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Title: A Chemical Admixture with Carbon Nanotubes

Author(s): Yuan Gao

Publication: Web Session

Volume: ws_S18_ChemicalAdmixtures_Gao.pdf


Appears on pages(s):



Date: 3/26/2018

Carbon nanotubes (CNT) are perhaps the most widely used nano materials in a wide range of applications. CNTs and CNFs (carbon nanofibers) have remarkable properties because of their nanoscale. Many attempts have been made world-wide to incorporate them in concrete. Adding CNT or CNF in concrete poses two challenges: cost and uniform dispersion. Researchers at Northwestern University have successfully tackled those challenges. CNT or CNF are ultrasonicated in an aqueous solution containing superplasticizers. The technique of dispersion will be discussed in this paper. We have observed that the addition of the aqueous solution containing a very small amount of well dispersed CNT or CNF (less than 0.1% by weight of cement) exhibit following remarkable benefits: (1) it reduces the autogenous shrinkage,(2) it delays onset of shrinkage cracking and reduces crack width,(3) it enhances the modulus of elasticity ,(4) it makes concrete piezoresistive (so called smart material), (5) it enhances fracture properties and (6) the addition of CNT or CNF delays the corrosion of reinforcing bars due to ingress of chloride. This paper will discuss these multi-functional properties.