Experimental study on the flexural behavior of reinforced concrete beams with Platre de Paris (gypsum) layers

Abstract

Nowadays, gypsum is gaining a lot of attention as a building material for interior decoration, especially ceilings and walls. Characterized with high fire resistance, low cost, easy to install and durability, gypsum can be used to achieve different architectural and aesthetic purposes. The aim of this study is to test gypsum as a structural component with reinforced concrete (RC), furthermore, to test its flexural behavior and its maximum load capacity. In order to achieve this goal, three beams were cast and tested after seven days. The first beam consisted of gypsum layers and concrete infills, the second beam was composed of gypsum only, and the third beam was composed of concrete only. The results showed that as the load increased, so did the deflection until it reached a maximum value after which it decreased. For the first beam, the deflection was 3.5 mm at the maximum load of 66 KN. As for the second beam, it broke at a maximum load of 70 KN with a 3 mm deflection, and the third beam broke at a deflection of 2.7 mm for a maximum stress load of 60 KN. On the other hand, for the failure mode of beams, the first beam first showed cracks at a load of 37 KN, and as the load capacity increased to 63 KN, extensive cracks took place causing the gypsum to separate from the concrete. As for the beam with gypsum only, cracks started to appear at a 35 KN load capacity but had less significant cracks than the first beam. The third beam composed of concrete only showed early cracks at 10 KN, however it was tested on day seven when it should be tested at least after day 14.