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.

High-fluidity and self-compacting concrete (SCC) mixes were developed using special aggregates for radiation-shielding concrete. The special aggregates comprised heavyweight and hydrous aggregates (crushed magnetite, crushed serpentine, and their mixtures), which were selected to provide an enhanced attenuation of gamma and neutron radiation, respectively. For the mixed concrete design with a bulk density of up to 3570 kg/m³, two cement types were used: Portland cement CEM I and slag cement CEM III/A. The basic properties of the fresh self-compacting concrete were evaluated and the lateral formwork pressure exerted by the freshly mixed self-compacting concrete was measured and analyzed. An original test setup was developed for the determination of the lateral pressure on the square column formwork with pressure measurements carried out using six strain gauge pressure transducers, which was adequate for heavyweight concrete mixture testing. Self-compacting concrete mixtures containing a magnetite aggregate or blends of serpentine and magnetite aggregates with a slump flow of at least 550 mm were developed. The lateral pressure on the formwork was directly proportional to the density of the self-compacting heavyweight concrete mixes. The maximum values of the lateral pressure recorded in the test at a casting speed of 1.5 m/h did not exceed 27 kPa and 55% of hydrostatic pressure. Concrete mixtures with basalt, magnetite, and magnetite/serpentine blended aggregates were found to develop sufficient shear strength for proper stability during casting.

Freeze–thaw resistance is a significant issue in the durability of concrete; however, it is not widely discussed in the context of limestone addition to concrete. The present study aims to compare the effect of the addition of different types of limestone powder on the frost resistance of ordinary and self-compacting concrete. Three types of limestone powder were added to concrete in an amount of 15% and 30% cement weight. Compositions with and without the air-entraining admixture were prepared in each instance. Research included tests of consistency, air content, air void distribution, compressive strength and freeze–thaw resistance after 100 and 200 freeze–thaw cycles. The obtained results indicate that in the case of both aerated and non-aerated concrete mixtures, weight loss and the decrease in strength after 100 freeze–thaw cycles did not exceed the allowable range. Concretes with limestone powder did not significantly differ in frost resistance from reference concretes. The type of limestone had an effect on the effectiveness of admixtures, as well as the compressive strength and freeze–thaw resistance of concretes without an air-entraining admixture.

The addition of carbon nanotubes (CNTs), which are hydrophobic materials, significantly influences the rheology of cementitious materials but requires important mix modifications in order to provide proper flowability for further use. This paper investigates the influence of various dosages of carbon nanotubes (0.05 wt.%, 0.1 wt.%, 0.2 wt.%, 0.5 wt.%, and 1 wt.%) on the flowability, rheological parameters, air content, and volume density of cement mortars. The results show an increase in the yield stress parameter with an increment in CNT dosage up to the threshold of 0.5 wt.% for mixes with an increased amount of cement. For standard proportions, it was on a stable level for all mixes except for 0.2 wt.%. The plastic viscosity parameter also increased with the CNT dosage; mixes with standard proportions of components were not higher than the reference, and mixes with an increased amount of cement were lower than the reference for dosages up to 0.5 wt.% of CNT. The addition of a superplasticizer and modifications of the ratio of the components were employed to achieve proper flowability and measure the rheological parameters. The presented results show that regardless of the negative influence of carbon nanotubes on the properties of fresh mortar, it is possible to achieve a stable flow and workability using simple modifications of the composition.

The article is an attempt to compare the impact of the use of various types of limestone as the main constituent of cement on selected mortar properties. Four different limestones were added in amount of 15, 30, 40% to CEM I 42.5 R to obtain limestone cemens. Rheological properties (yield stress, plastic viscosity) of fresh mortar, tensile and compressive mortar strength, early shrinkage, and drying shrinkage were tested. Obtained results indicate that both tensile and compressive strength decreases with the increase of the limestone content in cement. Limestone can worsen or improve workability, depending on distribution of limestone grains. The addition of limestone increases the early shrinkage, but reduces the shrinkage after 28 days. Studies show that the granulation of limestone plays an important role in determining the influence of limestone on mortar properties.

This article presents research on selected physical and mechanical properties of cement-based plasters and masonry mortars with consistency-improving additives, namely, traditional hydrated lime and a plasticizing and aerating mixture (APA), which, in practice, is often considered to be a lime substitute. Comparative analysis of the properties of mortars with alternative additives—lime or APA—was carried out, taking into consideration possible effects of cement, as two types of Portland cement were used for the research. For fresh mortar, mixture consistency, air content, resistance to segregation, and water retention were determined. Tests on hardened mortars included tests of porosity and impermeability, depth of penetration of water under pressure, drying shrinkage, as well as compressive and bending strength, modulus of elasticity, and adhesion of mortars to the base. In addition, research has shown that cement–lime mortars and cement mortars with APA admixture of similar consistency in the fresh state are characterized by significantly different properties. The results show, in most of the features analyzed, more favorable properties of mortars with the use of traditional lime. For shrinkage only, the use of admixture turned out to be more advantageous.