Curb is a short wall installed to hold the pavement from the sides and act as a barrier between yard and street. It is abutted with a gutter which is a flat concrete slab that drains out water away from the yard. Usually, curb and gutter are constructed together at a site.
In this article, we study the type of curbs, construction of curb and gutter and its advantages.
Types of Curbs
The classification of is based on the shape and size of a curb. Five prevalent types that are commonly seen are:
1. Mountable Curbs
Mountable curbs have a slight dip on one face of the curb so that it facilitates the vehicles to drive over them easily. These type of curbs are preferred at openings for pedestrians with shopping carts or strollers, and those who are on bicycles or roller-skates to cross safely on or off the sidewalk.
2. Mower Curbs
Mowers curbs are used only on the lawn or flowerbed areas. They have a very decorative look and provide a sturdy, reliable, and protective barrier between walkways and green zone.
Their unique shape makes it possible for lawnmowers to come close enough to ensure each blade of grass is evenly trimmed without damaging the topsoil or the machinery.
3. Barrier Curbs
This is the most commonly used curb all over the globe. As the name denotes, this type of curb is used as a barrier between vehicles and certain spaces (e.g. sidewalks, stores, parking spaces, etc.). Barrier curbs are typically comprised of asphalt aggregates or cement concrete.
4. Monolithic Curbs
Monolithic curbs are constructed or fused with the road and the top levels are matched to create more traction and make it easier for larger vehicles to pass without damaging the internal structure or foundation of the asphalt or concrete.
5. Slanted Curbs
Slanted curbs do not have any practical purpose instead they enhance the aesthetical appearance of the surrounding. These are purely decorative and ornamental curbs.
Construction of Curb and Gutter
Manual construction of a curb and gutter is explained below.
1. Marking and Excavation
The first and the foremost step of every construction activity is Marking. The path at which the curb and gutter have to be constructed are marked using marking powder. gradient is given to make sure all the water coming on it is efficiently drained.
The marked area is then excavated with manual or mechanical means up to a depth of 300mm. The excavated soil is stacked away from the site. All the loose soil and dirt is tamped firmly using hand tamper or mechanical compactor.
A gravel base mixed with cement is laid down and compacted. The gravel base for both curb and gutter is laid at once and the width of the gravel base will be the combined width of curb and gutter.
The formwork is built with the use of ply boards or steel moulds. The design of the formwork depends on the type of curb that is to be constructed. Form-work is built and secured with wood stakes driven into the ground with a hammer behind them.
Fasten the two boards together to hold the spacers in place using metal clamps or 1-by-2 boards nailed across the tops of the curb form boards about every foot. Spacers are provided at regular interval.
Plumb and level of the formwork are checked for proper alignment and perfect shape. Coat form-work with cooking oil or similar material to prevent concrete from adhering to the form-work.
3. Placing of Concrete
The concrete of design mix is placed in the formwork. Firstly, concrete is poured in the gutter-area and then the top of the curb formwork is filled with concrete. Proper compaction is ensured for a durable curb and gutter.
After the concrete has set, remove the front curb board and smoothen the curb and gutter surfaces with the help of special concrete finishing tools. The concrete in the gutter is finished with a finishing tool that makes indentations wherever spacers were placed in the curb form. Remove the spacers and fill those joints with concrete mortar.
As soon as the concrete has been placed and finished, it must be cured to develop strength and durability. Curbs must be protected against loss of moisture, rain damage, traffic, and extreme hot or cold temperatures.
Advantages of Curb and Gutter
- Adds attractiveness to parking lots and street. It also enhances adjacent properties by sharp demarcations between streets and lawns.
- Curbs act as a back support to the pavements. While laying pavement, curbs form a closed boundary and improve compaction during construction and help maintain the integrity of edges under traffic.
- Curbs reduce the amount of space or right-of-way required for a street by eliminating drainage swales and their flat side slopes
- Light reflective surfaces of concrete curbs delineate pavement edges and improve visibility for drivers at night, thus promoting safety.
- Curbs improve the efficiency of street sweepers by concentrating debris for easy, mechanical pickup.
- Gutters help in draining of the water successfully that slides down from the other side of the pavement thus avoiding the water from entering into the pavement area.