Stone materials processing waste used as secondary raw material for construction adhesives: preliminary results.

As is now widely known, any industrial activity produces wastes. These materials, more and more often, represent a logistic and environmental problem since they require regulations and treatments for disposal/storage that inevitably affect the general costs of the final product.

Wastes from stone materials processing, in short, retain all the mineralogical and compositional characteristics of the original materials even if, in some way, may be contaminated by the processing itself, or by wearing and tearing of industrial tools.

This research presents preliminary results from testing prototypes of construction adhesives made up recycling 1) a quartzite (India) stone waste mixed with 2) sand (also from India) as fine aggregates in mix design of the adhesives.

First, both wastes were characterized by physical, chemical and mineralogical points of view.

Particle size distribution along with X-ray Diffractometry, X-ray fluorescence and Scanning Electron Microscopy were carried out to acquire precise physical, mineralogical, and chemical information on wastes.

Experimental research started by mix designing different recipes considering a reference adhesive and a waste containing ones. Fresh doughs, as reported in European standard EN12004-2:2017, were cured for 28 days and used to stick on a concrete support three types of tiles with different grip: i) a polished metal plate, ii) a ceramic tile and a iii) natural stone slab. For each type a statistical valid number of sticked samples was tested.

After curing time, adhesive capabilities were tested by the Pull Off - Adhesion Test, as reported in European standard EN12004-2:2017, with very promising results, comparable to those obtained by normally marketed adhesives.

Further mix design additions useful for improving adhesive capabilities are currently under development.

Experimental procedures and results carried out in this research by using wastes from India can be safely extended to materials of different origins, proposing itself as an alternative method to storage for the reuse of these kind of wastes.