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<p>This study investigates the effect of ultrasonication duration and superplasticizer (SP) type on the dispersion of multi-walled carbon nanotubes (MWCNTs) and the resulting properties of fresh and hardened cement pastes. Two SPs—lignosulfonate-based (SP-S) and polycarboxylate ether-based (SP-R)—were used to co-disperse MWCNTs in aqueous suspensions. Various ultrasonication durations (5–20&#xa0;min) were applied to improve MWCNTs dispersion, which was evaluated by particle size distribution, pH, electrical conductivity (EC), and zeta potential. Results show that a 10-min ultrasonication time is optimal for reducing MWCNTs agglomerates, with SP-S achieving more stable dispersion (zeta potential up to − 49.6&#xa0;mV) than SP-R (− 24.2&#xa0;mV). SP-S reduced agglomerate size more effectively and increased EC, indicating better interaction with MWCNTs. SP-R, due to its acidic nature and lower ionic conductivity, led to inferior dispersion quality and more pronounced retardation of hydration. The rheology, setting time, hydration heat evolution, mineral composition (XRD), thermal behavior (DTA/TG), density, and compressive strength were analyzed. SP-S had a moderate influence on setting time and hydration, whereas SP-R significantly delayed both. Cement pastes with SP-S exhibited up to 24% higher compressive strength than pastes without SPs, while those with SP-R showed only up to 11% improvement. SP-S enhanced ettringite formation and hydrate content, as confirmed by XRD and TG data. The findings suggest that ultrasonication combined with SP-S is more effective in stabilizing MWCNT suspensions and improving cement paste properties. The study also highlights that SP dosage should not exceed 0.6%, and 10-min ultrasonication is optimal to avoid agglomeration and over-retardation.</p>

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Effect of MWCNTS and superplasticizers suspension ultrasonication duration on the properties of fresh and hardened state cement paste

  • 期刊论文

  • 发表日期：

    2026年7月4日

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  • Jolanta Pranckevičienė,
  • Ina Pundienė,
  • Yiying Du

摘要

This study investigates the effect of ultrasonication duration and superplasticizer (SP) type on the dispersion of multi-walled carbon nanotubes (MWCNTs) and the resulting properties of fresh and hardened cement pastes. Two SPs—lignosulfonate-based (SP-S) and polycarboxylate ether-based (SP-R)—were used to co-disperse MWCNTs in aqueous suspensions. Various ultrasonication durations (5–20 min) were applied to improve MWCNTs dispersion, which was evaluated by particle size distribution, pH, electrical conductivity (EC), and zeta potential. Results show that a 10-min ultrasonication time is optimal for reducing MWCNTs agglomerates, with SP-S achieving more stable dispersion (zeta potential up to − 49.6 mV) than SP-R (− 24.2 mV). SP-S reduced agglomerate size more effectively and increased EC, indicating better interaction with MWCNTs. SP-R, due to its acidic nature and lower ionic conductivity, led to inferior dispersion quality and more pronounced retardation of hydration. The rheology, setting time, hydration heat evolution, mineral composition (XRD), thermal behavior (DTA/TG), density, and compressive strength were analyzed. SP-S had a moderate influence on setting time and hydration, whereas SP-R significantly delayed both. Cement pastes with SP-S exhibited up to 24% higher compressive strength than pastes without SPs, while those with SP-R showed only up to 11% improvement. SP-S enhanced ettringite formation and hydrate content, as confirmed by XRD and TG data. The findings suggest that ultrasonication combined with SP-S is more effective in stabilizing MWCNT suspensions and improving cement paste properties. The study also highlights that SP dosage should not exceed 0.6%, and 10-min ultrasonication is optimal to avoid agglomeration and over-retardation.