Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. SWUTC/10/476660-00011-1 4. Title and Subtitle 5. Report Date Assessment the Potential of Using Carbon Nanotubes Reinforcements for Improving the Tensile/Flexural Strength and Fracture Toughness of Portland Cement Paste for Damage Resistant Concrete Transportation Infrastructures September 2010 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Rashid K. Abu Al-Rub and Bryan M. Tyson 476660-00011-1 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Texas Transportation Institute Zachry Department of Civil Engineering Texas A&M University College Station, TX 77843-3136 11. Contract or Grant No. DTRT07-G-0006 12. Sponsoring Organization Name and Address 13. Type of Report and Period Covered Southwest Region University Transportation Center Texas Transportation Institute Texas A&M University System College Station, Texas 77843-3135 Technical Report 14. Sponsoring Agency Code 15. Supplementary Notes Supported by a grant from the U.S. Department of Transportation, University Transportation Centers Program 16. Abstract The focus of this study was on exploring the use of nanotechnology-based nano-filaments, such as carbon nanotubes (CNTs) and nanofibers (CNFs), as reinforcement in improving the mechanical properties of Portland cement paste as a construction material. Due to their ultra-high strength and very high aspect ratios, CNTs and CNFs have been used as excellent reinforcements in enhancing the physical and mechanical properties of polymer, metallic, and ceramic composites. Very little attention has been devoted to explore the use of nano- filaments in the transportation industry. Therefore, this study aimed to bridge the gap between nano-filaments and transportation materials. This was achieved by testing the integration of CNTs and CNFs in ordinary Portland cement paste through state-of-the-art techniques. Different mixes in fixed proportions (e.g. water-to- cement ratio, air content, admixtures) along with varying concentrations of CNTs or CNFs were prepared. Different techniques commonly used for other materials (like polymers) were used in achieving uniform dispersion of nano-filaments in the cement paste matrix and strong nano-filaments/cement bonding. Small-scale specimens were prepared for mechanical testing in order to measure the modified mechanical properties as a function of nano-filaments concentration, type, and distribution. With 0.1% CNFs, the ultimate strain capacity increased by 142%, the flexural strength increased by 79%, and the fracture toughness increased by 242%. A scanning electron microscope (SEM) was used to discern the difference between crack bridging and fiber pullout. Test results showed that the strength, ductility, and fracture toughness can be improved with the addition of low concentrations of either CNTs or CNFs. 17. Key Words 18. Distribution Statement Carbon Nanotubes, Carbon Nanofibers, Cement, Dispersion, Fracture, Nano Reinforcements No restrictions. This document is available to the public through NTIS: National Technical Information Service Springfield, Virginia 22161 http://www.ntis.gov 19. Security Classification (of this report) 20. Security Classification (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 155 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
Assessment the Potential of Using Carbon Nanotubes Reinforcements for Improving the Tensile/Flexural Strength and Fracture Toughness of Portland Cement Paste for Damage Resistant Concrete
Jun 17, 2023
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