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A dowel bar is a small, round, smooth steel rod used to connect any concrete slab, column, or pavement mechanically without limiting the flexibility of the horizontal joint.
These bars are primarily utilized in jointed plain concrete pavement (JPCP) to support the increased stress and load caused by a moving vehicle. As d is the bar's diameter, the range of dowel bar lengths will be 45d to 50d.
The two types of dowel bars are stainless steel dowel bars and epoxy-coated dowel bars.
Contents:
Purpose of Dowel Bars
Dowel bars serve the following purposes:
- When two slabs are moved together, the impact loading created by the slab is reduced. Dowel bars transmit the weight from one slab to its neighboring slab.
- Corner cracking and joint faulting are reduced by using these bars.
- The performance of the paving joint is enhanced by these bars.
Size of Dowel Bars
Dowel bars are typically 18 inches long, 1.25 to 1.5 inches in diameter, and spaced 12 inches apart depending on the pavement's thickness. The dowel bars are either coated with epoxy or stainless steel to prevent rust.
Placement of Dowel Bars
The positioning of dowel bars involves the following steps:
- The bars must maintain a consistent 90-degree angle with the centerline.
- The joint or crack should have at least one-half of the dowel on each side, and a new channel must be carved for this purpose.
- These bars are generally positioned across the concrete pavement's transverse joints as the concrete movements occur at this place.
- They are placed near the middle of the slab and covered with a bond-forming substance to limit bonding to PCC.
- The dowel provides assistance in transferring loads, which makes it possible for neighboring slabs to expand and contract.
- The standard method for placing dowel bars when building new pavement is to lay 11 bars for a 12-foot lane commencing with the first bar placed 12 inches from the pavement edge, and all subsequent bars set 12 inches apart.
These bars are also used for slabs and columns in RCC walls in two different methods:
Method 1: The first method, which is the most popular and effective in terms of bonding, involves placing short-length bars in the desired location before pouring concrete. It is inexpensive since it doesn't need chemical bonding for bonding reasons.
Method 2: This method uses Hilti Chemical to fill the holes drilled into the concrete for strong bonding, but it is more costly since Hilti Chemical is required. This approach is used when extension bars are neglected before pouring concrete.
Advantages of using Dowel Bars
- The tension and deflection are decreased by using dowel bars.
- These bars help the slabs bear more weight by strengthening them.
- These bars also improve the initial pavement durability.
- Improvements in joint flexibility among the structural members.
- It increases the project's initial cost while lowering the life cycle cost.
Disadvantages of using Dowel Bars
- Problems arise during installation.
- Uneven and insufficiently compacted concrete around the dowel bars.
FAQs
A dowel bar is a small, round, smooth steel rod used to connect any concrete slab, column, or pavement mechanically without limiting the flexibility of the horizontal joint.
Dowel bars serve the following purposes:
1. When two slabs are moved together, the impact loading created by the slab is reduced. Dowel bars transmit the weight from one slab to its neighboring slab.
2. Corner cracking and joint faulting are reduced by using these bars.
3. The performance of the paving joint is enhanced by these bars.
Dowel bars are typically 18 inches long, 1.25 to 1.5 inches in diameter, and spaced 12 inches apart depending on the pavement's thickness. The dowel bars are either coated with epoxy or made of stainless steel to prevent rusting.
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