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Present paper studies metakaolin as a supplementary cementing material (SCM ) for concrete in terms of compressive strength development and k-value concept of CEN /TR 16639:2014. Sixteen different concrete compositions are studied in the range of water-to-cement ratio of w/c = 0.50-0.65. Results indicate that the effectiveness of metakaolin depends on the applied w/c-ratio and the applied cement substitution ratio; the smaller the w/c-ratio, the more effective the metakaolin; the higher the cement substitution ratio, the less effective the metakaolin. The k-value decreases by the increase of w/c-ratio, independently of the age of concrete. The higher the cement substitution ratio, the smaller the k-value. The k-value tends to reach a final value in time. [ABSTRACT FROM AUTHOR]

Reinforced concrete is a widely used construction material. However, corrosion of steel reinforcement might be a danger to its durability. In this paper the corrosion mechanism of steel reinforcement in concrete is introduced. Literature and case studies are reviewed on concrete crack width and its effect on reinforcement corrosion. The results found in different sources proved to be inconsistent. Crack width variation within concrete cover is presented as a reason. The influencing factors of reinforcement corrosion in concrete are collected with special regard to crack geometry. [ABSTRACT FROM AUTHOR]

Development and application of Fibre Reinforced Polymer (FRP) reinforcements in concrete structures have been accelerated in the last three decades. Durability of FRP reinforcements is expected to exceed that of conventional steel reinforcements as FRP reinforcements do not tend to corrode. Present paper intends to review experiences on characteristics of fiber reinforced polymers (FRP) for civil engineering applications and to discuss design considerations by applying FRP bars or tendons embedded in concrete as prestressed or non-prestressed reinforcement. Test results on FRP indicate high tensile strength, high fatigue strength as well as low relaxation and creep. Design recommendations are based on work carried out more than fifteen years ago on first generation reinforcing products. Design guidelines are necessary to enable the use of new materials, they should be made flexible enough to accommodate future developments and facilitate the quick adoption of innovative products. Present paper, therefore, introduces the most recent European research action (COST TU1207) that aims to develop a new generation of design guidelines for FRP materials based on European Standards. [ABSTRACT FROM AUTHOR]

An obituary is presented for professor Balázs György.