The Influence of the Initial Moisture Conditions of Coarse Aggregates on the Properties of RAC

Memoria tratta da "The New Boundaries of Structural Concrete: Session C – New Scenarios for Concrete", ACI IC - Bergamo 2013

This paper reports the main results of a wide experimental campaign recently carried out at the Laboratory of Materials testing and Structures (LMS) of the University of Salerno (Italy) on different batches of Recycled Aggregate Concrete (RAC) samples. Moving from a reference material made of only ordinary constituents, various concrete mixtures were designed and prepared by replacing different amounts of natural aggregates (i.e. 0%, 30% and 60%) with recycled ones. Two series of each one of such mixtures were designed and realised by employing either 24h-oven-dried (OD) aggregates or saturated surface-dried (SSD) ones. Moreover, two different nominal values of water-cement ratio were considered. Experimental tests were carried out to quantify both the workability of the mixture in the fresh state and the time evolution of strength during the first 28 days of curing and hardening. The results show a significant influence of the initial moisture conditions of the recycled aggregates, whose higher water absorption capacity significantly affects hydration process and material porosity of the hardened concrete. The analysis of the experimental results are aimed at quantifying such an influence and correlate it with the fundamental physical properties of concrete constituents.

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