## 2 Experimental Procedure
### Experimental Methodologies  
The tests performed to determine the mechanical strength of the specimens and the modulus of elasticity were carried out in accordance with applicable standards: EN 196-1 [24], EN 12390-13 [30], EN 12390-3 [31], and EN 12390-5 [32]. The flexural strength test was the first to be performed on parallelepiped specimens according to EN 12390-3 [27]. The two resulting \"halves\" constitute the compression test specimens. A Servosis ME -402 series electromechanical compression machine and one load cell (CLC--200 kN) were used for this purpose. The equipment was completed with a data logger (TSD-602; to record the load and strains) and two 8 mm neoprene sheets. The tests were performed with a deformation control planned in two different phases: first, the action was applied at a rate of 0.1 mm/s up to a load of about 0.3 kN; then, at a rate of 0.004 mm/s, up to failure. The test lasted for about 3 min. In the compression test, the action was first applied at a rate of 0.1 mm/s up to a load of about 3 kN; then the rate was reduced to 0.013 mm/s, up to failure. The test lasted for about 3 min. Suitable equipment was also used in this compression test, with two square compression plates of 40 mm on each side. The generation of the cones was checked; a requirement specified in standard EN 12390-3 [27]. The tests to determine the modulus of elasticity were performed on the cylindrical specimens. The methodology used is based on an adaptation of method B, which is described in standard EN 12390-13 [30]. Before the actual test, the top and bottom surfaces of the specimens had to be straightened: They should be flat and perpendicular to the axis of the sample (Figure 4). This is to ensure an even distribution of stresses on the surfaces of the sample. In this context, it is important to mention five other strategies that were used to perform the test:  
1. Use of specimens long enough to relieve possible stress concentrations;
2. Use of three strain gauges that guarantee the reliability of the average strain values;
3. Use of neoprene rubbers to eliminate possible surface irregularities;
4. The hinge that can partially eliminate possible deviations of these surfaces from the normal to the axis of the specimen; and
5. When placing the specimen, care was taken to place it centrally to ensure an even distribution of the load on the specimen. Figure 3: Instrumentation of cylindrical specimens. The \"setup\" of the test began by placing a washer and a metal plate on the bottom plate of the compression machine (Figure 5). The washer forms a partial hinge that, along with the hinge on the top plate of the Servosis electromechanical press, helps to center the action. Then, the load cell (for measuring the axial force) and another metal plate is placed. The specimen was finally placed between this last metal plate and the upper plate of the press, together with the neoprene sheets (8 mm), one on each side. The most important result of the tests to be performed was to determine the time evolution of the elastic modulus. But in this series of tests there were several alternative objectives. From the beginning, it was important to ensure that each test would take place in an elastic regime to ensure the integrity of the sample for the next test. It was also interesting to understand the extent to which it would be possible to guarantee this integrity, i.e., at what stress level would the behavior plastic degrade the sample. It was also interesting to see if the test load ratio would in any way affect the value of the modulus of elasticity. Considering these and many other issues, it was determined that the test methodology used in this work deviated from the above standard. Another point that can already be highlighted as complementary to the provisions of method B in, standard EN 12390-13 [30], concerns the load ratio chosen for the tests. As an alternative to the use of increasing stress, as recommended in the standard, the tests were performed with deformation control.