The deck part of reinforced concrete and prestressed concrete bridges usually includes deck pavement, waterproof and drainage facilities, expansion joints, sidewalks (or safety belts), kerbs, railings and lamp posts. Because the naturally exposed surface of the bridge deck is very sensitive to the influence of the atmosphere, the traffic between vehicles and pedestrians is also very important for aesthetics. According to the past practice, due to insufficient attention to the bridge deck, there are many disadvantages to the future bridge deck maintenance. Therefore, how to improve the structure and construction of bridge deck reasonably has attracted more and more attention.

First, the bridge deck pavement

Bridge deck pavement, also known as carriageway pavement, is used to protect the carriageway slab as a component of the main girder from direct wear of vehicle tires (or tracks), prevent the main girder from being eroded by rain, and make the concentrated load of vehicle wheel weight play a fixed distribution role.

Deck pavement occupies a considerable proportion in bridge dead load, especially for small-span bridges, the weight of pavement should be reduced as much as possible. If the bridge deck is paved with cement concrete, and the strength grade is not low: the strength grade of bridge deck concrete can be closely combined with the bridge deck during construction, then the paved concrete (excluding the wheel wear part, which is 1 ~ 2 cm thick) can also work together in the bridge deck to give full play to the role of this part of materials.

(A) the type of bridge deck pavement

At present, the deck pavement of reinforced concrete and prestressed concrete beam bridges adopts the following forms:

1. Ordinary cement concrete or asphalt concrete pavement

In small-span bridges in non-cold areas, a 5-8 cm ordinary cement concrete or asphalt concrete pavement can usually be directly paved on the bridge deck without special waterproof layer. The bridge deck is generally paved.

Concrete with the same or slightly higher strength grade as slab concrete requires better compactness when paving. In order to prevent slip and reduce light reflection, it is best to make concrete into a rough surface. Concrete pavement has low cost and good wear resistance, which is suitable for heavy traffic, but the maintenance period is longer than that of asphalt pavement, so it is more troublesome to maintain it in the future. Asphalt concrete pavement is light in weight and easy to maintain, and can be put into use in a few hours. The asphalt concrete pavement on the bridge can be made into single layer (5-8 cm) or double layer (4-5-8 cm at the bottom and 3-4-5 cm at the surface).

2. Waterproof concrete pavement

When bridges in non-frozen areas need proper waterproofing, waterproof concrete with a thickness of 8 ~ 10 cm can be paved on the bridge deck [Figure 4-2 (a)]. The strength grade of waterproof concrete is generally not lower than that of bridge deck concrete, and there is generally no need to set a surface layer on it. However, in order to prolong the service life of the bridge deck, it is advisable to lay 2cm thick asphalt surface treatment agent on it as a repairable wear layer.

3. Cement concrete or asphalt concrete pavement with adhesive waterproof layer.

Flexible bonded waterproof layer is often used on bridges with high waterproof requirements, or where cracks may occur because the bridge deck is located in the tensile area of the structure [Figure 4-2 (b)]. The adhesive waterproof layer is arranged on the low-strength concrete drainage triangular cushion. The method is as follows: firstly, the cushion layer is leveled with cement mortar; After hardening, coat a layer of hot asphalt bottom layer on it; Then coat it with a layer of linoleum (or sack cloth, glass fiber cloth, etc. ); Then coat a layer of asphalt mortar; Finally, apply a layer of asphalt mortar. Usually the so-called "three oils and two felts" waterproof layer has a thickness of 1-2 cm. In order to protect the adhesive waterproof layer from being damaged by pavement paving and renovation, fine stone concrete with a thickness of about 4cm and a strength grade of not less than C20 should be used as the protective layer. When sufficient strength is reached, asphalt concrete or cement concrete pavement will be laid. Due to the high cost and long construction time, the waterproof layer should be adopted after full consideration of technology and economy according to the climatic conditions in the bridge construction area and the importance of the bridge.

In addition, epoxy resin coating is adopted abroad to achieve the purpose of wear resistance, waterproof and reducing the dead weight of the bridge. The thickness of this kind of pavement is usually 0.3- 1.ocm. In order to ensure its firm combination with the bridge deck, the concrete bridge deck should be cleaned and painted before painting. Obviously, this kind of pavement is expensive.

For prefabricated beam bridges, when concrete and adhesive waterproof layer are used for deck pavement, in order to strengthen the strength of joints and avoid longitudinal cracks caused by condensation, a small (3 ~ 6 diameter) steel mesh with mesh size of15cmx15cm ~ 20cmx20cm is needed in the concrete pavement or the protective layer at joints. If the pavement participates in the stress at the joint, the specific configuration of reinforcement should be determined by calculation.