Viscometric characterisation of cement grout for prediction of prepacked concrete construction

Abstract

The ability of cement grout to penetrate voids of aggregate media, during the injection process of prepacked concrete construction, is strongly dependent on its viscosity. This paper reports experimental work on the viscometric characteristics of cement grout for the prediction of prepacked grouting process. Various factors influencing the measured results have been identified. Shear history dependent viscosity of cement grout requires that an experimental programme should be designed: (a) to ensure repeatability; and (b) to obtain meaningful results for the concerned construction process. Due consideration has been given to establish proper mixing and measuring programmes. Results were obtained through a set of carefully selected parameters to simulate the shear history during the grouting process. The Bingham model was adopted to characterise the shear rate dependency of the apparent viscosity. Time dependency of the Bingham parameters was obtained from a series of tests of the same batch under the specified initial mixing condition and subsequent agitation. Thixotropy loop tests were also carried out to analyse the sensitivity of the internal structure of cement grout to further shearing, thus comparing the mixing effect on rheological property of cement grout.