Study of the carbon nanomaterials synthesis on the cement binder

Abstract

The authors have developed a technology for creating a nanomodified binder for construction purposes, in which a uniform distribution of carbon nanomaterials is achieved by controlled synthesis of nanomaterials in the structure of the binder. The synthesis of carbon nanomaterials (CNM) was carried out by chemical vapour deposition of hydrocarbons on metal oxide catalysts. Cement CEM I 42.5H (M500 D0) and metal-oxide catalyst Ni-MgO (92.5 %-7.5 %, obtained by thermal method) were used as a raw material. The optimum catalyst/cement ratio of 0.2 was found to yield the specified CNM quality. If the catalyst/binder ratio is increased (without changing the other parameters), the specific yield value of the nanomodifier decreases, which can be explained by "poisoning" of the catalyst and, consequently, the formation of unstructured carbon. The nanomodifier was investigated by scanning electron microscopy, Raman spectroscopy and thermal gravimetry. Using Raman spectroscopy, the shape and position of the characteristic G and D bands showed that a material containing multi-walled carbon nanotubes (MWCNTs) was synthesized on the cement binder matrix. According to thermal gravimetry data, the obtained nanomodifier is resistant to thermal decomposition up to 500 °С. Experimental studies of the influence of the obtained additive on the characteristics of the construction composite were carried out on samples of fine-grained concrete. It is established that compressive strength for nanomodified samples increases by 18-20 %.

The effect of multi-walled carbon nanotubes on mechanical properties and water adsorption of lightweight foamed concrete

“…Concrete's strength and ductility can also be improved by using carbon nanotubes (CNTs) and nanofibers. Furthermore, the use of nanomodified cements or nano-sized paste additives can improve shrinkage characteristics and reduce permeability, both of which can increase the strength of concrete [12][13][14][15]. Concrete's long-term and early shrinkage could be effectively reduced with the addition of CNTs, that can be attributed to the filler, nucleation, and bridging properties of CNTs.…”