Mechanical, rheological, durability and microstructural properties of high performance self-compacting concrete containing SiO2 micro and nanoparticles

In this paper, mechanical, rheological, durability and microstructural properties of high performance self compacting concrete (HPSCC) incorporating SiO2 micro and nanoparticles have been investigated. For this purpose, a fraction of Portland cement was replaced by different amounts of microsilica, nanosilica and blend of micro and nanosilica as 10%, 2% and 10% + 2% respectively. Three different binder contents as 400,450 and 500 kg/m(3) with a constant water to binder ratio (w/b = 0.38) were investigated. Rheological properties were determined through slump flow time and diameter. V-funnel flow time and L-box tests and mechanical characteristics were determined. Durability properties were evaluated by water absorption, capillary absorption, Cl ion percentage and resistivity tests. Microstructure of the concrete was also assessed via scanning electron microscopy (SEM). The results showed that the properties improved significantly for the specimens containing micro and nanosilica. Improvement of Cl ion percentage and resistivity results in the micro and nanosilica blended mixtures was also noticeable. From the microstructure point of view, the SEM micrographs showed more refined and packed pore structure of the concrete containing admixtures especially at longer ages which could lead to enhancement of strength and the durability properties of HPSCC specimens. (C) 2011 Elsevier Ltd. All rights reserved.