01157614

Component

https://doi.org/10.3141/2142-08

http://scholar.google.com...lomo&publication_year=2010

A study is described of the stability (chemical composition and nanostructural change) of a synthetic calcium silicate hydrate gel in the presence of Ca(OH)2, the two main products of portland cement hydration, hours after alkalis, aluminum, and soluble silica were added to the mix. The sol–gel procedure was used to synthesize the gels. Calcium nitrate and sodium silicate solutions were used as the sources of calcium and silicon, respectively. The samples were prepared to a target Ca–Si ratio of 1.9. A 10-M NaOH solution was added to hold the pH at values greater than 13. All processes were conducted in a nitrogen atmosphere. The samples were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, nuclear magnetic resonance, transmission electron microscopy, and energy dispersive X-ray. The findings showed that addition of a high sodium hydroxide content led to silicate polymerization. The simultaneous addition of alkalis and aluminum induced a rise in the degree of silicate condensation in the gel [Q²(nAl) and possible cross-linking, Q³, via bridging tetrahedral aluminate], along with the formation of a calcium aluminosilicate hydrate similar to strätlingite. Finally, the simultaneous addition of alkalis, aluminum, and soluble silica favored the precipitation of an alkaline aluminosilicate hydrate gel with calcium replacing a high percentage of sodium and a composition clearly different from that of the other components.

01157601

NANO10-0017

English

pp 52-57

2010

Transportation Research Record: Journal of the Transportation Research Board

9780309142779

Print

Figures (6) ; References (19) ; Tables (1)

Alkali; Aluminum; Calcium hydroxide; Chemical composition; Electron microscopy; Fourier transforms; Gels; Hydration; Infrared spectroscopy; Nitrogen; Nuclear magnetic resonance; pH value; Portland cement; Silica

Calcium aluminosilicate; Calcium silicate hydrate; Energy dispersive x-ray spectrometry; X-ray diffraction

Materials; I32: Concrete

TRIS, TRB, ATRI

May 27 2010 8:37AM

• American Road Map for Research for Nanotechnology-Based Concrete Materials
• Carbon Nanofiber–Reinforced Cement-Based Materials
• Direct Synthesis of Carbon Nanofibers on Cement Particles
• Distribution of Carbon Nanofibers and Nanotubes in Cementitious Composites
• Enhancement of Reactive Powder Concrete via Nanocement Integration
• Exploratory Investigation of Nanomaterials to Improve Strength and Permeability of Concrete
• Laboratory Assessment of a Self-Healing Cementitious Composite
• Modeling Nanoindentation of Calcium Silicate Hydrate
• Molecular Dynamics Study of Interaction Between Corrosion Inhibitors, Nanoparticles, and Other Minerals in Hydrated Cement
• Molecular Dynamics to Understand the Mechanical Behavior of Cement Paste
• Nanocellulose and Microcellulose Fibers for Concrete
• Nanoengineering Ultra-High-Performance Concrete with Multiwalled Carbon Nanotubes
• Nanotechnology and Concrete: Concepts and Approach
• Nanotechnology to Manipulate the Aggregate–Cement Paste Bond Effects on Mortar Performance
• New Calcium Silicate Hydrate Network
• New Possibilities and Future Pathways of Nanoporous Thin Film Technology to Improve Concrete Performance
• Performance of Carbon Nanofiber–Cement Composites with a High-Range Water Reducer
• Scanning Transmission X-Ray Microscopic Study of Carbonated Calcium Silicate Hydrate
• Strength Enhancement of Cement Mortar with Carbon Nanotubes: Early Results and Potential