Experimental study on the shear behavior of reinforced concrete beams with Platre de Paris

Abstract

Cement is a popular binding construction material and also known to be one of the most expensive in the construction industry. Another material that has a significant use with the mixing of cement is gypsum. A thorough study experimenting the given mixture’s strength with reinforced concrete with respect to the amount of gypsum was performed in order to determine the shear behavior and maximum load capacity of cast beams. In order to reach property results, three beams were cast and the necessary tests were performed throughout a period of seven days. The first beam consisted of gypsum layers and concrete infills, the second one consisted of gypsum only, and the third one was purely concrete and considered the control beam. As the load on all three beams was increased, the number of cracks observed increased significantly, as well as a notable increase in deflection. Concerning the first beam, cracks were observed upon reaching a 38 KN load and increased while continuing to increase the load until reaching a maximum value of 63.5 KN, noting a layer separation of the two materials, with a deflection of 2.2 mm. As for the second beam, cracks started at a value of 34 KN increasing until reaching a maximum value of 69.4KN with a 2.85 mm deflection. The third beam exhibited cracks at 13 KN reaching a maximum value of 71.3 KN and a deflection of 3.8 mm. Further studies need to be performed in order to find a solution concerning the curing of concrete infill, find a way to protect the gypsum when used as exterior structures, and expend the study for vertical structures such as slabs, columns, and others.