Technology of Forming Tubular Concrete Columns

Introduction. In manufacturing tubular concrete columns, attention should be paid to a technology of filling a steel tube with a concrete mixture. In practice when a concrete mixture is being fed into a tube from the top, a proper quality of concreting a structure is not guaranteed. In this study, the aim was to test the effectiveness of a technology of forming columns with a self-sealing concrete mixture by means of pressure concreting. Materials and Methods. Experiments to study the effectiveness of the suggested technology for forming a tubular concrete column with a saturated content of longitudinal and spiral reinforcement were conducted on a transparent model. A self-compacting mix composition was selected that ensured the required workability, flowability, homogeneity, and absence of stratification. Through the course of the experiments, the process parameters were adjusted with the speed of filling the structure with the concrete mixture as the most important one. The uniformity of concrete distribution throughout the model was monitored. Research Results. The experiment indicated that the concrete mixture easily reached all of the areas of the structure with no loss of quality. No air bubbles were observed on the surface of the structure, indicating high-quality compaction of the mixture. Concrete strength and density variations in the upper, middle, and lower zones of the structure were minimum. The resulting concrete is characterized by a homogeneous structure, with a uniform, evenly distributed composition with no significant voids or inhomogeneities throughout the entire volume. Discussion and Conclusion. The absence of formwork, scaffolding, and other equipment, high speed of concreting significantly reduce the time and labor intensity of column installation. All of these, combined with the achieved concrete quality, open up avenues for a broad-scale use of the pressure concreting method in construction projects in the Russian Federation. Further work is needed in order to develop a method for ultrasonic quality control of concrete in tubular concrete columns.