*3.1. Compressive Strength*

The results for compressive strength are shown in Figure 2. The test was carried out on four samples for each variant. The graph shows the average value obtained from these measurements.

**Figure 2.** Results from the compressive strength test.

The best compressive strength was achieved by geopolymers with particle sizes of less than 200 μm—19 MPa. A slightly lower compressive strength was obtained by geopolymers from the base material fraction of 200 μm to 900 μm—18.2 MPa. A significant decrease in strength was noted for geopolymers whose particle sizes of the raw material were in the range of 900 μm to 1.25 mm—0.7 MPa.
