If the inspection of the components and the installation joint surfaces of prefabricated components is not in place before installation, two types of abnormal situations may occur. One is that the components cannot be installed. For example, the position deviation of the protruding steel bars of the lower components or cast-in-place layers is too large, the grouting sleeve is blocked or not vertical, the component itself has excessive size, etc., which will cause the components to be unable to be installed; the second is that the components cannot be installed. For example, the protruding steel bars of the lower components or cast-in-place layers are too short and cannot be inserted into the specified position of the sleeve, and the steel bars cannot form a reliable and effective connection. For example, the components have cracks, missing edges, and corners, which will cause the components to be unable to be installed.
When the composite slab is hoisted, if the independent support system is not firm and the elevation is not strictly controlled, the elevation of the four corners of the bottom surface of the composite slab may exceed the tolerance after the composite slab is hoisted, which will cause great trouble to the building structure acceptance and house decoration; the weak support is also likely to cause safety accidents. So, how can we install precast concrete components quickly and correctly?
Key Points for Inspection of Prefabricated Components Upon Arrival
First of all, strict control of the entire process of prefabricated component installation is a prerequisite for ensuring the quality of prefabricated component installation, and is also the basis for building qualified and high-quality prefabricated concrete buildings.
After the prefabricated components arrive at the site, they need to be inspected and accepted for their specifications, quantity, size, appearance quality, protruding steel bars, embedded parts, reserved holes, etc.
The surface of prefabricated components should be smooth and flat, and no serious quality defects such as missing edges, dropped corners, honeycombs, or rough surfaces should be allowed.
Key Points for Preparation Work Before Installation of Prefabricated Components
Inspection of the installation site. Check the specifications, quantity, location, and extension length of the steel bars to be connected to the prefabricated components. Also, check whether the cleaning, roughening, and wetting of the concrete installation joint surface meet the requirements.
Lay out the control lines for the installation of prefabricated components. Pop out the axis and control lines according to the construction drawings, and determine the component position edge lines according to the construction floor reference line and the construction drawings. Positioning marks such as component edge lines, center lines, and elevation control lines should be marked and distinguished.
Key Points for Temporary Support Installation and Removal
The upper support point of the vertical component should be set at 2/3 of the height of the prefabricated component; the support point of the vertical component on the ground should keep the horizontal angle between the inclined support and the ground between 45° and 60°.
Fix the footing of the vertical prefabricated component oblique support, preferably using the pre-embedded method, and pay attention to the accuracy of the pre-embedded position.
The spacing between independent supports of horizontal components must be strictly controlled and must not be increased arbitrarily. The distance between independent supports and the wall must also be controlled to ensure the stability of the entire system.
The temporary support system can only be removed after the strength of the post-poured concrete and grouting materials at the connection parts of the prefabricated components reaches the design requirements.