What is Dowel Bar in Construction?

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Introduction:
In the modern world, concrete is the most popular building material for many different types of buildings. Concrete pavements are one of the essential components of a construction site. Concrete slabs are made and put in place to make a solid pavement that can handle the traffic. Construction workers use dowel bars to ensure these pavements are strong and stable. These bars help make sure that the concrete slabs are mechanically connected in the right way.

Fig: Dowel Bars in Construction
Courtesy: Connect2india

What is Dowel Bar?
A dowel bar is a small circle, and a flat steel rod is used to help a technical joint between slabs that doesn’t restrict parallel movement. Most of the time, these bars will be used to attach cement pavement to the surface to hold in the extra pressure and weight of moving vehicles. Its diameter can be between 32 mm and 38 mm, and its length can be between 32 mm and 60 mm. The usual rule is to put them 305 mm apart on concrete slabs where there will be a lot of foot traffic.

Usually, these bars are smooth and coated with stainless steel to keep them from rusting. Some dowel bars are covered with epoxy so that they won’t stick to plain cement concrete (PCC). Notably, if a dowel bar is green, it has an epoxy coating. If it is shiny, it is covered with stainless steel.

The function of Dowel Bar:
The load is moved from one slab to another and the slabs’ natural ability to move and shift together reduces the amount of shock energy they can store. Reduce edge brokering and blame shifting at the junction. Building pavement connections is an activity we intend to cultivate. The dimensions of the dowel bars that served as the design’s foundation can be used to calculate a walkway that is 18″, 1.25 to 1.5″, and 12″ wide. Pure steel prevents rusting of the bars.

Purpose of Dowel Bar:

• The purpose of the dowel bar is to make joints work better.
• Dowel bars are kept to move weight across joints in concrete.
• Dowel bars are used to make joints less likely to break.
• It is used to stop corners from breaking.
• It is used to move the load from one member, like a slab, to another member, like another slab.

Uses of Dowel Bars:
Dowel bars connect two slabs of jointed plain cement concrete (JPCP) mechanically. These slabs are made and put in homes and businesses to handle a lot of foot traffic. This bar reduces bending and stress on the pavement’s leave and approaches concrete slabs. Their installation keeps the concrete slabs from moving side to side, making them better at moving loads.

Types of Dowel Bars:
i) Stainless Steel Dowel Bars:
Most stainless steel dowel bars are made from simple, round pieces of metal. They offer a way to connect concrete or other structures that will last and won’t rust. Since they come in different diameters, materials, and strengths, there is usually a dowel bar that is right for the job. Dowel bars are used to move weight from one concrete slab to another while allowing for thermal expansion along the axis of the dowel.

ii) Epoxy Coating Dowel Bars:
The dowel bar should be coated with an epoxy coating material picked from the official epoxy coating of steel. Once the coating is dry, it must be at least 7 milliliters thick. Dowel bars with bowling or other deformation controls can’t slide into the concrete. The point needs to be cut off. The chips made when cutting the coated bar must be taken away. Dowel bars should be supplied by the coating process in the approved certified reinforcing bars epoxy coaters and by selecting bars made by the supplier.

Specification and Installation of Dowel Bars:
The dowel bars’ size depends on how thick the pavement is. Most dowel bars are between 32 and 38 mm in diameter, 460 mm long, and 305 mm apart. The dowel bars are either coated or made of stainless steel to prevent corrosion. Dowel bars are always put in the middle of the slab’s thickness. They are put across the crack in the concrete pavement that runs from side to side to let it move.

The dowel bears the weight as the slab next to it expands and contracts simultaneously. The bars are set up to run along the middle of the slab. The biggest problem with installing the dowel bars is that the bars need to be set up right, and the concrete needs to be packed down more.

Advantages of Dowel Bars:

• Dowel bars are used to extend the structure easily. For this, only a small amount of drilling is needed to insert the steel.
• The horizontal movement of the dowel bar keeps the concrete pieces from falling apart.
• It makes it easier to work with the joints of structural members.
• Dowel bars lengthen the life of the first structural member.
• It raises the project’s initial cost but lowers its total cost over its lifetime.
• The load-carrying capacity of the slab is increased by using a dowel bar.
• A dowel bar is used to reduce stress and deflection.

Disadvantages of Dowel Bars:

• Dowel Bars require more work to design.
• Dowel bars are surrounded by concrete that is too hard.

Conclusion:
Dowel bars are round pieces of steel that are put across the horizontal joints of concrete members. They make it easier for loads to move across concrete joints. They also make it possible for people to move. It can be okay if the movement is made specifically for longitudinal joints.

References:

• Ltd, Precon Products. “What Are Dowel Bars? | Guides | Precon Products.” Precon Products, www.preconproducts.co.uk/guides/what-are-dowel-bars. Accessed 27 Nov. 2022.
• Civil, Tutorial Tips. “WHAT IS THE DOWEL BAR? – Construction Tips.” Tutorials Tips, 30 Apr. 2021, tutorialstipscivil.com/civil-topics/what-is-dowel-bar-use.
• “Dutcotennant.” Dutcotennant, www.dutcotennant.com/blog/all-about-dowel-bars-purpose-advantages-uses. Accessed 27 Nov. 2022.
• “Dowel Bars – Pavement Interactive.” Dowel Bars – Pavement Interactive, pavementinteractive.org/reference-desk/pavement-types-and-history/pavement-types/dowel-bar. Accessed 27 Nov. 2022.
• Ydsdevreocrete. “What Is a Dowel Bar and Why Are They Important for Concrete Project? | Reocrete | Concrete Prices | Concrete and Steel Suppliers | Brisbane.” Reocrete | Concrete Prices | Concrete & Steel Suppliers | Brisbane, 8 Sept. 2021, www.reocrete.com.au/what-is-a-dowel-bar-and-why-are-they-important-for-concrete-project.
• “Dowel Bar Its Purposes, Advantages and Uses – All about Engineering.” Dowel Bar Its Purposes, Advantages and Uses – All about Engineering, 17 Aug. 2020, allabouteng.com/dowel-bar-its-purposes-advantages-and-uses.

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