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This study is focused on the experimental investigation of compressive strength and durability properties of lightweight concrete mixtures with fine expanded glass and expanded clay aggregates using different microfillers. The paper proposes the relationships between the compressive strength and density of concrete mixtures with different proportions of the lightweight aggregates mentioned above. The performed experimental studies have revealed the tendencies of possible usage of different amounts of fine lightweight aggregates and their combinations in the production of concrete mixtures depending on the demands of practical application. Following the requirements for structural concrete subjected to environmental effects, durability properties (alkaline corrosion and freeze–thaw resistance) of the selected concrete mixtures with expanded glass aggregate were studied. The results of the experimental investigations have shown that durability of tested concrete specimens was sufficient. The study has concluded that the mixtures under consideration can be applied for the production of structural elements to which durability requirements are significant.

Present research was dedicated to investigation of finite element size effect on deformation predictions of reinforced concrete bending members. Experimental beams have been modelled by commercial finite element software ATENA, using two main approaches for simulating tension-stiffening: stress-crack width (fracture mechanics approach) and average stress-average strain relationships. The latter approach uses the ultimate strain adjusted according to the finite element size. It was shown that the modelled post-cracking behaviour of the beams is dependent on the finite element mesh size. To reduce this effect, a simple formula has been proposed for adjusting the length of the descending branch of the constitutive relationship. Post-cracking behaviour of a reinforced concrete bridge girder has been investigated assuming different finite element mesh sizes. The analysis has shown that the proposed technique allows reducing the dependence of calculation results on the finite element size.

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Abstract. This paper introduces the recent state of research on shrinkage of concrete. It reviews prediction models of shrinkage strain and curvature analysis methods of reinforced concrete members. New test data on concrete shrinkage has been presented. Various factors that influence shrinkage have been discussed. A calculation technique on short-term deformations of cracked reinforced concrete members including shrinkage has been introduced. The technique is based on layer model and smeared crack approach. Shrinkage influence on behaviour of reinforced concrete beams was investigated numerically and compared with test data reported in the literature. It has been shown that shrinkage has significantly reduced the cracking resistance and leads to larger deflections.

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