http://suspace.su.edu.bd/handle/123456789/2 2026-07-19T12:22:07Z http://suspace.su.edu.bd/handle/123456789/2876 Compressive Strength Optimization of Concrete Using Varying Percentages of Steel Slag as SCM Barmon, Prodip; Ahmed, Md Shaju; Bhuiyan, Md. Hanif; Hossain, Alam Compressive strength is the most important mechanical property of concrete, as it determines the load-carrying capacity and overall performance of structural elements such as columns, beams, slabs, and foundations. Conventional concrete mainly relies on natural aggregates to achieve the required compressive strength. However, due to increasing construction activities, the availability of natural aggregates is gradually decreasing, and their extraction is causing environmental problems. Steel-slag concrete is a type of concrete in which steel slag, an industrial by-product from the steel manufacturing process, is used as a partial or full replacement for natural aggregates. Steel slag has high hardness, angular particle shape, and rough surface texture, which can significantly influence the compressive behavior of concrete. These physical properties improve particle interlocking and enhance the bond between the cement paste and aggregate, leading to improved compressive strength. Several experimental studies have shown that concrete containing steel slag can achieve compressive strength comparable to or higher than conventional concrete, especially at later curing ages. The higher strength development is often attributed to the dense packing of slag particles and the presence of reactive compounds in steel slag that may contribute to secondary hydration reactions. As a result, steel-slag concrete tends to show improved strength gain over time. The compressive characteristics of steel-slag concrete are strongly affected by factors such as mix proportion, water-cement ratio, slag replacement level, curing age, and specimen size. At lower water-cement ratios, steel-slag concrete generally exhibits higher compressive strength due to reduced porosity. Proper mix design and proportioning are necessary to ensure strength, stability, and durability. Therefore, investigating the compressive characteristics of steel-slag concrete with different mixing ratios provides valuable information for developing sustainable and high-performance concrete while reducing dependence on natural aggregates and promoting industrial waste utilization 2025-12-23T00:00:00Z http://suspace.su.edu.bd/handle/123456789/2875 COST COMPARISON OF CFRP AND STEEL PLATE RETROFITTING OF RC COLUMNS UNDER CONTROLLED DRIFT Hasan, Md.Rakib; Khan, Al Shimbil; Akter, MT. Sumaiya; Mahmud, Abdullah Al Retrofitting of existing reinforced concrete (RC) buildings has been a major solution to raise structural capacity, deal with deformation, and prolong service life, especially in cases where the original structures lacked enough stiffness or ductility. As two of the most popular methods for strengthening, retrofitting with steel plates and carbon fiber reinforced polymer (CFRP) have different merits in terms of stiffness improvement, load-carrying capacity, installation needs, and total cost efficiency. For example, while steel plates can significantly increase the strength of a structure, they also increase the dead load considerably as well as require the welding to be done, which is labor-intensive and needs surface preparation. On the other hand, CFRP is a lightweight, high-strength composite material which can be very quickly applied with almost no architectural disruption. This research solely compares these two retrofitting systems by analytical modeling through ETABS and the comparison is based on their impact on stiffness, drift reduction, and structural elements' response, especially beams and columns. Since Bangladesh is located in a seismically active area that is affected by the Himalayan arc, Dauki fault, and Indo-Burman ranges, the retrofitted building model is also checked under BNBC 2020 earthquake loads to see if each method can effectively bring old BNBC 1993/2006-designed structures up to the current drift and lateral load requirements. The findings display that there are clear performance and cost trade-offs: steel plates can give high gains of stiffness but increase the weight of the structure and the complexity of installation, whereas CFRP can achieve very high strength-to-weight ratio and the application is quicker even though the material cost is higher. Thus, the research acts as a comparative performance-cost study that is of assistance to engineers in making the right choice of the most feasible and efficient method for retrofitting to enhance both the seismic resistance and the structural reliability of the existing reinforced concrete buildings in Bangladesh 2025-12-23T00:00:00Z http://suspace.su.edu.bd/handle/123456789/2874 Optimization of Compressive Strength in Concrete Using Nylon as a Synthetic Fiber. HASAN, HASIBUL; HOSSAIN, FORHAD; RAHMAN, MD.MIJANUR; SAYED, MD.ABU Fiber Reinforced Concrete (FRC) has emerged as an effective alternative to conventional concrete by improving structural performance through the incorporation of randomly distributed fibers. This study investigates the mechanical properties, workability, and overall performance of FRC using different fiber dosages. Experimental tests were conducted to evaluate compressive strength. Standard procedures following ASTM guidelines were used to prepare, cure, and test all specimens. The results indicate that the inclusion of fibers significantly reduces crack propagation, and improves concrete strengths. The overall structural efficiency and reduction in reinforcement demand can lead to long-term savings. Overall, the research confirms that Fiber Reinforced Concrete provides superior performance for structural applications, particularly where enhanced toughness, crack resistance, and durability are required. The findings highlight FRC as a viable solution for modern construction, offering improved safety, economy, and long-term serviceability. 2025-12-23T00:00:00Z http://suspace.su.edu.bd/handle/123456789/2873 Comparative Analysis of Compressive Strength of Concrete Using Different Brands of Local Cement and Admixture HOSSAIN CHY, MD. DELOWAR; MRIDHA, BORKOT ULLAH; ALAM, MD. CHAD; HABIB, SIYAM; ISLAM, RAKIBUL This research investigates the comparative compressive strength performance of concrete produced using different locally available cement brands and commonly used admixtures in Bangladesh. The study aims to evaluate how Shah Cement, Aman Cement, and Supercrete Cement combined with two widely applied chemical admixtures, PCA-1 (Sobute) and SikaPlast® PH 8395 affect the compressive strength of C30-grade concrete. To ensure uniformity, all concrete mixes were prepared using a fixed proportion of 1:1.5:3 and a water cement ratio of 0.45. Prior to casting, the raw materials were characterized through sieve analysis, unit weight tests, and specific gravity tests for both sand and stone aggregates. Concrete cylinders were then cast and cured for compressive strength tests at 14 and 28 days. The concrete compressive strength test results show clear differences among the three cement brands- Shah, Supercrete, and Aman- when combined with two admixtures: SikaPlast® PH 8395 and PCA-1 (Sobute). At 14 days, Shah Cement recorded average strengths of 26.0 MPa with SikaPlast® and 27.0 MPa with PCA-1 (Sobute), both nearing the 27 MPa target. Supercrete Cement showed 25.4 MPa with SikaPlast® and 25.9 MPa with PCA-1, slightly below the target but acceptable for early-age strength. Aman Cement achieved 26.4 MPa using SikaPlast® and 27.1 MPa using PCA-1, showing reliable consistency. By 28 days, all cements surpassed the 30 MPa target: Shah Cement reached 34.35 MPa with SikaPlast® and 34.47 MPa with PCA-1, the highest among all. Supercrete Cement attained 31.20 MPa with SikaPlast® and 31.65 MPa with PCA-1, while Aman Cement delivered 33.40 MPa with SikaPlast® and 33.57 MPa with PCA-1. Overall, the results indicate that PCA-1 (Sobute) consistently produced slightly higher strengths across all cement brands, with Shah Cement with PCA-1 (Sobute) achieving the best performance in both 14-day and 28-day tests. 2025-12-23T00:00:00Z