It is well known that the construction sector is among the most energy- and resource-intensive industrial activities. Therefore, the European Union has recently adopted a policy intended at promoting the use of recycled aggregates for concrete production (up to 70% for 2020), with the twofold aim of reducing the need for natural sources in the construction sector and minimising the environmental impact of the concrete industry. This research is intended at providing a contribution for better understanding and carefully predicting the effect of Recycled Concrete Aggregates (RCAs) on the resulting mechanical properties of structural concrete. First of all, it reports the results of a wide experimental campaign carried out at the Laboratory for testing Materials and Structures (LMS), University of Salerno, Italy. Several concrete mixtures were prepared and sampled by considering the variation of some relevant parameters and aspects, such as the water-to-cement ratio, the aggregates replacement ratio and the initial moisture conditions of the coarse aggregates. The time evolution of both the cubic compressive strength and the temperature developed by the hydration reaction were monitored during the hardening stage. Secondly, a theoretical model was employed for converting the measured temperatures into the corresponding values of degree of hydration supposed to be achieved into the concrete samples tested in compression. Finally, based on the resulting correlation between the compressive strength and the degree of hydration, a formulation is proposed for the mix-design of concrete made out with recycled aggregates. The proposed formulation represents a generalisation of the well-known Abram’s law to the case of Recycled Aggregate Concrete (RAC).

Sulla previsione delle proprietà meccaniche di calcestruzzi con aggregati riciclati

PEPE, MARCO;MARTINELLI, Enzo;FAELLA, Ciro;
2014

Abstract

It is well known that the construction sector is among the most energy- and resource-intensive industrial activities. Therefore, the European Union has recently adopted a policy intended at promoting the use of recycled aggregates for concrete production (up to 70% for 2020), with the twofold aim of reducing the need for natural sources in the construction sector and minimising the environmental impact of the concrete industry. This research is intended at providing a contribution for better understanding and carefully predicting the effect of Recycled Concrete Aggregates (RCAs) on the resulting mechanical properties of structural concrete. First of all, it reports the results of a wide experimental campaign carried out at the Laboratory for testing Materials and Structures (LMS), University of Salerno, Italy. Several concrete mixtures were prepared and sampled by considering the variation of some relevant parameters and aspects, such as the water-to-cement ratio, the aggregates replacement ratio and the initial moisture conditions of the coarse aggregates. The time evolution of both the cubic compressive strength and the temperature developed by the hydration reaction were monitored during the hardening stage. Secondly, a theoretical model was employed for converting the measured temperatures into the corresponding values of degree of hydration supposed to be achieved into the concrete samples tested in compression. Finally, based on the resulting correlation between the compressive strength and the degree of hydration, a formulation is proposed for the mix-design of concrete made out with recycled aggregates. The proposed formulation represents a generalisation of the well-known Abram’s law to the case of Recycled Aggregate Concrete (RAC).
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/4483063
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