Compression-Casting Enhances Reinforced Concrete Strength

A recent article published in Engineering introduced green compression-casting for fabricating reinforced concrete structures. The article examined the effects of various inferior concrete materials, including rubber, desert sand, recycled aggregate, and recycled powder concrete, on compression-cast concrete (CCC). Additionally, fiber-reinforced polymer (FRP)-based structural members were compared with those of normal concrete (NC).

Compression-Casting Enhances Reinforced Concrete Strength
Study: Green Compression-Cast Concrete Material and Its Fiber-Reinforced Polymer (FRP)-Reinforced Concrete Structures. Image Credit: Another77/Shutterstock.com

Background

High carbon emissions from the global construction industry pose severe climatic issues. Consequently, efforts are being made to reduce cement usage in concrete production while maintaining its strength. Partially substituting cement with industrial by-products, such as fly ash, blast silica fume, etc., is an effective approach.

Another approach is substituting traditional cement with innovative alternatives that need less energy and emit lesser CO2 emissions, such as alkali-activated geopolymers and limestone-calcined clay cement. Additionally, high-performance fibers, such as glass and carbon fibers, can improve the concrete’s toughness and crack resistance while reducing cement usage.

However, all these methods have certain limitations. To address these, the researchers recently developed a novel compression-casting technology (CCT) that can considerably enhance durability and strength and lower the cost of concrete. CCT utilizes high casting pressure while ensuring its uniform transmission to all parts of the concrete unit. The resulting CCC has the same composition as NC with no chemical or mineral additives.

Methods

The performance of CCC was evaluated through several systematic theoretical and experimental investigations. The carbon reduction advantages of CCC were quantified via a life-cycle assessment (LCA). 

The experiments involved several material tests, including mechanical, chloride penetration, carbonation, water absorption, freeze-thaw, and elevated temperature tests. A concrete specimen prepared through normal casting was considered as the reference sample. Alternatively, the samples prepared using CCT were termed “CCC-X,” with “X” representing the casting pressure. 

Multiple microscopic investigations were performed to comprehend the role of CCT in enhancing the mechanical properties of CCC, including scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and backscattered electron (BSE) analysis. Carbonation and uniaxial compressive strength tests were conducted according to standard procedures. Notably, the chloride diffusion coefficient of CCC specimens was determined through the rapid chloride migration (RCM) test.

NC was replaced by CCC of similar strength at 0%, 25%, 50%, 75%, and 100% ratios to evaluate the carbon reduction potential of CCT. Furthermore, the structural behavior of CCC specimens was examined in different configurations, including flexural tests of CCC beams, shear tests of CCC slabs, axial compression tests of FRP-confined CCC columns, and axial compression tests of steel fiber-reinforced CCC columns.

Results and Discussion

CCC samples’ compressive strength and elastic modulus were remarkably higher than the NC samples. The significant improvements in the mechanical characteristics of CCC were primarily attributed to the reduced water and air contents and the denser microstructure.

SEM images revealed fewer pores and a denser matrix for CCC-15 than for NC, consistent with the porosity results. Therefore, CCT could densify the matrix microstructure, reduce mortar porosity, and improve the interfacial transition zone (ITZ) quality, significantly enhancing the CCC’s mechanical properties and durability.

The compressive strength of the CCC specimens with or without CO2 exposure was higher than that of the NC specimens. Without CO2 exposure, the compressive strength of CCC-5 and CCC-15 increased by 81.8% and 118.2%, respectively, relative to that of the NC specimens. Moreover, the compressive strengths of the 28 d CO2-exposed CCC-5 and CCC-15 specimens increased by 36.2% and 61.7%, respectively. 

The CCC samples’ chloride penetration depths and diffusion coefficients were smaller than their NC counterpart, indicating that CCT could postpone chloride penetration. This was attributed to the inhibited chloride migration due to reduced porosity and densified microstructure of concrete.

Considering the period from 2025 to 2060, carbon emissions from NC and CCC production increased annually. However, CCC production had lower annual carbon emissions. Notably, the annual carbon emissions from CCC decreased by 7%, 14%, 20%, and 27% at replacement ratios of 25%, 50%, 75%, and 100%, respectively, compared to NC.

CCC brittleness could be overcome by FRP/steel confinement, adding steel fibers to concrete, and increasing the compression reinforcement in the flexural design. Moreover, the molding cost in the CCT method was estimated to be lower than NC casting.

Conclusion

Overall, the researchers comprehensively examined CCC materials and FRP-reinforced CCC structures to conclude that CCC had a higher strength and better mechanical performance than NC while substantially reducing greenhouse gas emissions. Moreover, CCC samples exhibited better resistance to water, fire, and chloride penetration.

CCT is generally regarded as more complex than regular concrete casting. However, it is much faster and more cost-effective than NC casting. This was demonstrated through the preliminary results on FRP-reinforced CCC structural members. The researchers suggest extensive characterization of CCC materials for practical applications.

Journal Reference

Wu, Y.-F., Yuan, F., & Hu, B. (2024). Green Compression-Cast Concrete Material and Its Fiber-Reinforced Polymer (FRP)-Reinforced Concrete Structures. Engineering. DOI: 10.1016/j.eng.2024.10.005, https://www.sciencedirect.com/science/article/pii/S2095809924006283

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Nidhi Dhull

Written by

Nidhi Dhull

Nidhi Dhull is a freelance scientific writer, editor, and reviewer with a PhD in Physics. Nidhi has an extensive research experience in material sciences. Her research has been mainly focused on biosensing applications of thin films. During her Ph.D., she developed a noninvasive immunosensor for cortisol hormone and a paper-based biosensor for E. coli bacteria. Her works have been published in reputed journals of publishers like Elsevier and Taylor & Francis. She has also made a significant contribution to some pending patents.  

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Dhull, Nidhi. (2024, November 05). Compression-Casting Enhances Reinforced Concrete Strength. AZoBuild. Retrieved on November 05, 2024 from https://www.azobuild.com/news.aspx?newsID=23640.

  • MLA

    Dhull, Nidhi. "Compression-Casting Enhances Reinforced Concrete Strength". AZoBuild. 05 November 2024. <https://www.azobuild.com/news.aspx?newsID=23640>.

  • Chicago

    Dhull, Nidhi. "Compression-Casting Enhances Reinforced Concrete Strength". AZoBuild. https://www.azobuild.com/news.aspx?newsID=23640. (accessed November 05, 2024).

  • Harvard

    Dhull, Nidhi. 2024. Compression-Casting Enhances Reinforced Concrete Strength. AZoBuild, viewed 05 November 2024, https://www.azobuild.com/news.aspx?newsID=23640.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this news story?

Leave your feedback
Your comment type
Submit

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.