In a recent article published in the Journal of Engineering and Applied Science, researchers investigated the flexural behavior of crushed clay brick lightweight concrete (LWC) beams strengthened with strain-hardening cementitious composite reinforced with glass fiber textile mesh (GFTM-RSHCC) at the tension zone. The research aims to enhance the structural performance of the beams by utilizing innovative reinforcement techniques.
Study: Enhanced Strength for Lightweight Concrete Beams. Image Credit: Roberto Sorin/Shutterstock.com
Background
The construction industry is constantly seeking innovative solutions to enhance the performance and durability of concrete structures. Traditional reinforcement methods have limitations in terms of load-carrying capacity and resistance to various forms of deterioration. As a result, there is a growing interest in exploring alternative materials and techniques to strengthen concrete elements and improve their structural integrity.
One area of focus in structural engineering is the development of LWC beams, which offer advantages such as reduced dead loads and improved seismic performance. However, the use of lightweight materials can pose challenges in terms of flexural strength and durability, especially in high-stress applications. Strengthening lightweight concrete beams to meet the required performance standards is essential for ensuring the safety and longevity of infrastructure projects.
The Current Study
The study involved fabricating and testing seven simply supported crushed clay brick LWC beams. Each beam, with a cross-section of 120 × 250 mm, a total length of 2400 mm, and a loaded span of 2200 mm, was subjected to a monotonic four-point loading scheme to evaluate its flexural behavior.
To strengthen the LWC beams, a rubberized strain-hardening cementitious composite reinforced with GFTM-RSHCC was applied at the tension side. The key parameters studied included the number of GFTM layers inside the RSHCC (1, 2, or 3) and the thickness of the GFTM-RSHCC layer (30 or 40 mm). Additionally, carbon fiber sheets (CFS) were incorporated at the shear side of the beams to prevent premature debonding failure and enhance the overall strength of the system.
Surface preparation was a critical step in the strengthening process to ensure proper adhesion between the RSHCC and the LWC substrate. The tension side surface of each beam was roughened to enhance adhesion and eliminate potential contaminants such as oil and foreign particles. This surface preparation aimed to create a clean and roughened surface for optimal bonding between the materials.
The experimental plan included detailed specifications for the materials used in the study. Crushed clay brick (CCB) aggregate was employed as an eco-friendly substitute for manufacturing lightweight concrete units. The mix properties of the LWC and RSHCC materials, including coarse aggregate, fine aggregate, cement, silica fume, water, superplasticizer, water-to-binder ratio, quartz sand, polypropylene fiber, and crumb rubber, were carefully selected to meet the desired performance criteria.
Results and Discussion
The findings revealed significant improvements in the flexural behavior of the crushed clay brick lightweight concrete (LWC) beams strengthened with rubberized strain-hardening cementitious composite reinforced with GFTM-RSHCC and CFS. The application of multiple layers of GFTM and varying thicknesses of the RSHCC layer led to notable enhancements in the ultimate loads and ductility of the beams compared to the control specimen.
Increasing the number of GFTM layers inside the RSHCC and the thickness of the RSHCC layer resulted in a progressive increase in the ultimate loads and ductility of the beams. The experimental data indicated improvements of up to 68 % in ultimate loads and 83 % in ductility compared to the control beam. These findings underscore the effectiveness of the GFTM-RSHCC strengthening technique in enhancing the load-carrying capacity and deformation properties of the LWC beams.
The incorporation of carbon fiber sheets at the shear side of the beams played a crucial role in preventing premature debonding failure and maximizing the strength of the system. By combining GFTM-RSHCC with CFS, the study demonstrated a synergistic effect that improved the overall performance of the strengthened beams. The experimental results highlighted the importance of proper surface preparation and material selection in achieving successful reinforcement and enhancing the structural integrity of concrete elements.
The proposed equation developed to predict the flexural capacity of the strengthened beams based on the contribution of the GFTM-RSHCC layer showed good agreement with the experimental results. This predictive model provides a valuable tool for engineers and researchers to assess the performance of similar strengthened structures and optimize the design parameters for enhanced structural efficiency.
Conclusion
In conclusion, this study emphasizes on the effectiveness of the GFTM-RSHCC and CFS reinforcement system in improving the flexural behavior of LWC beams. The findings contribute to the advancement of innovative strengthening techniques in structural engineering and highlight the potential for sustainable and resilient construction practices in the future. Further research in this area could lead to the development of optimized reinforcement strategies for a wide range of concrete structures, promoting safety, durability, and cost-effectiveness in construction projects.
Journal Reference
Issa, M.E., El-Shafey, N.F., Baraghith, A.T. et al. (2024). Flexural strengthening of LWRC beams using RSHCC reinforced with glass fiber textile mesh. Journal of Engineering and Applied Science 71, 132. https://doi.org/10.1186/s44147-024-00467-x, https://jeas.springeropen.com/articles/10.1186/s44147-024-00467-x
Article Revisions
- Jun 19 2024 - Title changed from "Enhanced Strength for Lightweight Concrete Beams" to "Reinforcement of Concrete Beams Using Glass Fiber Textile Mesh"