Paper presents the effect of products obtained during recycling of waste tyres on properties of concrete. Only by taking into account specific properties of each product obtained by recycling, it is possible to apply them in concrete industry for preparation of concrete products with special properties. Products incorporating waste tyres can then be ecologically, technically and economically competitive alternative to products traditionally used in engineering practice.

Major challenges of traditional linear concrete industry are utilisation of large amount of non-renewable resources and significant air emissions during production, utilisation and demolition of concrete structures. At the same time, concrete industry has a high potential for a positive shift towards more sustainable production and lower ecological footprint. One of the strategies is to use waste materials and byproducts from other industries as valuable raw materials in concrete industry. This loop can be closed only by taking into account properties of a certain waste material and using them for preparation of special purpose concrete products, in which these properties are favourable. Other strategy is designing concrete tailored for certain environment and service life, making it optimised for that specific purpose. The paper presents some of the available waste and recycled materials in Croatia and research focused on their potential application in civil engineering. The possibilities of utilisation are first explored in laboratory conditions, with the results presented in this paper as an outcome. Based on the obtained results some of the potential areas of application are proposed, in which concrete prepared with these waste materials becomes alternative to classical concrete. Both original scientific research results are presented, but also prototype of products produced based on the scientific research.

In this paper, for the case of gas oscillator two characteristic thermodynamic change of state, and for them defined functional dependence of the force from moving the piston in a nonlinear form were considered. In this paper small oscillations are observed and the linearization is performed by neglecting nonlinear term as the small size at isothermal change and with development obtained function in Taylor series for adiabatic change. Based on the analysis of analog oscillator of mechanical system, or the equivalent scheme of problems, characteristics oscillation parameters and the motion law of the observed thermodynamic system are defined. With this procedure greatly simplifying for problem solution was achieved with respect to classical procedure. At the end of the paper, an analysis of the obtained results were done and appropriate electrical analogy was setting. This is used for the presentation of the problem through appropriate electric circuits and analogy mathematical relations, which involve voltage and electric currents as electric sizes. Also, it was shown that the electrical analogy can be used for all mechanical and thermodynamic processes which describes by homogeneous second-order differential equations which are the most common in technical practice.

Starting from the expression for the thrust in the field of full utilization cross section scrapings and tool life, an expression is derived for the maximum required thrust of universal machine. Then, using a working diagram the analysis of the main features of the simultaneous utilization of machines was performed and determined the optimal area of its utilization for given optimal diameter of treatment. Based on this, the well-known machine using its structural details and the corresponding function workability, derived relations to determine the optimal coefficient slenderness of scrapings suitable for practical use. In this case we think that is known critical material for work piece. Considering the critical and authoritative material of the work piece, based on the expression for the cutting speed was determined by the characteristic constant workability as the basis for establishing optimum tool material which is adequate for optimum regime. Both obtained relation can be considered as general model that can be applied directly to solving setting problems. Also, given the possibilities of practical application of the presented relations, especially in the case of other typical kinds of treatment. Finally, the model is verified on a one calculation example from practice for a Specific machine tool, where certain important characteristics of the optimal treatment are defined.