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The presented article concentrates on the influence of various concrete additives in the form of fibers on the mechanical parameters of concrete so as to obtain the effect of gradual changes in these parameters, which is very important in the transition zone of the railway track. Steel, polymer and glass fibers, as well as concrete without additives, were accepted for the study. The effect of additives on the consistency of the mixture, compressive strength, frost resistance and elastic modulus was studied. The research concerned concrete samples and models of elements of the ballastless railway surface, i.e., track slab and concrete block supports. The track slab model was made of concrete without additives, while the models of supports were made both without and with additives. The studies were carried out in laboratory conditions. As a result, the tested concrete samples with various additives were ranked so that they could be used as a material for elements of the railway surface in the transition zones of engineering facilities on railway roads, which is important from the point of view of reducing the threshold effect occurring in these zones. Detailed laboratory tests were presented, the results of these studies were discussed, and final conclusions were drawn regarding the technology of materials and the methodology of constructing the transition zones of the railway surface in order to avoid or at least reduce the threshold effect existing in such zones.

The construction industry in the 21st century faces numerous global challenges associated with growing concerns for the environment. Therefore, this review focuses on the role of lignin and its derivatives in sustainable construction. Lignin's properties are defined in terms of their structure/property relationships and how structural differences arising from lignin extraction methods influence its application within the construction sector. Lignin and lignin composites allow the partial replacement of petroleum products, making the final materials and the entire construction sector more sustainable. The latest technological developments associated with cement composites, rigid polyurethane foams, paints and coatings, phenolic or epoxy resins, and bitumen replacements are discussed in terms of key engineering parameters. The application of life cycle assessment in construction, which is important from the point of view of estimating the environmental impact of various solutions and materials, is also discussed., (Copyright © 2021 Elsevier B.V. All rights reserved.)

One of the main by-products of brown coal burning is calcareous fly ash (CFA). Apart from other applications, it is used as a main component of cement, or as an active mineral additive to concrete. The present study involves the impact of the raw and processed calcareous fly ash (CFA) on the changes of rheological properties of mortars. The said impact was determined by using the coefficient of variation (CV) given in percentage. CFA samples collected from various sources were subjected to testing. The samples were collected from two electrofilters of blocks with boilers of different combustion parameters and from the retention tanks of the CFA sales department (CFA T) in which CFAs from various boilers are mixed. It has been demonstrated that the degree of the impact of CFA addition on the rheological properties of mortars depends on the source of this addition and on bulk density. The present work demonstrates the negative impact of raw CFA on mortar workability, and hence it is questionable to support its use in concrete technology.