## 3 Results and Discussion  
The results of the grain-size analysis of silica sand and EPP aggregate are illustrated in Figure 5. According to the grain size curves, the EPP grains were found smaller than 8 mm and diameter of silica sand particles ranged from 0.063 \(\upmu\)m to 2 \(\upmu\)m. As further processing of EPP to obtain finer particles was refused in order to ensure low cost and low energy embedded in raw materials, the granulometry of EPP was considered as good in general for substitution of sand in composition of MOC cement composites. For the reduction of the thermal conductivity values of the tested MOC cement composites it was desirable to select the filler having a low thermal conductivity compared to silica sand commonly used in the construction industry. Thermal and physical properties of both investigated aggregates are summarized in Table 4.  
The longer the time of compaction, the higher thermal conductivity and volumetric heat capacity values were measured. It was due to the increasing packing density with compaction and reduction of \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Aggregate**} & **Specific Density** & **Time of** & **Powder Density** & \(\mathbf{\lambda}\) & \(\mathbf{C_{\mathrm{p}}}\) (\(\mathbf{\times 10^{6}}\) \\  & **(kg\(\cdot\)m\({}^{-3}\))** & **Compaction (s)** & **(kg\(\cdot\)m\({}^{-3}\))** & **(W\(\cdot\)m\({}^{-1}\)\(\cdot\)K\({}^{-1}\))** & **J\(\cdot\)m\({}^{-3}\)\(\cdot\)K\({}^{-1}\))** \\ \hline EPP & 105 & 0 & 18.9 & 0.042 & 0.049 \\  & & 10 & 22.4 & 0.043 & 0.055 \\  & & 30 & 23.3 & 0.044 & 0.058 \\  & & 60 & 23.9 & 0.044 & 0.061 \\  & & 180 & 24.3 & 0.047 & 0.062 \\ Silica sand & 2652 & 0 & 1657 & 0.410 & 1.569 \\  & & 10 & 1910 & 0.562 & 1.681 \\  & & 20 & 1916 & 0.575 & 1.683 \\  & & 30 & 1922 & 0.576 & 1.684 \\  & & 60 & 1927 & 0.577 & 1.689 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Thermo-physical parameters of used aggregates (influence of time of compaction). Figure 5: Granulometric curves of used silica sand and EPP particles. Sieve size is given in logarithmic scale. air volume between the aggregate particles. As expected, the EPP particles in comparison with those of silica sand exhibited significantly lower heat transport and heat storage. It corresponded with their low specific density, chemical origin, and structure. Nevertheless, for the practical purposes, the low thermal conductivity of EPP is beneficial for the production of lightweight MOC cement composites with an improved thermal insulation function. In Table 5, the workability of fresh mixtures expressed in terms of flow diameter is given. Generally, the workability of fresh mixtures affects particularly the amount and size of used filler. The shape of the particles also plays a role [32; 42]. Results showed that mixtures containing EPP with the higher particle size and expected higher specific surface compared to those of silica sand exhibited considerably reduced workability than the control mixture with silica filler. However, for the intended application of MOC cement composites in thermal insulation floor layers or prefabricated panels and slab with EPP was the achieved workability quite sufficient. The workability of mixtures EPP-MOC and EPP-MOC-IH was almost the same, hydrophobic agents had no clear effect on the flow. In Table 6, the structural parameters of the developed MOC cement composites are summarized. The observed R-MOC bulk density value of 2130 kg\(\cdot\)m\({}^{-3}\) was similar as the dry density of 2142 kg\(\cdot\)m\({}^{-3}\) reported for reference MOC composite by [PERSON] et al. [12]. With the addition of the EPP aggregate, the bulk density of composites significantly decreased to 42.6% and 43.5% for EPP-MOC and EPP-MOC-IH respectively, compared to R-MOC. It can be explained by the lower specific density of EPP particles (see Table 4). According to EN 206-1 [43], the developed EPP-MOC and EPP-MOC-IH may be classified based on their bulk densities as lightweight concretes in class LC 1.0.