Valorization of Fine Recycled Aggregates Contaminated with Gypsum Residues: Characterization and Evaluation of the Risk for Secondary Ettringite Formation.

Fine recycled aggregates (FRA) (0/4 mm) are up to now not valorized on a high enough level because of characteristics like an elevated water absorption, higher fines content, and the presence of contaminations. Leftover gypsum residues from the construction site can cause internal sulfate attack when FRA are incorporated into new structures. Concern about this deteriorating reaction plays an important role in the rejection of FRA. In this study, samples of FRA from different recycling centers were characterized and incorporated into mortars. They were then subjected to swelling tests in order to evaluate the development of sulfate attack. Reference materials with different amounts of sulfates were used as a comparison. Results showed a variable sulfate content in industrial FRA, depending heavily on the source of the materials. In all but one case, the total amounts surpassed the acceptable sulfate contents specified in the European standard EN 206, meaning the FRA would be rejected for reuse in concrete. Nevertheless, swelling tests demonstrated that these contamination levels did not pose a risk for sulfate attack. These results indicated that the incorporation of FRA leads to acceptable mechanical performances and that the sulfate limit could be reviewed to be less strict.

"Recovery came first": desistance versus recovery in the criminal careers of drug-using offenders.

The aim of our paper is to gain insight in the desistance process of drug-using offenders. We explore the components of change in the desistance process of drug-using offenders by using the cognitive transformation theory of Giordano et al. as a theoretical framework. The desistance process of drug-using offenders entails a two-fold process: desistance of criminal offending and recovery. The results however indicate that desistance is subordinate to recovery because of the fact that drug-using offenders especially see themselves as drug users and not as "criminals." Their first goal was to start recovery from drug use. They were convinced that recovery from drug use would lead them to a stop in their offending. In the discussion, we explore the implications of this result for further research.