Influence of cement grouts composition on the rheological behaviour

The influence of water to cement ratio, HRWRA content and viscosity modifying admixture content on the rheological characteristics of cement grouts considered as Herschel-Bulkley fluids is studied experimentally. Results show that cement grouts without chemical admixtures and cement grouts containing only a viscosity modifying admixture present a shear-thinning behaviour with an approximately constant value for the exponent n of Herschel-Bulkley model. On the contrary, grouts containing a HRWRA content near the saturation point exhibit quasi Binghamian behaviour. The Herschel-Bulkley model describes properly the rheological behaviour of cement grouts without chemical admixtures. It can be applied correctly to grouts containing HRWRA and/or viscosity modifying admixture in a shear rate range comprised between 4 s(-1) and 100 s(-1) and can be used to predict satisfactorily the Marsh cone flow time of cement grouts of widely varying compositions. (C) 2010 Elsevier Ltd. All rights reserved.