The Stabilization Mechanism of Nano-SiO₂ Precursor Solution

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Fabrication of nano-silica (NS) mineral powder faces challenges like high cost and particle agglomeration.
• Utilizing a precursor solution of NS in cement-based materials offers a potential mitigation strategy.

Purpose of the Study:

• To investigate and optimize the liquid-phase preparation technology for nano-silica precursor solutions.
• To determine the optimal conditions for precipitating nano-silica particles and their subsequent reaction in cementitious systems.

Main Methods:

• Synthesized NS precursor solutions using various acids (HCl, HNO3, HBO3, HCOOH, CH3COOH) and sodium silicate solutions.
• Varied acetic acid concentration (1-15%), sodium silicate concentration (20-38%), and solution pH (4-8).
• Analyzed NS precipitation indexes including time, morphology, and distribution.

Main Results:

• The optimal precursor solution comprised ≤3% acetic acid and ≤25% sodium silicate at pH 6.
• Adding the precursor to Ca(OH)2 saturated solution activated it, leading to NS particle precipitation and calcium silicate gel formation.
• Incorporating NS precursor into cement paste resulted in CSH gel formation and improved compactness.

Conclusions:

• An optimized liquid-phase preparation technique for NS precursor solutions was established, addressing cost and agglomeration issues.
• The developed NS precursor effectively reacts within cementitious matrices to form CSH gel, enhancing material properties.