Wyniki wyszukiwania - BazTech

1

Jak zwiększyć przyczepność stal zbrojeniowa-beton?

Kucharska Milena, Dybeł Piotr

Builder

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2019

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R.23, nr 1

65--67

EN

The paper analyses the impact of casting direction of self-compacting concrete (SCC) on its bond quality to steel reinforcing bars. Tests were performed on high performance self-compacting concretes with different amount of silica fume to cement mass. Experiment was carried out on 480 mm height specimens, which allowed determining changes of bond condition along its height. The ribbed reinforcing bars have been placed perpendicularly to the direction of casting. Casting was performed from two points – from the bottom and the top of the form. Research has shown that casting from the bottom of the form improves bond strength and quality.

2

Experimental assessment of the casting position factor of reinforcing bars in high performance concretes (HPC, HPSCC)

Dybeł Piotr, Kucharska Milena

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 1

127--136

EN

This paper concerns the problem of the experimental assessment of the casting position factor in comparison to the current normative guidelines. Our experiment was performed on three types of concrete: high-performance concrete (HPC), high-performance self-compacting concrete (HPSCC) and normal strength concrete (NSC) used as a reference. The HPC and the HPSCC were made in respectively, two and four different variants that differed in the content of silica fume. To assess the casting position factor, three types of elements with heights of 480, 800 and 1600 mm were used. In each element, a ribbed reinforcing bar with a diameter of 16 mm was embedded perpendicularly to the direction of concreting. The bond was examined using pull-out test. The test results showed that regardless of the type and composition of concrete, the linear change of the casting position factor with element's height was observed. No significant differences in the changes of the casting position factor with height were noted between the HPC and the HPSCC. The experiment revealed that the new generation concretes were characterized by a much lower value of the casting position factor in comparison to the current normative guidelines.

3

Influence of silica fume content on the quality of bond conditions in high-performance concrete specimens

Dybeł P., Furtak K.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 4

795--805

EN

The paper presents the analysis of the impact of silica fume content in high-performance concrete (HPC) on bond conditions along the height of tested elements. The tests were performed on the specimens made of six different HPC mixes with varying content of silica fume (0, 5 and 10% by mass of cement) and superplasticizer. The used specimens allowed for determining the changes of bond at individual levels of elements with a total height of 480 and 960 mm. The rebars in the elements were placed perpendicularly to the direction of concreting. The reference element, characterised by the parallel orientation to the direction of concreting, was also prepared. The tests indicated that the quality of bond conditions in HPC deteriorates as the distance from the formwork bottom increases. The experiment results indicate that concrete modification with silica fume can both increase and decrease the quality of bond conditions. The influence of silica fume depends on the thickness of the concrete cover, which determines the mechanism of bond failure.