01157608

Component

https://doi.org/10.3141/2142-12

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

Calcium silicate hydrate (C-S-H) is the main hydration product of portland cement. Studying the structural and chemical decomposition of C-S-H after carbonation is critical for determining the durability and serviceability of concrete. Recent studies showed that the mechanical properties are likely to be enhanced when mineral admixtures and polymers are introduced. So far, no molecular-level studies have been conducted on carbonated C-S-H material to clarify these effects. In this research, scanning transmission X-ray microscopy (STXM) is used to study C-S-H modified with two organic polymers (hexadecyltrimethylammonium and polyethylene glycol 200) and exposed to different reaction times with CO2. STXM uses light in the soft X-ray region where a number of atomic resonances are present. By tuning the X-ray energies to a certain absorption edge, elemental and chemical identification was performed. The energy of the X-rays was tuned to the C K-edge, Ca L2,3-edge, and Si K-edge. Detailed images were also recorded with a lateral resolution of 30 nm. Structural, elemental, and chemical heterogeneities were spatially identified. Significant differences were found in carbon spectra in the atmospheric and 48-h continuous CO2-carbonated C-S-H samples, suggesting that carbon-containing precipitates formed within a C-S-H matrix differ depending on the extent of carbonation. Si K-edge spectra suggest increased polymerization of silicates depending on the duration of CO2 exposure. This study found that the degree of silicate polymerization and the coordination environment for carbon-containing mineral phases vary with the CO2 exposure level.

01157601

NANO10-0062

English

pp 83-88

2010

Transportation Research Record: Journal of the Transportation Research Board

9780309142779

Print

Figures (5) ; References (20)

Carbon dioxide; Carbonation; Concrete; Decomposition; Durability; Polymerization; Portland cement

Calcium silicate hydrate; Scanning transmission X-ray microscopy

Materials; I32: Concrete

TRIS, TRB, ATRI

May 27 2010 10:20AM

• 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
• Stability of Synthetic Calcium Silicate Hydrate Gels in Presence of Alkalis, Aluminum, and Soluble Silica
• Strength Enhancement of Cement Mortar with Carbon Nanotubes: Early Results and Potential