Advanced Cement Based Nanocomposites
Considerable research and development efforts have been directed towards high strength/high performance concrete with engineered properties, using three main concepts: a low water to binder ratio (w/b), and the partial replacement of cement by fine supplementary cementitious or pozzolanic materials and/or fibers. To better understand how material composition and microstructural modifications determine the concrete structural performance, and to develop new materials with specific properties, researchers at ACBM have taken a materials science approach with an application to nanotechnology to optimize the processing and micro/nanoscale structure of cement based materials. In particular, due to their exceptional mechanical properties, the reinforcing effect of highly dispersed multiwall carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs) in cement paste matrix was investigated. The major challenge however, associated with the incorporation of MWCNTs and CNFs in cement based materials is poor dispersion. In this study, effective dispersion of different length MWCNTs in water was achieved by applying ultrasonic energy and with the use of a surfactant. The excellent reinforcing capabilities of the MWCNTs are demonstrated by the enhanced fracture resistance properties of the cementitious matrix. Additionally, nanoindentation results suggest that the use of MWCNTs can increase the amount of high stiffness C-S-H and decrease the porosity. Besides the benefits of the reinforcing effect, autogenous shrinkage test results indicate that MWCNTs can also have a beneficial effect on the early strain capacity of the cementitious matrix, improving this way the early age and long term durability of the cementitious nanocomposites.
KeywordsCement Paste Carbon Nanofibers Cement Base Material Ultrasonic Energy Autogenous Shrinkage
Unable to display preview. Download preview PDF.
- 1.Lawler, J.S.: Hybrid fiber-reinforced in mortar and concrete. PhD thesis, Northwestern University (2001)Google Scholar
- 2.Akkaya, Y., Shah, S.P., Ghandehari, M.: Influence of fiber dispersion on the performance of microfiber reinforced cement composites. ACI Special Publications 216: Innovations in Fiber-Reinforced Concrete for Value, SP-216-1, 1-18 (2003)Google Scholar
- 8.Makar, J.M., Beaudoin, J.J.: Carbon Nanotubes and Their Applications in the Construction Industry. In: Bartos, P.J.M., Hughes, J.J., Trtik, P., Zhu, W. (eds.) in Nanotechnology in Construction Proceedings of the 1st International Symposium on Nanotechnology in Construction, pp. 331–341. Royal Society of Chemistry (2004)Google Scholar
- 9.Makar, J.M., Margeson, J., Luh, J.: Carbon nanotube/cement composites – Early results and potential applications. In: Proceedings of the 3rd International Conference on Construction Materials: Performance, Innovations and Structural Implication, Vancouver, B.C., Canada, pp. 1–10 (2005)Google Scholar
- 12.Konsta-Gdoutos, M.S., Metaxa, Z.S., Shah, S.P.: Nanoimaging of highly dispersed carbon nanotube reinforced cement based materials. In: Gettu, R. (ed.) Proceedings of the Seventh International RILEM Symposium on Fiber Reinforced Concrete: Design and Applications, pp. 125–131. RILEM Publications S.A.R.L. (2008)Google Scholar
- 14.Hielscher, T.: Ultrasonic production of nano-size dispersions and emulsions. In: Proceedings of 1st Workshop on NanoTechnology Transfer in Europe, TIMA Editions, Grenoble, France, pp. 138–143 (2006)Google Scholar
- 16.Mondal, P., Shah, S.P., Marks, L.D.: Nanoscale characterization of cementitious materials. ACI Mater. J. 105, 174–179 (2008)Google Scholar
- 19.Mondal, P.: Nanomechanical properties of cementitious materials. PhD thesis, Evanston, Northwestern University (2008)Google Scholar
- 21.Tazawa, E. (ed.): Autogenous shrinkage of concrete. E&FN Spon, London (1999)Google Scholar
- 22.Konsta-Gdoutos, M.S., Shah, S.P., Dattatraya, D.J.: Relationships between engineering characteristics and material properties of high strength-high performance concrete. In: Dhir, R.V., Newlands, M.D., Csetenvi, L.J. (eds.) Proceedings of International Symposia Celebrating Concrete: People and Practice, in Role of Cement Science in Sustainable Development, pp. 37–46. Tomas Telford Limited (2003)Google Scholar