*2.1. Materials*

The "quartzite" natural stone (NS) waste, commercially called "Cristallo", was supplied by Pettrys company, located in Cachoeiro de Itapemirim, ES, Brazil. The raw stone material was collected directly from the company.

As a comparison material, a commercial stone (CS) called "Branco Aldan" was used. It was supplied by Empresa Guidoni, located in São Domingos do Norte, ES, Brazil. The commercial artificial stone is composed of quartz powder, additives, and polyester resin, information provided by the company.

The quartzite waste was classified by the sieves 8 to 200 mesh and divided into three different particle sizes. The larger particles (coarse) were classified in the range of 2.38 to 2.00 mm, the medium particles were between 2.00 and 0.630 mm, and fine particles were less than 0.630 mm [7–9,21].

The waste particles were agglutinated by two types of resins. The natural resin, vegetable polyurethane derived from castor oil, is bicomponent, that is, it results from the mixture between a component A, prepolymer (methylene diphenyl diisocyanate), with 1.22 g/cm<sup>3</sup> relative density, and a component B, a polyol (castor oil-base) with a 0.96 g/cm<sup>3</sup> typical density. The resin in 1:1.2 ratio of component B was supplied by the company IMPERVEG (Aguaí, Brazil). The other resin, epoxy, was a bisphenol A diglycidyl ether-MC130 and the hardener, FD129, triethylenetetramine (TETA), used in proportion of 13 wt% of resin, were both supplied by the company EPOXYFIBER (Rio de Janeiro, Brazi).
