Types of cracks in building structures
“Cracks”-a construction problem that plagues most people. Our company also often receives inquiries about cracks. Many owners find cracks on the walls, beams, floors, etc. of their houses. They are all worried about whether the cracks will Impact construction. Today we will tell you what are the types of cracks in building structures, as well as the choice of crack repair and reinforcement methods.
The focus of the crack repair project is to design the repair according to the type of crack, determine the repair material, repair method and time. For each method, the focus is: interface treatment, quality control of building construction crack construction process and repair quality inspection, building structure There are many ways to classify cracks. This article classifies cracks from the perspective of easy repair.
According to the causes of structural cracks, they can be roughly divided into the following four categories:
(1) Static crack
It is a crack caused by past events and its shape, size and number have stabilized and no longer developed. It is characterized by a stable width and length of cracks. The materials and methods used during repair can only be related to the thickness of the cracks, but to the stiffness or flexibility of the materials Nothing.
(2) movable crack
It is the crack width and length that can not be kept stable under the existing environment and working conditions, and it is easy to be closed and closed with the stress and deformation of the structural members or the changes in the ambient temperature and humidity, such as temperature cracks. When repairing, the cause should be eliminated and observed for a period of time to confirm that it is stable, and then repaired according to the treatment method of static cracks; when the cause cannot be completely eliminated, but it is confirmed that the safety of the structure and components does not pose a hazard, Repairs can be made with elastic and flexible materials.
(3) Unstable cracks
It is a crack whose length, width or number is still developing, but will terminate after a period of time. In general, such cracks should be stopped or repaired before they are repaired or strengthened, such as concrete shrinkage cracks.
(4) Unrepairable cracks
It is the crack whose width and length cannot be kept stable, which will become wider and longer with time. If the rust cracks along the longitudinal direction of the steel bars, no matter how fine the cracks, it will continue to develop.
Construction crack repair method:
(1) Surface closure method
For fine independent cracks (ω ≤ 0.2mm) and reticular cracks on the surface of concrete, a low viscosity and good permeability repair glue can be used to close the crack channels.
(2) Pressure grouting method
Used for large structure penetrating cracks, severe honeycomb defects of large volume concrete, and deep and winding cracks.
(3) Injection method
Use a certain pressure to repair the glue with low viscosity and high strength. Injected into the crack cavity. It is practical to reinforce and seal independent cracks, penetrating cracks and local honeycomb defects with 0.1≤ω≤1.5mm static.
(4) Filling and sealing method
V-shaped grooves with a groove depth of not less than 20 mm and a groove width of not less than 15 mm were cut along the cracks along the riding surface on the surface of the component and then filled with modified epoxy mortar or elastic joint filler material. For the treatment of active cracks and stationary cracks with ω≥0.5mm.