Dybeł Piotr, Kucharska Milena
Faculty of Civil Engineering and Resource Management, AGH University of Krakow, Al. A. Mickiewicza 30, 30-059 Krakow, Poland.
Materials (Basel). 2024 Aug 12;17(16):4005. doi: 10.3390/ma17164005.
This paper presents a study on the influence of the layered casting technology of self-compacting concrete (SCC) on the load-bearing capacity of interlayer bond in slab elements. The research was conducted on slab elements with dimensions of 750 × 750 × 150 mm, concreted from a single point of concrete delivery. The aim of this study was to analyse the influence of the height of the concreting top layer on the bond strength between the layers. The study utilised top layer heights of 50, 75, and 100 mm, which, according to the authors' experience, are the most common cases when making slab elements. The interlayer bond was determined by investigating the splitting tensile strength of cubic specimens cut from the concrete slabs. Computed tomography (CT) was employed to image the contact zone between the concrete layers. Based on the analysis of the CT imaging and the results of the strength tests, it was shown that the interlayer bond is influenced by both the height of the top layer and its free-spread distance from the casting point. A reduction in the interlayer bond strength was observed with decreasing the height of the top layer and increasing distance from the mixture supply point. The relationships obtained were linear and had a clearly negative slope. It was concluded that the valid recommendations and standards for the multilayer casting of SCC are too general. Therefore, we propose to detail the recommendations to reduce the risk of cold joints, which diminish the bond strength of the interlayer joints.
本文介绍了一项关于自密实混凝土（SCC）分层浇筑技术对平板构件层间粘结承载能力影响的研究。研究对象是尺寸为750×750×150mm的平板构件，从混凝土浇筑的单个点进行浇筑。本研究的目的是分析浇筑顶层高度对层间粘结强度的影响。该研究采用了50、75和100mm的顶层高度，根据作者的经验，这些是制作平板构件时最常见的情况。通过研究从混凝土板切割的立方体试件的劈裂抗拉强度来确定层间粘结。采用计算机断层扫描（CT）对混凝土层之间的接触区域进行成像。基于CT成像分析和强度试验结果表明，层间粘结受顶层高度及其从浇筑点的自由扩散距离的影响。随着顶层高度的降低和距混合料供应点距离的增加，观察到层间粘结强度降低。所得到的关系是线性的，且斜率明显为负。得出的结论是，现行的自密实混凝土多层浇筑的建议和标准过于笼统。因此，我们建议详细说明这些建议，以降低冷缝风险，冷缝会削弱层间接缝的粘结强度。
