Abstract
The desire to preserve the environment is becoming more and more important in our societies. The setting up of the search for the so-called sustainable development reflects this commitment. To follow this way of sustainable development, governments are putting the industries under an ever-increasing pressure to reduce the various pollutions they generate. In the case of the cement industry, CO2 emissions and consumption of raw materials are mainly referred to reduce its environmental impact. The development of cement with mineral additions, mostly spawned from industrial processes, is a way of reducing the amount of clinker in Portland cement and therefore decreasing emissions. Such cements already exist and use industrial by-products such as blast furnace slag, silica fume or fly ash. Moreover, these cements with additions are interesting because they have specific properties, very different from CEM I type Portland cements. This last point of the specific properties of cement with additions associated with the increasing pressure of sustainable development constitutes the basement on which is built the thesis. Our work aims at developing a methodology for development of cement with mineral additions. Such a methodology would allow cement manufacturers to develop new products while walking the line of sustainable development by promoting by-products of other industries. The originality of our methodology rely on maximum use of numerical tools and simulation as a replacement of experimental works that are the main part of studies that aim at developing such cements. The main interests of our approach are cost and time reductions for cement development. Development times can be very long when they include durability studies. The work done for the thesis has first consisted in giving the methodology a functional realty. This methodology is split in three successive steps for testing the relevance of an industrial by-product as a potential addition in cement. To do this, three softwares were selected : • CHESS, a geochemical computing code, used for the first step, • VCCTL, cement paste microstructure generating code, used for the second step, • HYTEC, reactive transport simulation code, used for the third step. We had to adapt those softwares to their use in the field of the methodology in order to establish a synergy of operation between them. This adaptation has led us to perform a significant modification of the VCCTL source code in order to expand its capacity to take into account unknown additions. The work has then focused on the practical validation of the methodology by its confrontation with the results of experimental studies. This practical validation was initially focused on an OPC and then on blends of OPC with either blast furnace slag or fly ash circulating fluidized bed (CVLFC). The results achieved confirm the interest of the approach but they are also letting foresee the current limitations mostly linked to the numerical tools.