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Marius Florin Dragoescu
Department of Applied Chemistry and Materials Science, University "Politehnica" of Bucharest, Romania
Aerospace Engineering Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Engineering

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Manufacture of Cellular Glass Using Oak Leaves as a Foaming Vegetable Agent Lucian Paunescu; Sorin Mircea Axinte; Marius Florin Dragoescu; Felicia Cosmulescu
Journal La Multiapp Vol. 1 No. 4 (2020): Journal La Multiapp
Publisher : Newinera Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37899/journallamultiapp.v1i4.210

Abstract

Abstract The manufacture experimentation of a cellular glass exclusively from mineral waste and natural residues using the unconventional technique of microwave irradiation was the objective of the research whose results are presented in the paper. The originality of the paper results from the use of oak leaves as a vegetable foaming agent as well as the use of microwave energy in heating processes of the raw material powder mixture for manufacturing thermal insulating materials for the building construction. Worldwide, these processes use only conventional heating techniques. The experimental results led to the conclusion that both the use of waste and residues, as well as the unconventional heating technique allow to obtain porous materials with structural homogeneity having apparent densities and thermal conductivities that can decrease up to 0.34 g/cm3, and 0.071 W/m·K respectively. The compressive strength corresponding to the materials with the lowest values of density and thermal conductivity has an acceptable value (1.2 MPa) for the field of application. The specific energy consumption is around 1 kWh/kg, being approximately at the same level with the values of industrial consumptions achieved by conventional techniques.
Manufacturing Ceramic Foams at Very High Temperature by the Unconventional Process of Direct Microwave Heating Lucian Paunescu; Sorin Mircea Axinte; Marius Florin Dragoescu; Felicia Cosmulescu
Journal La Multiapp Vol. 1 No. 4 (2020): Journal La Multiapp
Publisher : Newinera Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37899/journallamultiapp.v1i4.228

Abstract

Abstract SiC ceramic foams were manufactured by direct microwave heating up to 1520 ºC. Silicon carbide (42-68 wt.%), quartz sand as a silica supplier (20-38 wt.%), coal fly ash (12-20 wt.%) and a constant water addition of 15 wt.% were used as starting materials. The ceramic foam samples had semi-open microstructures in which neighboring cells are partially connected to each other and partially closed. Due to the very dense cellular walls and the very low cells size (below 21 μm), the compressive strength had very high values (41.3-56.5MPa), the porosity was within an average value range (52.4-57.6%) and the thermal conductivity and the apparent density had relatively high values. In energy terms, the technique of direct microwave heating was very advantageous, the specific energy consumption being very low (1.04-1.21 kWh/kg) compared to the consumptions achieved by conventional methods. The application field of SiC ceramic foams obtained by the bonding method and using silica as a bonding agent includes hot gas or molten metal filters, porous burners, catalytic supports and others. From the four tested experimental variants, it could be concluded that the optimal sample was that achieved at 1520 ºC with 68% silicon carbide, 20% quartz sand, 12% coal fly ash and 15% water addition, having the porosity of 57.6%, thermal conductivity of 0.174 W/m·K, compressive strength of 56.5 MPa and the equivalent pore size between 9-21 μm.
Glass-ceramic Foams Made of Very High Coal Fly Ash Weight Ratio by the Direct Microwave Heating Technique Lucian Paunescu; Sorin Mircea Axinte; Marius Florin Dragoescu; Felicia Cosmulescu
Journal La Multiapp Vol. 1 No. 4 (2020): Journal La Multiapp
Publisher : Newinera Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37899/journallamultiapp.v1i4.242

Abstract

A high mechanical strength glass-ceramic foam was produced by direct microwave heating at 853 ºC of a very high weight ratio of coal fly ash (82%), calcium carbonate (5%) as a foaming agent, sodium carbonate (13%) as a fluxing agent and water addition (10%). Due to the excellent energy efficiency of the direct microwave heating, the heating rate had a very high value (32 ºC/min), much higher than the heating rate of conventional processes and led to a very low value of the specific energy consumption (0.72 kWh/kg). The physical and mechanical characteristics of the optimal glass-ceramic foam sample were: apparent density of 1.44 g/cm3, porosity of 26.2%, thermal conductivity of 0.281 W/m·K, compressive strength of 41.3 MPa and water absorption of 0.5%. Given the features of the glass-ceramic foam (very high compressive strength, acceptable porosity and thermal conductivity, very low water permeability, fireproof, chemical stability, no-toxicity, etc., the application domain of this material type may include road and railway constructions, bridge abutments and retaining walls, foundations, drainages, sports grounds and other types of constructions that require high mechanical stress.
Unconventional Technique for Producing Borosilicate Glass Foam Lucian Paunescu; Marius Florin Dragoescu; Sorin Mircea Axinte; Felicia Cosmulescu
Journal La Multiapp Vol. 1 No. 6 (2020): Journal La Multiapp
Publisher : Newinera Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37899/journallamultiapp.v1i6.272

Abstract

The study aims to test an advanced technique but insufficiently valued in the world in the process of experimental manufacture of borosilicate glass foam. It is about the unconventional technique of heating solids by using the microwave radiation converted into heat. The experimental equipment on which the tests were performed was a 0.8-kW microwave oven commonly used in the household with constructive adaptations to be operational at high temperature. The adopted manufacturing recipe was composed of borosilicate glass waste with the addition of calcium carbonate, boric acid and water in different weight proportions. The material was sintered at 829-834 ºC by predominantly direct microwave heating and the optimal foamed product had characteristics similar to those manufactured by conventional techniques (apparent density of 0.33 g/cm3, thermal conductivity of 0.070 W/m•K, compressive strength of 3.1 MPa and a homogeneous microstructure with pore size between 0.7-1.0 mm). The energy efficiency of the unconventional manufacturing process was remarkable, the specific energy consumption being only 0.92 kWh/kg.
Ultra-light Colorless and Green Glass Foam Produced by Microwave Radiation Lucian Paunescu; Sorin Mircea Axinte; Felicia Cosmulescu; Marius Florin Dragoescu; Bogdan Valentin Paunescu
Journal La Multiapp Vol. 2 No. 1 (2021): Journal La Multiapp
Publisher : Newinera Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37899/journallamultiapp.v2i1.286

Abstract

Abstract According to the research objective that was the basis of the paper, an ultra-light glass foam with an apparent density of 0.14 g/cm3 was experimentally made from 98.9% post-consumer glass bottle and 1% CaCO3 as a foaming agent by sintering/foaming at 823 ºC in microwave field with a very low specific energy consumption (0.70 kWh/kg). A very advanced mechanical processing of glass waste (below 32 μm) and a very fine granulation (below 6.3 μm) of CaCO3 were the solutions adopted to obtain this high-performance product. The originality of the work is the use of the unconventional technique of predominantly direct microwave heating with a very high energy efficiency, applied by authors in recent years and presented in several previous papers.
Adequate Correlation between the Physical and Mechanical Properties of Glass Foam Lucian Paunescu; Sorin Mircea Axinte; Marius Florin Dragoescu; Felicia Cosmulescu
Journal La Multiapp Vol. 2 No. 4 (2021): Journal La Multiapp
Publisher : Newinera Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37899/journallamultiapp.v2i4.415

Abstract

The paper presents experimental results obtained in the manufacturing process of a glass foam by adequate correlation between its physical and thermal properties (density, porosity, thermal conductivity) and mechanical (compressive strength) by a slight controlled overheating of the foamed material. Using a powder mixture of glass waste (87-91.5 %), coal fly ash (3-9 %) and silicon carbide (4-5.5 %) microwave heated at 935-975 ºC by this unconventional technique, constituting the originality of the work, was obtained a glass-ceramic foam with moderate compressive strength (1.8-2.6 MPa) and very low thermal conductivity (0.058-0.070 W/m·K). The material overheating generated a homogeneous porous structure characterized by closed cells with relatively large dimensions (without the tendency to join neighboring cells) making it difficult to transfer heat across the material. The foamed product is suitable for the manufacture of thermal insulation blocks for the inner or outer walls of the building without excessive mechanical stress, being an advantageous alternative by comparison with known types of polymeric or fiberglass thermal insulation materials.
Granulated Expanded Glass Manufacturing Method Using Electromagnetic Waves Lucian Paunescu; Sorin Mircea Axinte; Felicia Cosmulescu; Marius Florin Dragoescu
Journal La Multiapp Vol. 2 No. 5 (2021): Journal La Multiapp
Publisher : Newinera Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37899/journallamultiapp.v2i5.478

Abstract

The paper presents experimental results obtained in the process of experimental manufacture in a microwave oven of lightweight granulated glass aggregates. The process was conducted to obtain the highest dimensional class (between 18-23 mm), the almost spherical shape of the aggregates being facilitated by cold processing of raw spherical pellets (between 11-15 mm) containing the powder mixture formed by glass waste, borax. calcium carbonate, aqueous sodium silicate solution and water addition and then rotation of the high electromagnetic wave susceptible ceramic crucible containing raw pellets during the heat treatment at temperatures between 822-835 ºC. In terms of quality, the expanded glass aggregate granules are almost similar to those manufactured in conventional rotary kilns heated by burning fuel, having the following characteristics: bulk density of 0.17 g/cm3, compressive strength of 2.2 MPa, thermal conductivity of 0.047 W/m·K, water absorption of 1 vol. % and pore size between 0.3-0.6 mm. The experimental product has not yet been tested as a raw material in the manufacture of some light weight concretes, but the use of similar granulated glass aggregates manufactured in the world confirms the ability of this aggregate type to produce light weight and energy efficient concretes for building construction.
Co-Authors Bogdan Valentin Paunescu Felicia Cosmulescu Lucian Paunescu Lucian Paunescu Lucian Paunescu Lucian Paunescu Sorin Mircea Axinte Sorin Mircea Axinte