In the construction industry carbonate aggregates are commonly used in processes such as concrete production. Aggregates which contain (in their mineral composition) dolomite and an admixture of clay minerals and amorphous silica , can react with alkalis. These reactions can lead to a destructive expansion in concrete. This article explains the mechanisms and the essence of this phenomenon. What is more, some effective and fast methods of the estimation and evaluation of Polish aggregates consisting of carbonate rocks suggests effective methods to determine the usefulness of Polish carbonate aggregates in concrete production are discussed in the paper. Underneath the quality criteria to determine the reactivity of the aggregates will be given. It has been agreed that alkaline reaction and expansion are two separate phenomena related to each other genetically. The aggregates in which reactions caused by clay-siliceous admixtures occur are subjected to expansion. Mineral composition of expansive aggregates as well as their texture indicate that epigenetic dolomites with a distinctive texture are the most reactive. The phase transformations do not end with a complete disintegration of dolomite. They have a cyclical character. They consist of interchangeable reactions of dedolomitization and dolomitization of secondary calcite formed as a result of dolomite's disintegration. The secondary calcite can be effected by Mg+2 ions from pores' solutions and it can form a secondary dolomite. The Mg2+ ions originate from brucite [Mg(OH)2], created in dolomitization process. As a consequence of its reaction with silica, brucite can dissolve and enrich secondary calcite with magnesium. Therefore the reactions which take place in reactive carbonate aggregates and concrete that ismade of it are in fact ongoing processes which consist of dolomite's changes into calcite and vice versa. They are reactions between dedolomitization products (brucite, silica) and products from outside (water, alkalis). The described dedolomitization reactions are a phase of the process that enables expansion due to formation of pressure in inter-granular cracks, with pressure being a result of dry clay-minerals' expansion under the influence of water solutions. Loosening of the aggregate's structure as an effect of dedolomitization reaction makes it easier for water solutions to migrate far into the aggregate's grains followed by their contact with clay minerals.

An advanced evaluation technique, helpful in the fire resistance assessment of a simple steel structure exposed to fire is presented and discussed in detail on the example of an unrestrained and uniformly heated steel beam. The proposed design methodology deals with the generalised probability-based approach in which the most probable failure point is formally identified. The random nature of all variables considered in the detailed analysis is taken into account. The critical temperature of the steel from which the considered beam is made of is accepted here as the authoritative safety measure. This temperature value is associated with the fire resistance limit state defined for the maximum acceptable value of failure probability. When forecasting the failure probability, not only the risk of a potential fire being initiated but also not being effectively extinguished is included in the calculation. Various levels of the target failure probability may be assumed in such the analysis, depending on the selected reliability class. They are specified in general by setting an appropriate value of the required reliability index β fire req. In the presented design algorithm no representative values of the considered random variables are specified. The critical temperature estimates obtained from these calculations are always less restrictive in comparison with the corresponding solutions computed after applying the conventional standard procedure.

The paper presents pursuits of the truth in building materials engineering. Some definitions of “what truth is” were presented. Partial truths were specified: the truth of scientific reasoning, the truth of scientific assessment, the truth of development directions and the splendour of scientific truth. All categories are addressed to the building materials engineering. In the chapter “Load capacity and stability vs entropy” definitions of entropy and exergy were presented followed by their influence on building construction, illustrated by the “Seneca cliff” and “Energy pyramid”. Chapter 3 presents the truth of scientific reasoning was presented. Three partial truths were indicated: the truth of experimental fact, the truth of scientific reasoning and the truth of scientific presentation. In the chapter “Truth of scientific assessment” two main assessment methods were presented: peer review and a bibliometric parametric assessment as well as their impact on the results and authors. The risks associated with the sole parametric assessment were shown as the two basic factors of a parametric assessment – citation number and Hirsch index – need time to "mature". Additionally, the influence of digitalisation of the assessment of a scientist and a scientific unit on the commoditisation and dehumanisation of science was outlined. In the chapter “Truth of development directions: defined past – fuzzy future” the megatrends observed in technology in the last few decades years were indicated along with new possible trends. Milestones in the development of C-PCs (Concrete-Polymer Composites) were presented. The new paradigm for the new development cycle was proposed.