# Microstructure, Durability and Mechanical Properties of
## 2 Materials and Methods  
### Materials and Sample Preparation  
The tests were performed on mortars, which were prepared with different binders. First of all, reference mortars were made with ordinary Portland cement without additions, CEM I 42.5 R (Spanish and European standard UNE-EN 197-1 [31]), and they were named as REF in the presentation of the results.  
In addition, mortars prepared with three ternary binders were analyzed. The first one, designated as SL, incorporated 15% (in weight) ground granulated blast furnace slag and 15% limestone as additions, replacing cement CEM I 42.5 R. The second one was named as SF, in which the abovementioned CEM I 42.5 was partially substituted by 15% ground granulated blast furnace slag and 15% fly ash. The third ternary binder was designated as FL and the cement CEM I 42.5 R was replaced in part by 15% fly ash and 15% limestone additions.  
On the other hand, three binary binders were also studied in which 30% (in weight) of the cement CEM I 42.5 R was replaced by one of the additions used for preparing the abovementioned ternary binders. These binary binders were named as L, S and F,containing 30% limestone, ground granulated blast furnace slag and fly ash, respectively. In order to facilitate the comprehension of the meaning of the different designations established for the binders, they are compiled in Table 1.  
The additions of fly ash, ground granulated blast furnace slag and limestone verified the prescriptions of the standard UNE-EN 197-1 [31] for being used in the production of commercial cements. These additions were provided by the company Cementos Portland Valderrivas (Spain) and they are currently used in the production of the blended cements manufactured by this company. The prepared binders accomplished the prescriptions for a standardized commercial cement type CEM II/B, defined by the standard UNE-EN 197-1 [31]. The reason for choosing that cement type is because the cements type II [31] are nowadays the most produced in Spain, so this could facilitate a wider possible real application of the results obtained in this research.  
The specimens of all the binders studied were prepared with water to binder ratio 0.5. Fine aggregate was used according to the standard UNE-EN 196-1 [32] and the aggregate to cement ratio was 3:1 for all the mortar series.  
Three different types of specimens were prepared. On one hand, two cylindrical specimens were made, a first type with dimensions 10 cm diameter and 22 cm height and a second one with dimensions 5 cm diameter and 6 cm height. Moreover, prismatic samples with dimensions 4 cm \(\times\) 4 cm \(\times\) 16 cm were also prepared.  
During their first 24 h, all specimens were kept in chamber with 95% relative humidity (RH) and 20 \({}^{\circ}\)C temperature. After that time, they were de-molded and the samples were kept in an optimum laboratory condition (20 \({}^{\circ}\)C and 100% RH) until the testing age. This condition consisted of storing the specimens in hermetically sealed containers, which contained distilled water in their bottom part for achieving a 100% relative humidity environment. The mortar samples were placed into the containers avoiding contact with water using a rack beyond the water level. In addition, these containers were kept in a chamber with a controlled temperature 20 \({}^{\circ}\)C. The dimensions of the hermetically sealed containers used were 325 \(\times\) 265 \(\times\) 150 mm. Finally, the tests were performed at 28 and 250 hardening days.