A recycled natural resource as secondary raw material for versatile technological applications: the quarry waste from zeolite-rich tuffs

Natural resources, along with critical raw materials, are increasingly considered a focus for technological applications. Widely available and inexpensive natural resources, such as zeolite-rich geomaterials, possess minero-chemical characteristics that make them very useful in various technological applications, representing a strategic choice with a strong green connotation. In this research, the possibility of recycling waste powders from quarrying operations of zeolite-rich tuffs in technological applications for the construction sector and drug delivery was investigated. Waste powders collected from quarries operating on the Sorano Formation (Tuscany - Italy), were used for a preliminary characterization, performed to evaluate zeolite content and potential pollution deriving from industrial processing. Thereafter, the specific technological characterization was carried out to define the waste attitude to represent a promising candidate raw material for Lightweight Expanded Aggregates (LEA) production, partial substitution component with pozzolanic activity in cement formulations, carrier for active pharmaceutical molecules. Experimental results, obtained following European normative, proved that was possible to produce waste-based LEA with comparable features with those reported for currently marketed products, that waste powders exhibited pozzolanic activity evidencing the possible use as addition for blended cements and, finally, the use of a cationic surfactant determined a surface-modification of natural zeolites (contained in waste samples) which encouraged for an early loading trial of active pharmaceutical molecules. This research can be safely extended to other quarry waste, with similar mineralogical and chemical composition, leading to a strong contribution in the waste management of this sector.