Multiscale structure of calcium- and magnesium-silicate-hydrate gels

Chiang, Wei-Shan; Ferraro, Giovanni; Fratini, Emiliano; Yeh, Yi‐Qi; Jeng, U-S.; Chen, S. H.

doi:10.1039/c4ta02479f

Cited by 77 publications

(62 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…. M–S–H exhibited a rather short coherence length, close to 12 Å indicating a poorly crystalline nature and the nano‐sized particles as previously discussed . The X‐ray PDF analyses of the M–S–H samples with NaOH were very similar to the one of M–S–H prepared in the absence of alkalis regardless of the amount of NaOH present.…”

Section: Resultssupporting

confidence: 66%

Alkali binding by magnesium silicate hydrates

et al. 2019

View full text Add to dashboard Cite

The binding of Na+, K+, and Li+ by magnesium silicate hydrate (M–S–H) was investigated in batch sorption experiments. Sorption isotherms and cation exchange measurements indicated the binding of alkalis in cation exchange sites compensating the negative surface charge of M–S–H. Higher pH values led to further deprotonation of the silanol groups and a higher alkali uptake by M–S–H. No significant incorporation of alkalis in the main silica or magnesium oxide sheets was observed. However, the silica sheets were less polymerized in the presence of higher alkali hydroxide concentrations.

show abstract

Section: Resultssupporting

confidence: 66%

Alkali binding by magnesium silicate hydrates

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The fundamental assumption for developing coarse-grained C-S-H models is the concept of disk-like building blocks1130, which have been identified in recent experimental works182337. It has been found that disk-like objects with high aspect ratio (diameter-to-thickness ratio) exist in C-S-H.…”

Section: Methodsmentioning

confidence: 99%

Mesoscopic packing of disk-like building blocks in calcium silicate hydrate

Zhou

Lau

2016

Sci Rep

View full text Add to dashboard Cite

At 100-nanometer length scale, the mesoscopic structure of calcium silicate hydrate (C-S-H) plays a critical role in determining the macroscopic material properties, such as porosity. In order to explore the mesoscopic structure of C-S-H, we employ two effective techniques, nanoindentation test and molecular dynamics simulation. Grid nanoindentation tests find different porosity of C-S-H in cement paste specimens prepared at varied water-to-cement (w/c) ratios. The w/c-ratio-induced porosity difference can be ascribed to the aspect ratio (diameter-to-thickness ratio) of disk-like C-S-H building blocks. The molecular dynamics simulation, with a mesoscopic C-S-H model, reveals 3 typical packing patterns and relates the packing density to the aspect ratio. Illustrated with disk-like C-S-H building blocks, this study provides a description of C-S-H structures in complement to spherical-particle C-S-H models at the sub-micron scale.

show abstract

“…The GB potential provides a six degrees of freedom interaction function between aspherical particles. While C–S–H nanolayers are not necessarily aspherical, they have a small thickness compared to the extension of pseudo‐octahedral Ca‐O sheets ratio . Here, for the sake of simplicity, we approximate the shape of C–S–H layers with an oblate object with radii of ( a , b , c ), where c < a = b .…”

Section: The Effective Interaction Between C–s–h Nanolayersmentioning

confidence: 99%

Nanolayered attributes of calcium‐silicate‐hydrate gels

et al. 2019

View full text Add to dashboard Cite

Calcium‐silicate‐hydrates (C–S–H) gel, the main binding phase in cementitious materials, has a complex multiscale texture. Despite decades of intensive research, the relation between C–S–H's chemical composition and mesoscale texture remains experimentally limited to probe and theoretically elusive to comprehend. While the nanogranular texture explains a wide range of experimental observations, understanding the fundamental processes that control particles’ size and shape are still obscure. This paper strives to establish a link between the chemistry of C–S–H nanolayers at the molecular level and formation of C–S–H globules at the mesoscale via the potential‐of‐mean‐force (PMF) coarse‐graining approach. We propose a new thermomechanical load‐cycling scheme that effectively packs polydisperse coarse‐grained nanolayers and creates representative C–S–H gel structures at various packing densities. We find that the C–S–H nanolayers percolate at ~10% packing fraction, significantly below the percolation of ideal hard contact oblate particles and rather close to that of overlapping ellipsoids. The agglomeration of C–S–H nanolayers leads to the formation of globular clusters with the effective thickness of ~5 nm, in striking agreement with small angle neutron and X‐ray scattering measurements as well as nanoscale imaging observations. The study of pore structure and local packing distribution in the course of densification shows a transition from a connected pore network to isolated nanoporosity. Furthermore, the calculated mechanical properties are in excellent agreement with statistical nanoindentation experiments, positioning nanolayered morphology as a finer description of C–S–H globule models. Such high‐resolution description becomes indispensable when investigating phenomena that involve internal building blocks of globules such as shrinkage and creep.

show abstract

Multiscale structure of calcium- and magnesium-silicate-hydrate gels

Cited by 77 publications

References 40 publications

Alkali binding by magnesium silicate hydrates

Alkali binding by magnesium silicate hydrates

Mesoscopic packing of disk-like building blocks in calcium silicate hydrate

Nanolayered attributes of calcium‐silicate‐hydrate gels

Contact Info

Product

Resources

About