The paper presents the preliminary results of research on determining the possibilities of using available on the market commercial gypsum kinds as a binder for foundry moulding and core sandmixes. Construction gypsum and plaster gypsum, finishing coat and jewelry casting gypsum were tested. Elemental composition of gypsum kinds were carried out using a scanning electron microscope (SEM) with EDS/EDX probe, their crystal structure and phase composition was determined by analyzing the results of X-ray diffraction measurements (XRD) and thermogravimetric studies (TG-DTA). Evaluation of the mechanical properties of selected materials was carried out at the tensile strength test of the dog-bone samples after initial hardening of gypsum mortar at 25 °C for 5 h and drying at 110 °C for 24 hours. The impact of the properties of the used commercial gypsum kinds on the possibility of their use as a valuable binders in the manufacture of the foundry sandmixes for moulds and cores was evaluated. Construction gypsum and finishing coat have the highest tensile strength. Plaster gypsum and finishing coat have the longest setting time. In all tested types of gypsum, the initial water loss during heating occurs at a temperature of about 200 °C. The lowest valuable properties as a binder for sand moulding mixtures has jewelry casting gypsum mass.

The paper presents results of initial research on the possibility of applying microwave radiation in an innovative process of making casting

moulds from silica sand, where gypsum CaSO4∙2H2O was acting as a binding material. In the research were compared strengths and

technological properties of moulding mixture subjected to: natural bonding process at ambient temperature or natural curing with

additional microwave drying or heating with the use of microwaves immediately after samples were formed. Used in the research

moulding sands, in which dry constituents i.e. sand matrix and gypsum were mixed in the ratio: 89/11. On the basis of the results of

strength tests which were obtained by various curing methods, beneficial effect of using microwaves at 2.45 GHz for drying up was

observed after 1, 2 and 5 hours since moisture sandmix was formed. Applying the microwaves for hardening just after forming the samples

guarantees satisfactory results in the obtained mechanical parameters. In addition, it has been noted that, from a technological and

economic point of view, drying the silica sand with gypsum binder in microwave field can be an alternative to traditional molding sand

technologies.