Thermo-Mechanical Performance of Sustainable Lightweight Sandwich Panels Utilizing Ultra-High-Performance Fiber-Reinforced Concrete

Sandwich panels, consisting of two concrete wythes that encase an insulating core, are designed to improve energy efficiency and reduce the weight of construction applications. This research examines the thermal and flexural properties of a novel sandwich panel that incorporates ultra-high-performance fiber-reinforced concrete (UHPFRC) and cellular lightweight concrete (CLC) as its core material. Seven sandwich panel specimens were tested for their thermo-flexural performance using four-point bending tests. The experimental parameters included variations in UHPFRC thickness (20 mm and 30 mm) and different shear connector types (shear keys, steel bars, and post-tension steel bars). The study also assessed the effects of adding steel mesh reinforcement to the UHPFRC layer and evaluated the performance of UHPFRC box sections without a CLC core. The analysis concentrated on several critical factors, such as initial, ultimate, and serviceability loads, load–deflection relationships, load–end slip, load–strain relationships, composite action ratios, crack patterns, and failure modes. The thermal properties of the UHPFRC and CLC were evaluated using a transient plane source technique. The results demonstrated that panels using post-tension steel bars as shear connectors achieved flexural performance, and the most favorable composite action ratios reached 68.8%. Conversely, the box section exhibited a brittle failure mode when compared to the other sandwich panels tested. To effectively evaluate mechanical and thermal properties, it is important to design panels that have adequate load-bearing capacity while maintaining low thermal conductivity. This study introduced a thermo-mechanical performance coefficient to evaluate both the thermal and mechanical performance of the panels. The findings indicated that sandwich panels with post-tension steel bars achieved the highest thermo-mechanical performance, while those with steel connectors had the lowest performance.

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