Thermal conductivity measurement of common building materials using simplified steady-state heat flow apparatus

How accurately can simplified laboratory apparatus characterize thermal properties of building materials commonly used in Argentine construction? This research evaluates steady-state heat flow methods for determining thermal conductivity of regional building materials, comparing results against established literature values to assess measurement reliability achievable with accessible equipment. The investigation examined five material categories including concrete, clay brick, hollow concrete block, traditional adobe, and modern insulation materials representative of construction practices across diverse Argentine climate zones [1]. The experimental program was conducted at the Buenos Aires Institute of Technology construction materials laboratory from March through November 2024, employing a custom-fabricated guarded hot plate apparatus designed for educational and regional testing applications. A total of 156 individual thermal conductivity determinations were performed across 52 samples representing materials sourced from suppliers throughout the Buenos Aires metropolitan region and Northern provinces. Results demonstrated that the simplified apparatus achieved thermal conductivity measurements within 6.8% of published literature values when averaged across all material categories. Concrete samples showed mean measured conductivity of 1.56 W/m·K compared to literature range of 1.4 to 1.7 W/m·K. Clay brick measurements averaged 0.74 W/m·K against literature values of 0.6 to 0.8 W/m·K. Hollow concrete blocks yielded 0.44 W/m·K measurements consistent with published ranges of 0.4 to 0.5 W/m·K for similar void configurations. Statistical analysis revealed that measurement variability arose primarily from sample heterogeneity rather than apparatus limitations, particularly for porous materials where moisture content and void distribution significantly influenced measured properties. Coefficient of variation across replicate measurements on homogeneous samples remained below 4.2%, demonstrating acceptable instrumental precision for engineering characterization purposes. The research established measurement protocols optimized for regional conditions including humidity control requirements, sample conditioning procedures, and temperature gradient specifications enabling consistent results across diverse material types. These protocols support expanded testing capabilities at institutions throughout Argentina and neighboring countries where access to certified commercial testing laboratories remains limited or economically prohibitive.