Site preparation before installation
A be familiar with the drawings and installation procedures, and check and accept the flatness, straightness and joint clearance of the special-shaped side beam of expansion joint.
Mechanical equipment and small machines are well equipped. In particular, the bridges provided by construction vehicles must be solid in quality and sufficient in quantity to ensure the smooth construction.
C, prepare enough canvas, plastic sheeting, tape and other materials to prevent road pollution.
D prepare enough plastic films, grass stalks, water carriers, etc. For maintenance.
grade
A. After the asphalt concrete pavement of bridge deck is completed (continuous paving covers expansion joints) and accepted, determine the groove width according to the requirements of construction drawing, accurately set out, saw the joints with a cutting machine and straighten them. The asphalt concrete pavement except the sawing seam must be carefully covered with plastic sheets and sealed with adhesive tape to prevent the stone powder produced during sawing from polluting the pavement. Sawing seam should be neat and straight, pay attention to cut through asphalt concrete to avoid loosening concrete outside the seam when slotting.
Pneumatic pick for groove B. The depth of grooving shall not be less than 12cm, and the asphalt concrete and loose cement concrete in the grooving shall be chiseled clean to the hard layer, and the floating dust and sundries shall be removed with a powerful blower or a high-pressure water gun. After slotting, vehicles should be prohibited from passing, and it is forbidden for construction personnel to trample on the edges on both sides of the slot to avoid damaging the asphalt concrete on both sides of the slot.
C, sundries in the gap between the beam ends, especially concrete blocks, must be cleaned up, and then filled with foam plastic. If there is a beam slab from the top to the back wall, the beam end should be chiseled away.
D, straighten out and adjust the embedded steel bars in the groove, repair the missing or broken embedded steel bars, and evenly replant them with steel glue or epoxy resin, with the replanting depth not less than 15cm. Please ask the owner's representative and supervisor to check the replanted reinforcement.
E, all waste generated after slotting must be cleared in time to ensure the cleanliness of the construction site.
Joint installation
A. Before installing the expansion joint, when the actual temperature during installation is quite different from the factory temperature, the clearance value of assembly and positioning should be adjusted. The positioning width error of expansion joint is 2mm, and the required error is the same symbol. Positive and negative errors are not allowed at the same time in different positions of joints.
B during installation, the center line of expansion joint coincides with the center line of beam end. If the expansion joint is long, it needs to be transported in sections, and then docked after arriving at the site. When docking, the upper planes of the two expansion joints should be placed on the same horizontal plane, so that the joints of the two expansion joints are close together and aligned. Use high-quality covered electrode to weld one by one. When welding, the top surface should be welded first, then the side surface, and finally the bottom surface. Should be layered welding, ensure the quality, and timely removal of welding slag. After welding, smooth the top surface with a portable grinder.
Elevation control and fixation of C-type expansion joint
Gantry crane and 10× 10 angle steel are used as positioning angle steel, so that the top surface of expansion joint is about 2 ~ 3 mm higher than the standard height of asphalt concrete surface on both sides, and the elevation of expansion joint is controlled, and then the longitudinal straightness of expansion joint is also adjusted. After the elevation and straightness of expansion joints are adjusted to meet the design requirements, temporary fixation can be carried out. When fixing, the anchoring device on the side beam of expansion joint and the embedded steel bar in the reserved groove should be welded with a solder joint every 2-3 anchor bars in turn from one end of the bridge width to the other end, and the two sides should be welded symmetrically to ensure that the expansion joint will not shift again after leveling. It is forbidden to weld from one end to cause expansion joint warping. The steel bars bound and formed shall be padded with steel bar heads.
Welding of d-type expansion joint
After fixing, the elevation of expansion joint should be re-measured. After confirming that there is no deformation or deviation in the process of temporary fixation, the anchoring reinforcement and embedded reinforcement on the special-shaped steel beam should be welded on both sides at the same time, preferably at one time. If there are difficulties, you can weld one side first, and then weld all the other sides after reaching the predetermined installation temperature. Pay attention to the distance between the solder joint and the section steel not less than 5cm to avoid deformation of the section steel. At the same time of welding, it is necessary to detect the flatness of special-shaped steel with a three-meter ruler and a feeler gauge at any time, and the flatness should be controlled within the range of 0-2mm, otherwise it is easy to bump. In fixed welding, there is often a phenomenon that the embedded steel bar in the reserved groove is inconsistent with the anchoring steel bar of the special-shaped steel beam. U-shaped, L-shaped and S-shaped steel bars should be used for reinforcement to ensure the firm connection between the joint and the beam. The weld length at the joint should be no less than 10cm, and shallow contact should be adopted according to the specification requirements to ensure the welding length. Spot welding, skip welding and missing welding are strictly prohibited. After the expansion joint is welded firmly, the preset temporary fixing fixture and positioning angle steel should be cut off with a gas cutting gun as soon as possible to make it expand freely. At this time, the site should be strictly protected to prevent the vehicle from being pressed by mistake.
E template installation. The formwork is made of foam board, fiberboard and metal plate. Formwork shall be firm and tight, and shall not move when concrete is vibrated, and prevent mortar from flowing into expansion joints, so as not to affect expansion and contraction. In order to prevent concrete from entering the inner groove of the steel from the upper seam, the top of the steel must be sealed with adhesive tape.
F steel mesh should be set on both sides, and the top of ribbed steel mesh should be 3cm lower than the road elevation, and φ 5 ribbed steel mesh (10× 10) anti-crack steel mesh should be set.
G. The concrete construction of bridge expansion joints will cut off the drainage of blind ditches on both sides of the bridge, resulting in water damage of bridge deck pavement. The water in the blind ditch outside the bridge deck should be drained by plastic hoses, and the drainage hoses should be buried in place when pouring concrete.
concrete pouring
A. Before pouring, plastic sheets should be laid on both sides of the joint to ensure that the concrete will not pollute the pavement.
B concrete vibrating must be carried out on both sides at the same time. In order to ensure the compactness of concrete, especially the compactness of concrete under section steel, use vibrating rod to vibrate until there are no more bubbles.
C. After the concrete is vibrated and compacted, rub out the cement slurry with a trowel and press it regularly for 4-5 times. Pay special attention to smoothness in this process. The concrete surface should be slightly lower than the top surface of asphalt pavement 1-2mm. Too high or too low will cause the vehicle to bump.
Health maintenance
A, after the completion of the cement concrete pouring, covered with sacks or straw, strict sprinkler maintenance, maintenance time of not less than 7 days. Vehicles are not allowed to pass during the health maintenance period.
B, after curing, after the strength of cement concrete reaches more than 50% of the design strength, rubber sealing strips can be installed. Before installation, all leaking foam boards, fiberboards and concrete blocks must be cleaned and embedded in rubber strip.
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