The UHPC pavement construction of the steel deck of the main bridge of Shengli Yellow River Bridge was successfully completed

On November 5, the UHPC pavement construction of the steel deck of the main bridge of Shengli Yellow River Bridge was successfully completed.

The UHPC ultra-high-performance concrete for Shengli Yellow River Bridge was poured for the first time on October 17, and it took 18 days to complete all the paving tasks successfully under the premise of safety and high quality.

The Shengli Yellow River Bridge is located in the lowermost reaches of the Yellow River, connecting the two sides of the tail, and the transportation pressure is great. The original deck of the main bridge is 4 cm asphalt concrete + 3.5 cm modified asphalt layer. After 33 years of operation, the bridge deck has dents, ruts, net cracks and other diseases.

UHPC ultra-high performance concrete is a special engineering material with ultra-high strength, ultra-low water absorption, ultra-strong durability and erosion resistance. The compressive strength can reach more than 120 MPa, which is 3-6 times that of ordinary concrete. Its mechanical properties are close to that of steel structures, and it has excellent anti-knock, anti-corrosion and anti-wear properties.

The UHPC layer forms a steel-UHPC composite structure through shear nails, steel mesh and steel bridge decks, so that the concrete and steel beams are jointly stressed. Improving the lateral stiffness of the bridge deck can greatly reduce the local stress concentration caused by the wheel load and alleviate the fatigue cracking problem of the orthotropic bridge deck. At the same time, the high strength and high durability of UHPC can reduce the disease of the bridge deck concrete in the later stage. Compared with other asphalt pavements, SMA-10 high-viscosity and high-elastic asphalt has better elasticity, low temperature and high temperature performance, and bending resistance, which can significantly reduce common asphalt pavement diseases such as rutting, cracks, and bulges during operation, and improve driving comfort and service life.

There are many differences between UHPC and ordinary concrete in terms of raw materials, proportions, and operational performance. In order to ensure the smooth completion of UHPC paving, the project department investigated and consulted a number of raw material suppliers, and personally conducted indoor and field tests. After many repeated adjustments, it reached the design target.

The deck of the main bridge is densely reinforced, and UHPC is required to have good fluidity during paving to ensure that the concrete can be poured densely. At the same time, the slope of the main bridge is relatively large, and the poured concrete will flow. How to ensure that the design alignment requirements are met, this requires higher material ratio and paving. In order to ensure its quality, from research to on-site construction, the Shengli Yellow River Bridge project team determined the final UHPC ratio through thousands of practices, synchronous summarization and practice.

In order to ensure the construction quality of UHPC and improve the construction efficiency, the project department has introduced advanced construction equipment. The use of UHPC placing machine for "3D printing" cloth can effectively control the thickness of the cloth, and solve the problem of isotropic distribution of steel fibers in the process of pumping concrete by a pump truck, ensuring the uniform distribution of steel fibers in UHPC concrete. The ultrasonic laser leveling machine is used to automatically control the elevation and achieve the accuracy of the elevation. At the same time, it can be leveled twice, which ensures the flatness of the paving and makes the bridge deck slope after paving meet the design requirements. The use of automatic mulching film health care realizes automatic mulching immediately after the paving is completed, which solves the problems of strong wind on the bridge deck and easy water loss and cracking of UHPC.

The successful completion of the UHPC bridge deck pavement this time marks a breakthrough in another key node of the project, and also adds a new chapter to the great grand chapter of the official opening of the Shengli Yellow River Bridge.