2.2.4. Mechanical Properties

Granite, polyurethane and ASPU 3-point bend rupture stress were determined. The test was performed in a Instron model 5582 universal machine, following the EN 14617-2 [22] and annex F of the NBR 15845 [23] standards guidelines. For each material, six specimens were used in the dimensions 10 <sup>×</sup> <sup>25</sup> <sup>×</sup> 100 mm<sup>3</sup> . The test was performed under 0.25 mm/min loading rate, 100 kN load cell and 80 mm distance between the two points.

The bend stress was calculated using Equation (1):

$$
\sigma\_{\rm F} = \frac{(3F \times L)}{2b \times e^2} \tag{1}
$$

where: *σ<sup>F</sup>* = bend rupture stress (MPa); *F* = load (N); *L* = distance between support bars (mm); *b* = width of specimen after test (mm); *e* = minimum thickness of specimen (mm).
