Application of nano-silica in concrete

This report presents the achievements of the 2012 second quarter focusing on the application of nS in concrete. In this context, nano-silica precipitated from the olivine dissolution in acid (OnS) and nano-silica sludge (nSS) were used for the experimental work. The activities performed include: a) Study of the effects of admixtures on cement/nano-silica pastes applying rheometric tests to assess changes in the viscosity caused by the volumetric substitutions of cement. These rheological tests were complemented with isothermal calorimetric measurements. b) Tests on mortar level were carried out using standard sand, cement and different nano-silica to study the effect on the behavior in fresh state (slump changes) and to determine the pozzolanic effect of nano-silica on the compressive and tensile splitting strength. c) Experiments were performed to determine the maximum amount of olivine nano-silica to be used as cement replacement in normal (vibrated) concrete. d) Completion of studies to determine the effect of nSS as a cement replacement in self compacting mortars (SCM). The aim of the aforementioned activities was to investigate the main characteristics and the behavior of the olivine nano-silica and its interaction with the cement paste. These activities were based on the reported project plan and other extra activities requested by the partners involved in the project. Some general conclusions and recommendations have been drawn from these results