Bridge Maintenance

Project

There are 125 and 30 m prefabricated T beams in a bridge project, including 75 middle beams and 50 side beams, all of which are made of C50 concrete. On May 6, 2008, after inspection by professionals, it was discovered that the prefabricated T-beam had cracks in both the horizontal and vertical directions. After the inspection, the main factors were as follows.

(1) The temperature change in May in the area where the project is located is very obvious, and it can even rise directly from 10 ℃ to over 30 ℃. Due to the large temperature changes, it is too late to adjust the proportion of concrete in many cases, and the proportion parameters of winter are used, which causes serious hydration heat and causes cracking problems;

(2) The prefabrication yard is set in the middle of the valley. The wind will enter the space and the speed will become faster. The water on the surface of the building structure will be evaporated, causing surface tension to cause cracking.

Once cracks occur in the bridge structure, certain safety problems will occur, and the service life of the bridge will be shortened.

Therefore, the construction personnel need to have sufficient knowledge of the disease and at the same time check the structural performance.

In order to ensure that the quality of the bridge project can meet the specified requirements, it is necessary to summarize a practical and feasible reinforcement construction plan.

The main method of reinforcement

The bridge reinforcement design plan needs to be negotiated and determined by the owner, design unit, supervision unit, and construction unit. The 30 mT beams that have been severely damaged will be strengthened, totaling 13 times. According to the specific situation of the project, the method of grouting and carbon fiber reinforcement is selected to reinforce the entire part. The specific process is shown below.

(1) Crack sealing treatment

Non-penetrating cracks whose crack width is less than 0.10mm are filled with epoxy mortar material. Main construction method: Use tools to cut the crack into a "V"-shaped groove, the top size is 15-20 mm, and the depth is about 20 mm

The cracks where the humidity exceeds 6% should be dried using iodine tungsten lamps or hot air blowing. Then use a wire brush to clean up the impurities in this position to ensure that the internal cleanliness meets the standard. Remove the impurities in the 15-25 mm cracks on both sides of the tank and keep it dry.

Before the sealing starts, it is necessary to apply an epoxy resin solution with a thickness of 1 to 2 mm on the surface of the "V" groove to ensure the uniformity of the surface, and there should be no wrinkles and bubbles.

2) Pressure grouting method

In the case where the crack width exceeds 0.10 mm or a through crack is formed, pressure grouting is required to fill the crack position.

(3) Paste carbon fiber

According to the specific requirements of the project, 300 g/m2 carbon fiber cloth with a thickness of 0.167mm is selected as the reinforced fiber material to ensure that its various technical parameters can meet the requirements. Structural adhesives should choose products that can meet the requirements of carbon fiber materials and meet the requirements of national standards, and the materials have quality certification documents to ensure that the quality of the materials meets the standards.

Concluding remarks

(1) Because this kind of material has a certain degree of conductivity, try not to get close to the power source during use. If it is around high-voltage lines, take necessary protective measures.

(2) Bridge engineering is a very important transportation infrastructure in my country. In actual use, maintenance and repair efforts need to be increased. Take more favorable management measures and organize personnel to conduct regular inspections. If there are any cracks and other diseases, measures must be taken to deal with them, and the construction process must be strictly implemented to effectively prevent serious traffic accidents in the application of bridge engineering.