Some technological parameters of overlapping layers when using self-compacting concrete mixtures
Abstract
Some technological parameters of overlapping layers when using self-compacting concrete mixtures
Incoming article date: 10.12.2022The overlapping time of the layers during the layer-by-layer laying of the concrete mixture during the construction of massive monolithic reinforced concrete structures is an important technological parameter of concreting, linking the rate of concreting, the thickness of the laid layers and the design parameters. For traditional concrete mixtures compacted by vibration, this parameter is determined by the persistence of the concrete mixture, taking into account its temperature. When using self-compacting concrete mixtures, the time of overlapping layers, in addition to traditional factors, significantly depends on the period of formation of the "elephant skin". The influence of the overlapping time of the layers on the strength of their adhesion, depending on the properties of the concrete mixture and the method of its laying, was studied. The ultimate tensile strength in bending was used as a criterion for adhesion strength. It has been confirmed that when using a traditional concrete mix compacted by vibration without superplasticizing additives based on polycarboxylate esters, the overlapping time of the layers of 2 hours provides a seam of equal strength with the main body. For self-compacting concrete mixes using vibration when laying subsequent layers after the first, the overlapping time corresponds to the storage index and increases to 6 hours, and when layered without vibration, the adhesion strength decreases by about 20%, 70% and more than 90% with an overlapping time of 2.4 and 6 hours, respectively.
Keywords: self-compacting concrete mixes, massive reinforced concrete structures, overcoating time, "elephant skin"