How the old and new concrete are connected, how the old and new concrete are connected

1. On the hardened concrete surface, remove the cement film, loose stones and weak concrete layer, and add fully moistened, rinsed clean and no stagnant water;

2. Before pouring concrete, first in the construction joint.

Spread a layer of cement mortar.

or cement mortar of the same composition as the concrete inside.

3. When pouring concrete, it is necessary to vibrate the secret chamber carefully to make the new and old concrete tightly combined.

4. The general situation is handled according to the construction joint, including cleaning and chiseling.

Cleaning, (setting up water stop strips), sweeping cement slurry, pouring concrete, curing, etc. However, the connection of new and old concrete in the form of non-construction joints can be connected by adding bolts and other methods according to the actual situation.

Personally, I think that the treatment of concrete should first depend on the direction in which the concrete is stressed, and the position is not important.

1. Under conventional pressure, the foundation, plate, and light pavement can be treated according to the construction joints: cleaning, chiseling, cleaning, (setting up waterstop strips), sweeping cement slurry, post-pouring concrete, curing, etc.

2. There are tensile requirements, columns, beams, can be considered to be connected with the old concrete reinforcement, if there is no reinforcement skeleton, should be used drilling and planting reinforcement method, pre-planting reinforcement, and then pouring. Note that it is best to use an interface agent connection.

3. Note that concrete is mainly compressive, and the joints should be minimized.

1. First of all, on the surface of the old concrete that has been hardened, chisel away the loose stones, chisel into a convex and concave surface, and remove the weathering, deterioration, honeycomb, hemp surface and loose part of the old concrete, and then remove the cement film and loose stones and the weak concrete layer, and add it has been fully wetted, and then rinse it clean and no stagnant water shall be retained.

2. In the second step, before pouring concrete, the surface is brushed clean with hot alkaline water, and then immediately rinsed with clean water to prevent oil from blocking the combination of new and old concrete, and then a layer of cement mortar or cement mortar with the same composition as the concrete is laid at the construction joint.

3. In the third step, when pouring concrete, the anchor bar is embedded on the old concrete to connect it with the new concrete. It is also possible to drill holes in old concrete and anchor bars with structural glue. Then carefully vibrate the chamber so that the old and new concrete are tightly combined.

4. In the last step, Fengru is treated according to the method of disturbing fiber joints, and after the slurry on the surface of the old concrete is removed, it is necessary to wipe the high-grade cement mortar or the silver Li Qi treatment agent on the interface to increase the cementing force. However, the connection of new and old concrete in the form of non-construction joints can be connected by adding bolts and other methods according to the actual situation.

The hydration products of the interface layer grow in the old concrete or extend into the voids of the old concrete to form a dense structure, and the unhydrated or incompletely hydrated part of the old concrete grows in the new concrete. The physical-mechanical meshing force formed by the very rough surface of the old concrete.

The Van der Waals force of the interface is mainly caused by the molecular interaction between the crystals in the old and new concrete, and the main chemical force is the reaction of the cement hydration products in the old concrete with the interface agent to generate new substances and bond the new and old concrete together.

Generally, the greater the roughness of the bonding surface, the higher the bonding strength of the new and old concrete. However, when the roughness reaches a certain level, its influence on the bonding properties of new and old concrete is weakened.

In order to reduce the floating slurry skin and weak mortar layer of the old concrete, the concrete mix ratio and pouring speed should be strictly controlled at the horizontal construction joints to ensure that its quality is solid on the inside and less floating slurry on the outside, so as to avoid concrete segregation at the joints; There should be no loose aggregate particles on the surface of the joint, and the surface should be brushed with a wire brush as soon as possible after hardening, and the following work should be done before pouring new concrete: 1) In order to eliminate the deformation of the formwork due to expansion or contraction, re-strengthen the formwork. 2) Use compressed air or water jet to remove the debris on the surface of the old concrete and the mortar adhered to the formwork.

3) Make the surface of the old concrete fully absorb water and soak it, but there is no excess water. 4) Pour a few centimeters of cement mortar first. When pouring new concrete, it is necessary to fully vibrate both sides of the construction joint, which is combined with the dense range of concrete.

In order to reduce the temperature difference of the new concrete, the method of cooling the new concrete of the joint or heating the old concrete is adopted.

To obtain the best adhesive strength at the joint of the old and new concrete, the main thing is to remove oil and dust, if necessary, the interface is haired, reinforced, and fully sprinkled with water and then poured with concrete mortar of the same grade!

The construction surface of the old concrete should be chiseled to expose the aggregate, and the loose materials such as slurry and sundries should be removed before the new concrete is poured, and the mixture will be mixed.

The concrete stubble surface is fully moistened. In the junction of the old concrete and the new concrete, the 1:1 cement mortar grouting treatment is adopted, and attention is paid to the treatment of the cooling of the new concrete and the heating of the old concrete.

The use of interface agent and planting reinforcement can increase the integrity of concrete.

I checked the information, and the process is like this:

1. On the hardened concrete surface, remove the cement film, loose stones and weak concrete layer, and add fully moistened, rinsed clean and no stagnant water;

2. Before pouring concrete, lay a layer of cement mortar or cement mortar with the same composition as the concrete at the construction joint.

3. When pouring concrete, you need to carefully vibrate the secret room to make the old and new concrete tightly combined, I hope it will help you.