Many studies on the rheology of cement grouts have shown that these materials are viscoplastic fluids presenting a yield stress. They can present a theological behavior of shear-thinning type or shear-thickening type. In all the cases, this behavior can be described satisfactorily by the Herschel-Bulkley model, characterized by three parameters tau(o), K and n, which relate the shear stress to the shear rate. The present study aims at relating the rheological parameters of cement grouts to their flow time through the Marsh cone which characterizes in a practical way the fluidity of grouts. A semi-analytical approach has been established initially on simple assumptions and then corrected based on numerical simulation results. It presents a deviation lower than 12% compared to numerical simulations for a wide range of theological characteristics of the Herschel-Bulkley fluids. It has also been validated experimentally with success on some studied cement grouts of various water/cement ratios. (c) 2006 Elsevier B.V. All rights reserved.