Several Points Worth Noting when Dismantling Hollow Plastic Templates

Several points worth noting when dismantling hollow plastic templates

In the construction process, Hollow Plastic Formwork is gradually being widely used due to its many advantages such as light weight, high strength, smooth surface, and reusability. However, to ensure construction quality and good turnover of formwork, there are a series of important precautions that cannot be ignored when removing the shuttering.

Grasp the appropriate demoulding time

The strength development of concrete is a gradual process. If the formwork is removed too early and the concrete strength does not reach a sufficient level to support itself and the upper structure load, it is highly likely to lead to serious quality and safety accidents such as cracks, deformation, and even collapse of the concrete structure. Different building parts have different requirements for concrete strength. For example, for non load bearing side formwork, it can only be removed when the concrete strength can ensure that its surface and edges are not damaged due to the removal of the formwork. Generally, it should be removed 1-2 days after the concrete is poured (depending on specific factors such as temperature, cement type, and mix proportion). For load-bearing formwork such as beams, slabs, etc., the dismantling time must be strictly determined based on the design strength grade of the concrete. Demolition is only allowed when the concrete strength reaches 75% or more of the design strength (for beams and slabs with spans less than 8m) or 100% (for beams, slabs, and cantilever components with spans greater than 8m). In practical operation, it is possible to accurately determine whether the concrete has reached the specified demoulding strength through on-site production of concrete test blocks cured under the same conditions and testing.

Follow the correct demoulding sequence

The order of demoulding should be based on the principles of supporting before dismantling, supporting after dismantling, non load bearing parts before load bearing parts, and from top to bottom. For example, when dismantling column formwork, the column hoops and connecting bolts should be removed first, and then the formwork should be gently pried to detach from the concrete. For beam and slab formwork, first remove the beam side formwork, then remove the slab bottom formwork, and finally remove the beam bottom formwork. When dismantling a large area of floor formwork, it should be gradually removed from the mid span to the surrounding areas to avoid uneven structural deformation caused by concentrated removal of one side of the formwork. Meanwhile, during the demolition process, attention should be paid to protecting the surrounding completed concrete structures to prevent damage caused by collisions during template removal

Adopt appropriate demoulding techniques

When dismantling hollow plastic formwork, it is strictly prohibited to use tools such as hammers or pry bars to violently strike and pry the formwork. This not only causes serious damage to the formwork, affecting its reusability, but may also damage the surface of the concrete structure, resulting in quality problems such as rough surfaces, missing edges and corners. Special demoulding tools, such as pry bars, should be used to gently pry the formwork from the joints to gradually detach it from the concrete surface. For some parts that are tightly bonded to concrete, thin iron sheets can be inserted between the formwork and concrete for separation, and then the formwork can be slowly removed. During the process of template removal, a dedicated person should be arranged to command and ensure the safety of the operators, in order to avoid accidents caused by the sudden fall of the template resulting in casualties.

Clean and maintain templates properly

After the template is removed, it should be cleaned in a timely manner. To remove residual concrete, cement slurry, and other debris from the surface of the formwork, tools such as shovels and wire brushes can be used, but care should be taken to avoid damaging the formwork surface. After cleaning, inspect the template and promptly repair any deformation, damage, or other issues. For templates with slight deformation, they can be corrected through methods such as cold bending or hot bending; For severely damaged templates, replacement is necessary. At the same time, classify and store the cleaned and repaired templates properly for future use. Proper cleaning and maintenance of templates can not only extend their service life and reduce construction costs, but also ensure their effectiveness in subsequent construction and improve the quality of concrete structure formation.