Functionalised nanoclays as microstructure modifiers for calcium and magnesium silicate hydrates

Ordinary Portland cement production contributes significantly to global CO2 emissions. Calcium silicate hydrate (C-S-H) is a primary binding phase in concrete. Magnesium silicate hydrate (M-S-H) is a potential eco-friendly alternative with similar properties but lower strength. Prior research has shown that C-S-H forms disk-like structures that influence concrete performance. However, no prior work had resolved how to improve M-S-H properties effectively. This gap motivated the investigation of nanomaterials as microstructure modifiers. Aluminosilicate nanoclays are known for their ability to interact with hydrated phases. That uncertainty drove the need to assess how nanoclays could influence hydrate microstructure. No prior work had resolved the effect of functional groups on hydrate formation. This paper introduces a new approach to enhance hydrate properties through nanoclay functionalization.

The study aimed to evaluate how functionalised nanoclays affect the microstructure of silicate hydrates. The specific problem is the weak mechanical properties of M-S-H compared to C-S-H. The motivation is to develop greener concrete materials with improved performance. The authors propose using functionalised nanoclays to modify hydrate formation. The goal is to understand how nanoclay functional groups influence hydrate structure. No prior work had resolved the impact of carboxylic or polycarboxylic moieties on these gels. The study tests whether functionalised nanoclays can improve hydrate microstructure. The approach involves comparing C-S-H and M-S-H with and without nanoclay additives.

The study used a multi-technique approach to analyze hydrate microstructure. Small- and wide-angle X-ray scattering (SWAXS) was employed to assess structural changes. Scanning electron microscopy (SEM) provided morphological insights. The researchers synthesized C-S-H and M-S-H gels with and without functionalised nanoclays. The nanoclays included HNT-COOH and HNT-PAA variants. The functional groups were selected to test their interaction with calcium and magnesium ions. The team compared disk-like globule sizes and layer spacing in hydrates. The results were analyzed to determine the role of nanoclay functionalization in hydrate formation.

The inclusion of functionalised nanoclays altered the microstructure of silicate hydrates. In C-S-H, HNTs reduced the size of disk-like globules without affecting layer spacing. The effect was less pronounced in M-S-H due to weaker interactions with Mg2+ ions. SEM showed better integration of HNT-PAA into hydration products. PAA-functionalised surfaces reduced aggregate size in hydrate gels. The morphology of C-S-H with HNT-COOH remained largely unchanged at the micron scale. M-S-H with HNT-COOH retained its aggregate structure. The results suggest that functional groups influence hydrate formation differently. The study provides evidence that nanoclay functionalization can modify hydrate microstructure.

The authors suggest that functionalised nanoclays can modify hydrate microstructure. The findings indicate that HNTs reduce globule size in C-S-H without altering layer spacing. In M-S-H, the effect is weaker due to Mg2+ interactions. The study proposes that PAA-functionalised nanoclays integrate better into hydration products. The authors suggest that functional groups influence hydrate formation differently. The results align with the hypothesis that nanoclay functionalization affects hydrate structure. The authors propose that this approach could improve hydrate properties. The study concludes that functionalised nanoclays are viable microstructure modifiers.