Experimental and numerical investigations of thermal properties of insulated concrete sandwich panels with fiberglass shear connectors

A new design of a structural sandwich panel, consisting of a combination of concrete, insulation and connectors, was tested using a hot box apparatus to evaluate its thermal properties and energy efficiency. The three materials of the prefabricated panel were arranged to provide both structural and thermal efficiencies. The main objective of this work was to find the thermal resistance (R-value) of the new panel for different designs. Ten different panels were tested using the hot box approach. Each panel had a unique design in order to determine the effect of the design on the thermal behavior of the panel. The design parameters included the number, size, distribution and material of the connectors, and the number and spacing of the concrete studs. Most of the connectors were made from glass fiber reinforced polymer (GFRP) while steel connectors were used in one panel for comparison purposes. The hot box apparatus was constructed using large precast concrete box culvert units with octagonal cross sections and was carefully insulated. The metering chamber air was heated up to a temperature of 24.5 °C and the climate chamber air was reduced to −4.3 °C in most cases of the tested panels. The experimental R-values ranged from 2.84 to 4.68 m2K/W, compared to 2.74 m2K/W for the steel-reinforced control panel. A one-dimensional heat transfer model was also developed to predict the R-values.