Nanomaterials and Nanotechnology for High-Performance Cement Composites

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Title: Nanomaterials and Nanotechnology for High-Performance Cement Composites

Author(s): K. Sobolev, I. Flores, R. Hermosillo, and L.M. Torres-Martínez

Publication: Special Publication

Volume: 254

Issue:

Appears on pages(s): 93-120

Keywords: compressive strength; high performance; mechanochemical activation; nano-SiO2; nanolayer; nanoparticle; superplasticizer

Date: 10/1/2008

Abstract:
Nanotechnology has changed our vision, expectations, and abilities to control the material world. The developments in nanoscience can also have a great impact on the field of construction materials. Portland cement, one of the largest commodities consumed by mankind, is obviously the product with great, but not completely explored, potential. Better understanding and engineering of complex structure of cement-based materials at nanolevel will definitely result in a new generation of concrete, stronger and more durable, with desired stressstrain behavior and, possibly, with the whole range of newly introduced "smart" properties. The reported research examined the mechanical properties of mortars with nano-SiO2 synthesized by sol-gel method. Experimental results demonstrate an increase in compressive strength of mortars with developed nanoparticles at early stages of hardening followed by the strength reduction at later age (versus the reference). Addition of superplasticizer was proposed to overcome this obstacle. Superplasticized mortars with selected nano-SiO2 demonstrated a 15-20% increase of compressive strength, reaching up to 144.8 MPa (21 ksi) at 90-day age. Mechanochemical activation was found to be effective method to improve the strength of cement-based materials. It was proposed that this process is governed by the solid state interaction between the organic modifiers and cement. During this process, the surface of cement particles attaches the functional groups introduced from the modifiers; so the organo-mineral nano-layers or nano-grids are formed on the surface of cement. The developed high-performance cements demonstrate the 28-day compressive strength at the range of 93 - 115 MPa (13.5-16.7 ksi), which is higher than 72 - 89 Mpa (10.4-12.9 ksi), the strength of reference cements.