Selection of material for cores hardened with carbon dioxide

The work presents the investigation results concerning the bending and the tensile strength of specimens made of various types of core sands. The investigated core sands for bending tests have been prepared of silica sand from Nowogród Dobrzański and, alternatively, of H33 German sand, both containing a variety of binders, namely Carbophen 5692, Carbophen 7170, Carbophen 8178, Novatec 1000, or SuperEko 2000 phenolic resins, as well as water glass. The tensile strength has been investigated for specimens made of silica sand from Nowogród Dobrzański and the sand supplied by Hüttenes-Albertus Polska, both types bond with Carbophen 5692, Novatec 1000, or SuperEko 2000 resins. All specimens have been tested immediately after the CO2 hardening process, then after 1 hour and after 24 hours. It has been found that the type of sand grains significantly affects both the bending and the tensile strength. Furthermore, for each type of sand the best bending strength has been achieved for Carbophen 7170, Carbophen 8178, and Novatec 1000 resins, whereas the best tensile strength has been offered by specimens bond with Carbophen 5692 resin.