Advances in Cement Research · 2008 · 412 citations · 21 references
Natural SciencesMaterials EngineeringMaterials ScienceFunctional MaterialsNanomaterialsPolymer MaterialsCarbon NanotubesCementitious MaterialsConcrete MaterialsMaterial PropertiesNanocompositesNanotubesCarbon Nanotube CompositesCarbon Nanotube Mechanical PropertiesCement PasteCompressive StrengthHydration BehaviorMechanical Properties Of Carbon NanotubesMulti-walled Carbon NanotubesWorkability
The study examined how surface decoration methods influence the wetability of multi‑walled carbon nanotubes and the mechanical properties of cement paste containing them. Researchers compared two decoration strategies: functionalisation with polyacrylic acid polymers alone, and polyacrylic acid polymers combined with gum Arabic. Stable, homogeneous MWCNT dispersions produced with polyacrylic acid functionalisation yielded cement pastes with good workability and up to a 50 % increase in compressive strength at low MWCNT loadings, likely due to chemical bonds between the nanotube OH groups and the CSH phase, whereas dispersions containing gum Arabic were only stable for about 2 h, caused slower hydration, and did not alter mechanical properties when polyacrylic polymers were used alone.
The present study investigated the effects of the method of surface decoration on the wetability of multi-walled carbon nanotubes (MWCNTs) and the mechanical properties of the cement paste incorporating these dispersions. The results showed that stable and homogenous dispersions of MWCNTs in water can be obtained by using surface functionalisation combined with decoration using polyacrylic acid polymers. The cement paste specimens incorporating these dispersions revealed good workability and an increase in the compressive strength of nearly 50% even with only a small addition of the MWCNTs, namely 0·045–0·15% of the cement weight. These results indicate the existence of chemical bonds between the OH groups of the functionalised MWCNTs and probably the CSH phase of the cement matrix, which enhanced the transfer of stresses. A second method that was studied included decoration of MWCNTs with polyacrylic acid polymers and gum Arabic. These dispersions appeared to be homogeneous only for approximately 2 h after which a progressive sedimentation occurred. Good workability was found for the cement pastes produced with all of the dispersions; the only significant difference being the slower hydration of the cement incorporating gum Arabic. The mechanical properties of the cement pastes incorporating MWCNTs treated with polyacrylic polymers were unchanged.
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