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

Abstract

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.

Research on Cracking Mechanism of Early-Age Restrained Concrete under High-Temperature and Low-Humidity Environment

“…The relationship between the damage degree D and the loading age t (d) of specimens 1 and 2 was fitted by a cubic curve model [ 36 ]. The quantitative relationship between the damage degree D and the loading age t (d) was obtained, as shown in Equations (2) and (3).…”

Novel Approach to Handling Microfiber‐Rich Dye Effluent for Sustainable Water Conservation

“…e SEM analysis of the concrete highlighted the hydration property, the development of pore after complete curing displayed improved pore size, and this might be due to the change in weather condition that is supported by the foundation of dye wastewater. e sizes of pore in the concrete are based on mix proportion of base material supported by mechanical properties and heat transfer rate [32]. Similar work has been carried out in fabricating aerogels and the outcomes are highlighted in such a way that temperature and environmental conditions are deciding factors for change in porosity and stability of thermal insulation [33].…”

Influence of Waste Tire Particles on Freeze–Thaw Resistance and Impermeability Performance of Waste Tires/Sand-Based Autoclaved Aerated Concrete Composites

“…The B05 SAAC samples with 1.0 wt.% waste tires were obtained because the ordinary concrete containing 1.0 wt.% waste tire provided better performance than the ordinary concrete without waste tire [24]. Therefore, the samples with the size of 100 mm × 100 mm × 100 mm were prepared in the factory by three different types (waste tire content was 1.0%, and waste tire particle size were 2 mm, 750 µm, 375 µm respectively).…”

“…According to GB/T 11968-2020 "Autoclaved aerated concrete blocks", B05 SAAC compressive strength 2.47 MPa meets the grade requirements of B05 SAAC. Since the pore sizes of the SAAC composites ranged from 0.5 to 1.5 mm [24], therefore, the 750-µm-sized particles were suitable for the pore sizes of SAAC composites. This resulted in the improved compressive strength of composites [25].…”