Influences of calcium carbonate nanoparticles on the workability and strength of 3D printing cementitious materials containing limestone powder

Effect of TiO2 Nanoparticles on the Fresh Performance of 3D-Printed Cementitious Materials

“…By increasing the yield stress of the mixes through nano-TiO 2 incorporation, the number of printable layers also increased. This relation was confirmed by Yang et al [ 23 ], which simultaneously observed increases in the yield stress and reductions in the vertical displacement of freshly printed mortars (also at 30 min) with nano-CaCO 3 incorporation, improving their resistance against collapse. For instance, 1% and 2% nano-CaCO 3 incorporation in limestone replacement reduced the vertical displacement of printed elements by 11.1% and 44.4%, respectively, compared with that containing only limestone.…”

“…Regarding (i), Roussel et al [ 60 ] demonstrated that the time-dependent rigidification of cementitious suspensions occurs due to the combination of flocculation (confirmed by Yang et al [ 23 ]) and the progressive formation of hydration products—more specifically C-S-H, according to the authors—that form a rigid network. In addition, Qian [ 61 ] reported that the rigidification rate of a cementitious paste increases with a reduced inter-particle distance due to the higher pseudo-contact between particles and consequently higher C-S-H bridging.…”

“…Kruger et al [ 18 ] observed progressive increases (up to 76%) in the yield stress of 3DP mortar with 0–3% nano-SiO 2 incorporation. Yang et al [ 23 ] also reported higher yield stress increases over time for nanoparticle-containing 3DP mixes: the yield stress increased from 30 to 110 min by 39, 322, and 751%, respectively, for 0, 1, and 2% replacement of limestone with nano-CaCO 3 . In turn, specifically regarding nano-TiO 2 incorporation in cementitious systems, the direct comparison of our results is difficult since most of the existing works only evaluated empirical properties such as slump flow, V-funnel time, and superplasticizer demand [ 27 , 28 ].…”

“…Zhang et al [ 33 ] observed increased heat releases within the first two hours of hydration when incorporated silica fume and/or nanoclay in pastes used for 3DP application. Yang et al [ 23 ] replaced 0–3 wt.% limestone filler with nano-CaCO 3 in 3DP cement mortars, observing reductions in the induction period and increases in the cumulative heat release in calorimetry (e.g., by 14% at 24 h for 2% replacement) with the incorporation of the nanoparticles. The authors attributed this trend to the extra nucleation sites provided by the high surface area of the nanomaterial discussed above (as expected).…”

“…Nanosilica particles promote a refined pore network as well as longer C-S-H chains and a lower Ca/Si ratio [ 22 ]. Yang et al [ 23 ] and Sikora et al [ 24 ] respectively used calcium carbonate and silica nanoparticles to improve the fresh performance of 3DP mixes, discussed in Section 3 .…”