Detailed rules for supervision and control of waterproof layer on railway bridge deck

A, cement reinforced concrete bridge deck pavement construction supervision and control points and measures

1. Bridge deck pavement can only be carried out after the completion of various construction procedures of beams.

2. Ensure the construction quality of hinge joints between precast beams.

3. Ensure the quality of the joint (bond) between the top surface of beam slab and cement concrete bridge deck pavement.

(1) The top surface of beam and slab must be cleaned.

(2) Anchor shear bracing steel for cement concrete bridge deck pavement should be embedded in the top surface of precast beam or box girder, and steel mesh for bridge deck pavement should be welded with it. The anchorage shear vertical reinforcement should be 4-8 ㎡, and the value should be taken at the place where the shear stress is large at the beam end or bearing. You can embed it as follows:

(1) the middle of the precast beam top can be embedded with Ф10-12 steel bars, with a spacing of about 300-500mm and a height of about 500mm.

(2) The box girder is embedded Ф10-12 at the top, with a longitudinal spacing of about 300-500mm, a transverse spacing of 500- 1000mm and an exposed height of about 50mm.

(3) If there is no embedded anchor bar at the top of the beam, drill a hole at the top of the beam, insert anchor bar Ф12, the embedding depth is not more than 50mm, and the exposed height is about 50 mm ... The gap between the steel bars in the hole is filled with cement mortar.

(3) Before the construction of cement concrete bridge deck pavement, the top of the beam should be wetted with water.

4. Ensure the installation quality of steel mesh for cement concrete bridge deck pavement.

(1) If the thickness of the upper protective layer is too small, it may lead to:

(1) The bridge deck roof is easy to form grid cracks, and the bridge deck is damaged prematurely after opening to traffic.

(2) Steel Netease rusted.

(3) After long-term use, the concrete at the top of the bridge deck is worn off, exposing the steel mesh.

(4) The steel mesh and concrete can not form the best stress combination, and their stress function and structural function are greatly reduced.

(2) Precast mortar blocks should not be used for laying steel wire mesh on cement concrete bridge deck for the following reasons:

① Mortar precast blocks are often low in strength and not dense, and the amount of steel mesh used for cushion is also large. The surface of bridge deck pavement is inherently thin, which makes the local strength of cement concrete bridge deck pavement low, and it is prone to pit and groove damage under repeated vehicle loads.

(2) Precast block pad is easy to move, which makes the protective layer under the steel mesh thinner and even clings to the top surface of the beam, causing premature damage to the bridge deck. The steel mesh can be directly supported on the anchorage shear reinforcement at the top of the beam, or it can be supported by welding short vertical reinforcement.

5. Supervise the contractor to select and install the template correctly.

6. Control the thickness and quality of bridge deck pavement.

7. In order to ensure the quality of cement concrete bridge deck pavement, the following measures must be taken to correctly set and deal with longitudinal and transverse construction joints:

(1) Set the position of the longitudinal construction joint at the lane dividing line to minimize the contact between the wheels and it, thus greatly prolonging the service life of the bridge deck.

(2) Location of transverse construction joints: ① Strengthen the construction organization, carry out continuous construction as far as possible, and set no or less transverse construction joints. (2) try to set in the reserved slot of expansion joint.

(3) The longitudinal and transverse construction joints of cement concrete bridge deck pavement shall be chiseled into vertical planes. The design thickness of bridge deck pavement is inherently thin (generally 80- 100mm). If it is not chiseled into a vertical plane, the pavement constructed in the later period will be very thin and easy to break and crack. (1) construction joints should be along the point 1 point 5 chisel into a vertical plane. (2) Before construction, the sub-layer concrete shall be washed clean and a layer of cement slurry shall be brushed.

(4) Only when the concrete strength of bridge deck pavement meets the specification requirements can the construction wall be chiseled to prevent the surrounding concrete from loosening, cracking, corner collapse, edge collapse and other phenomena on the bridge deck, leaving quality hidden dangers.

8. Carefully check whether the mixture ratio of cement concrete bridge deck pavement designed by the contractor is correct.

(1) When the bridge deck is designed as waterproof concrete, the mixture ratio cannot be designed and constructed according to ordinary concrete.

(2) The minimum cement dosage should not be less than 30kg/m3, and the maximum cement dosage should not be greater than kg/m3. When the cement content is too high; There are many laitance on the bridge deck, and the bridge deck is prone to shrinkage cracks. Too little cement content; The poor workability of concrete is not conducive to the leveling and flattening of bridge deck.

(3) If reducing agent is needed, retarding early strength water reducer can be selected, and it can only be used after strict test, sampling and trial paving. If the early strength water reducer is used improperly, it may cause: ① serious bleeding and shrinkage cracks; (2) The bridge deck is finally set before plastering, which affects the quality of plastering and embossing; ③ Adverse reaction with cement, affecting the strength of concrete.

9. Supervise the contractor to strictly control the concrete construction mixture ratio.

10. Before construction, the contractor shall be urged to take rain-proof, high-temperature prevention and anti-freezing measures. Measures should be taken to prevent rain and high temperature before the construction of cement concrete bridge deck pavement: (1) Watch the weather forecast and pay attention to the weather conditions before the construction. (2) In hot summer, concrete pouring should be carried out in the morning or afternoon when the temperature is low. (3) When constructing concrete bridge deck pavement in hot summer, the cold water washed by sand and gravel should be cooled down, and the water consumption should be reduced accordingly when mixing concrete. And the top surface of the beam should be washed with cold water in advance to cool down.

1 1. Ensure the quality of structural flatness.

12. After the construction of bridge deck pavement concrete, the contractor shall be urged to saw off the false joints in time. Otherwise, under the action of temperature stress, transverse irregular cracks will soon appear, which will affect the service life of the bridge deck. The spacing between false seams should not be too large, and the position should be appropriate. The spacing of false joints is generally 15-20m, and the positions are generally located at the top of pier and in the middle of span (there is no need to set the middle of span in light music). The bridge deck should be reinforced with joint reinforcement at the beam end or the crack position with negative bending moment according to the design requirements. The diameter of steel bars at bridge deck joints shall not be less than12mm; ; The length should not be less than 1.2m or determined according to the influence range of negative bending moment. 13. After the construction of bridge deck pavement concrete, the contractor shall be urged to cover and maintain in time.

Second, the steel fiber reinforced concrete bridge deck pavement construction supervision and control points and measures

1 Strictly control the material of steel fiber. Supervision engineer must strictly control the quality of steel fiber and insist on inspection before use. In addition to the provisions of Steel Fiber for Concrete (YB/T 15 1), steel fiber shall also meet the following requirements:

The tensile strength of (1) monofilament steel fiber should not be less than 600MPa.

(2) The length of steel fiber should match the maximum nominal particle size of concrete coarse aggregate, and the shortest length should be greater than1/3 of the maximum nominal particle size of coarse aggregate; The maximum length should not be less than 2 times of the maximum nominal particle size of coarse aggregate; The deviation of steel fiber length from the nominal value should not exceed 10%.

2. Strictly control the caking phenomenon of steel fiber reinforced concrete. The mixing of steel fiber reinforced concrete shall meet the following requirements in addition to the provisions of ordinary concrete specifications:

(1) When the volume ratio of steel fiber is high and the mixture is dry, the primary mixing amount of the mixing building should not be greater than 80% of its rated mixing amount. There shall be no steel fiber caking in the mixture.

(2) The feeding sequence and method of steel fiber reinforced concrete mixing should be determined by trial mixing or experience on the principle that steel fiber does not agglomerate during mixing and a certain productivity is guaranteed. Steel fiber, cement, coarse and fine aggregate should be dry mixed first and then wet mixed with water; Steel fibers can also be dispersed in the mixing process by using a steel fiber disperser.

(3) The mixing time of steel fiber reinforced concrete should be determined by field mixing test, and it should be 20-30s longer than the pure mixing time specified by ordinary concrete. When the mixing method of dry mixing first and then adding water is adopted, the dry mixing time should not be less than 65438±0min.

(4) It is forbidden to mix steel fiber concrete manually.

(5) The dispersion and uniformity of steel fiber in concrete should be ensured, and the deviation of steel fiber content detected by water washing method should not be greater than 65438 05% of the designed dosage.

3. Ensure the quality of steel fiber reinforced concrete bridge deck pavement.

4. Supervise the contractor to do a good job of vibrating and leveling the steel fiber reinforced concrete bridge deck.

5. Special technical requirements for steel fiber reinforced concrete pavement construction

(1) It is forbidden to use chlorine-containing additives and other additives harmful to steel fiber corrosion in steel fiber concrete on bridge deck.

(2) The construction speed of steel fiber reinforced concrete must be accelerated as much as possible, otherwise it will soon coagulate and spread because of its short setting time and fast hardening. Therefore, the longest allowable time of steel fiber reinforced concrete mixture from delivery to transportation and completion of paving should not exceed the regulations.

Note: * refers to the average daytime temperature during construction. After using retarder to extend the setting time, the values in this table can be increased by 0.20 ~ 0.35 h..

(3) In the process of pouring and paving, it is forbidden to add water, because the mixture is dry, but it can be sprayed to prevent the surface moisture from evaporating.

(4) Anti-skid grooves must be made of hard grooves, and anti-skid structures shall not be made of coarse sacks, brushes and brooms.

Three, asphalt concrete bridge deck pavement construction supervision and control points and measures

Asphalt concrete bridge deck pavement generally includes ordinary asphalt concrete and modified asphalt concrete, the latter is widely used. The following "asphalt concrete" generally includes ordinary asphalt concrete and modified asphalt concrete. Before the construction of asphalt concrete, the beam top or integral layer top of cast-in-place concrete should be flat, rough, dry and neat, free of dust, sleigh and oil pollution, and the cross slope of bridge deck meets the requirements. When it does not meet the requirements, it should be treated, and sharp protrusions and pits should be polished or repaired.

1. In order to ensure the construction quality of waterproof layer, the whole bridge deck must be laid. It can meet the requirements of no holes, no leakage, no broken lines, no warping and no wrinkles. Waterproof layer should be laid at the corner (yin and yang angle) and small parts with irregular shapes. Prevent damage to the waterproof layer. In recent years, M 1500 waterproof agent is often sprayed on the waterproof layer of bridge deck. During construction, the contractor shall be urged to strictly follow the product description and strictly manage to prevent insufficient spraying or leakage.

2 urge the contractor to construct viscous asphalt in strict accordance with the specification requirements.

3. Strictly control the quality of coarse aggregate and fine aggregate.

(1) The specification of coarse aggregate should be strictly controlled in the batching process of asphalt concrete pavement:

(1) Strictly deal with the maximum particle size of coarse aggregate to make it conform to the specification requirements.

(2) The particle size of coarse aggregate of each grade shall meet the requirements of Technical Specification for Construction of Highway Asphalt Pavement. When the produced coarse aggregate does not conform to the specification, but it is confirmed that the gradation matched with other materials can meet the use requirements of various asphalt surface minerals (the synthetic gradation of mixed minerals should meet the specification requirements), it can be used.

(3) The specifications of each block and the screen residue of each hole should be basically stable. If there is a big change, the reasons should be found out and corrected and controlled so as not to affect the gradation of the mixture.

(2) Asphalt concrete pavement should try not to use coarse aggregate and fine aggregate made of acid rocks such as granite and quartzite (the adhesion between aggregate and asphalt can not meet the requirements) or natural sand with poor adhesion to asphalt. If it is necessary to use it due to conditions, the contractor shall be urged to take the following anti-stripping measures: ① Dry-ground hydrated lime or quicklime powder is used, and cement is used as part of the filler, and its dosage should be 65,438 0% of the total mineral aggregate. (2) Adding anti-stripping agent into asphalt. ③ Coarse aggregate and fine aggregate treated with lime slurry.

(3) In the stockyard, the contractor shall be urged to pile aggregate according to different types, quality specifications, materials and sequence, and shall not be confused or taken at will, and the junction shall be separated by brick walls. Require the contractor's aggregate yard to be waterproof and pollution-proof; (1) The ground of the stockyard shall be hardened, and it shall not be directly stacked on the dirt ground. (2) Around the drainage ditch should be dug to prevent flooding. ③ Take other measures to prevent aggregate from being polluted. (4) Fine aggregate shall be covered with canvas and other scaffolding.

4. Strictly control the quality of (modified) asphalt ① When choosing (modified) asphalt brand, sampling test should be conducted first, and it can be selected only after it meets the design and specification requirements. (2) When the (modified) asphalt comes into the site, the quality inspection sheet of the refinery asphalt shall be attached. The arrival (modified) asphalt must be self-inspected, sampled and tested in strict accordance with the batch and frequency, and can only be used after all indicators meet the specification requirements. (3) Bitumen stored for a long time should be sampled and tested before use, and can only be used after it is qualified. Do not meet the requirements shall not be used.

5. Asphalt storage, transportation and storage methods should be appropriate. (1) in the process of using asphalt, the storage temperature shall not be lower than 130℃ and higher than 180℃. ② In winter, asphalt can be stored at low temperature during non-use period. ③ Good waterproof measures should be taken during the storage, transportation, use and storage of asphalt, such as sealed tank storage and transportation; Rain water or steam from heating pipes should be prevented from entering asphalt tanks (pools).

6. Strictly control the mix design of asphalt mixture. Before starting construction, the contractor must be required to design the mixture ratio in strict accordance with the design and specification requirements, and it can only be used after being reported to the laboratory of the supervision center for examination and approval.

7. Supervise the contractor to pave the test section of each asphalt bridge deck. The contractor shall be required to report the paving scheme and commencement report of each asphalt bridge deck test section, which can be implemented only after being approved by the supervisor. After the paving of the test section is completed, the contractor shall be urged to make a careful summary and report the report to the supervisor. After the supervisor approves it, the contractor may proceed to the next step.

8. The mixing of asphalt mixture is strictly controlled in the asphalt mixture yard (i.e. backcourt), and experienced supervision engineers are specially arranged for inspection. At the same time, the contractor must be required to arrange experienced technicians and operators for inspection to ensure the mixing quality of asphalt mixture.

9. Strictly control the transportation quality of asphalt mixture.

10. Strictly control the paving quality of asphalt mixture.

1 1. Strictly control the rolling quality and testing of asphalt mixture.

12. After asphalt concrete pavement construction, the location and treatment methods of expansion joints should be appropriate. If it is not handled properly, it may cause: insufficient compaction of asphalt concrete in the range of expansion joint notch, cracks and so on. The concrete surface of the expansion joint notch is uneven with the adjacent asphalt concrete pavement, which causes the vehicle to bump and the impact force is too large, resulting in premature cracking and damage of the pavement near the expansion joint.

13. Urge the contractor to take measures to ensure that the structural depth of the anti-slide layer meets the requirements.