Experimental determination and fractal modeling of the effective thermal conductivity of autoclaved aerated concrete: Effects of moisture content

Author(s):  
Hong-Qing Jin ◽  
Xiao-Li Yao ◽  
Li-Wu Fan ◽  
Xu Xu ◽  
Zi-Tao Yu
2016 ◽  
Vol 824 ◽  
pp. 100-107 ◽  
Author(s):  
Alena Struhárová

Bulk density and moisture content are factors that significantly affect the physical properties of autoclaved aerated concrete (AAC) including thermal conductivity and other thermo-technical characteristics. This article shows the results of measurements of compressive strength, capillary absorption, water absorption and porosity of AAC (ash on fluidized fly ash) at different bulk density and also the results of thermal conductivity of AAC at different bulk density and variable moisture content of the material. The thermo-technical properties were measured using the Isomet 2104, a portable measuring device. Acquired results demonstrate dependence of physical properties including thermal conductivity of AAC on bulk density and moisture content. The reliability and accuracy of the method of measuring was also shown.


Author(s):  
M.V. Zavoloka ◽  
◽  
Yu.M. Zavoloka ◽  
І.І. Grynyova ◽  
Yu.V. Zavoloka ◽  
...  

Abstract. In the context of tightening the thermo-technical requirements for building envelopes, the benefits and advantages of energy-efficient wall material of autoclaved aerated concrete and aerated concrete products are shown. Domestic and foreign researches in the field of rational use of autoclaved aerated concrete for external walls in modern construction of energy-efficient buildings and optimization of structural solutions of aerated concrete walls are generalized. The most important thermos-physical characteristic for assessing the thermal resistance of external walls made of aerated concrete is the value of the thermal conductivity coefficient. The moisture content of aerated concrete has a significant effect on thermal conductivity, the release moisture is several times higher than the calculated moisture content stipulated by the standards for construction heat engineering and operating conditions. In the initial stages of construction, the moisture content of aerated concrete exceeds the moisture content established in the normative documentation by operating conditions, which requires recalculation of the thermal resistance of the walls of buildings taking into account the real moisture content of aerated concrete used during construction. A detailed explanation of the dependence of the heat flow through the enclosing structure on its resistance to heat transfer, established in the form of a hyperbola, is given, and the dependence of the difference in thermal conductivity on the moisture content of aerated concrete blocks is presented. When analyzing the effect of moisture on the thermal conductivity of aerated concrete, was used the characteristic deviation ± Δλ of thermal conductivity of aerated concrete in a wet state from the thermal conductivity of concrete in a dry state was used. Based on the results of the experiment carried out at OSACEA, the main conclusions and recommendations for determining the coefficient of thermal conductivity of aerated concrete in dry and wet conditions are given. Some aspects of energy saving in construction practice are presented, based on materials prepared by Doctor of Technical Sciences, prof. Gagarin V.G. The need to improve specific energy-saving measures is shown, which should be economically viable and not reduce the durability of construction objects. Generalized conclusions and recommendations are given.


2019 ◽  
Vol 196 ◽  
pp. 555-563 ◽  
Author(s):  
Anuar Ulykbanov ◽  
Eldar Sharafutdinov ◽  
Chul-Woo Chung ◽  
Dichuan Zhang ◽  
Chang-Seon Shon

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