Abstract:
The article presents the results of research on the influence of soapstock used in the composition
of two-component modified additive. Standard tests of beam samples for flexural and
compressive strength, and standard cubic samples for water absorption and frost resistance
were performed. Tests were performed for samples with different contents of soapstock (Sp): 5,
7.5, 10 and 12.5 % by weight of cement, microsilica and phosphogypsum. The strength
measurements of the beam samples showed that the maximum effect concerning the increase in
material strength was achieved at 5% of the soapstock content. However, it should be noted that
the subsequent decrease in strength with increasing concentration of soapstock is not
significant, up to Sp=10% does not exceed 1%. Thus, the optimal concentration of soapstock, at
which the maximum effect on the strength of the material will be achieved, is 5-10%. The
obtained curve of dependence of water absorption change on the soapstock concentration
showed the optimal gradient of water absorption, which corresponds to Sp=10%. With further
increase of soapstock, the decrease of water absorption index is not significant. Tests on frost
resistance showed that the maximum resistance to cyclic freezing is observed in samples with
Sp=10%, further increase reduces frost resistance. The regularity in the increase of frost
resistance with increasing concentration of soapstock is logical because with each increase in
concentration, the hydrophobization of the material increases. However, if the hydrophobicity of
samples with Sp=12.5%, although not significantly, still increases about Sp=10%, the frost
resistance decreases.
