مطالعه‌ي آزمايشگاهي خصوصيات مكانيكي و عملكرد حرارتي فوم بتن اتوكلاوي حاوي مواد تغييرفازدهنده با شكل پايدار توسط ميكروسيليس و خاكستربادي

The building sector accounts for a substantial share of global energy consumption, an‎d the development of building materials with improved thermal performance is regarded as an effective strategy for enhancing energy efficiency in buildings. This study investigates the effect of incorporating shape-stabilized polyethylene glycol 600 (PEG 600) on the mechanical, physical, microstructural, an‎d thermal performance of autoclaved foamed concrete. In this research, autoclaved foamed concrete panels with a thickness of 10 cm an‎d containing 10 an‎d 20 wt.% PEG 600 were produced. Silica fume an‎d fly ash, as pozzolanic additives, were used to stabilize the phase-change material (PCM) an‎d reduce the likelihood of leakage. The thermal performance of the specimens was eva‎luated using a diurnal temperature simulation apparatus under representative summer an‎d autumn daily temperature profiles for the cities of Isfahan an‎d Tabriz, Iran. The investigated thermal performance indices included the reduction in indoor peak temperature, maximum indoor temperature, stan‎dard deviation of the diurnal temperature profile, an‎d thermal response time lag. In addition, density, slump flow, compressive strength, splitting tensile strength, water absorption, an‎d durability under 100 freeze–thaw cycles were experimentally eva‎luated. The microstructure an‎d elemental composition of the specimens were examined using scanning electron microscopy (SEM) an‎d energy-dispersive X-ray spectroscopy (EDS). The results showed that the incorporation of 10 an‎d 20 wt.% PEG 600 in the fly-ash-containing mixtures reduced the 28-day compressive strength by approximately 30% an‎d 69%, respectively, compared with the control mixture. In contrast, in the silica-fume-containing mixture, the reduction in compressive strength was limited to approximately 5.5%, indicating the compensating role of silica fume in maintaining matrix continuity an‎d mitigating the adverse effect of the phase-change material. Overall, the simultaneous use of silica fume compensated for a considerable portion of the compressive strength loss, reaching approximately 92%. Regarding splitting tensile strength, the addition of 10 an‎d 20 wt.% PEG 600 led to reductions of approximately 71% an‎d 70%, respectively, in the fly-ash-containing mixtures, whereas the reduction in the silica-fume-containing mixture was approximately 66%, indicating the partial compensating effect of silica fume on tensile behavior. Furthermore, fly ash played an effective role in improving the workability of the fresh mixture an‎d promoting the uniformity of the porous structure. Microstructural observations indicated a more homogeneous pore distribution an‎d improved internal cohesion in the modified specimens. From a thermal perspective, the presence of the phase-change material increased the thermal inertia of the panels, reduced the amplitude of indoor temperature fluctuations, an‎d delayed the occurrence of peak temperature. Under hot-weather conditions, the indoor peak temperature was reduced by up to approximately 4.2 °C, while under cold-weather conditions, the nighttime temperature dro‎p was attenuated by up to approximately 2.9 °C. Overall, the findings of this study demonstrate that the targeted incorporation of a shape-stabilized phase-change material into autoclaved foamed concrete, in combination with pozzolanic additives, can establish a balance between improved thermal performance an‎d the preservation of mechanical properties. Therefore, the developed material shows promising potential for application in energy-efficient buildings.

مرتضي مدح خوان

كياچهر بهفرنيا , مريم داعي