Highly dispersed carbon nanotube reinforced cement based materials.pdf

Cement and Concrete Research 40 (2010) 1052–1059 Contents lists available at ScienceDirect Cement and Concrete Research j ourna l homepage: ht tp : / /ees.e lsev ie /CEMCON/defau l t .aspHighly dispersed carbon nanotube reinforced cement based materials Maria S. Konsta-Gdoutos a,?, Zoi S. Metaxa a,b, Surendra P. Shah b a Department of Civil Engineering, Democritus University of Thrace, Xanthi, Greece b Center for Advanced Cement-Based Materials, Northwestern University, Evanston, Illinois, USA? Corresponding author. Tel.: +30 25410 79658; fax: E-mail address: mkonsta@civil.duth.gr (M.S. Konsta- 0008-8846/$ – see front matter ? 2010 Elsevier Ltd. Al doi:10.1016/j.cemconres.2010.02.015a b s t r a c ta r t i c l e i n f oArticle history: Received 10 December 2008 Accepted 28 February 2010 Keywords: Carbon nanotubes DispersionA Mechanical propertiesC Scanning electron microscopy (SEM)B Fiber reinforcementEThe remarkable mechanical properties of carbon nanotubes (CNT) suggest that they are ideal candidates for high performance cementitious composites. The major challenge however, associated with the incorporation of CNTs in cement based materials is poor dispersion. In this study, effective dispersion of different length multiwall carbon nanotubes (MWCNTs) in water was achieved by applying ultrasonic energy and in combination with the use of a surfactant. The effects of ultrasonic energy and surfactant concentration on the dispersion of MWCNTs at an amount of 0.08 wt.% of cement were investigated. It is shown that for proper dispersion the application of ultrasonic energy is absolutely required and for complete dispersion there exists an optimum weight ratio of surfactant to CNTs. For a constant ratio of surfactant to MWCNTs, the effects of MWCNT type (short and long) and concentration on the fracture properties, nanoscale properties and microstructure of nanocomposite materials were also studied. Results suggest that MWCNTs improve the nano- and macromechanical properti