DESIGN AND SIMULATION OF CONCRETE BEAMS BY USING FLY ASH AS A PARTIAL REPLACEMENT FOR CEMENT

Abstract

Concrete is one of the most widely used construction materials, but its high demand comes at a significant environmental cost due to the pollution caused by cement production. This research explores a practical and sustainable solution by replacing part of the cement with fly ash and studying its effects on concrete's performance. Among the different mixes tested, concrete with 15% fly ash delivered the best results, achieving a flexural strength of 2.557 MPa—outperforming mixes with 0% and 20% fly ash. It also became easier to work with, as the slump increased from 64 mm to 71 mm with higher fly ash content, improving placement and handling. Crack resistance was also enhanced, with the 15% fly ash mix showing the shallowest crack depth at just 101 mm. This is because fly ash fills tiny gaps in the concrete and reacts with leftover materials, creating a stronger, more durable structure. On the structural side, when this mix was used in building models in ETABS, it showed better resistance to lateral forces, with reduced story displacements in both directions. While there was a slight drop in stiffness, the overall performance of the material improved significantly. These findings highlight how using 15% fly ash in concrete strikes a balance between strength, workability, and sustainability, offering a simple yet impactful way to build greener, more efficient structures.