with mineral powders, such as titanium dioxide (TiO23xMgSi2Oy), were prepared by electrospinning polymeric suspensions containing 20 wt.% PVDF and 3 wt.% powder. The piezoelectric polymer was combined with powders having antibacterial, piezoelectric, or bioactive properties, respectively, in the desire to obtain multifunctional materials compatible with the requirements of the medical field. All powders were characterized in terms of morphology and crystalline structure, which confirmed the nanometric character of TiO223xMgSi2Oy. The final fibrous scaffolds were homogeneous, composed of individual fibres with a diameter below 1 μm and decorated with aggregates of inorganic particles, placed either inside the fibres or attached to their surface. The biological evaluation demonstrated the superiority of the composites towards the plain polymer in terms of cell viability.
Keywords
Polyvinylidene fluoride; Titanium dioxide; Barium titanate; Akermanite; Electrospinning; Tissue Engineering
DR.R.SHANMUGAM
Abstract
The modernization developments globally lead to an abundance of infrastructure progression. This progression is consequential to numerous sources of predicament like scarcity of construction resources on the other hand increases productivity thrown away from industry. Of late, managing scrap is the principal concern faced globally. The throwaway problem is the most significant issue facing the world as a source of ecological contamination. Recent growth in transportation has generated an immense number of motor vehicles creating an enormous quantum of scrap tyres. This paper investigates incorporating the salvage of scrap tyre rubber of coarse aggregate in M30 eco-friendly composite blocks as a fragmentary substitution. As per the recent government norms M30 eco-friendly composite is used for principally constructional works. This research is to appraise the accomplishment of steel slag as coarse aggregate in the fly-ash-based eco-friendly composite. Eco-friendly composite(EFC) is 100 % cement Scrap tyre rubber and steel slag were progressively incorporated with 0%, 5%, 10%, 15% ,and 20% to substitute coarse aggregate with sisal fiber in, 4% of fly ash. Properties of coarse aggregates, fine aggregates, fly ash and scrap tyre rubber were found. Paver Blocks were cast and tested for 7, 14 and 28 days of strength. The result shows that the compressive and flexural strength of M30 eco-friendly composite with scrap tyre rubber is 5% for Blocks is optimal. Laboratory tests were carried out and the conclusion was made based on the results. The outcome shows that the mechanical characteristics of M30 eco-friendly composite with scrap tyre rubber are 5% for eco-friendly composite (EFC) Blocks are most advantageous. Also, structural characteristics were studied.
Keywords
Eco-friendly composite, fly ash, Sisal fiber, Steel slag, Scrap tyre rubber
SUBBIAN MAKESH KUMAR, SARANGAPANI CHITHRA
Abstract
In the search for sustainable development in the field of the construction sector, scientific advancements in the use of alternative materials in Self-Compacting Concrete (SCC) are of primary interest among researchers. The present study also attempted to use industrial waste materials such as Fly Ash (FA), Cement Kiln Dust (CKD), and Ecosand (ES) in the preparation of SCC, optimizing their mixture formulation using Taguchi-based Grey Relational Analysis (GRA). Batch optimization trials were conducted using a Taguchi L9 orthogonal array with different replacement levels of CKD (5%, 10%, 15%), FA (25%, 30%, 35%), and ES (10%, 20%, 30%) in SCC. Fresh properties, including slump flow, T500 time, V funnel time, L box passing ratio, and J ring step height, as well as hardened properties like compressive strength, flexural strength, and split tensile strength, were considered as responses. The Taguchi-based GRA results revealed an optimized mixture composition of 53 kg/m3 CKD, 184 kg/m3 FA, and 84 kg/m3 ES. Furthermore, a confirmation test was carried out to validate the model, and the error percentage was found to be less than 10%. ANOVA results indicated that the influencing parameters followed the order of CKD > ES > FA. Based on these findings, Taguchi-based GRA can be considered an ideal tool for optimizing concrete mixes.
Keywords
multi-response optimization, Taguchi based GRA, SCC, Industrial wastes, CKD, ecosand
R. JEYA PRAKASH, B. SOUNDARA, K.S. ELANGO, S. CHRISTIAN JOHNSON
Abstract
Due to Infrastructure development city streets are being covered with concrete pavements in which it makes the pavement surface impermeable. During monsoon period, the importance of counter action against the stormwater runoff develops a stress among the Central and the State Governments of India. It also attracts the attention of the Road and Transport officials mainly because of the difficulties faced with poor drainage system during heavy intensity of rainfall. The productive application of pervious concrete includes its usage for light volume transportation and it also diminishes the additional design for stormwater drainage. This concrete also holds potential to accommodate shoulders in heavy traffic roadway transportation. The behaviour of pervious pavement under various loading scenario can be well understand using Finite Element Method Analysis (FEMA). For primary assessment of pervious concrete (PC) as pavements, computer modelling software is preferable and economical comparing to ground evaluation after installation. In this paper, a EverFE (Finite Element Analysis) tool has been used to develop and determine the loading characteristics of pervious pavement based on the experimental values obtained through preliminary studies.
Keywords
Pervious Concrete Pavement, Fibre Reinforced Pervious Concrete, Critical Loading, Finite Element analysis, Stress, Deflection
ȘTEFAN GEORGE CĂLINOIU, CORNELIA BÎCLEȘANU, ANAMARIA FLORESCU, CĂTĂLIN CONSTANTIN DUMITRU, MIHAI EFTIMIE, ANTON FICAI
Abstract
The aim of this study is to compare the mechanical strength in compression, tension and FTIR microscopy of 2 types of dental adhesives: 4th generation, considered the "gold standard" and the latest generation adhesives called universal adhesives.
In the dental community, I have noticed that opinions regarding the two adhesives are divided. More comfortable and younger doctors prefer universal adhesive because it gives them easier and faster working times. And the experienced doctors who used the 4th generation adhesive claim that after using the universal adhesive they returned to the "gold standard".
We compared the two adhesives regarding the adhesion they achieve through compressive forces and tensile forces. The compression was carried out with the help of a press and on blocks of Gradia Direct Posterior filling material, which after the first test, the blocks were reformed with the help of the 2 adhesives and retested. After the traction that was performed on extracted teeth on which fillings were made similar to clinical situations, the detachment area was studied under the FTIR microscope.
In tests, All-Bond 3® Bisco adhesive had higher bond strength and compressive strength than CLEARFIL™ Universal Bond Quick Kuraray. Following the tensile tests, the values obtained showed a higher adhesion to the 4th generation adhesive. Also, the interface area where debonding occurred showed that the 4th generation adhesive is superior in terms of adhesion to dental tissues.
Keywords
universal, 4th generation adhesives. compressive, tensile, adhesion
SEBASTIAN VÂLCEA, BOGDAN DUMITRIU, VALENTIN NIȚESCU, MIRCEA BEURAN, MIHAI ȘTEFAN
Abstract
Postoperative pancreatic fistula is the leading cause of morbidity and mortality in patients undergoing pancreatic resection. The pancreatic duct stenting technique during pancreatic anastomosis does not reduce the incidence of postoperative pancreatic fistula after cephalic pancreatoduodenectomy. The drainage method includes the use of an external or internal stent . The current literature suggests that the use of an internal pancreatic duct stent does not help to reduce the leakage rate of pancreatic anastomosis after pancreatic resection, and it may increase the risk of pancreatic fistulas in soft pancreases [1].
We report here the case of a 74-year-old patient, who 15 years ago underwent a Whipple-type cephalic duodenopancreatectomy, the operative indication being a Vaterian ampulla, for which the anastomosis prosthesis was performed with a plastic stent placed intraoperatively at the level of the Wirsung canal later, in 2022, he developed a late pancreatic fistula through the migration of the transparietal stent to the skin level.
Pancreatic postoperative fistula represents a major cause of morbidity and mortality in pancreatic surgery. Therefore, many surgical techniques have been undertaken and tested to prevent the occurrence of pancreatic fistula and its related complications, also useful for decreasing mortality rates among these patients.
Keywords
stent, fistula, pancreas, morbidity
BENOUIS ALI, AIT KACI DJAFAR,ZAHI RACHID, MOULGADA ABDELMADJIDÉ, ZAGANE MOHAMMED EL SALLAH,MOHAMMED BENTAHAR, BOUTABOUT BENALI
Abstract
This study represents an in-depth exploration of stress distribution within polymethylmethacrylate (PMMA) orthopedic cement, a critical material used in hip prostheses. Focusing on the inherent fragility of the cement and its intricate interface with implants, our research meticulously investigates stress patterns surrounding individual cavities. What sets this study apart is its nuanced examination of interactions between multiple cavities and their consequential effects on both stress intensity and distribution. The findings from this research offer nuanced and illuminating insights into the interconnected nature of cavities, aligning closely with observations derived from real-world experiments. This study significantly advances our understanding of potential damage phenomena within total hip prostheses. Moreover, it establishes a robust foundation for potential advancements in the design and performance of prostheses, taking into account the complex interplay within orthopedic cement. These insights pave the way for more targeted improvements in the mechanical behavior of hip prostheses, thereby contributing to the ongoing evolution of orthopedic implant technology.
Keywords
Cement, implant, stress, bone, defect, rupture
MARISELVAM.P, VELMURUGAN.T, G.KARTHIKEYAN
Abstract
This paper focuses on the thermal properties of R-Glass/Epoxy laminate in response to temperature variations. The elastic properties and coefficient of thermal expansion in the material s principal direction were measured across the temperature range from room temperature to the cure temperature. These properties were then characterized as functions of temperature. Using the characterized properties and the principles of classical lamination theory, a method was proposed to predict the changes in the coefficient of thermal expansion for a general laminate subjected to temperature variations. The measured values of the coefficient of thermal expansion for laminates with varying angle plies were compared with the predicted values. The experimental results demonstrate that the proposed method accurately predicts the changes in the coefficient of thermal expansion for a general laminate under temperature variations. Additionally, an analytical formulation was proposed and validated to predict the changes in the coefficient of thermal expansion for R-Glass/Epoxy laminates subjected to temperature variations.
Keywords
R-Glass/Epoxy laminate, Thermal properties, Analytical model, Thermal expansion, Experimental
BRUNA MOREIRA, CARLOS JESUS, RAPHAELE MALHEIRO, AIRES CAMÕES
Abstract
Promoting the circular economy is one of the main tools to achieve carbon neutrality by 2050. The culture of using residues in cementitious materials, mainly in concrete, is already established, favouring circularity. Fly ash is commonly used in blended cement or concrete production as supplementary cementing material. However, waste glass is not as commonly used as a cement substitute. In this context, this research contributes to the knowledge about the use of waste glass as partial cement replacement, developing an experimental work. Glass bottles were transformed into glass powder using two different grinding processes. They were produced glass powders with different colours and fineness. These powders were used to produce mortars with 25% of glass powder replacing cement. Mortars containing fly ash were also produced. Their compressive strengths were evaluated over time. Results concluded that white, green, and brown glass powders are acceptable to be used as cement replacements. The results also identify glass powder as a potential substitute for fly ash.
Keywords
Glass powder; Fly ash; Cementitious materials; Circular economy; Low CO2
LEONID DVORKIN, VADIM ZHITKOVSKY, YURI RIBAKOV
Abstract
Reactive powder concrete (RPC) is an efficient type of fine-grained concrete with extreme strength and durability characteristics. The use of RPC allows the construction of such unique objects as pedestrian and automobile bridges, thin-walled architectural forms, protective structures, hazardous waste storage facilities, etc. Obtaining RPC provides for the mandatory use of a significant amount of microsilica as an active mineral additive, which is not always available for use. The article presents the results of comparing the strength characteristics of RPC obtained on microsilica and with its complete replacement with fly ash activated by milling with sodium silicate fluoride. The studies were carried out using mathematical planning of the experiment. Experimental-statistical models of RPC water demand and compressive and flexural strength at different ages have been obtained and analyzed. It is shown that the use of activated ash in the RPC makes it possible to obtain concrete with a strength of 100...110 MPa in 28 days. A method for calculating the composition of the RPC using the obtained models is proposed.
Keywords
reactive powder concrete, fly ash, microsilica, planning of experiments, experimental-statistical model, strength, concrete mix composition, design
İSMAİL HOCAOĞLU
Abstract
New construction materials have begun to be produced by using nano-technology. Nano aluminum oxide (nano-Al2O3) is known to have high electrical conductivity. In addition, nano-Al2O3 can increase the material s physical features and mechanical strength by spreading perfectly into cementitious composites like other nanomaterials. In this study, direct current (20V-DC) and alternating current (20V-AC) were applied to the nano-Al2O3-added to 300 dosage mortars (when they were fresh situation) for one day. It also investigated the mechanical-physical properties and microstructure of the mortars when nano-Al2O3 (0%, 1%, 1.5%, and 2% by weight instead of cement) was added. To determine the changes in the mortar s internal temperatures depending on DC and AC, the hydration temperatures of the mortars were measured every 60 seconds. It was observed that the optimum nano-Al2O3 ratio was 1%. It was also concluded that AC application was more effective in increasing the hydration temperature of the mortar. In terms of mechanical strength, It was seen that when DC-applied mortars were cured for 7 days and AC-applied mortars were cured for 28 days, they took higher values. Another result obtained from the study is that alternating cure improves the microstructure better than the direct current in cement-based materials.
Keywords
Nano aluminum oxide; Alternating current; Direct current; Internal temperature; Microstructure
PAVEL TOPALĂ, ALEXANDR OJEGOV, VITALIE BEȘLIU, DANIELA RĂILEANU
Abstract
Micro- and nano-technology is nowadays a field of production that grows up vigorously and attempts to solve the material and energy crisis that has affected all mankind on the one hand, and, on the other hand, it comes with new solutions in miniaturization of the technique and solving the problems faced by the compatibility of existing materials with the living matter, i.e. it comes with apply for a better life. The recent studies regarding the interaction of surface materials with plasma pulsed electrical discharges caused by a solitary discharge have shown that under the action of PEDM the active surfaces of the parts applied in machine building, electronics, chemical industry, food industry, medicine, etc. micro-modifications of these surfaces can take place, along with the formation of 3D-structured carbon films with micrometric thicknesses, synthesis of amorphous films of oxides and hydroxides of nanometres thicknesses. The application of surface micro-geometry modifications ensures the increase of the thermoelectric current of the electrons up to 10 times, the surface-active resistance by 107 times, the resistance to corrosion in the aggressive media from 2 to 100 times.
Keywords
micro-, nanotechnologies, pellicle, film, corrosion, emission, resistance