Picker A et al. (2017), Mesocrystalline calcium silicate hydrate: A bio...

ECB-ART-45904

Sci Adv 2017 Nov 29;311:e1701216. doi: 10.1126/sciadv.1701216.

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Mesocrystalline calcium silicate hydrate: A bioinspired route toward elastic concrete materials.

Picker A , Nicoleau L , Burghard Z , Bill J , Zlotnikov I , Labbez C , Nonat A , Cölfen H .

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Calcium silicate hydrate (C-S-H) is the binder in concrete, the most used synthetic material in the world. The main weakness of concrete is the lack of elasticity and poor flexural strength considerably limiting its potential, making reinforcing steel constructions necessary. Although the properties of C-S-H could be significantly improved in organic hybrids, the full potential of this approach could not be reached because of the random C-S-H nanoplatelet structure. Taking inspiration from a sea urchin spine with highly ordered nanoparticles in the biomineral mesocrystal, we report a bioinspired route toward a C-S-H mesocrystal with highly aligned C-S-H nanoplatelets interspaced with a polymeric binder. A material with a bending strength similar to nacre is obtained, outperforming all C-S-H-based materials known to date. This strategy could greatly benefit future construction processes because fracture toughness and elasticity of brittle cementitious materials can be largely enhanced on the nanoscale.

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Genes referenced: LOC100887844 stk36

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	Fig. 1. TEM analysis of C-S-H.(A) Cryo-TEM of colloidally stabilized C-S-H crystallites at pH 12 and (B) TEM analysis of aggregated C-S-H crystallites in the absence of stabilizing agents. The approximate literature known size of 60 × 30 × 5 nm3 (36) can be assumed in both micrographs.
	Fig. 2. Polarized optical and scanning electron micrographs of C-S-H mesocrystals.(A) to (C) were obtained from approach A, and (D) to (F) from approach B. For (A), (D), and (E), same colors indicate same orientations. The POM analysis suggests a long-range order of the agglomerated C-S-H crystallites over several hundreds of micrometers. (B) reveals a secondary structuring of the C-S-H superstructures, whereas (C) and (F) show the alignment of the single C-S-H crystallites into layers, and no microporosity can be detected.
	Fig. 3. TEM analysis of the mesocrystals obtained from approach A.(A) reveals single crystalline scattering behavior indicating a perfect mutual alignment of the C-S-H nanoparticles in three-dimension (3D). (B) shows the existence of single-isolated C-S-H crystallites at the edge. Because the building blocks are not fused together whereas they scatter like single crystals, the obtained agglomerates are mesocrystals.
	Fig. 4. Visualization of the pronounced flexibility and elasticity of a C-S-H mesocrystal lever prepared by FIB (focused ion beam).(A) to (F) Picture series of the bending video (available as movie S1) under the scanning electron microscope. The elasticity is revealed because the C-S-H mesocrystal cantilever fully relaxes after the application of a mechanical stress by a micromanipulator (upper left corner). The dashed line in (F) indicates the position of the C-S-H mesocrystal cantilever before bending. Scale bars, 10 μm.

References [+] :

Bergström, Mesocrystals in Biominerals and Colloidal Arrays. 2015, Pubmed, Echinobase