*2.3. Production of Artificial Stone Plates*

% = % ∗ ௦ % ∗ ௦ ሺ100 െ %ሻ ∗ (2) where: Artificial stone plates with a dimension of 100 × 100 × 10 mm were developed, with epoxy and natural vegetable polyurethane polymer resins, using the vacuum, vibration, and compression method. Initially, the quartzite particles were dried in an oven for 24 h at 100 ◦C to release moisture, then weighed and mixed with the resin in a vi-

*MAR*% = Minimum amount of resin to fill the void volume;

% = Void volume present in the mixture of particles;

for the hard body impact test required by the standard.

*ρQ* = Quartzite density, calculated by pycnometry.

*2.3. Production of Artificial Stone Plates* 

bration system under vacuum. Two plates were made of each resin in the dimensions 200 × 200 × 10 mm, for the hard body impact test required by the standard.

The mixture was taken to a Marcone MA 098-A hydraulic press for the plates production, with 3 MPa compression pressure and temperature of 90 ◦C for plates produced with epoxy resin and 80 ◦C for plates produced with polyurethane resin [7,24]. After pressing, the mold was disconnected from the vacuum system and cooled to room temperature to remove the plate. The plates with 85 wt% of artificial quartzite stone were developed with epoxy resin (AS-EP) and vegetable polyurethane resin (AS-PU), were subjected to a finishing step by polishing with sandpaper, and then cut with diamond disc to prepare samples for the tests according to the standards. subjected to a finishing step by polishing with sandpaper, and then cut with diamond disc to prepare samples for the tests according to the standards. *2.4. Characterization of Artificial Stone Plates*  The apparent density and porosity as well as the water absorption were evaluated based on Annex B of the ABNT/NBR 15845 Brazilian standard, which establishes the

### *2.4. Characterization of Artificial Stone Plates* applications of stone materials for the coating of building constructions [25].

The apparent density and porosity as well as the water absorption were evaluated based on Annex B of the ABNT/NBR 15845 Brazilian standard, which establishes the applications of stone materials for the coating of building constructions [25]. The three-point flexural strength test was performed on our INSTRON universal testing machine, model 5582, based on F Annex of ABNT/NBR 15845 Brazilian standard

The three-point flexural strength test was performed on our INSTRON universal testing machine, model 5582, based on F Annex of ABNT/NBR 15845 Brazilian standard [25]. The specimen's dimensions were 100 × 25 × 10 mm and the test was performed under 0.25 mm/min loading rate, 100 kN load cell, and 80 mm distance between the two points (Figure 2). [25]. The specimen's dimensions were 100 × 25 × 10 mm and the test was performed under 0.25 mm/min loading rate, 100 kN load cell, and 80 mm distance between the two points (Figure 2).

**Figure 2.** Specimen during the three-point bending test. **Figure 2.** Specimen during the three-point bending test.

A stone bend strength is directly related to the stone's material porosity, structure, and texture. The test was carried out in dry conditions. The first stage consists of putting A stone bend strength is directly related to the stone's material porosity, structure, and texture. The test was carried out in dry conditions. The first stage consists of putting the specimens in a ventilated oven for 48 h at 70 ◦C and waiting 1 h for them to cool down to room temperature. Figure 3 shows the specimen before and after the bend test.

the specimens in a ventilated oven for 48 h at 70 °C and waiting 1 h for them to cool down

**Figure 3.** Image of the specimens, before and after the bending test. (**a**) AS-PU; (**b**) fractured AS-PU;

speed defined by the standards. The bend strength is calculated by Equation (3), and then

3

=

The second stage is performed by applying a slow and steady load with increment

2ଶ (3)

to room temperature. Figure 3 shows the specimen before and after the bend test.

(**c**) AS-EP; and (**d**) Fractured AS-EP.

the arithmetic average is calculated.

**Figure 2.** Specimen during the three-point bending test.

**Figure 3.** Image of the specimens, before and after the bending test. (**a**) AS-PU; (**b**) fractured AS-PU; (**c**) AS-EP; and (**d**) Fractured AS-EP. **Figure 3.** Image of the specimens, before and after the bending test. (**a**) AS-PU; (**b**) fractured AS-PU; (**c**) AS-EP; and (**d**) Fractured AS-EP.

The second stage is performed by applying a slow and steady load with increment speed defined by the standards. The bend strength is calculated by Equation (3), and then The second stage is performed by applying a slow and steady load with increment speed defined by the standards. The bend strength is calculated by Equation (3), and then the arithmetic average is calculated.

=

$$R = \frac{\Im PL}{2bd^2} \tag{3}$$

2ଶ (3)

subjected to a finishing step by polishing with sandpaper, and then cut with diamond disc

The apparent density and porosity as well as the water absorption were evaluated

The three-point flexural strength test was performed on our INSTRON universal

A stone bend strength is directly related to the stone's material porosity, structure,

and texture. The test was carried out in dry conditions. The first stage consists of putting the specimens in a ventilated oven for 48 h at 70 °C and waiting 1 h for them to cool down

to room temperature. Figure 3 shows the specimen before and after the bend test.

based on Annex B of the ABNT/NBR 15845 Brazilian standard, which establishes the

testing machine, model 5582, based on F Annex of ABNT/NBR 15845 Brazilian standard [25]. The specimen's dimensions were 100 × 25 × 10 mm and the test was performed under 0.25 mm/min loading rate, 100 kN load cell, and 80 mm distance between the two points

applications of stone materials for the coating of building constructions [25].

to prepare samples for the tests according to the standards.

*2.4. Characterization of Artificial Stone Plates* 

(Figure 2).

where:

*R* = bend rupture stress (MPa);

*P* = rupture load (N);

*L* = distance between the action cleavers (mm);

*b* = width of the specimen after test (mm);

*d* = minimum thickness of the specimen (mm).

Abrasive wear tests were performed using a MAQTEST Amsler equipment on three samples with 70 × 70 × 40 mm, according to ABNT/NBR 12042 Brazilian standard [26]. The samples' thicknesses were measured before the wear test and then measured again after abrasive wearing suffered in 500 and 1000 m track.

The hard body impact test was performed using three 10 × 200 × 200 mm samples, according to Annex H of ABNT/NBR 15845 Brazilian standard [25]. It consists of releasing a 1 kg steel ball, at increasing heights, from 20 cm on, over the sample. The stone plate, seated on a sand mattress, receives the impacts until it cracks and rupture occurs. The height at which the material breaks occur is used to calculate the breaking energy using Equation (4).

$$\mathcal{W} = m \ast \mathcal{g} \ast h \tag{4}$$

*W* = breaking energy (J);

*m* = steel ball weight (Kg);

*g* = gravity acceleration (9.806 m/s<sup>2</sup> );

*h* = breaking height (m).

The microstructure of the fracture surface of bend-ruptured specimens was analyzed by a scanning electron microscope (SEM) in a model Super Scan SSX-550 from Shimadzu. The samples were prepared using an adhesive carbon tape enveloped by a gold surface.

Petrography, the main diagnostic technique for pathologies of stone materials, is the analysis of thin sections of stone by transmitted light microscopy, in order to identify, among other things, changes of minerals and microcracks. Using Buehler Petrothin Section System sec-

tioning equipment, the petrographic slides of AS-EP and AS-PU were prepared. The analysis was performed by a geologist in a ZEISS polarized light petrographic microscope.
