Enhancement of Cement Paste with Carboxylated Carbon Nanotubes and Poly(Vinyl Alcohol)
Cement has been a major consumable material for construction in the world since its invention, but its low flexural strength is the main defect affecting the service life of structures. To adapt cement-based materials to a more stringent environment, carboxylated carbon nanotubes (CNTs-COOH) and poly(vinyl alcohol) (PVA) are proposed to enhance the mechanical properties of cement paste. This study systematically verifies the synergistic effect of CNTs-COOH/PVA on the performance of cement paste. First, UV-Vis spectroscopy and FTIR spectroscopy prove that CNTs-COOH can provide attachment sites for PVA and PVA can improve the dispersion and stability of CNTs-COOH in water, which demonstrates the feasibility of synergistically enhancing cement paste. When a 0.015% CNTs-COOH suspension with 0.1% PVA is added, the flexural strength of the cement paste increases by 73, 32, and 42% compared with control specimens at curing ages of 3, 7, and 28 days, respectively. The strength enhancement mechanism is revealed from the aspects of cement matrix enhancement and interface enhancement. Thermogravimetric (TG) analysis and mercury intrusion porosimetry (MIP) prove that CNTs-COOH can enhance the hydration degree of the cement matrix and fill the pores introduced by PVA. Based on the fact that PVA can improve the dispersibility and the nucleation site effect of CNTs-COOH in cement paste, molecular dynamics simulation confirms that PVA can bridge CNTs-COOH and C-S-H to enhance the interfacial bonding by 64.1%.
Y. Zhao et al., "Enhancement of Cement Paste with Carboxylated Carbon Nanotubes and Poly(Vinyl Alcohol)," ACS Applied Nano Materials, American Chemical Society, Jan 2022.
The definitive version is available at https://doi.org/10.1021/acsanm.2c00875
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Carboxylated Carbon Nanotubes; Cement Paste; Enhancement; Molecular Dynamics; Poly(Vinyl Alcohol)
International Standard Serial Number (ISSN)
Article - Journal
© 2022 American Chemical Society, All rights reserved.
01 Jan 2022
This work was financially supported by the National Natural Science Foundation of China under the grants 52078332, U2006223, and 51925805, the Natural Science Foundation of Hebei Province under the grant E2020402079, and the Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering (SZU) under the grant 2020B1212060074.