The study is focused on ultra-light foam concrete (FC) aimed as a thermal insulation material. Two important properties of such material were investigated: compressive strength and thermal conductivity. In the conducted tests, the influence of the air-dry density (200–500 kg/m³), type of foaming agent (synthetic and protein) and binder type (ordinary Portland cement—OPC; calcium sulphoaluminate cement—CSA; metakaolin; siliceous fly ash—SFA; calcareous fly ash—CFA) on the mentioned properties were examined. The results confirmed the dependence of compressive strength and thermal conductivity on the FC density but also indicated the important effect of the nature of the foaming agent and the binder type. The best thermo-mechanical properties were obtained for the foam concrete made of protein-based foaming agent, OPC and metakaolin. Simultaneously, the use of CSA mixed with metakaolin and foam based on the synthetic foaming agent also shows satisfactory properties.

The utilization of metallurgical sludge waste as a 10-30 % replacement of natural sand has been investigated in this paper for its effect on the initial setting time and hydration heat evolution of cement and the mechanical properties of mortars. The results revealed that the addition of metallurgical sludge waste increased the water demand by up to 30 %, delayed the initial setting time by 3 h for 10 %, to over 25 h for 30 % sand replacement, decreased the hydration heat evolution rate by 30 % for 30 % sand replacement, and negatively affected the mortars' mechanical properties from 5 to 40 % for 20 % sand replacement, and from 30 to 50 % for 30 % sand replacement. For 10 % of sand replacement compressive strength was similar to the reference mortar. In order to obtain a shorter initial setting time, decrease the shrinkage and accelerate hydration heat evolution, part of the Portland cement (CEM I) was replaced by calcium sulphoaluminate cement (CSA). It was found that this method was effective for 20-30 % of CEM I replacement by 10 % of CSA and 10-30 % of CEM I replacement by 20-30 % of CSA in the case of setting acceleration, and for 10 % replacement in case of hydration heat evolution.

This paper presents the results of research into the heat of hydration and activation energy of calcium sulphoaluminate (CSA) cement in terms of the dependence on curing temperature and water/cement ratio. Cement pastes with water/cement ratios in the range of 0.3–0.6 were tested by isothermal calorimetry at 20 °C, 35 °C and 50 °C, with the evolved hydration heat and its rate monitored for 168 h from mixing water with cement. Reference pastes with ordinary Portland cement (OPC) were also tested in the same range. The apparent activation energy of CSA and OPC was determined based on the results of the measurements. CSA pastes exhibited complex thermal behaviour that differed significantly from the thermal behaviour of ordinary Portland cement. The results show that both the w/c ratio and elevated temperature have a meaningful effect on the heat emission and the hydration process of CSA cement pastes. The determined apparent activation energy of CSA revealed its substantial variability and dependence, both on the w/c ratio and the curing temperature.