رسائل ماجيستير
English
2021
Developing and testing of full-scale lightweight sandwich wall panels with high thermal insulation properties
Mashael Salim Said Al-Bahriyah , Sherif El-Gamal, Ali Al-Nuaim
كلية الهندسة-جامعة السلطان قابوس · عمان
Moving towards high thermal insulation wall solutions can significantly enhance energy conservation on both environmental and economic levels. This research focuses on the development and investigation of full-scale sandwich wall panels with superior thermal insulation properties. The implementation of such wall panels is expected to improve electrical energy preservation, reduce construction costs, and shorten building time compared to conventional masonry walls.
A total of twelve full-scale specimens were fabricated with dimensions of 2.2 m (height) × 0.5 m (width) × 200 mm (thickness). The study examined three primary parameters: type of concrete (normal concrete versus lightweight concrete), shear tie spacing (20 cm and 40 cm), and internal reinforcement (panels reinforced with glass fiber reinforced polymer (GFRP) bars versus non-reinforced panels).
Laboratory tests were conducted to evaluate the panels under axial compression, out-of-plane bending, and in-plane bending. Additionally, fifty-four concrete cubes, eighteen cylinders, and eighteen prisms were cast to assess key concrete mix properties including workability, compressive strength, tensile strength, flexural strength, and thermal conductivity.
Results showed that all lightweight concrete panels demonstrated satisfactory ultimate capacities. Although these capacities were lower than those of normal concrete panels, they remained acceptable, particularly for use as non-load-bearing walls. The maximum reductions observed were approximately 54.1% in axial compression capacity, 32.3% in out-of-plane bending capacity, and 52.9% in in-plane bending capacity.
Thermal conductivity values ranged from 0.519 to 0.585 W/m·K for normal concrete sandwich panels, while lightweight concrete panels exhibited lower values, ranging between 0.435 and 0.450 W/m·K, indicating better insulation performance.
Moreover, reducing shear tie spacing from 40 cm to 20 cm increased the axial compression capacity of normal concrete sandwich panels by 27.2%. Conversely, the same reduction in spacing decreased the failure load by 18.4% in lightweight concrete panels, likely due to improper distribution of expanded polystyrene (EPS) within the panel caused by excessive vibration during casting.
Finally, the use of longitudinal GFRP reinforcement substantially improved bending capacities: out-of-plane bending capacity increased by 91.2% and 124.6%, and in-plane bending capacity increased by 24.5% and 224.6%, respectively, compared to unreinforced panels.