Super plasticizer assisted bath ultra sonication for dispersion of multi walled carbon nanotubes in cement composites

Abstract

This paper presents the observations and findings from an experimental study for dispersion of multiwalled carbon nanotubes (MWCNTs) by bath ultra-sonication in the presence of polycarboxylate ether (PCE) based superplasticizer. Commercial brand of superplasticizer (SP) compatible with cement was adopted for exploring its usage as surfactant during aqueous dispersion of MWCNTs. Cement composite pastes were evaluated for variation in compressive strength and fresh property for a fixed addition percentage of MWCNT. Aqueous dispersion of MWCNTs for incorporation to cement pastes was prepared considering three different sonication process variables; time period of sonication, SP to MWCNT dosage during sonication and temperature of sonication medium. A total of 168 experimental variations were evaluated for compressive strength of resulting cement–carbon nanotubes composite pastes at 7 days age to arrive at an optimal process of bath ultra-sonication with governing variables. Results showed that a sonication time period in the range of 4–5 hours with an SP to MWCNT ratio of 2.5–3 was necessary for satisfactory dispersion of MWCNTs over different temperature ranges of sonication bath medium. Further, the temperature of sonication medium in the range of 35–40^°C during aqueous dispersion of MWCNTs was observed to induce noticeable enhancement in strength of composite system indicating improvement in dispersion within an optimal range of sonication medium temperature. Microscopic observations for optimal process variables of dispersion during bath ultra sonication showed evidence of physical changes in MWCNTs from an agglomerated state of particles to separated state.

Graphical Abstract

HIGHLIGHTS

• Bath ultra-sonication is explored for dispersion of Multi-walled carbon nanotubes (MWCNTs) with cement compatible Poly carboxylic Ether based Superplasticizer (SP) as a surfactant for benefit of large-scale application in the construction sector.

• Total of 168 experimental variations studied considering three process variables: Time of sonication; dosage of superplasticizer during sonication with respect to MWCNT weight and temperature of sonication bath.

• Compressive strength variation for the composite system used for arriving at optimal sonication process variables.

• Noticeable effects in the composite system were observed for minimum 4 hours of bath ultra-sonication with SP to MWCNT ratio of 2.5 and for a sonication temperature of 35 °C.

Keywords:

• Bath ultra-sonication
• sonication time
• superplasticizer dosage
• sonication temperature
• cement-MWCNT composites compressive strength
• microscopic separation with dispersion treatment

Acknowledgements

The authors acknowledge B.M.S College of Engineering for necessary institutional support during the research period. The authors express gratitude to Late. Shri. C V Parthasarathi, Former Instructor, Concrete Laboratory, BMSCE, for his presence and assistance during the experimentation. The authors thank Dr. Dhananjaya N and Dr. Venkatesh R, Faculty, Physics Department, BMSIT; Akarsh M K and Kiran S (M.Tech- Construction Technology Students, BMSCE) and the staff of Concrete Laboratory, BMSCE, for their patience and support during the study.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.