Towards Early Age Characterisation of Eco-Concrete Containing Blast-Furnace Slag and Limestone Filler

It is estimated that concrete represents 5% of the anthropogenic CO2 emissions, mainly originating from the production of cement, the most essential component of concrete. The recent awareness to the environmental challenges facing our civilization has led the cement industry to consider substituting cement by mineral additions, by-products of existing industries. In this work, a combination of limestone filler and blast furnace slag is used to design an “eco-concrete”, defined as a concrete combining a massive decrease of the cement content as well as mechanical properties and potential durability equivalent to a normal strength concrete. This research reviews the main concrete mix design parameters and their importance when designing an eco-concrete, resulting in five compositions containing various amounts of water, limestone filler and slag. The independent and combined effects of these parameters are observed on the development of the main concrete properties through the use of specific experimental equipment. Continuous non-destructive methodologies to assess efficiently and accurately the properties of any cement-based materials are developed by combining adapted traditional measurements and ultrasonic testing. The question of the early age cracking risk of these concretes is introduced by studying the effect of temperature on the main concrete properties, and a unified model is proposed for taking its effect of the early age autogenous deformation. Finally, new experimental observations are made regarding the behaviour of concrete under fully restrained deformations. The proposed eco-concrete meets many of the requirements of a sustainable construction material.Doctorat en Sciences de l'ingénieur et technologie