Tie Bars and Dowel Bars- Application and Advantages

What are Tie Bars?

The tie bar is the deformed rebar or connection used to hold the stiff slab in place and create the aggregate interlock between the slabs. Although the load is not transferred, minimal load transfer is occasionally possible. It’s employed to reduce transverse cracking. Moreover, it prevents segregation and unequal lane deflection.

Application of Tie Bars: 

1. It’s used for minimizing diagonal cracking.
2. To keep the concrete aggregate interlocked, tie bars are utilised to hold the faces of stiff slabs in close proximity.
3. It is used to connect two lanes on a simple jointed concrete pavement and aids in preventing lane separation and differential deflection.

Advantages: 

1. Two lanes are joined by it.
2. Cracking is lessened.
3. Separation and disparate deflection are avoided.
4. High deflection and excessive tension are prevented.

Specifications:

The width of the slab and the thickness of the concrete surface determine the size of the tie bars. The tie bars are typically formed of TOR steel bars and range in diameter from 12 to 16 mm.

The bar ranges in length from 550 to 640 mm. After one lane is paved, tie bars are installed one at a time, either manually or with the aid of a tie bar installer. Installed in the middle of the slab, the tie bar is bent back until the neighbouring lane is ready for paving. When slip-form pavers are utilised, the tie bar is put at the slab edge, creating a longitudinal junction.

What are Dowel Bars?

A dowel is just a cylindrical rod that can be constructed of plastic, wood, or metal. A dowel bar is typically made of short, round, mild steel bars with no resistance to horizontal movement at the junction. It is used to mechanically link many slabs to the bars. It can also be described as the steel reinforcing bars that are extended in a framed structure to a specific length in preparation for the building of the concrete. Typically, round steel bars are installed in concrete structures to distribute the load evenly throughout the structure and prevent joint movement.

Application:

• 1. It is applied to join the new and old concrete structures.
• It is utilised to join the column at the slab’s level in order to join the following column and slab.
• It is applied to enhance the functionality of the paving joints. It lessens the load’s impact on the joints of the pavement.
• It is used to lessen corner cracks. The usage of the dowel bars generally reduces the rate of concrete deterioration in the structure’s corners.
• It is utilised to transfer the load from one slab to the other since it links two slabs, either new or old.

Advantages:

1. The weight-carrying capacity of the slab is increased because the load is transferred from one slab to the other. 
2. It extends the lifespan of the pavement by enhancing the performance of the joints and decreasing the impact of load on the joints.
3. It lessens the tension and deflection on the concrete.
4. If the dowel is offered, expanding the structure is simple.

Specifications: 

The size of the dowel bars needed depends on the pavement’s thickness. The dowel bars are typically 460mm long, 32 to 38 mm in diameter and 305 mm apart from one another.

To prevent corrosion, the dowel bars are either coated or constructed of stainless steel. Always place dowel bars in the middle of the slab. They are positioned across the concrete pavement’s transverse joint to provide mobility.

Because the surrounding slab will expand and contract together, the dowel will distribute the load. The bars are positioned parallel to the slab’s midline.

Differences between Tie Bars and Dowel Bars