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This paper presents the effects of long-term exposure of concrete structures to marine environment using as an example concrete blocks of a pier exposed to seawater for more than three decades. The blocks were tested to determine their mechanical characteristics (compressive strength), durability (gas permeability and capillary absorption), and chemical properties (quantity of chloride and sulphate ions). In addition, concrete behaviour in sea water was modelled using software packages Stadium and Conclife.

The ways in which concrete properties are influenced by waste tyre recyclates, used as secondary raw materials, are presented in the paper. Taking advantage of these properties, several special-purpose construction products, containing raw materials obtained by tyre recycling, have been developed at the Faculty of Civil Engineering, University of Zagreb. Each of these innovative products represents an environment-friendly, functional and cost-effective alternative to products traditionally used in engineering practice.

An essential step in the condition assessment of reinforced concrete structures and evaluation of the residual capacity is the determination of the arrangement and quantity of reinforcement as well as the geometry of the structural elements. The objective of this paper is to present the fundamentals in the application of two non-destructive methods, cover meter and ground penetrating radar, in the determination of the above structural features. A comparison of the two methods is presented and their capabilities, advantages and disadvantages are shown through nine case studies.

This paper presents the pilot project of application of recycled aggregate during construction of a new day hospital in Zadar. The project included the demolition of an existing hospital building and the use of generated construction waste as recycled aggregate in the construction of a part of the building. The 16/32 mm fraction of aggregate was obtained by mechanical processing of the generated waste which was then tested in accordance with the HRN EN 206 and HRN EN 12620 standards. Four concrete mixes were prepared, and the fresh (slump, density, air content) and hardened properties were tested (compressive strength, modulus of elasticity, capillary absorption, water permeability, drying shrinkage). The obtained results confirm that by complying with the standards for recycled aggregates and knowing their origin it is possible to produce concrete with properties equivalent to those of ordinary concrete for specified durability conditions.

The trend of wood biomass use as a renewable energy source has contributed to an increase in the quantity of wood biomass ash (WBA) that is regarded as waste. Currently, 70 % of WBA is landfilled, 20 % is used in agriculture, and 10 % is used for other purposes. The aim of this paper is to carry out an extensive analysis of the current situation regarding WBA production in Croatia and other European countries. An overview of the types and properties of WBA in relation to the type of wood biomass is given, and parameters relevant for WBA use in concrete industry are presented.

Properties of concrete elements under fatigue load can be enhanced by adding steel fibres to the concrete mixture. An experimental study of recycled steel fibre reinforced concrete elements subjected to cyclic load is described. Fatigue design models are presented according to the fib Model Code 2010, ACI 215, and JSCE guidance. Design model calculations are compared to the results of experimental analyses. It can be observed that, as a rule, all design models underestimate the experimentally obtained fatigue resistance of concrete elements. The adjustment of the fib Model Code design model is proposed.