Durability of mortar matrices of low-cement concrete with specific additions

The decarbonization of concrete sector is a priority to counteract the global environmental harmful. Knowing that Portland cement is responsible for huge anthropogenic emissions worldwide, the significant reduction of cement content in concrete mixtures is a key issue, combined with the optimization of mechanical and durability performances, allowing to improve concrete eco-efficiency. The present work fits in a research project that consists in improving the durability of concrete used to produce reinforced concrete poles for the electric distribution lines. The main goals for this research are: the optimized formulation of concrete matrices by maximizing compactness, reducing cement content up to 50% and incorporating different additions, in order to promote performance and durability; study the influence of different specific additions, combined with high compactness, on different exposures to carbonation or chloride ingression and; predict the service life of the structures/poles for those exposure conditions. Two matrices formulations were considered, fresh moulded concrete with dry consistency and formwork moulded concrete with plastic consistency, considering 350 kg/m(3) of powder content in optimized mixtures. For each one, different cement content and several additions (limestone filler, fly ash, natural pozzolan and electric furnace slag) were considered to replace the cement, which were single used or combined. The mortar matrices of the concrete formulation were characterized regarding main durability properties (capillary water absorption, electrical resistivity, accelerated carbonation and chloride ingression) and compared with reference cement-based mixtures. The service life of structures produced with those concrete matrices was estimated, taking into account the deterioration caused by the reinforcement corrosion induced by concrete carbonation or by chlorides attack. Results revealed that, depending on the specific addition, it is possible to formulate eco-efficient concrete matrices with less binder powder and half of the cement content and obtain durability parameters equal to or better than the reference fully cement-based mixtures.