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Leaching test protocol for assessing the eco-compatibility of hardened woody biomass fly ash-cement mixtures

pubblicazioni - Memoria

Leaching test protocol for assessing the eco-compatibility of hardened woody biomass fly ash-cement mixtures

Nel lavoro è proposto un protocollo sperimentale finalizzato a valutare la compatibilità ambientale delle miscele indurite di cemento e cenere leggera da biomassa in termini di “pH di lavoro”, cioè quell’intervallo di pH in corrispondenza del quale non si manifestano pericolosi rilasci di elementi contaminanti. Tale protocollo è basato sia su prove normalizzate (UNI-EN 12457-2 e UNI-CEN/TS 14429) che prove non normalizzate, come la versione modificata della norma Olandese NEN 7345.

A woody biomass fly ash (FA) coming from of an Italian chipped-wood burning plant was tested for its environmental characterization and for evaluating the eco-compatibility of its possible reuse as a mineral addition in Portland cement pastes (FA/cement ratios of 15:85 and 30:70 by mass). The European leaching tests UNI-EN 12457-2 and UNI-CEN/TS 14429 were carried out on both FA and granular samples of hardened FA-cement pastes. Dynamic leaching tests were also performed on monolithic FA-cement specimens according to a modified version of the Dutch NEN 7345 test. All these leaching tests were framed in a protocol proposal aimed at diverting FA from landfilling to recycling and reuse and at assessing the eco-compatibility of hardened FA-cement mixtures in terms of their “working pH”, i.e., the pH range for which there is no dangerous contaminant release. Limits for non-hazardous waste landfilling were found to be appropriate for evaluating the “working pH” of waste forms and “working pH” values of not less than 6.2 and 7.0 were determined for the two FA-cement pastes investigated.

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