Why do we need to add back reinforcement to stone?
What is the function of stone back reinforcement? What material should be used for the back reinforcement of stone?
What are the main reasons for the rusting of steel bars?
What are the technical requirements for marble back reinforcement?

PART01

What is stone back reinforcement?

Stone back reinforcement refers to the method of adding steel bars through grooves on the back of marble (usually marble needs to be reinforced), which is a way to reinforce marble and prevent it from breaking. After cutting stone into boards, the thickness is very thin and it is very easy to break. In order to increase the strength of the stone, it is necessary to ensure that the stone does not break during processing, transportation, and installation to avoid affecting the overall aesthetic.

Stone back reinforcement is actually a type of “planting reinforcement” technology (steel bar rooting technology). “Planting reinforcement” technology refers to drilling holes on the original concrete structure, injecting structural adhesive, and rotating new steel bars into the holes. This technology is widely used for design changes, adding reinforcement and modification projects such as beams, columns, cantilever beams, and slabs.

PART02

What are the materials for stone reinforcement?

The materials of stone back reinforcement bars include iron, galvanized, stainless steel, copper, aluminum alloy, and fiber, each of which has its own characteristics in strengthening marble. The most ideal reinforcement material is stainless steel bars, which will not rust and have high reinforcement strength, but the cost is high.

Plastic rods are flexible materials that do not have sufficient reinforcement strength when reinforcing large-sized, slender, or heavy stones. In these situations, plastic rods cannot be used for reinforcement.

Considering cost and reinforcement strength factors, general stone enterprises choose steel bars as stone backing bars.
However, everything has its pros and cons. Although adding steel bars to marble can provide reinforcement and protection, it may lead to a type of stone damage, and it is also an extremely difficult to treat stone damage, which is the rusting of steel bars. The problem of difficult treatment of steel bar rust has had a negative impact on the stone industry.

PART03

Why does the steel bar rust and deteriorate?

1. Iron reinforcement bars are eroded by moisture during stone processing, gradually oxidizing and rusting, and then migrating to the surface of the stone through the fine pores, forming regular rust spots.
2. After the installation of the stone, the reinforcement strip of the back reinforcement is corroded by the acidic water vapor of the cement in the stone base layer, which oxidizes and rusts, and migrates to the surface of the stone to form yellow rust spots.
The rust caused by the back reinforcement of iron stone cannot be completely treated. Due to the fact that the pollution source is inside the stone, the stone is corroded by acidic substances and water vapor in the base layer after installation. As the water vapor continues to rise, pollutants continuously migrate to the surface of the stone, forming stubborn rust spots. Even if rust removal products are used to temporarily restore some of the rust stains on the surface of the stone, there is still a possibility that the rusted back bars of the pollution source will continue to rust.
The rust spots caused by the back reinforcement bars of iron stone cannot be completely cured, so it is necessary to strictly control the installation process and correct material selection when implanting reinforcement bars in the stone. To avoid adverse effects on the stone industry, try not to use iron backing bars, especially light colored marble.

PART04

What are the technical requirements for marble back reinforcement?

01. Requirements for board thickness
The diameter of the steel bars reinforced with marble engineering boards is usually 6mm, and the depth of the groove for adding steel bars is 8mm. If the distance between the 20mm thick engineering slab steel bars and the stone surface is between 11mm and 12mm, even if the steel bars are buried in the stone and rust, the possibility of rust penetrating the stone surface by 12mm is extremely small.
However, now the thickness of the large slab has increased from 20mm to 15mm, and there are even thinner ones. Based on the 15mm thickness of the slab, the distance between the steel bars and the stone surface is only 7mm, and even less than 7mm. The steel bars rust, and rust can easily rise to the stone surface with the help of water inside the stone. This is a very important reason for the surface damage of stone caused by the rust of steel bars used as backing bars.

If steel bars are added to the 12mm thick stone in the picture, only 4mm diameter steel bars can be added. If 6mm steel bars are added, the distance between the steel bars and the surface of the stone is less than 5mm.
Suggestion: For marble reinforced with steel bars as backing bars, the distance between the steel bars and the surface of the stone should be>10mm. Once the steel bars rust, the rust will not easily rise to the surface of the stone. Of course, if the waterproofing of the stone is done well, this possibility will not exist. Therefore, the waterproofing of stone reinforced with steel bars as backing bars should be done well to prevent water from seeping into the stone.
02. Requirements for rust and oil removal of steel bars
Steel bars are highly susceptible to rusting, and they quickly rust when placed in a damp environment. Therefore, when marble uses steel bars as backing bars, it is necessary to carefully remove rust to achieve a rust free surface of the steel bars.
03. Requirements for cleanliness and dryness inside the steel reinforcement groove
Drying the steel bars in the groove can prevent rusting of the steel bars in the stone, but many stone processing enterprises do not strictly adhere to this process requirement. Once the steel reinforcement groove is opened, use a gas pipe to blow the water inside the groove. If there is no water on the surface of the groove, add steel reinforcement.
In this case, adding steel bars will cause the moisture in the stone to rust under long-term action after sealing the steel bar groove with glue. If the stone is very thin, the rust can easily rise to the surface of the stone, causing it to turn yellow.
04. Requirements for glue and modulation
Special adhesive should be used for reinforcing steel bars, and the adhesive should be prepared strictly in proportion. After reinforcing the steel bars with glue, the glue should be firmly combined with the steel bars.
Some steel bars and glue are not tightly and firmly bonded together, and when the steel bars are forcefully pulled out, they detach. The glue does not wrap the steel bars at all, and water passes through the glue, causing the steel bars to rust.
05. Quality requirements for large board adhesive repair

If steel bars are added to the 12mm thick stone in the picture, only 4mm diameter steel bars can be added. If 6mm steel bars are added, the distance between the steel bars and the surface of the stone is less than 5mm.
Suggestion: For marble reinforced with steel bars as backing bars, the distance between the steel bars and the surface of the stone should be>10mm. Once the steel bars rust, the rust will not easily rise to the surface of the stone. Of course, if the waterproofing of the stone is done well, this possibility will not exist. Therefore, the waterproofing of stone reinforced with steel bars as backing bars should be done well to prevent water from seeping into the stone.
02. Requirements for rust and oil removal of steel bars
Steel bars are highly susceptible to rusting, and they quickly rust when placed in a damp environment. Therefore, when marble uses steel bars as backing bars, it is necessary to carefully remove rust to achieve a rust free surface of the steel bars.
03. Requirements for cleanliness and dryness inside the steel reinforcement groove
Drying the steel bars in the groove can prevent rusting of the steel bars in the stone, but many stone processing enterprises do not strictly adhere to this process requirement. Once the steel reinforcement groove is opened, use a gas pipe to blow the water inside the groove. If there is no water on the surface of the groove, add steel reinforcement.
In this case, adding steel bars will cause the moisture in the stone to rust under long-term action after sealing the steel bar groove with glue. If the stone is very thin, the rust can easily rise to the surface of the stone, causing it to turn yellow.
04. Requirements for glue and modulation
Special adhesive should be used for reinforcing steel bars, and the adhesive should be prepared strictly in proportion. After reinforcing the steel bars with glue, the glue should be firmly combined with the steel bars.
Some steel bars and glue are not tightly and firmly bonded together, and when the steel bars are forcefully pulled out, they detach. The glue does not wrap the steel bars at all, and water passes through the glue, causing the steel bars to rust.
05. Quality requirements for large board adhesive repair

Carefully follow the process, standardize and standardize the work, and ensure that the back reinforcement stone does not undergo any damage.
The function of marble back reinforcement is only to reinforce the stone. Is there any other way to reinforce the stone? Feel free to leave a comment in the comments section.