01088467

Component

The durability of concrete, defined as its service life, is highly influenced by pore structure. This pore structure, comprised of a connected pore network in cement paste and a highly porous area know as the interfacial transition zone (ITZ), hosts and controls the transport phenomenon in concrete. It is well known that the ITZ is a particular area with a high porosity and a tendency to develop microcracking. Previous research has shown that around 50% of the bulk matrix microstructure corresponds to the ITZ. The objective of this research was to explore the possibilities of using metal oxide nanoparticles, in particular silica and alumina oxides, to improve the properties of the ITZ. To reach this objective these materials were placed directly on the surface of the aggregates as a nanoporous film. The total amount of deposited material was 2x10-5% of the weight of the aggregate. The shear strength and the microstructure of a control sample were compared with aggregates containing silica and alumina oxide nanoporous films. Results showed that the presence of these nanoporous films increased the shear strength up to 50% after 14 days of curing. The microstructure analysis revealed that these metal oxides also increased the size of the different mineral phases of the ITZ. In particular, average size of ettringite needles increased 3 and 4 times due to the presence of silica and alumina oxides, respectively.

01084478

08-1833

English

10p

2008

Transportation Research Board 87th Annual Meeting

DVD

Figures; Photos; References (21) ; Tables (1)

Concrete; Durability; Ettringite; Microcracking; Service life; Shear strength

Nanoporous gel; Transition zones

Design; Highways; Materials; I32: Concrete

Transportation Research Board Annual Meeting 2008 Paper #08-1833

TRIS, TRB

Jan 29 2008 4:10PM