Effect of diatomite addition on fresh and hardened properties of mortars investigated through mixture experiments

Abstract

This paper reports an experimental research on the use of diatomite in mortars as a lightweight and pozzolanic filler. Samples with 52–67 wt-% Portland cement, 0–10 wt-% diatomite and 33–38 wt-% water were prepared. The formulation of mortars was based on rheology and flow table measurements, applying a design of mixture experiments. Entrained air, fresh apparent density, setting time, temperature of hydration as well as the compressive strength, water absorption and apparent porosity of samples cured for 28 days were determined. The use of mixture design restricts the number of formulations. However, all tested mixtures exhibited suitable workability. When diatomite is added, the yield stress, initial plastic viscosity and the entrained air increased, while other properties decreased. In addition, the compressive strength of mortars was above 30 MPa, and the results showed that the level of influence of diatomite will depend on the water content of the mixtures.