Document Type

Concrete and geopolymer materials paper

Publication details

Rupasinghe, M, San Nicolas, R, Mendis, P & Sofi, M 2014, 'Analysing the pozzolanic reactivity of nano-silica in cement paste', in ST Smith (ed.), 23rd Australasian Conference on the Mechanics of Structures and Materials (ACMSM23), vol. I, Byron Bay, NSW, 9-12 December, Southern Cross University, Lismore, NSW, pp. 131-136. ISBN: 9780994152008.

Peer Reviewed



Nano-engineering of concrete is a research area gaining significant interest at present. It involves engineering of concrete at the nano-meter scale by inclusion of nano-materials in order to improve the structure of concrete from the nano-meter scale through to higher dimensions. This paper explores the hydration characteristics of cement paste with nano-silica, focusing on the pozzolanic reactivity. It considers replacing the cement content of the cement paste by small amounts of nano-silica (at percentage replacement levels of 4, 8 and 12 by weight of cement) and compares the hydration characteristics of these mixes against the plain cement paste. Colloidal nano-silica is used in this research. Thermal Gravimetric Analysis (TGA) has been carried out on the cement pastes at different ages to analyse the Calcium Hydroxide (CH) content of the nano- modified pastes. It is shown that the CH content of the mixes including nano-silica is lower than that of the plain cement paste, indicating that nano-silica reacts with the cement paste through a pozzolanic reaction. Increased pozzolanic activity results in higher amounts of Calcium Silicate Hydrate in the paste, which in turn results in higher compressive strength for nano-silica modified cement pastes.