VARIOUS DURABILITY ASPECTS OF CEMENT PASTES AND CONCRETES WITH SUPPLEMENTARY CEMENTITIOUS MATERIALS

The use of supplementary cementitious materials (SCMs) as a constituent for concrete receives considerable attention, due to the lower CO2 emission of these materials compared to the production of classic Portland cement. Furthermore, concretes incorporating SCMs show some improved durability properties. SCMs are mainly pozzolanic materials (Fly Ash or Metakaolin) or alkali-activated materials such as ground granulated blast slag (GGBS). In this paper, the durability of concretes and cement pastes, which incorporate SCMs as partial replacement of cement, has been investigated in comparison with the CEM-I material one. Here, SCMs are Metakaolin, fly ash and GGBS. Water porosity, chloride migration and diffusion, electrical resistivity and natural and accelerated carbonation tests have been performed, in particular in order to assess durability indicators. The changes in the durability properties with the water curing time (from 7 days to more than 1 year) have been investigated. Coupled aggressions are also studied on these materials. For example, the materials are put in contact with chloride and sulphate solutions after partial carbonation. In addition, some aspects of the microstructure and of the pore structure are investigated (for example by Mercury Intrusion Porosimetry), in order to better understand the results obtained relatively to durability indicators. The results show an evolution of the properties as a function of the cement replacement ratio by SCMs: the durability with regard to chloride penetration is improved but the resistance to carbonation is reduced (whatever the SCM type and content).