Thermal conductivity of lightweight aggregate based on coal fly ash

2012 ◽  
Vol 110 (1) ◽  
pp. 489-495 ◽  
Author(s):  
Dmitar Zorić ◽  
Dušan Lazar ◽  
Ognjen Rudić ◽  
Miroslava Radeka ◽  
Jonjaua Ranogajec ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Coal Fly Ash ◽  
Lightweight Aggregate

scholarly journals Compressive Strength and Thermal Conductivity of Fly Ash Geopolymer Concrete Incorporated with Lightweight Aggregate, Expanded Clay Aggregate and Foaming Agent

2019 ◽  
Vol 70 (11) ◽  
pp. 4021-4028 ◽  
Author(s):  
Liew Yun Ming ◽  
Andrei Victor Sandu ◽  
Heah Cheng Yong ◽  
Yuyun Tajunnisa ◽  
Siti Fatimah Azzahran ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide Solution ◽  
Density Ratio ◽  
Lightweight Aggregate ◽  
Alkali Activation ◽  
Geopolymer Concrete ◽  
River Sand ◽  
Foaming Agent

This paper investigates the effect of incorporation of lightweight aggregate and foam in the preparation of lightweight aggregate geopolymer concrete (LWAGC) and lightweight aggregate foamed geopolymer concrete (LWAFGC). The geopolymer paste was formed by alkali activation of Class F fly ash in mixture of sodium silicate and sodium hydroxide solution. LWAGC was incorporated with expanded clay lightweight aggregate and river sand while hydrogen peroxide was added as foaming agent for LWAFGC. Results showed that LWAGC and LWAFGC achieved an excellent 28-day compressive strength of 60 MPa and 20 MPa, respectively. The bulk densities were 1815 kg/m3 for LWAGC and 1593 kg/m3 for LWAFGC. Even so, low thermal conductivity of 0.12 W/mK and 0.09 W/mK were reported. It was concluded that the joint effect of lightweight aggregate and foam produced geopolymer concrete with good mechanical strength while having excellent thermal insulating properties. The geopolymer concretes possessed high strength-to-density ratio to be regarded as lightweight high-performance structures.

scholarly journals Fabrication and Fireproofing Performance of the Coal Fly Ash-Metakaolin-Based Geopolymer Foams

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1750 ◽  
Author(s):  
Xi Peng ◽  
Qin Shuai ◽  
Han Li ◽  
Qin Ding ◽  
Yan Gu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Physical Properties ◽  
Fire Resistance ◽  
Coal Fly Ash ◽  
Structure Stability ◽  
Dry Density ◽  
Porous Blocks ◽  
Resistance Tests ◽  
Skeleton Structure

This paper aims to investigate the influence of coal fly ash (CFA) addition on the fireproof properties of the metakaolin-based geopolymer foams. The physical properties, thermal conductivity and fire resistance of the CFA-metakaolin-based geopolymer foams are discussed. The CFA-metakaolin-based geopolymer foams achieve a dry density between 259.43 kg/m3 and 349.73 kg/m3, a porosity between 71.78% and 72.98%, a thermal conductivity between 0.0871 W/(m·K) and 0.0944 W/(m·K) and a compressive strength between 0.38 MPa and 0.56 MPa, exhibiting better physical properties than that of the porous blocks without CFA addition. It is also found that the CFA addition could decrease the viscous sintering temperature and change the phase compositions of sintering products, resulting in the porous structure deterioration in a certain extent and obvious rise of the final reverse-side temperature during the fire-resistance tests. Fortunately, the conversion of the amorphous geopolymer gel to ceramics has helped to maintain the main skeleton structure stability. The CFA-metakaolin-based geopolymer foams still exhibit excellent fire resistance, and the reverse-side temperatures are always within 250 °C after 3 h fire-resistance tests.

scholarly journals Compressive Strength and Thermal Conductivity of Fly Ash Geopolymer Concrete Incorporated with Lightweight Aggregate, Expanded Clay Aggregate and Foaming Agent

2019 ◽  
Vol 70 (11) ◽  
pp. 4021-4028
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Lightweight Concrete ◽  
Sodium Hydroxide Solution ◽  
Density Ratio ◽  
Lightweight Aggregate ◽  
Alkali Activation ◽  
Geopolymer Concrete ◽  
Foaming Agent

This paper investigates the effect of incorporation of lightweight aggregate and foam in the preparation of lightweight aggregate geopolymer concrete (LWAGC) and lightweight aggregate foamed geopolymer concrete (LWAFGC). The geopolymer paste was formed by alkali activation of Class F fly ash in mixture of sodium silicate and sodium hydroxide solution. LWAGC was incorporated with expanded clay lightweight aggregate and river sand while hydrogen peroxide was added as foaming agent for LWAFGC. Results showed that LWAGC and LWAFGC achieved an excellent 28-day compressive strength of 60 MPa and 20 MPa, respectively. The bulk densities were 1815 kg/m3 for LWAGC and 1593 kg/m3 for LWAFGC. Even so, low thermal conductivity of 0.12 W/mK and 0.09 W/mK were reported. It was concluded that the joint effect of lightweight aggregate and foam produced geopolymer concrete with good mechanical strength while having excellent thermal insulating properties. The geopolymer concretes possessed high strength-to-density ratio to be regarded as lightweight high-performance structures. Keywords: Lightweight Concrete; Geopolymer; Expanded Clay Aggregate; Foam

scholarly journals Manufacturing Ceramic Foams at Very High Temperature by the Unconventional Process of Direct Microwave Heating

2020 ◽  
Vol 1 (4) ◽  
pp. 7-17
Author(s):  
Lucian Paunescu ◽  
Sorin Mircea Axinte ◽  
Marius Florin Dragoescu ◽  
Felicia Cosmulescu
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Compressive Strength ◽  
Fly Ash ◽  
Microwave Heating ◽  
Coal Fly Ash ◽  
Water Addition ◽  
Ceramic Foams ◽  
Sic Ceramic ◽  
Very High

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.

Effect of ball milling on the thermal conductivity and viscosity of Indian coal fly ash nanofluid

Heat Transfer ◽  
2020 ◽  
Vol 49 (8) ◽  
pp. 4475-4490 ◽  
Author(s):  
Praveen Kanti ◽  
K. V. Sharma ◽  
C. G. Ramachandra ◽  
Alina Adriana Minea
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Ball Milling ◽  
Coal Fly Ash ◽  
Indian Coal

scholarly journals Study on Thermal Insulation Zeolite by Coal Fly Ash

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Huiping Song ◽  
Nan Zheng ◽  
Fangbin Xue ◽  
Fangqin Cheng
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Thermal Insulation ◽  
Crystallization Temperature ◽  
Coal Fly Ash ◽  
Insulation Material ◽  
Liquid Ratio ◽  
Silica Alumina ◽  
Solid Liquid ◽  
Silica Alumina Ratio

This paper takes the coal fly ash as the material and makes zeolite with low thermal conductivity under a two-step synthesis for the purpose of thermal insulation. It studies main factors affecting zeolite such as the different concentration of NaOH, the solid-liquid ratio, the silica-alumina ratio, and the crystallization temperature. The optimal conditions were obtained that the NaOH concentration was 3 mol/L, the solid-liquid ratio was 10 : 1, the silica-alumina ratio was 2, and the crystallization temperature was 12°C. Zeolites have multiple pores and skeletal structures under SEM observation. The mean particle size was 2.78 um of concentrated distribution. The pore volume was 0.148 m3/g measured by BET analysis, the specific surface was 118.6 m2/g, and the thermal conductivity was 0.153 W/(m·K). Zeolite was proved to be a qualified insulation material which can be used in thermal insulation coating as a new material of energy conservation.

scholarly journals Pembuatan Refraktori Dari Refraktori Bekas Pakai Kiln Dan Flyash Batubara Dengan Variasi Tekanan Greenbody [Recycling of Used Refractory of Kiln and Coal Fly Ash by Various of Greenbody Presure]

Metalurgi ◽  
2018 ◽  
Vol 32 (3) ◽  
pp. 97
Author(s):  
Ayu Septriana ◽  
Azhar Azhar ◽  
Widi Astuti
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Bulk Density ◽  
Coal Fly Ash ◽  
Aggregate Size ◽  
Apparent Porosity ◽  
Green Body ◽  
Hot Plate

Refractory is one type of ceramic material which is thermostable (high temperature resistant) and has the ability to maintain a good physical and chemical condition at high temperature. Manufacture of refractory in this study using used kiln refractory from cement industry and 15% coal fly ash as additional. This research analyzed the effect of green body pressure produced by physical properties of refractory which made from mixture of used refractory and coal fly ash. Used refractory crushed into large aggregate size -40 +80 mesh and small aggregate size -80 mesh, while fly ash -100 mesh. Then, the two of material mixed. Raw material pressed by press hydrauliuc, with a cube-shaped mold in 5 x 5 x 5 cm size. The pressure of green body varied in 8, 9, 10, 12, and 13 tons. The product tested by archimedes methode to getting apparent porosity and bulk density, and guarded hot plate methode standard use ASTM (C 177-04) to getting the cold crushing strengh and thermal conductivity. Higher pressure molding green body product was obtained with higher compressive strength and bulk density, with lower value of the apparent thermal conductivity and porosity. The highest value for the compressive strength and bulk density was 4.48 MPa; 1.119 g / cm3; the lowest value of thermal conductivity and apparent porosity is 11.60 W / m.K; 22.034%. Those values obtained from green pressure body 13 tons.AbstrakRefraktori merupakan salah satu jenis bahan keramik yang tahan terhadap panas (temperatur tinggi) dan memiliki kemampuan untuk mempertahankan kondisinya baik secara fisik maupun kimia pada temperatur tinggi tersebut. Pembuatan refraktori pada penelitian ini menggunakan bahan baku refraktori bekas pakai kiln pabrik semen dengan tambahan 15% fly ash batu bara. Penelitian ini menganalisis pengaruh tekanan green body dari campuran refraktori bekas pakai dan fly ash batu bara yang dihasilkan terhadap sifat fisik refraktori tersebut. Bahan baku refraktori bekas pakai dihaluskan dengan distribusi ukuran agregat besar -40+80 mesh dan ukuran agregat kecil -80 mesh, sedangkan fly ash batu bara berukuran -100 mesh. Pemadatan bahan baku dilakukan dengan menggunakan alat press hydraulic, dengan cetakan berbentuk kubus dengan ukuran 5 x 5 x 5 cm. Dilakukan variasi tekanan campuran green body sebesar 8, 9, 10, 11, 12, dan 13 ton. Pengujian produk dilakukan dengan uji porositas (apparent porosity) dan densitas (bulk density) dengan metode archimedes, kuat tekan (cold crushing strenght), dan uji konduktivitas termal bahan dilakukan dengan metode guarded hot plate menggunakan standarASTM (C 177-04). Pengaruh tekanan green body dari campuran fly ash batu bara dan refraktori bekas pakai kiln terhadap sifat fisik refraktori adalah semakin tinggi tekanan pencetakan green body, maka semakin tinggi nilai kuat tekan dan densitasnya, sedangkan nilai konduktivitas termal dan porositas akan semakin rendah. Nilai tertinggi untuk kuat tekan dan densitas adalah 4,48MPa; 1,119 gr/cm3; nilai terendah konduktivitas termal dan porositas adalah 11,60 W/m.K; 22,034 %. Nilai-nilai tersebut didapatkan dari tekanan green body 13 ton.  

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