Location

Cuba

Keywords

pozzolan, cement, concrete, durability, chloride, carbonation

Abstract

This work presents the results of an investigation carried out to assess durability of concrete made with a calcined clay- limestone-Portland cement with 47% of clinker, hereafter named LC3, produced during an industrial trial in 2013. LC3 was used to cast concrete blocks and later expose them at a natural location at the northern coast of Cuba. Reference concrete was cast with Cuban Portland cement having 88% of clinker. Throughout three years (2015, 2016, 2017) concrete cores were systematically taken and the specimens were subjected to a testing program that included Formation factor, chloride profiling, surface resistivity, air permeability and carbonation depth. The studies proved that concrete made with the new binder presents a more refined capillary pore network, thus the movement of ions through the concrete matrix is slower than in normal PC concrete. Experimental measurement of the chloride profiles, Formation factor, surface resistivity and air permeability confirm an improvement of performance in the range of 2-3 compared to PC concrete. This is attributed to the presence of calcined clay in the new system and the synergy with limestone. For concrete exposed in coastal areas in hot & humid regions, carbonation is hindered by the high Relative Humidity, which saturates the pore system and reduces CO2 diffusion. The use of LC3 in concrete in very aggressive –chloride- conditions could yield a better performance against steel corrosion, as the tests on surface resistivity have proven.

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Performance of Concrete Made with a Calcined Clay – Limestone-Portland Cement Exposed to Natural Conditions

Cuba

This work presents the results of an investigation carried out to assess durability of concrete made with a calcined clay- limestone-Portland cement with 47% of clinker, hereafter named LC3, produced during an industrial trial in 2013. LC3 was used to cast concrete blocks and later expose them at a natural location at the northern coast of Cuba. Reference concrete was cast with Cuban Portland cement having 88% of clinker. Throughout three years (2015, 2016, 2017) concrete cores were systematically taken and the specimens were subjected to a testing program that included Formation factor, chloride profiling, surface resistivity, air permeability and carbonation depth. The studies proved that concrete made with the new binder presents a more refined capillary pore network, thus the movement of ions through the concrete matrix is slower than in normal PC concrete. Experimental measurement of the chloride profiles, Formation factor, surface resistivity and air permeability confirm an improvement of performance in the range of 2-3 compared to PC concrete. This is attributed to the presence of calcined clay in the new system and the synergy with limestone. For concrete exposed in coastal areas in hot & humid regions, carbonation is hindered by the high Relative Humidity, which saturates the pore system and reduces CO2 diffusion. The use of LC3 in concrete in very aggressive –chloride- conditions could yield a better performance against steel corrosion, as the tests on surface resistivity have proven.