Effect of nanosilica addition on the fresh properties and shrinkage of mortars with fly ash and superplasticizer

• Fresh and hardened properties of cement mortars with nS, FA and SP are modeled.
• Mortar flowability is affected by nS content and SP dosage, but not by FA content.
• Higher nS contents require higher SP dosages to maintain acceptable flowability.
• Increasing nS content significantly reduces plastic shrinkage.
• The optimum nS content appears to be 1.7% over cement weight.

The ongoing use of various mineral additions along with chemical admixtures such as superplasticizers justifies the need for further research. Understanding and quantifying their effects and possible synergies on the fresh and hardened properties of cement-based materials is necessary, especially if some of these components are known to have a pozzolanic effect. This paper describes and models the fresh and hardened properties of cement mortars including nanosilica and fly ash, and relates their properties to the proportioning of these materials and the superplasticizer dosage. Mini-slump, Marsh cone and Lombardi cone tests were used to examine the properties of the fresh mortars, and to assess density, plastic shrinkage, and drying shrinkage up to 20 days. The equations presented in this paper make it possible to optimize mortar proportionings to the required levels of performance in both fresh and hardened states.