01157606

Component

https://doi.org/10.3141/2142-11

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

The tensile strength of cement paste is one of the most important mechanical properties that influence shrinkage cracks in cementitious materials. Cement pastes that exhibit low tensile strength tend to exhibit greater shrinkage crack potential and reduced durability. Increasing the tensile strength in cement paste can minimize the shrinkage cracking potential. It is believed that the strength and cohesion of cement paste are controlled by the formation of calcium silicate hydrate (C-S-H) gel. To enhance macroscopic mechanical properties (tensile strength), it is necessary to understand the structure and behavior of C-S-H gel at the atomic level. Previously, molecular statics was used to determine minimal potential energy and the mechanical properties of crystalline C-S-H structures. From this study, a plausible atomic structure of C-S-H gel is proposed. This research effort builds on the aforementioned work by using molecular dynamics to derive tensile and compressive strengths of C-S-H structures from uniaxial stress–strain data. The results from the molecular dynamics simulations showed that the maximum strengths (i.e., compressive and tensile) for the proposed C-S-H structures are three orders of magnitude higher than the strength at the macrolevel. However, the tensile strength of the proposed C-S-H gel is 23% of the compressive strength. This research also concludes that electrostatic forces and bond forces in the silicate chains are the main contributors to cement strength at the atomic level and that breakage in silicate chains leads to low tensile strength in C-S-H gel.

01157601

NANO10-0038

English

pp 75-82

2010

Transportation Research Record: Journal of the Transportation Research Board

9780309142779

Print

Figures (8) ; References (23) ; Tables (2)

Cement; Cement paste; Chemical composition; Compressive strength; Mechanical properties; Shrinkage; Simulation; Tensile strength

Calcium silicate hydrate; Molecular dynamics; Shrinkage cracking

Materials; I32: Concrete

TRIS, TRB, ATRI

May 27 2010 10:02AM

• 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
• 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
• 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