A Performance Evaluation of Prestressed Concrete Beams and RCC Beams in Modern Construction in Structural Engineering

Abstract - Prestressed concrete is a special type of reinforced concrete in which internal forces are intentionally created in advance, before the structure carries any external load. This is done by stretching high-strength steel tendons placed inside the concrete. The main aim of prestressing is to balance the tensile stresses that occur when the structure is loaded, which improves the overall behaviour of concrete. Since concrete performs well in compression but is weak in tension, compressive forces are introduced in advance so that the tensile stresses produced during use are reduced or completely removed. As a result, cracking is minimized, the load-carrying capacity increases, deflection decreases, and durability improves. In post-tensioning, high-strength steel strands or bars are used as reinforcement. Strands are commonly applied in horizontal members such as slabs, beams, foundations, and bridges, whereas bars are mostly used in vertical members like columns and walls. A typical post-tensioning steel strand has a tensile strength of around 1860 N/mm², which is much higher than that of ordinary reinforcing steel (rebar), whose tensile strength is usually about 600 N/mm². During this project, we carefully observed and studied different site operations related to post-tensioned beams. We also examined the various tendon diameters and types used to apply prestressing forces in the structure. For this project, M40 grade concrete was used. Ultrafine Slag was added as a partial replacement for cement by weight in the concrete mix. The prestressing operation was carried out after seven days, when the concrete reached a strength of approximately 25 N/mm². A prestressing power pack along with a mono-strand stressing jack was used to perform the stressing process. When the tendons are pulled, they try to return to their original length, but they are held in place by anchorages. A comparison was also made between post-tensioned members and conventional reinforced cement concrete (RCC) members of the same span, including a detailed cost analysis. Through this project, we also learned important aspects of professional construction practices and site management. Keywords: Concrete, Ultrafine Slag, Prestressed Concrete, Post-Tensioning, Tendons, Grouting.