Conception of eco-friendly cement based on natural pozzolan to improve rheological behavior of concrete

The pozzolan of Beni- Saf region (North-West Algeria) is a natural material of volcanic origin with an ability to react with lime in the presence of water and to form compounds with binding properties. Therefore, its use in the production of new cementitious materials will protect the environment. It will therefore be interesting to exploit this source as a partial cement substitution. In this work, a rheometric investigation was carried out to assess the performance of the natural pozzolan substituted to cement at variable rates ranging from 5%, 10%, 15% to 20% in order to obtain an ecological concrete. As the rheological behavior of concrete depends on the behavior of the cement paste, the effect of pozzolan on the latter was analyzed using static flow tests and dynamic creep and oscillation tests. The results of the rheometric tests have shown that in flow, the pozzolan improves the fluidity and in oscillation mode, it generates a viscous behavior of the cementitious pastes compared to elastic behavior of the control paste. Furthermore, the transient study (creep / recovery) made it possible to highlight the liquid viscoelastic character of the cement pastes. With 10% of pozzolan, the rheological behavior of the paste is viscous liquid which seems to be the best. The use of pozzolan as cement substitution has significant economic, environmental and technical advantages, namely the development of natural pozzolan, reduction of CO2 emissions during the manufacture of cement as well as energy reduction and finally improvement of the properties of fresh concrete.