Synthesis of hydrophilic polymers with comb structure by free radical copolymerization for cementitious formulations

Résumé

Superplasticizers are nowadays one of the most important constituents of modern concrete. They have generally been used to decrease the viscosity of cement suspensions or to reduce the amount of mixing water necessary, achieving concretes with higher mechanical properties. Due to the high amount of concrete used in construction, superplasticizers have become one of the most important polymeric admixtures for cement industry. However, the knowledge of the interaction between these materials and cementitious materials is still not fully understood and most of the optimization products and dosages is performed based on trial and error. Furthermore, in several works the microstructure of the PCEs is unknown or only partially known, which makes very difficult to obtain relevant conclusions on how the PCEs work. Nevertheless, researches like Flatt et al. have devoted a great deal of research on the field of MPEG-type PCE microstructure and OPC fresh and hardened properties with the aim of optimizing the microstructure and mastering the fluidity and retardation of the hydration. Despite the work developed by Flatt et al. the interaction of the PCEs with different cement phases and the effect on their hydration retardation is still unknown.The main objective of this thesis is to study the fundamental effects of the interaction of the model MPEG-PCE macromolecules and the cement particles. Therefore, the project will consists mainly of two different parts. The first one will be devoted to the controlled synthesis by free radical copolymerization of MAA and PEGMA macromonomer and characterization with well-defined microstructure. Microstructure of the PCE¿s macromolecules will be defined by the backbone length, the side chain length or the amount of side chain or anionic carboxylic groups in the backbone. The second task of the thesis will be devoted to analyzing the interaction of the model macromolecules synthesized in the first part with the aim of establishing fundamental knowledge on the structure-property relationship. For this purpose Portland cements and different clinker phases present in OPC will be used.