When increasing the degree of fluidity of previously aerated cementitious mixtures, there is a problem of maintaining their correct aeration. Most of the available superplasticizers cause a significant increase of the air content of concrete mixtures. The problem of compatibility of superplasticizer and air-entraining admixture increases in case of multicomponent Portland cement, due to different effects of these additives. It comes down to achieving a compatibility of the three variables mentioned in the title of the paper, due to the required air entrainment and consistency of mixture. Achieving compatibility of such a system requires a series of experimental studies that were presented in the paper together with their resulting indications. In case of previously air-entrained concrete that is made with an air-entraining cement, after the addition of new generation SP occurs very large increase in air entrainment. The air-content of mixture according to EN 480-1 may be higher than 13%.

This article presents recent research on cements containing GGBFS and their modifications with accelerating admixtures. The initial setting time and hydration heat evolution results are presented for cement CEM II/B-S and CEM III/A manufactured with three Portland clinkers of various phase compositions. The research was carried out at 8 °C and 20 °C. The main objective is to assess the behavior of blended cements in cooperation with modern admixtures that contain nucleation seeds. The authors aimed to compare and evaluate different methods to reduce setting time, namely, the effects of temperature, the specific surface area of cement and GGBFS, the type of Portland clinker, the content of GGBFS, and presence of accelerators. Many of these aspects appear in separate studies, and the authors wanted a more comprehensive coverage of the subject. Those methods of reducing the setting time can be ranked: the most effective is to increase the temperature of the ingredients and the surroundings, the second is to reduce the GGBFS content in cement, and the use of accelerators, and the least effective is the additional milling of Portland clinker. However, of these methods, only the use of accelerators is acceptable in terms of sustainability. Prospective research is a detailed study on the amounts of C-S-H phase and portlandite to determine the hydration rate.

Ground granulated blast furnace slag (GGBFS) is a by-product of steel manufacturing process. As such it is commonly used in concrete technology as component of blended cements or addition for concrete. Utilization of GGBFS conforms to idea of sustainability. Unfortunately, slag may lead to delay of setting and hardening of concrete. It is undesirable effect for manufacturing of precast elements or executing of concrete works during lower temperature period. Attempt to acceleration of hydration process of such cements by hardening accelerating admixtures (ACC) was made. Paper shows results of compressive strength, hydration heat and initial setting time examinations. Portland cement (CEM I 52,5R) and cement with addition of 35% of GGBFS (which corresponds to normative range of CEM II/B-S) were tested. Tests have involved four accelerating admixtures with different chemical base (calcium formate, C-S-H crystal seeds, calcium nitrate and trietanolamine). Initial setting time was measured by Vicat apparatus. Compressive strength of mortars was measured after 12, 24, 48hours and 7 and 28 days of curing in climatic chamber. Hydration heat tests were conducted using isothermal calorimeter TAM AIR III during 72hours after cement contact with water. Tests were conducted in 20°C. Water-binder ratio of mortars for compressive strength tests and cement pastes for hydration heat examinations was equal 0,5. Research had shown that all accelerators cause shortening of initial setting time by 40-50% depending on admixtures chemical base. The most efficient was accelerator based on C-S-H crystal seeds. Increase of hydration heat exhalation rate was observed. Summary hydration heat after 72hours was greater in presence of hardening accelerating admixtures. Those admixtures caused also the increase of early compressive strength of standard mortars. Higher percentage growth of compressive strength was observed for cement with GGBFS addition. Calcium nitrate, calcium formate and C-S-H crystal seeds based admixtures were the most efficient for Portland cement mortars and the latter for cement with GGBFS addition

The main goal of presented research was to examine usability of cements containing calcareous fly ash (W) from technological point of view. In the paper the results of tests concerning the influence of CEM II and CEM IV cements containing fly ash (W) on rheological properties, air content, setting times and plastic shrinkage of mortars are presented and discussed. Moreover, compatibility of plasticizers with cements containing fly ash (W) was also studied. Additionally, setting time and hydration heat of cements containing calcareous fly ash (W) were determined. In a broader aspect, the research contributes to promulgation of the possibility of using calcareous fly ash (W) in cement and concrete technology, what greatly benefits the environment protection (utilization of waste fly ash). Calcareous fly ash can be used successfully as the main component of cement. Cements produced by blending with processed fly ash or cements produced by interginding are characterized by acceptable technological properties. In respect to CEM I cements, cements containing calcareous fly ash worsen workability, decrease air content, delay setting time of mixtures. Cements with calcareous fly ash show good compatibility with plasticizers.

The results of concrete tests on cements with mineral additives indicate that, despite better tightness and higher strength, there are problems with frost resistance of non-aerated concretes, even under conditions of moderate exposure to frost. In order to minimize problems with obtaining frost-resistant concrete, an attempt was made to create air-entraining cement. In this paper are presented frost resistance of concrete with air-entraining cement. The researches were carried for concretes made of multicomponent Portland, metallurgical and multi-component cements additionally differentiated by the type of air-entraining admixture (synthetic and natural) and the method of cement preparation (cement mixed together, common ground cement). There were tested internal frost resistance of concrete and a salt frost scaling of concrete.