Thixotropic Behavior of Cement Pastes Under Large Amplitude Oscillatory Shear

Abstract

Cement-based materials exhibit highly complex rheological properties, in particular yielding and thixotropy. These two properties can be characterized by considering rebuilding under a constant stress (creep) after shear at high rate. The rebuilding kinetics can be considered through the time evolution of the viscoelastic properties. However at the beginning of the rebuilding process the oscillatory behavior may be non-linear since the microstructure is destroyed by the shear flow. In the present investigation the rebuilding kinetics of cement pastes under oscillatory stress is considered through the transition from large amplitude oscillatory shear (LAOS) regime to small amplitude oscillatory shear (SAOS) regime. Three different cement paste mixes are considered: plain cement, nano-clay blended cement paste and cellulose ether blended cement paste. These three mixes are selected in order to deal with qualitatively different rheological properties.

Keywords

• thixotropy
• creep
• laos
• cement pastes