Experiment on Magnetic Compaction to Reduce Bugholes in Free-Form Concrete Panels

Abstract

Free-form concrete panel (FCP) molds require precise manufacturing because each mold demands a unique shape. Therefore, automation technology for producing these molds is being developed. However, when concrete is cast in a free-form mold and subjected to the impact of compaction to distribute it, deformation occurs in the precisely designed form. Consequently, free-form molds are often produced manually, which results in bugholes on the surface of FCPs. These bugholes lead to quality issues in the panels, including deterioration in aesthetics and strength. This study aims to develop a magnetic compaction technology that installs an object which rotates due to magnetic force inside a free-form mold and applies magnetic force from the bottom to perform compaction according to the free form. By comparing a control group using the existing manual FCP production method and an experimental group using magnetic compaction, strength was measured and bughole incidence was verified. As a result, although the experimental group was subjected to rotary motion, no material separation or deterioration in strength occurred. Furthermore, a similar standard deviation of 62.23 mm2 and a mean difference of 187.42 mm2 were observed between the control group and the experimental group. The results of the t-test showed that at a 95% confidence level, the t-value was −16.35 and the p-value was 0.00. This confirms that the incidence of bugholes was reduced in the experimental group where magnetic compaction was applied. This research may contribute to reducing the occurrence of bugholes in existing free-form concrete panels and securing both aesthetics and strength.

Keywords

• free-form concrete panel
• bughole
• bughole incidence
• magnetic compaction
• <i>t</i>-test