## 2 Materials and Methods
### Experimental Programme  
A schematic representation of the experimental programme developed is shown in Figure 4.  
In this way, in the first phase, a study of the masonry mortar's physical properties has been conducted through the following tests:  
* Bulk density of mortars according to UNE-EN 1015-10 [77]. To determine this value, the average of three measurements taken on samples of dimension 4 \(\times\) 4 \(\times\) 16 cm\({}^{3}\) is used. The bulk density is obtained by dividing the mass of the specimen previously dried in an oven for 24 h (65 \(\pm\) 5 \({}^{\circ}\)C) by the apparent volume of the hardened mortar sample. * Mortar thermal conductivity was determined according to the UNE-EN ISO 8990:1997 standard [78]. For this purpose, a mini thermal hot-box equipped with thermocouples and a datalogger for accumulating temperature data was used. A total of three samples were tested for each type of mortar, with dimensions of 24 \(\times\) 24 \(\times\) 3 cm\({}^{3}\). The measurements were taken 24 h after the start of the test to obtain a stationary heat flux. * Water absorption coefficient by capillarity according to UNE-EN 1015-18 [79]. In this way, six half-samples are obtained from 4 \(\times\) 4 \(\times\) 16 cm\({}^{3}\) samples so that the fractured face with the open matrix is the one in contact with the water. Thus, these half-samples, previously dried for 24 h in an oven (65 \(\pm\) 5 \({}^{\circ}\)C), are immersed vertically in water to a depth of 10 \(\pm\) 1 mm. The capillary absorption coefficient is determined with the help of Equation (1): \[C=0.1\cdot(M_{90}-M_{10})\] (1) where \(C\) is the capillary absorption coefficient, and \(M_{10}\) and \(M_{90}\) correspond to the mass of the sample at 10 and 90 min of testing. * Open porosity determined according to UNE-EN 1396 [80]. It is defined as the ratio between the accessible pore volume and mortar apparent volume. To determine this index, a total of three samples of each type were used and Equation (2): \[Open_{Por}=\left(\frac{W_{sat}-W_{0}}{W_{sat}-W_{imm}}\right)\times 100\] (2) where \(Open_{Por}\) shows the open porosity index in percentage, \(W_{sat}\) is mass of water saturated sample, \(W_{imm}\) immersed weight of the water-saturated sample determined by hydrostatic balance, and \(W_{0}\) is the weight of the dried sample. Figure 4: Experimental programme scheme. * Mortar shrinkage over time according to the recommendations of the UNE 80-112-89 standard [81]. For this test, three samples of each type of mortar of dimension 2.5 \(\times\) 2.5 \(\times\) 28.7 cm\({}^{3}\) were used. This test allows the determination of the dimensional stability of the mortars over time and is expressed as the longitudinal variation in mm/m experienced by the samples over 120 days. On the other hand, the mechanical properties of these eco-friendly cement mortars have been studied. The tests carried out in this second phase include:
* Mortar bonding strength according to UNE-EN 1015-12 [82]. For this purpose, a layer of each mortar type of approximately one centimeter thickness is applied to a previously moistened ceramic block. The ceramic piece is moistened immersed in water for 24 h, in such a way that the suction of the water from the mortar mixing by the ceramic piece is avoided. Subsequently, with the help of adhesion equipment, metal discs with a diameter of 50 mm are glued with epoxy resin on the hardened sample. The tensile test determines the adhesion strength between the mortar and the application surface. A total of five samples were tested for each mortar type. * Mortar surface hardness, determined by using a Shore D durometer (Smooth-On, Inc., Macungie, PA, USA), following the recommendations of UNE-EN-ISO 868 standard [83]. A total of three 4 \(\times\) 4 \(\times\) 16 cm\({}^{3}\) samples were analyzed for each dosage, taking five measurements on the two plane-parallel faces that were in contact with the mold and separating each measurement by a minimum distance of 2 cm from each other.