Preliminary Assessment Of Durability Of A Low Carbon Concrete Made With Limestone Calcined Clay Portland Cement

Through a collaborative research effort between the Ecole Polytechnique Federal de Lausanne and CIDEM a new kind of cementitious binder has been developed based on the synergy between calcined clays and limestone. Industrial trials carried out in Cuba during 2013-2015 have proven that the new cement is very effective even with clinker content as low as 50%. This paper presents preliminary results of a full program of assessment of durability of concrete cast with the new cement. Concrete elements have been cast and placed on an exposure site in the northern coast of Cuba. Cores have been taken, and have been tested for chloride ingress and migration, carbonation and air permeability. Concrete made with the cement containing calcined clays and limestone appears to have a more tortuous pore structure, and an increased chloride binding capacity due to the presence of alumina phases, which helps decreasing the movement of chloride ions through the matrix. For the same-reason, and despite the low free lime content, this concrete shows a reduced carbonation compared to the one made with Portland cement, at age 15 month, placed on seashore in the hot and humid tropical zone. Air permeability measurements confirm the lower permeability of the concrete subject of study; this is very consistent with the results of chloride ingress and migration and carbonation.