Prefabricated House Demoulding Method Tutorial

The demoulding of prefabricated houses should follow the following steps and key points:

I. Strength Requirements for Formwork Removal Before removing the formwork, ensure that the concrete strength meets the design requirements. If the design does not specify clearly, follow the current national standard 'Code for Acceptance of Construction Quality of Concrete Structures' (GB50204). For example, the removal of non-load-bearing formwork generally requires the concrete strength to reach above 2.5MPa to ensure that the surface and edges of the components are not damaged. For load-bearing formwork, a comprehensive assessment based on the span of the component and the growth of concrete strength is necessary to avoid structural deformation or collapse due to insufficient strength.

II. Special Requirements for Post-tensioned Prestressed Components For post-tensioned prestressed components, the side formwork should be removed before prestress tensioning to avoid hindering the transfer of prestress during the tensioning process. The removal of the bottom formwork should be handled on a case-by-case basis: if the component requires final tensioning (i.e., all prestressed tendons are tensioned), the bottom formwork should be removed after final tensioning; if only initial tensioning (partial prestressed tendon tensioning) is performed, the bottom formwork should be removed after initial tensioning is completed. This requirement aims to ensure the effective transfer of prestress to the concrete structure and avoid prestress loss or component cracking due to formwork constraints.

III. Demoulding Operation Requirements

1. Protecting Component Surfaces: During demoulding, use specialized tools (such as crowbars, hooks, etc.) to avoid directly striking or pulling the formwork to prevent defects such as scratches, missing edges, or chipped corners on the concrete surface.
2. Thoroughly Removing Connections: Before lifting the formwork away from the workstation, check and remove all bolts, buckles, and other connectors to ensure complete separation between the formwork and the concrete structure. When moving the formwork, operate slowly and steadily to avoid colliding with the edges of the component or reserved holes.
3. Assisted Demoulding Methods: For large or complex components, auxiliary measures can be adopted to reduce the difficulty of demoulding. For example, adjust the position of the component by flipping an iron frame, place flexible materials such as tires at the bottom as buffers, use the lever principle to stand the component up, and then separate the component from the formwork by pushing the tire or gently kicking. This method requires two people to cooperate and ensure coordinated movements to avoid component overturning or personnel injury.

IV. Subsequent Treatment of Formwork After removing the formwork, immediately clean any residual concrete, mortar, and other debris from the surface to prevent difficulty in removal after curing. After cleaning, evenly apply a release agent (such as water-based or oil-based release agents) to reduce the risk of sticking during the next use. For deformed or damaged formwork, repair or replace it promptly to ensure its flatness and stiffness meet construction requirements and avoid affecting the quality of subsequent components.