Research on the mix design and performance optimization of C50 concrete for shield tunnel segments

A total of 26 shield tunnel sections are planned for a certain project in Guangzhou Metro, with a total production volume of 40448 precast tunnel segments.

The main lining segments of the project have a unified specification: outer diameter of 6400mm, inner diameter of 5800mm, and solid thickness of 300mm; the ring width is divided into two standardized sizes, namely 1500mm and 1200mm.

In order to adapt to tunnel curve excavation construction and meet the practical needs of on-site posture correction, the tunnel lining is based on the standard segment ring configuration, and is assembled by combining multiple types of segments to adapt to different curvature radius curves of the line; The matching wedge-shaped ring adopts a double-sided wedge-shaped structure, and the overall wedge-shaped difference is set to 48mm.

Pfeifer VS Box

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Factors and measures affecting concrete strength

Cement, as the active ingredient of concrete material, directly affects the strength of concrete.

Erection Anchor

In concrete production, the higher the grade of cement, the higher the strength of the produced concrete.

There are also high requirements for the fineness of cement, which directly affects the crack resistance and frost resistance of concrete.

Therefore, strict control should be exercised in the selection and use of cement to ensure its adaptability and maintainability.

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Daily science popularization: Is concrete afraid of water? Why can bridge piers stay in water for a long time?

The bathroom at home is leaking, and the ceiling downstairs is peeling.

Many people’s first reaction is: Is concrete afraid of water? You can turn your head and look at the bridge piers in the river.

Cast In Plate

One after another, the concrete pillars are soaked in the water all year round, unable to avoid wind, waves, rising and falling tides, and sediment erosion.

It seems that they are not so delicate.

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Technologies to enhance the constructibility of 3D concrete printing

3D concrete printing technology can break free from template constraints and achieve automated construction of complex components, making it an important development direction for digital construction.

However, one of the core issues facing this technology is the lack of constructiveness.

The so-called constructiveness refers to the ability of concrete to continuously print to the target height during the layer by layer stacking process without significant deformation or collapse.

Plastic Rebar Chairs

During the printing process, materials require lower yield strength and viscosity during the pumping and extrusion stages to ensure flow and transport; During the sedimentation and stacking stages, it is necessary to rapidly increase the yield strength to support subsequent layer loads.

Therefore, how to quickly switch between “easy pumping” and “easy forming” of concrete has become a key issue in the design of 3D printed concrete materials and equipment.

This article systematically summarizes the main technologies for improving the construction performance of 3D printed concrete around this issue.

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