Introduction of polymers into the cement composites improves same of the properties of concretes and mortars. Therefore, the polymer-cement composites are successfully used in construction. The model of microstructure formation in cement composites modified with thermoplastic polymer (pre-mix modifiers) has already been developed and successfully implemented. However, the formation of microstructure in the case of epoxy-cement composites (containing post-mix modifier) demonstrates same peculiarities which should be taken into account when modelling the process. The microstructure of epoxy-cement composites and its formation is discussed in the paper. The model is offered, formulated on the basis of the microscopic observations and results of testing.
In the recent years structural health monitoring (SHM) has gathered spectacular attention in civil engineering applications. Application of such composites enable to improve the safety and performance of structures. Recent advances in nanotechnology have led to development of new family of sensors – self-sensing materials. These materials enable to create the so-called “smart concrete” exhibiting self-sensing ability. Application of selfsensing materials in cement-based materials enables to detect their own state of strain or stress reflected as a change in their electrical properties. The variation of strain or stress is associated with the variation in material’s electrical characteristics, such as resistance or impedance. Therefore, it is possible to efficiently detect and localize crack formation and propagation in selected concrete element. This review is devoted to present contemporary developments in application of nanomaterials in self-sensing cement-based composites and future directions in the field of smart structures.
The introduction of the sustainable development elements in the construction industry leads to finding new ways of using waste minerals that are difficult in storage and recycling. Coal combustion products have been already introduced into building materials as a part of cement or concrete but they have been thought insufficiently compatible with the polymer-cement binders . The paper presents results of the mechanical properties of polymer-cement composites containing two types of mineral additives: waste perlite powder that is generated during the perlite expanding process, and calcium fly ash which is the byproduct of burning coal in conventional furnaces. Mechanical tests of polymer-cement composites modified with wastes were carried out after 28 and 90 days of curing. As a part of preliminary study specific surface area and particle size distribution of mineral wastes were determined.
The European eel (Anguilla anguilla) is a catadromous fish with a complicated life cycle. The long-term impact of anthropopressure, environmental pollution and diseases have led to a risk of extinction. The aim of the present study was to determine the influence of Anguillid herpesvirus-1 infection on the innate immunity of European eel from natural conditions. Spleen phagocyte respiratory burst activity and potential killing activity, as well as pronephros lymphocyte proliferation stimulated by concanavalin A or lipopolysaccharide were measured. The analyses of the results showed that all studied parameters were significantly higher (P<0.05) in AngHV-1-negative fish compared to the ones where the presence of viral DNA was confirmed.