COMPETITIVE ADSORPTION OF POLYMERS AT THE SURFACE OF CEMENT PARTICLES

In order to reach the rheological target requirements for Self Compacting concretes, mix design engineers have the freedom to mix various organic molecules. These polymers either stay in the interstitial fluid modifying its rheological behaviour or adsorb at the surface of cement grains modifying their colloidal interactions. When the polymers added to the system are both adsorbing species, the outcome of competitive adsorption between molecules dictates the rheological behaviour of the SCC. In this work, we study competitive adsorption of a so-called viscosity agent and of a plasticizer molecule. We develop a new protocol using Dynamic Light Scattering to distinguish the relative adsorption of different fractions of the admixtures. This protocol allows us to evaluate in a more quantitative manner the adsorbed amount of each polymer and to determine the key parameters dictating the behaviour of admixture in combination.