Properties control in autoclave aerated concrete by choosing of pore forming Al-agent

Фомина, Е. В.; Chulenyov, Anatolii S.; Kozhukhova, N. I.

doi:10.1088/1757-899x/365/3/032044

Cited by 6 publications

(3 citation statements)

References 1 publication

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“…The reason for the formation of macropores is an increase in volume due to the effect of aeration; micropores are located in the walls between macropores [25][26][27][28]. For example, the porosity of aerated concrete averages 70-80%, and about 45-55% of this porosity is the porosity caused by the chemical reaction of aluminum powder in an alkali solution [29,30]. The "porous microstructure of the concrete matrix is mainly represented by a weakly crystallized C-S-H phase and tobermorite 1.1 nm in size" [31,32].…”

Section: Introductionmentioning

confidence: 99%

Influence of Recipe Factors on the Structure and Properties of Non-Autoclaved Aerated Concrete of Increased Strength

et al. 2022

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At present, the load-bearing enclosing structures of buildings and structures are designed and built considering the increasing requirements for energy efficiency and energy saving of such structures. This is due to the need for a thrifty attitude to the energy consumed and the need to strive for the greening of construction and increase the energy efficiency of buildings and structures. In this regard, one of the most effective and proven building materials is cellular concrete. The purpose of this study was to study the influence of some prescription factors on the structure formation and properties of non-autoclaved aerated concrete with improved characteristics. Standard test methods were used, as well as SEM analysis of the structure of aerated concrete. Non-autoclaved aerated concrete with the replacement of part of the cement with microsilica in an amount from 4% to 16% MS showed higher strength characteristics compared to aerated concrete, where part of the cement was replaced by the addition of granulated blast-furnace slag and a complex additive. The maximum value of compressive strength was recorded for aerated concrete with 16% MS addition. The largest increase in the coefficients of constructive quality was observed in compositions of aerated concrete with the addition of silica fume from 11% to 46% compared with the control composition. The addition of microsilica makes it possible to achieve an improvement in the thermal conductivity characteristics of non-autoclaved aerated concrete (up to 10%). Replacing part of the cement with slag and complex additives does not have a significant effect on thermal conductivity. The obtained dependencies were confirmed by the analysis of the structure formation of the studied aerated concrete at the micro level. An improvement in the microstructure of aerated concrete with the addition of microsilica in comparison with samples of the control composition has been proven.

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Section: Introductionmentioning

confidence: 99%

Influence of Recipe Factors on the Structure and Properties of Non-Autoclaved Aerated Concrete of Increased Strength

et al. 2022

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“…The gas overflow after the addition of the expansion agent forms millions of uniformly sized and evenly distributed air voids in the concrete matrix, which are much bigger than the ordinary concrete [ 2 , 28 , 29 ]. In recent years, a large number of studies proved that the thermal insulating ability of porous concrete is significantly affected by its pore structure [ 30 , 31 ]. To intensively study the heat transfer performance of porous materials, many studies attempted to link thermal conductivity with its pore structure parameters [ 32 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

Simulation and Experimental Substantiation of the Thermal Properties of Non-Autoclaved Aerated Concrete with Recycled Concrete Powder

Wang

et al. 2022

Materials

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Non-autoclaved aerated concrete (NAAC) is a two-phase material with a concrete matrix and air, exhibits good thermal insulation performance and shows good potential in the insulating construction industry. In this study, recycled concrete fine powder was used as an auxiliary cementing material, and the NAAC with different porosity and distribution was fabricated by the non-autoclaved method at different curing temperatures. The effect of porosity on the thermal conductivity and mechanical strength of NAAC is analyzed by experimental tests. A prediction method of thermal conductivity combining pore structure reconstruction and numerical simulation was proposed, which is established by two steps. Firstly, the pore size distributions of NAAC with different porosities were characterized by stereology image analyses. Secondly, the thermal conductivity prediction model based on the pore structure information was established by a COMSOL steady-state heat transfer module. The thermal conductivity results of COMSOL simulations were compared with the experiments and other theoretical models to verify the reliability of the model. The model was used to evaluate the effect of porosity, pore size distribution and the concrete matrix’s thermal conductivity on the thermal conductivity of NAAC; these are hard to measure when only using laboratory experiments. The results show that with the increase in curing temperature, the porosity of NAAC increases, and the number and volume proportion of macropores increase. The numerical results suggest that the error between the COMSOL simulations and the experiments was less than 10% under different porosities, which is smaller than other models and has strong reliability. The prediction accuracy of this model increases with the increase in NAAC porosity. The steady thermal conductivity of NAAC is less sensitive to the distribution and dispersion of pore size in a given porosity. With the increase in porosity, the thermal conductivity of NAAC is linearly negatively correlated with that of the concrete matrix, and the correlation is close to 1.

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“…It is known that the thermal performance of AAC relates to the porosity: the larger the porosity, the lower the thermal conductivity, which is greatly affected by the addition of an Al component, because the air pore is mainly made of aluminum powder [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. By using Al powder, Al paste and highly dispersed Al particles, different pore shapes of AAC can be generated.…”

Section: Introductionmentioning

confidence: 99%

Effect of Pore Structure on Thermal Conductivity and Mechanical Properties of Autoclaved Aerated Concrete

Chen

Jing

et al. 2021

Materials

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With the premise of investigating mechanical properties, the thermal conductivity of autoclaved aerated concrete (AAC) is a key index of self-insulation block walls for building energy conservation. This study focused on the effect of pore structures on the mechanical performance and thermal conductivity of AAC with the comparison of AAC base materials. Different kinds of AAC and their base materials were prepared and experimentally investigated. While maintaining a consistent mix proportion of the AAC base material, the pore structure of AAC was changed by the dosage of aluminum power/paste, foam stabilizer, and varying the stirring time of aluminum paste. The steam curing systems of AAC and the base material were determined based on SEM (Scanning Electronic Microscopy) and XRD (X-ray Diffraction) tests. With almost the same apparent density, the pore size decreased with the increasing content of foam stabilizer, and the mixing time of aluminum paste and foam stabilizer has a great influence on pore size. The thermal conductivity test and compressive test results indicated that that pore size had an effect on the thermal conductivity, but it had little effect on the compressive strength, and the thermal conductivity of sand aeration AAC was 8.3% higher than that of fly ash aeration AAC; the compressive strength was 10.4% higher, too. With almost the same apparent density, the regression mathematical model indicates that the thermal conductivity of AAC increased gradually with the increase of pore size, but it had little effect on the compressive strength. From the test results of basic mechanical properties, the mechanical model of cubic compressive strength, elastic modulus, axial compressive strength, and splitting tensile strength was obtained. The proposed stress–strain relationship model could well describe the relationship of AAC and the base material at the rising section of the curve.

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Properties control in autoclave aerated concrete by choosing of pore forming Al-agent

Cited by 6 publications

References 1 publication

Influence of Recipe Factors on the Structure and Properties of Non-Autoclaved Aerated Concrete of Increased Strength

Influence of Recipe Factors on the Structure and Properties of Non-Autoclaved Aerated Concrete of Increased Strength

Simulation and Experimental Substantiation of the Thermal Properties of Non-Autoclaved Aerated Concrete with Recycled Concrete Powder

Effect of Pore Structure on Thermal Conductivity and Mechanical Properties of Autoclaved Aerated Concrete

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