scholarly journals Foam Glass Gravel Experimentally Made in a 10 kW-Microwave Oven

2021 ◽  
Vol 2 (2) ◽  
pp. 37-46
Author(s):  
Lucian Paunescu ◽  
Sorin Mircea Axinte ◽  
Felicia Cosmulescu

Abstract                                                         The experimental manufacture of foam glass gravel from glass waste has been quantitatively extended by increasing the power of the microwave oven from 0.8 to10 kW, the authors' interest being focused on the quality of the foamed product. The work equipment was rather improvised, the existing used oven not being adequate except to small extent for the requirements of the experiment, but it allowed obtaining a product similar to those industrially manufactured by conventional techniques. Using a recipe previously tested on the 0.8 kW-microwave oven composed of 1 wt.% glycerol as a liquid foaming agent together with 8 wt.% water glass as an enveloping agent and 8 wt.% water as a binder, the main features of the foam glass gravel lumps were: bulk density of 0.22 g/cm3, porosity of 88.9%, thermal conductivity of 0.057 W/m·K, compressive strength of 5.9 MPa and pore size between 0.10-0.30 mm. The specific energy consumption was negatively influenced by the excessive internal volume of the oven, but even under these conditions its value was relatively low (between 1.53-1.69 kWh/kg).

2021 ◽  
Vol 316 ◽  
pp. 153-158
Author(s):  
Boris M. Goltsman ◽  
Lyubov A. Yatsenko ◽  
Natalia S. Goltsman

The article discusses the peculiarities of the "water-glass – glycerol" foaming mixture components interaction during foam glass synthesis. The important role of the foaming additive type in the foam glass porous structure formation was described, the main foaming substances were listed. The obtaining and researching technology of the samples was described, the compositions of the initial batches using the "water-glass – glycerol" mixture were developed. It was shown that a material with a highly porous structure and density below 500 kg/m3 can be obtained only with the combined introduction of water-glass and glycerol. In this case, mixtures with a predominance of water-glass in the foaming mixture possess optimal properties. Using DSC, it was shown that the addition of water-glass to the mixture completely eliminates the evaporation of glycerol at lower temperatures and intensifies its combustion at higher temperatures. Thus, the addition of water-glass to the glycerol-based foam glass batch allows glycerol to be saved up to higher temperatures that increases the resulting material porosity.


2021 ◽  
Vol 1 (6) ◽  
pp. 12-22
Author(s):  
Lucian Paunescu ◽  
Marius Florin Dragoescu ◽  
Sorin Mircea Axinte ◽  
Felicia Cosmulescu

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.


2020 ◽  
Vol 26 (1) ◽  
pp. 57-64
Author(s):  
LUCIAN PAUNESCU ◽  
MARIUS FLORIN DRAGOESCU ◽  
SORIN MIRCEA AXINTE

The paper presents experimental results obtained in the process of making glass foam from glass waste using a cheap foaming agent (natural dolomite). The originality of the work is the application of the microwave energy, unlike the conventional techniques commonly used in the world. The main advantage highlighted by the experiments is the very low specific energy consumption (below 1.5 kWh/kg), due to the peculiarities of the microwave heating technique. The foamed product has physical, mechanical and morphological characteristics (density between 0.30-0.32 g/cm3, thermal conductivity between 0.064-0.067 W/m·K, compressive strength in the range 2.2-2.6 MPa), which are similar to those of foams made by conventional methods and are suitable for its use as insulating material in construction.


2020 ◽  
Vol 26 (3) ◽  
pp. 173-180
Author(s):  
LUCIAN PAUNESCU ◽  
MARIUS FLORIN DRAGOESCU ◽  
SORIN MIRCEA AXINTE

The paper presents recent achievements in the microwave use for manufacturing foam glass gravel from recycled glass waste and silicon carbide. The aim was to obtain a product with physical and mechanical characteristics almost similar to those of industrially manufactured materials by conventional heating techniques, but with a higher energy efficiency. A foam glass with the thermal conductivity of 0.075 W/m·K and the compressive strength of 7.5 MPa was experimentally obtained. The specific energy consumption was of 1.0 kWh/kg comparable with the industrial processes and it could reach values up to 25% lower by using a high power industrial microwave equipment.


Author(s):  
Adesoji Matthew Olaniyan ◽  
John Adeyemi Adeoti ◽  
Musiliu Olusola Sunmonu

Laboratory experiments were conducted to determine the effect of foaming agent (egg white (EW)), foam stabilizer (carboxyl methyl cellulose (CMC)) and whipping time on drying rate and quality of tomato (Lycopersicon esculentus) paste dried under air oven, microwave oven and mechanical dryer. A 43 factorial experiment in Randomized Complete Block Design (RCBD) was used to study the effect of four levels each of foaming agent (5%, 10%, 15% and 20%EW), foam stabilizer (0.15%, 0.30%, 0.45% and 0.60%CMC) and whipping time (3, 5, 7 and 9[Formula: see text]min) on the drying rate and the quality of foam-mat dried tomato powder in the three drying equipment. Each trial was performed in triplicates making a total number of 576 samples that were individually tested and measured. 25[Formula: see text]g sample of the paste was dried to a moisture content of 7.60% (wb) for 8[Formula: see text]h in mechanical dryer and oven dryer at temperatures of 55[Formula: see text]C and 50[Formula: see text]C, respectively, and 10[Formula: see text]min in microwave oven at 540[Formula: see text]W. Data obtained from the experiments were statistically analyzed using the analysis of variance (ANOVA) while the Duncan’s Multiple Range Test was used to compare the means. Results showed that the drying rate increased with increase in foaming agent, foam stabilizer and whipping with minimum values of 9.21[Formula: see text]g/h obtained in mechanical dryer, 9.31[Formula: see text]g/h in air oven and 8.05[Formula: see text]g/h in microwave oven. Increase in foaming agent, foam stabilizer and whipping time did not cause any adverse effect on vitamin C, ash, protein, fat, carbohydrate, crude fiber contents of the samples. Samples reached a stable moisture content of 7.60% (wb) in less than 8[Formula: see text]h in mechanical dryer and air and less than 10[Formula: see text]min in microwave oven. The results of the study showed that EW, CMC and whipping time influenced the drying rate and quality of foam-mat dried tomato powder.


2021 ◽  
Vol 2 (1) ◽  
pp. 1-12
Author(s):  
Lucian Paunescu ◽  
Sorin Mircea Axinte ◽  
Felicia Cosmulescu ◽  
Marius Florin Dragoescu ◽  
Bogdan Valentin Paunescu

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.


2021 ◽  
Vol 2 (1) ◽  
pp. 20-28
Author(s):  
Lucian Paunescu

Abstract                                                         The paper aimed at the experimental manufacture of a foam glass gravel type by sintering at over 900 ºC a powder mixture composed of recycled glass waste (92%), sodium borate (6%), kaolin (0.3%), silicon carbide (1.7%) and water addition (12%). The originality of the work was the application of the unconventional technique of microwave heating through a predominantly direct heating procedure. The product foamed at 908 ºC had a very fine porous structure (pore size between 0.05-0.20 mm) and a compressive strength above the usual level of foam glass gravels (7.8 MPa). The apparent density of 0.28 g/cm3 corresponding to a bulk density of 0.20 g/cm3 and the thermal conductivity of 0.075 W/m·K ensures the thermal insulating character of the material required for use in the specific field of applications of foam glass gravel. The manufacturing process had an excellent energy efficiency, the specific energy consumption decreasing up to 0.70 kWh/kg.


2020 ◽  
Vol 26 (1) ◽  
Author(s):  
LUCIAN PAUNESCU ◽  
MARIUS FLORIN DRAGOESCU ◽  
SORIN MIRCEA AXINTE

<p>The paper presents experimental results obtained in the process of making glass foam from glass waste using a cheap foaming agent (natural dolomite). The originality of the work is the application of the microwave energy, unlike the conventional techniques commonly used in the world. The main advantage highlighted by the experiments is the very low specific energy consumption (below 1.5 kWh/kg), due to the peculiarities of the microwave heating technique. The foamed product has physical, mechanical and morphological characteristics (density between 0.30-0.32 g/cm<sup>3</sup>, thermal conductivity between 0.064-0.067 W/m·K, compressive strength in the range 2.2-2.6 MPa), which are similar to those of foams made by conventional methods and are suitable for its use as insulating material in construction.</p>


2018 ◽  
Vol 15 (29) ◽  
pp. 75-81
Author(s):  
E. M. RANGEL ◽  
C. de O. CARVALHO ◽  
D. R. ARSAND

The treatment of effluents is essential for the maintenance of the quality of water resources. Among the treatments used, photodegradation is on the rise. Although it is promising, the separation/recovery of photocatalysts in suspension is laborious and costly. In addition, the incorrect disposition of residues causes concern, for example, the glass originated from fluorescent lamps, which presents difficult destination and recovery. In this context, the objective of this work was to synthesize foam glass as substrate for the catalyst (ZnO), from glass residues of fluorescent lamps applying CaCO3 as foaming agent, observing the efficiency of this material in the photodegradation of Alizarin S dye in aqueous solution. To obtain the catalyst foam glass, the characterization was made on the glass and in the foaming agent, followed by its formulation, conformation and burning. Finally, the dye photodegradation tests were done. The results allow to conclude that the foam glass show a great potential as a support for ZnO in catalyzed photodegradation techniques, presenting very similar results when compared to suspended ZnO. It is worth mentioning that the material produced reduces the environmental impact caused by incorrect allocation of fluorescent lamps and solves a problem in the effluent treatment process.


2020 ◽  
Vol 52 (3) ◽  
pp. 269-281
Author(s):  
Suhail Jaafar ◽  
Mohd Zaid ◽  
Khamirul Matori ◽  
Mohd Ghazali ◽  
Mohd Shofri ◽  
...  

This study aims to fabricate low-cost foam glass-ceramic using soda-lime-silica (SLS) glass waste and clamshells (CS) as foaming agent in content between 1 and 12 wt.% by conventional powder processing method. The samples were undergoing sintering process between 700 and 1000?C with holding time of 30 minutes and characterized according to the physical and structural properties. Samples containing 3 wt.% CS treated at 800?C show the greatest size of porosity. As the sintering temperature increased, the samples tend to become less dense. However, for the samples sintered at 900 and 1000?C, the trend of the density changes because of the excess CO2 gases generated during the heat treatment process promotes an increase in internal pressure, which results in the rupture of the pore walls. For linear expansion, for samples with a sintering temperature of 800?C and higher, the increment of the temperature will lead to the decrement of linear expansion (%). As the sintering temperature increases from 700 to 800?C, the water absorption (%) increases. However, the percentage of water absorption decreases with the further increment of sintering temperature. The XRD characterization showed the formation of wollastonite phase (CaSiO3) and further revealed the formation of greater peaks of CaSiO3 at the higher sintering temperatures. The results of compressive mechanical strength between 0.15 and 1.50 MPa indicate that the obtained glass-ceramic foams have potential for building material applications.


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