Determining the Surfactant Consistent with Concrete in order to Achieve the Maximum Possible Dispersion of Multiwalled Carbon Nanotubes in Keeping the Plain Concrete Properties

Abstract

A new surfactant combination compatible with concrete formulation is proposed to avoid unwanted air bubbles created during mixing process in the absence of a defoamer and to achieve the uniform and the maximum possible dispersion of multiwalled carbon nanotubes (MWCNTs) in water and subsequently in concrete. To achieve this goal, three steps have been defined: (1) concrete was made with different types and amount of surfactants containing a constant amount of MWCNTs (0.05 wt%) and the air bubbles were eliminated with a proper defoamer. (2) Finding a compatible surfactant with concrete compositions and eliminating unwanted air bubbles in the absence of a common defoamer are of fundamental importance to significantly increase concrete mechanical properties. In this step, the results showed that the polycarboxylate superplasticizer (SP-C) (as a compatible surfactant) dispersed MWCNTs worse than SDS/DTAB but unwanted air bubbles were removed, so the defoamer can be omitted in the mixing process.(3) To solve the problem, a new compatible surfactant composition was developed and different ratios of surfactants were tested and evaluated by means of performance criteria mentioned above. The results showed that the new surfactant composition (SDS and SP-C) can disperse MWCNTs around 24% more efficiently than the other surfactant compositions.

A state-of-the-art on self-sensing concrete: Materials, fabrication and properties

“…However, Azhari [110] claimed that methylcellulose could negatively affect the mechanical properties owing to the air-entraining effect. High level of SDS concentration could also lead to an increasing of air bubbles and a reduction on concrete mechanical properties [35,72,111]. Adresi, Hassani [111] suggested that the proportions would be 1:9, 1:12, 1:5 of a combination of SDS and superplasticizer, when making ordinary concrete, high compressive strength concrete, and requiring a large amount carbon nanotubes dispersed in aqueous phase, respectively.…”

“…High level of SDS concentration could also lead to an increasing of air bubbles and a reduction on concrete mechanical properties [35,72,111]. Adresi, Hassani [111] suggested that the proportions would be 1:9, 1:12, 1:5 of a combination of SDS and superplasticizer, when making ordinary concrete, high compressive strength concrete, and requiring a large amount carbon nanotubes dispersed in aqueous phase, respectively. There was also other researches regarding the negative effect of surfactant.…”

“…In addition, low content of surfactant could reduce bubble formation. Adresi, Hassani [111] achieved a higher dispersion of multi-walled carbon nanotubes with a lower content of surfactant by mixing cationic and anionic surfactants together. Similarly, it was proved that both SDBS, an anionic surfactant, and CTAB, a cationic surfactant, with the concentration of 0.004% and 0.4% respectively, could stabilize graphene nanosheets effectively [113].…”

Mechano-Physical Properties and Microstructure of Carbon Nanotube Reinforced Cement Paste after Thermal Load

“…A very high degree of CNT dispersion and stable aqueous solution (stable for a few months) is obtained in the presence of SDS, which was investigated by UV spectroscopy and transmission electron microscopy (TEM) [ 27 ]. Some studies on the use of the CNT dispersion with SDS [ 32 , 33 , 34 ], NaDDBS [ 35 ], and DMAc for cementitious composites, were conducted, but this aspect is not yet well researched.…”

Use of silica particles to improve dispersion of -COOH CNTs/carbon fibers to produce HyFRCC

“…Similarly, Randhawa et alet al [26] investigated the effect of surfactant concentration on dispersion and functionalization using Triton X-100 and suggested better functionalization of CNTs with COOH after dispersion, the optimum surfactant being 1.3 wt%. Various researches have suggested that there should be an optimum surfactant to MWCNTs ratio for the most efficient dispersion [27][28][29]. Konsta-Gdoutas et alet al [29] state that a weight ratio of surfactant to MWCNTs close to 4 is required for effective dispersion of nanotubes.…”