Effect of the concrete´s component on the heat shock bearing capacity of tunnel linings

During the last decades, the increasing number of incidents in road and railway tunnels have attracted public attention to the danger of tunnel fires. These incidents established that quickly accumulating, huge amount of evolved heat impairs the reinforced concrete structures of tunnel linings. Designing of fire-bearing linings, it is necessary to understand the behaviour of the linings impacted by bumping heat load. In this paper, the results of our heat load examinations of residual strength (compressive strength and split-tensile strength) parameters on different mixtures of concrete were summarised

Analysis of plate glass columns: The influence of fixing and the coupling parameter

The design methods of the load bearing glass columns developed extremely in the last years. Numerous glass researchers have been trying to optimize the glass structures in terms of cost-effectiveness and safety. The authors carried out several laboratory experiments to analyze the key factors of the glass column design. Factors are investigated in the present article for example the influence of the fixing at the end of the glass columns, which essentially modifies the load bearing capacity of structures. The efficiency of the gluing of the interlayer foil (the coupling parameter) was analyzed based on the individual laboratory experiments

Effect of air entraining admixture on the properties of self-compacting concrete incorporating supplementary cementitious materials

Self-compacting concrete has gained a wide range of applications as a result of its unique properties, which can offer high strength and durable type of concrete with the proper selection of the raw materials. The purpose of this study was to show the effect of the use of high dosage of air entraining admixture on the properties of self-compacting concrete. An experimental investigation on the frost-salt scaling resistance of conventional and air entraining selfcompacting concrete incorporating slag-blended cement and supplementary cementitious materials was carried out. Further fresh and hardened properties tests including slump flow, V-funnel, compressive strength, splitting tensile strength, air void characteristics and water absorption tests were performed to obtain an objective evaluation between air and non-air entrained self-compacting concrete mixtures. Air void characteristics were evaluated through the automated image analysis procedure to enrich this investigation. Results indicate the following: the air entraining admixture highly decreased the compressive strength up to 52% and the metakaolin was the governing supplementary cementitious material concerning the scaling resistance and water absorption in comparison with the silica fume

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Thermal Properties and Modeling of Fiber Reinforced Concretes

AbstractThe aim of the paper is to define the thermal properties (thermal conductivity, density and specific heat capacity) of steel, plastic and glass fiber reinforced concretes that are widely used for industrial floors, and to determine equivalent concrete thermal conductivity values for numerical thermal modelling of steel fibre reinforced concretes. In conclusion with the measurements, simulations and correlations, in the field of building physics and energy design we are able to calculate the fibre reinforced concrete's thermal behaviour accurately

Concrete strength tendency in the wall of cylindrical spun-cast concrete elements

The aim of the research was to characterize the concrete mixtures for spun-cast concrete and to determine the relationship between the compacting ratio and the manner of segregation. In the research 23 specimens of 9 different mixtures with low w/c ratio were tested. Investigated parameters included w/c, spinning speed, duration, and properties of the aggregate. The strength of the concrete in the outer, middle and inner region of the spun-cast element and of the vibrated cube was assessed by testing drilled cores. The optimal compacting energy caused by spinning was defined for different mixtures. Statistical regression functions depending on the parameters above were defined for the change of strength in the wall of the element