# Rheological Properties of Lunar Mortars
## 3 Materials and Methods  
The tested micro-mortars consisted of water, cement, quartz powder, or regolith simulant. The tested mortars consisted of the abovementioned components, supplemented with fine aggregates of up to 2 mm. The explanation of why standard sand was used as aggregate is provided later in the chapter. The technical characteristics of the components used to prepare tested specimens are presented below. For the mixing water in tested pastes and mortars, tap water was used, meeting the requirements of standard EN 1008. As a binder the CEM I 42.5 R, i.e., ordinary Portland cement of strength class 42.5 and high early strength (R), compliant with the EN 197-1 and EN 197-2 standards, was used. The basic technical properties of the cement declared by the manufacturer are given in Table 3.  
As mentioned earlier, a search was made for a filler (or rather a micro-filler) that would constitute the aggregate fraction as similar as possible to lunar regolith in terms of granulation and morphology. Ultimately, a commercially available quartz filler (mechanically crushed quartz in powder form) was selected. The own test results showing the characterization of the chosen powder are given in the next section. Standard sand meeting the requirements of EN 196-1 was used as fine aggregate. The use of standard sand was justified for two reasons. First, there was no intention to introduce additional material variables (and the lunar mortars were finally compared to the results of the standard mortar). Secondly, standard sand has a very low content of dusty particles--the standard allows a maximum of 2% of grains smaller than 0.08 mm. Therefore, with these particles, it was possible to very precisely dose micro-fillers (i.e., quartz powder or lunar regolith simulant). As the aim of the research was to maximize the share of lunar regolith simulant, in some cases, it was necessary to use a superplasticizer. A very effective commercial superplasticizer (based on polycarboxylate ethers) was used, the recommended dosing of which was up to 1.5% in relation to the cement mass. The density of the lunar regolith simulant and quartz powder was determined using the Le Chatelier volumenometer (consisting of a flat-bottomed flask) according to the procedure described in the EN 1936 standard. The presented values are the average of 3 results. The particle size distribution (PSD) measurements were performed by the laser scattering method using the laser analyzer Horiba LA-300 (Kyoto, Japan). The test involved passing laser beams through a 0.1% sodium polymetaphosphate solution containing particles of tested material dispersed by ultrasounds and determining the particle size (in the range of 0.01-600 \(\upmu\)m). The values of statistical parameters describing the micro-fillers particle size distributions, as well as specific surface area and abovementioned density are given in Table 4. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Physical and Mechanical Properties** & **EN 197-1 Requirements** & **Average Values** \\ \hline Beginning of setting time [min] & min. 60 & 192 \\ Compressive strength after 2 days & min. 20.0 & 29.1 \\ Compressive strength after 28 days & 42.5–62.5 & 55.5 \\ Specific surface area [cm\({}^{2}\)/g] & - & 3816 \\ Water for standard consistency [\%] & - & 27.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Physical and mechanical properties of cement. A Nikon Eclipse E-200F PLUS fluorescence microscope with trinocular attachment and a digital camera were used to determine the lunar regolith simulant morphology. The proper micrograph is given in Figure 4.  
The consistency was tested using three methods. In the case of mortars (aggregate up to 2 mm), the consistency was tested with the standard flow table method (according to the procedure in EN 1015-3 standard). In the case of micro-mortars, the consistency was tested using Vicat apparatus, as in the case of standard consistency according to EN 196-3, and using a modified flow table method--developed particularly for the needs of