Application of chemical anchor in curtain wall
-In the curtain wall project, embedded parts are usually used to connect the main keel to the main body of the building, so that the strategy of the curtain wall is passed to the foundation project. For light curtain walls such as metal curtain walls and glass, the requirements on the stress of the embedded parts are relatively simple; such as stone curtain walls, their own heavy loop curtain wall projects (general stone curtain walls 90 ~ 120kg / m2) and general The area is larger in all cases. Therefore, the stress requirements of the embedded parts are higher. At the same time, the main keel of the stone curtain wall mostly adopts about 6m profile steel and spans about 2 floors. According to the requirements in the acceptance specifications of the stone curtain wall, there must be 3 ~ 5 anchor points within 2 storeys. Embedded parts often use iron plates of 200mmx300mm. Therefore, it is impossible for the embedded part to have much adjusted bit value, which requires the construction position of the embedded part to be quite accurate.
-In general, the embedded parts are placed on the reinforcement before the concrete is poured.During the harbour and vibration of the concrete, some of the parts may be displaced and their positions cannot meet the requirements of the main keel of the curtain wall for the embedded parts. This requires the use of post-implantation methods to repair and anchor point locations.
-How to make the quality of the post-embedded embedded parts meet the stress requirements of the embedded parts in the acceptance specification has always been a difficult problem in curtain wall engineering. In recent years of construction, we have tried to use chemical bolts to post-embedded parts to add embedded parts at the required locations to meet the requirements of the curtain wall for the embedded position. Sometimes the anchoring point is set by chemical post-embedding method in the construction of the whole curtain wall, which helps the position of the embedment to be accurate and reduces the waste of construction. The post-embedded embedded parts are shown in the figure:
-Because the embedded parts were later added to the concrete, its own limitations determine the particularity of the anchoring method and construction technology of the embedded parts, and its construction quality will directly affect the safety performance of the curtain wall. Therefore, it has become the focus of attention of all parties. The experience gained in the construction of the embedded parts behind the curtain wall in the past few years is recorded for your reference and correction.
-There are two inherent methods for anchoring embedded parts. One is to anchor the embedded part with expansion bolts. In this way, the anchoring force of the expanded shell anchor is relatively restricted by objective conditions, and its ability to resist corrosion after long-term exposure to air is also poor. Even if the same expansion bolt is used on the same concrete, the anchoring force also changes greatly, which is mainly due to the quality change caused by the workers’ construction operations. Another method of anchoring the embedded parts is to use chemical bolts to anchor the embedded parts, and use a saturated resin (the entry “resin” provided by the industry encyclopedia) to firmly bond the anchor rod with the concrete (the entry “bond” by the industry Encyclopedia provided), the resin also protects the anchor rod from corrosion.
-There are two types of anchoring adhesives commonly used, one is an equal mixing type; the other is a fast-drying dosage form, that is, a certain proportion of catalyst is added to the anchoring adhesive to enable the anchoring adhesive to reach a predetermined strength within a specified time.
-The concrete construction process of anchoring iron plates with chemical bolts is now described as follows:
-(1) Cleaning and positioning of the base layer, cleaning and leveling the surface of the concrete at the required position of the anchor point, and sintering the ordinary clay (the entry “sintering” provided by the industry encyclopedia) bricks will reduce the strength of the chemical bolt by 3 ~ 5 times, can make the iron plate flat.
Application of chemical anchor in curtain wall
-(2) The position of the hole is 5D from the edge of the concrete (D is the diameter of the anchor rod). In special cases, the steel bars in the concrete need to be cut off, and the construction must be approved by the relevant engineer.
-(3) The drilling should be perpendicular to the concrete wall surface, so that the anchor bolts and buried iron are vertical.
-(4) Chemical anchoring (the entry “Chemical anchoring” provided by the industry encyclopedia) Iron plate also has very strict requirements on the diameter of the drilled hole in the concrete. The diameter of the drilled hole is too small to function as an anchoring glue. Generally, the diameter of the drilled hole is 4 to 5mm larger than the diameter of the anchor rod, and the depth is 100mm, so that the anchoring adhesive can fully contact the anchor rod and the amount of anchoring adhesive can be saved.
-(5) The cleaning of the borehole is a very important part. The dust in the hole will play a very important role in the anchoring glue. You can use a high-pressure air pump to clean the dust in the hole. The method of the air cylinder, the diameter of the brush used should be about the same as the diameter of the hole. Use the brush to push and pull in the hole several times to clean the dust in the hole and then blow it a few times, so that the dust in the hole is repeated several times. Clean up thoroughly. Water washing method cannot be used to clean the dust in the holes, because the anchoring glue and water are incompatible, and the nature of the concrete determines that it is easy to form a medium on the surface of the anchoring glue and affect the anchoring force of the anchoring glue.
-(6) The injection of the anchoring glue into the hole should be done by split injection. The anchoring glue is mixed in the required proportion so that the setting time of the anchoring glue is controlled within 30 minutes, so that there is sufficient time to inject the anchoring glue into the hole. . Some anchoring glues are relatively viscous and easily generate air bubbles when injected into the holes, which seriously affects the anchoring quality of the anchoring glue. Some of the anchoring glue is closed, and it is not easy to generate air bubbles.
-(7) Slowly push the anchor rod into the hole to prevent waste from overflowing the anchoring glue, but stop pushing the anchor rod into the hole when the anchor rod is exposed 40mm, and then transfer the anchor rod clockwise inside the hole 2 ~ 3 weeks to make the anchoring glue completely contact the anchor rod.
-(8) After the anchor rod is at rest for 3 hours in the anchorage, most anchoring glue can reach the required strength, and the embedded parts can be installed on the anchor rod.
