Sustainable construction: viability of gypsum components in full-scale reinforced beams

Numerous studies focus on developing new eco-friendly and fire-resistant concrete mix designs, including the incorporation of gypsum. This research focused on assessing the mechanical properties of gypsum when integrated into full-scale structural concrete beams. As a first step, two control specimens were investigated: small 50 mm gypsum cubes with different retarder ratios and 200 mm × 100 mm cylinders cast using two procedures, employing a half-concrete, half-gypsum mix. The compressive strength tests conducted on the gypsum cubes have shown that a retarder-to-binder ratio of 0.35% is the most suitable combination. Three full-scale beams with identical reinforcement details were cast as proof of concept. The first was a normal reinforced concrete beam; the second was a gypsum-reinforced beam; and the third was a reinforced concrete beam infill covered with gypsum. The three beams were tested under two-point loadings. The first beam carried the highest load, 118.7 kN, while exhibiting the lowest deflection, 20.2 mm. The second and third beams supported a maximum load of 110.4 and 110.2 kN, respectively. However, the second beam exhibited the highest deflection, 29.5 mm, and the third displayed a deflection of 23.6 mm.