Response of the ultra high performance concrete under dynamic compressive loading

Ultra high performance concrete is a modern cementitious material which exhibits excellent mechanical properties such as damage tolerance, fracture toughness and durability. These features make this materials suitable for wide range of applications where is the material subjected to different modes of loading and different loading rates.This paper deals with measurement of the Ultra high performance concrete reinforced with steel fibres in quasi-static compression mode of deformation and two elevated strain rates using split Hopkinson pressure bar. The results of the measurement show high increase of the mechanical properties with elevated strain rate

Response of the ultra high performance concrete under dynamic compressive loading

Ultra high performance concrete is a modern cementitious material which exhibits excellent mechanical properties such as damage tolerance, fracture toughness and durability. These features make this materials suitable for wide range of applications where is the material subjected to different modes of loading and different loading rates. This paper deals with measurement of the Ultra high performance concrete reinforced with steel fibres in quasi-static compression mode of deformation and two elevated strain rates using split Hopkinson pressure bar. The results of the measurement show high increase of the mechanical properties with elevated strain rate

The effect of the backfat thickness loss on reproduction in lactating sows

The work discusses the influence of the backfat thickness change, during sow´s lactation, on their subsequent litter characteristics. The reproduction potential of 478 sows of two genotypes was assessed. The genotypes were 50 Large White (LWD) sows and 428 crossbreeds Large White x Landrace (LWD x L) sows. The backfat thickness decline was examined in accordance to P2, backfat thickness in sows during lactation namely 1 day before planned parturition as well as weaning.From the obtained results it can be stated that the backfat thickness decline level during lactation has a small influence on the number of total born piglets. In contrast, the number of piglets born alive increased when backfat thickness rate increased. With a moderate backfat thickness decline, the average birthweight piglets gradually increased. However, the opposite trend was shown for the average weight at weaning. The backfat thickness decline level during sow´s lactation influences their farrowing interval. Animals with a lower increase of the backfat thickness subsequently showed a shorter farrowing interval (148.99, respectively 151.86 days), as well as a shorter weaning – estrus interval

The Experimental Timber–UHPC Composite Bridge

This paper describes the development of an innovative timber–concrete composite bridge system and especially focuses on the evaluation of the load tests of an experimental bridge structure. The load-bearing structure was designed as glue-laminated timber beams connected with only 60-mm-thick precast bridge deck segments made of ultra-high-performance concrete (UHPC). To verify the production details and behavior of the designed structure, we built a full-scale experimental structure and performed a load test. The load test was arranged as a four-point bending test. First, we performed the overall load test until failure. Some bridge deck segments were consequently cut from the structure in order to run further load tests of the bridge deck in the transversal direction. The results of the experiments were evaluated in detail and compared with analytical calculations

High Temperature Exposure of HPC – Experimental Analysis of Residual Properties and Thermal Response

The effect of high temperature exposure on properties of a newly designed High Performance Concrete (HPC) is studied in the paper. The HPC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000°C respectively. Among the basic physical properties, bulk density, matrix density and total open porosity are measured. The mechanical resistivity against disruptive temperature action is characterised by compressive strength, flexural strength and dynamic modulus of elasticity. To study the chemical and physical processes in HPC during its high-temperature exposure, Simultaneous Thermal Analysis (STA) is performed. Linear thermal expansion coefficient is determined as function of temperature using thermodilatometry (TDA). In order to describe the changes in microstructure of HPC induced by high temperature loading, MIP measurement of pore size distribution is done. Increase of the total open porosity and connected decrease of the mechanical parameters for temperatures higher than 200 °C were identified

High Temperature Exposure of HPC – Experimental Analysis of Residual Properties and Thermal Response

The effect of high temperature exposure on properties of a newly designed High Performance Concrete (HPC) is studied in the paper. The HPC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000°C respectively. Among the basic physical properties, bulk density, matrix density and total open porosity are measured. The mechanical resistivity against disruptive temperature action is characterised by compressive strength, flexural strength and dynamic modulus of elasticity. To study the chemical and physical processes in HPC during its high-temperature exposure, Simultaneous Thermal Analysis (STA) is performed. Linear thermal expansion coefficient is determined as function of temperature using thermodilatometry (TDA). In order to describe the changes in microstructure of HPC induced by high temperature loading, MIP measurement of pore size distribution is done. Increase of the total open porosity and connected decrease of the mechanical parameters for temperatures higher than 200 °C were identified