Cement is the most important construction material used nowadays as a binder in different building materials formulations. Its importance is not only due to its binding function in all cementitious materials including polymer modified mortars (PMM), but also to its relatively low costs. In comparison with ordinary cement-based mortars, PMM are more specialized and more sophisticated.
One of the constituent of PMM could be cellulose ether (CE), which is used as an addition in many construction applications. It is introduced into industrial mortars formulations to adjust their workability by controlling the water balance and to provide rheological properties for enhancing applications easiness. Moreover, CE is the most important regulator for aqueous systems because of its high water retention capacity . It increases the viscosity of the liquid as a function of molecular weight and addition level.
However, it induces a retardation of cement hydration . Quantifying this delay is necessary for the control of hardening and its optimisation. The control of the hydration process  and then the carbonation attack, to which coating mortars are particularly exposed
[4–6], are one of the many factors which govern the quality of CE-modified-mortars and their physical properties . The study of hydration kinetics of cements has been the objective of many researches.
Indeed, Papadakis et al.  and Tennis and Jennings  consider that each of the four anhydrous constituents of cement hydrates independently of the others. This result was confirmed by Copeland et al.  and Granju and Grandet  who show that the evolution of hydration degrees is different from one cement constituent to another. Papadakis et al.  propose the relationship (1) to calculate the reaction rate of anhydrous constituents of cement.