How to connect old and new concrete structures
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Encountered this on site: the foundation of the moving equipment needs to be raised. How should the concrete structures from the old and new concrete be connected? Question for all experts out there
It is understood that the old concrete should be chiseled to create a rough surface; an interface agent is used at the boundary between the old and new concrete, and the structure is enlarged to meet the new required dimensions. I’m not sure if it’s reasonable: o
From what I observed on site, the actual procedure involves roughening the existing foundation to expose the rebar inside the concrete, connecting the rebar of the new structure to the old rebar (welding is the best method), and then pouring concrete by installing formwork according to the new requirements
What the original poster means is to add something on top of the existing structure. In my opinion, the main factors that need to be considered are providing vertical reinforcement, in addition to treatments such as texturing the surface, as well as increasing the grade of the concrete used for pouring later. Please correct me!
(Transferred) The construction team’s approach: the existing surface is roughened, and the rebar is extended (when welding steel bars, low-hydrogen electrodes are used for single-sided welding, with a weld length of 15D)； Double-sided welding, weld length 7D ； Depending on the specific circumstances, bonding can also be used; to enhance the strength of the joint, the grade of the concrete poured later is increased, and an interface agent is used between the old and new concrete. Experts, please offer your feedback and suggest better approaches:$
I agree with what was said above; however, the junction between the old and new concrete is the weak point of the entire structure. The stress on this weak area needs to be calculated, but it wasn’t taken into account during construction. If the foundation of the equipment is large, reinforcing bars can be used, without affecting the rebar in the existing foundation. But no matter what method is used, it is essential to remove any loose material from the surface that has been roughened on the original foundation; after cleaning it with water, an interface agent should be applied.