Comparative study on effects of Class F fly ash, nano silica and silica fume on properties of high performance self compacting concrete

This paper presents the effects of some admixtures including silica nanoparticles, silica fume and Class F fly ash on different properties of high performance self compacting concrete (HPSCC). For this purpose, a fraction of Portland cement with the aim of cement content reduction was replaced different fractions of pozzolanic admixtures. The rheological properties of fresh concrete were observed through slump flow time and diameter and V-funnel flow time. Thermal properties were investigated via thermogravimetric analysis (TGA) test. Transport properties evaluated by water absorption, capillary absorption and chloride ion penetration tests. The results indicated that increase of fly ash content improves the rheological properties of HPSCC. The results also showed that mechanical and transport properties improved in the mixtures containing admixtures especially blend of silica nanoparticles and silica fume. It can also be concluded that higher amount of mineral admixtures combined with small fractions of nanopowders could be promising technique toward high performance concrete as a key material along with energy saving in construction and building technology.