Thermal Effectiveness Enhancement of Autoclaved Aerated Concrete Wall with PCM-Contained Conical Holes to Reduce the Cooling Load

This work investigates and improves the thermal dynamics of autoclaved aerated concrete (AAC) wall containing phase change material (PCM). The PCM is paraffin wax loaded into conical holes drilled into the AAC. Filled AAC with three different numbers of PCM-filled holes (2, 3, and 4 conical holes, which are designated as AAC-2H, AAC-3H, and AAC-4H, respectively) as well as the unfilled original AAC were both tested under two different conditions: indoors (with controlled temperature) and outdoors (with actual weather). For the indoor experiment, a heater was used as a thermal source and set up to maintain the testing temperature at one of three levels: 40 °C, 50 °C, or 60 °C. The wall temperature was then measured on the surface with each horizontally-positioned wall as well as four different positions at various depths below the surface of the wall. It was found that AAC-4H was the optimum condition, which can produce outstandingly a time lag of approximately 27%, reduce a decrement factor of approximately 31%, and also decrease the room temperature. This reached approximately 9% when compared with that of ordinary AAC at the controlled testing temperature of 60 °C. All samples were further tested in actual weather to confirm the thermal performances of AAC-4H. Thermal effectiveness of AAC-4H was improved by extending approximately a 14.3% time lag, which reduces approximately a 4.3% decrement factor and achieving approximately 5% lower room temperature when compared with ordinary AAC.

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Reducing Heat Conduction of Autoclaved Aerated Concrete Wall Using Phase Change Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.807-809.2779 ◽

2013 ◽

Vol 807-809 ◽

pp. 2779-2783

Author(s):

Atthakorn Thongtha ◽

Somchai Maneewan ◽

Chantana Punlek ◽

Yothin Ungkoon

Keyword(s):

Heat Conduction ◽

Phase Change ◽

Phase Change Material ◽

Thermal Source ◽

Concrete Wall ◽

Autoclaved Aerated Concrete ◽

Thermal Delay ◽

Aerated Concrete ◽

Change Material ◽

Minimum Heat

In this work, the effect of the salt hydrated phase change material (PCM) on microstructure and heat conduction of the autoclaved aerated concrete (AAC) was studied. The microstructure in the AAC and AAC with composed phase change material was imaged by scanning electron microscopy (SEM). The ability in heat conduction was compared among AAC (AAC1), AAC with composed phase change material (0.417 (AAC2) and 0.833 (AAC3) kg/m2 in contents), and AAC which was composed by PCM (0.417 (AAC4) and 0.833 (AAC5) kg/m2 in contents) and was coated by the cement in 2 sides. These ones were tested the thermal delay at 40, 50 and 60 °C using the heater that was the thermal source. It was found that the optimum content of PCM on top surface was found at 0.417 kg/m2 because the minimum heat conduction and the lowest average temperatures of inside wall and inside room were shown in this sample at 40, 50 and 60 °C.

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Seismic behavior of reinforced autoclaved aerated concrete wall panels

ce/papers ◽

10.1002/cepa.818 ◽

2018 ◽

Vol 2 (4) ◽

pp. 259-265

Author(s):

Armin Taghipour ◽

Erdem Canbay ◽

Baris Binici ◽

Alper Aldemir ◽

Uğur Uzgan ◽

...

Keyword(s):

Seismic Behavior ◽

Concrete Wall ◽

Autoclaved Aerated Concrete ◽

Wall Panels ◽

Aerated Concrete

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REGULATION OF PROCESS AND RECIPE PARAMETERS ON THE BASIS OF MODELING PHYSICAL AND MECHANICAL PROPERTIES OF AUTOCLAVED AERATED CONCRETE

Bulletin of Belgorod State Technological University named after V G Shukhov ◽

10.34031/article_5ce292c52da5c9.83158267 ◽

2019 ◽

Vol 4 (5) ◽

pp. 36-41

Author(s):

Роман Шорстов ◽

Roman Shorstov

Keyword(s):

Mechanical Properties ◽

Physical And Mechanical Properties ◽

High Strength ◽

Maximum Temperature ◽

Molding Sand ◽

Autoclaved Aerated Concrete ◽

Aerated Concrete ◽

Set Up ◽

Favorable Conditions ◽

Mixing Water

The article discusses the possibility of regulation by changing the amount of aluminum paste, the temperature of the mixing water and the sides of mold for the expansion of molding sand of autoclaved aerated concrete. Also, the achievement of a given maximum temperature of the array, which determines the nature of the pore structure and physico-mechanical properties of products. Mathematical models for optimizing the physicomechanical properties of autoclaved aerated concrete by regulating technological and prescription parameters are obtained using the method of mathematical planning of an experiment. It is established, optimal parameters are the mixing water temperature of 40 ... 45 ° C, the amount of aluminum paste - 0.6% of the binder mass, the temperature of the sides of the form 85 ... 90 ° C, which creates favorable conditions for the expansion of the gas-concrete mixture and the combination of pore formation and set-up structural strength of the array, allowing to obtain an optimal porous structure with smaller and uniform porosity with a sufficiently low density and high strength

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In Situ X-ray Diffraction at High Temperatures: Formation of Ca2SiO4 and Ternesite in Recycled Autoclaved Aerated Concrete

Minerals ◽

10.3390/min11080789 ◽

2021 ◽

Vol 11 (8) ◽

pp. 789

Author(s):

Angela Ullrich ◽

Krassimir Garbev ◽

Britta Bergfeldt

Keyword(s):

Room Temperature ◽

X Ray Diffraction ◽

Sulfate Content ◽

In Situ Xrd ◽

Autoclaved Aerated Concrete ◽

Thermal Expansion Coefficients ◽

Slow Quench ◽

Aerated Concrete ◽

Heating Up

This study provides an insight into possible recycling processes for autoclaved aerated concrete (AAC) at low temperatures (<1000 °C). Belite binders were synthesized from wastes of AAC by the addition of CaCO3 and adaption of the molar CaO/SiO2 (C/S ratio) in the range of 2 to 2.5. An in situ XRD study performed during heating up to 1000 °C and subsequent quenching to room temperature evidenced the formation of ternesite besides C2S in sulfate-containing systems. Several factors influencing the reaction kinetics and the evolution of the phase composition were investigated thoroughly. Increased sulfate content and dwelling time during heating increase the ternesite content and promote the formation of highly crystalline α’H-C2S. The C/S-ratio of the starting materials has to be adjusted to the sulfate content in order to prevent the formation of ternesite at the expense of C2S. Ternesite remains stable during quenching to room temperature or even increases in amount, except in cases of very low cooling rates or high residual quartz contents (C/S-ratio ≤ 2). Temperature and range of α’H-C2S to β-C2S phase transition on quenching strongly depend on the cooling rate. The onset temperature for β-C2S formation varies between 540 °C (slow quench) and 450 °C (fast quench). Thermal expansion coefficients of ternesite are calculated showing similarity with C2S. The incorporation of CaSO4 modules in the structure switches the direction of maximum compression.

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