Abstract
A self-compacting concrete (SCC) mixture, due to its special rheological properties, may be placed differently than in traditional variants. The paper presents the results of a study on the effect of a bottom-up placing direction on the quality of bond conditions between steel and self-compacting concrete. Elements with overall dimensions of 160 × 480 × 1600 mm consisting of elementary samples with dimensions of the bond test basic modules were constructed. Ribbed steel rebars with diameters of 16 mm were used and located in formworks perpendicularly to the concrete placing direction. Bond tests were carried out according to the pull-out method. The bottom-up placing contributed to the uniformity of the bond conditions quality in the test elements and an overall improvement of the bond properties, especially in its top part. Given the increasing implementation of alternative methods of mix placing and the promising results, the topic should be further investigated.
Highlights
The unique rheological properties of self-compacting concrete (SCC) are widely known to provide a more effective way of placing it in the form
The application of self-compacting concretes in the construction industry brings a number of benefits throughout the entire life cycle of the structure in technological, economic, environmental and social terms
It is associated with the elimination of mechanical compaction, reduction of concrete surface trowelling, reduction of concreting and finishing time, material modifications of the mix and better mechanical characteristics of the hardened concrete
Summary
The unique rheological properties of self-compacting concrete (SCC) are widely known to provide a more effective way of placing it in the form. The application of self-compacting concretes in the construction industry brings a number of benefits throughout the entire life cycle of the structure in technological, economic, environmental and social terms. It is associated with the elimination of mechanical compaction, reduction of concrete surface trowelling, reduction of concreting and finishing time, material modifications of the mix (replacement of part of cement with mineral additives) and better mechanical characteristics of the hardened concrete. In the case of many points, it is necessary to adjust their quantity and location to the rheological properties of the SCC mix used, especially its viscosity (wall) Another technological innovation is the possibility of concreting both traditionally from the top (Figure 1a) and the bottom of the form. According to the general European guidelines for SCC concreting [1], when placing the mix from the bottom, the pumping point should be as close as possible to the middle of the span of the wall, in order to reduce the flow distance
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