Investigation of defects and causes If the corrugated tube is not compacted, the steel winch will be corroded, and the prestress will be lost in advance, which will shorten the bridge life. The formation defect of corrugated pipe is mainly that the cement slurry is not filled with the entire corrugated pipe, resulting in a large crescent-shaped gap at the top of the corrugated tube, and even a phenomenon of dew. Another phenomenon is that the strength of the slurry is not enough to make the slurry, steel winch, and concrete beam form a unified whole. The main reasons for this quality defect are: 1. The improper selection of cement slurry and additive resulted in a large ratio of cement ash. 2. When the cement mud is prepared, the fluidity and water rate do not meet the requirements, so that some of the bellows are occupied by the water produced, and the water is absorbed or evaporated, resulting in voids. 3. The construction staff's grouting operation is not correct, the grouting speed is too