Compressive strength. The compressive strength of SPs was performed on the test specimens - cubes
100 x 100 x 100 mm according to ČSN EN 12390-3. The results of the compressive strength of SPs (in different
ages) prepared according to three chosen recipes are shown in Fig.2. Each of the test specimens was until the
mechanical loading on the test press stored in a laboratory environment and the resulting strength is average value
of three specimens. The highest compressive strength was achieved in solidification formula 3B (the sample of the
age of 28 days – 1.4 MPa). Compressive strengths of solidification products were declining in time, however with
formulas 3A and 3B occurred after 180 days maturation of samples a slight increase. Asavapisit et al. [4] and
Antemir [5] state that failing to achieve sufficient strength is an indicator of poor microstructure and imperfect
hydration of solidification product that can result in increased leachability of contaminants. The requirements for
the compressive strength vary depending on the end use of solidification product and in some developed countries
also on local legislation. To determine the density of solidification products the same specimens as in the test of
compressive strength were used. The highest density had specimens in the time of their filling to the forms (fresh
state).