The investigation results of the influence of the reclaim additions on the properties of moulding sands with the GEOPOL geopolymer
binder developed by the SAND TEAM Company were presented. Two brands of hardeners were applied in the tested compositions, the
first one was developed by the SAND TEAM Company, marked SA72 and the new hardener offered by the KRATOS Company, marked
KR72. The main purpose of investigations was to determine the influence of reclaim fractions and the applied hardener on the basic
moulding sands properties, such as: bending and tensile strength, permeability and grindability. The unfavourable influence of the reclaim
additions into moulding sands on the tested properties as well as an increased hardening rate, were found. Moulding sands, in which the
hardener KR72 of the KRATOS Company was used, were less sensitive to the reclaim additions.
The results of investigations of moulding sands with an inorganic binder called GEOPOL, developed by the SAND TEAM Company are
presented in the paper. Hardeners of various hardening rates are used for moulding sands with this binder. The main aim of investigations
was determination of the influence of the hardening rate of moulding sands with the GEOPOL binder on technological properties of these
sands (bending strength, tensile strength, permeability and grindability). In addition, the final strength of moulding sands of the selected
compositions was determined by two methods: by splitting strength and shear strength measurements. No essential influence of the
hardening rate on such parameters as: permeability, grindability and final strength was found. However, the sand in which the slowest
hardener (SA 72) were used, after 1 hour of holding, had the tensile and bending strength practically zero. Thus, the time needed for taking
to pieces the mould made of such moulding sand will be 1.5 - 2 hours.
A thermo-insulating moulding sand with a binder made of aluminosilicate microspheres with organic binder was subjected to testing. The aim of the analysis was to determine selected technological properties of the developed compounds. Compressive strength, friability and gas permeability were determined. The binder content was changed within a range of 5÷20 wt% with a 5% step. The applied matrix is characterized by good thermo-insulating properties and a small size of grains, while synthetic organic binder has favourable functional properties, among which the most noteworthy are the extended life and setting time, good rheological properties as well as high resistance to chemical agents. The intended use of the compound is the casting of 3D CRS (Composite Reinforced Skeletons), which are characterized by a well-developed heat transfer surface area, good absorption of impact energy, low mass and a target thickness of connectors within a range of 1.5÷3 mm. The construction of 3D CRS castings is an original concept developed by the employees of the Department of Foundry Engineering at the Silesian University of Technology.