Road

• Road is an open, generally public way for the passage of vehicles, people, and animals.
• Pavement is finished with a hard smooth surface. It helped make them durable and able to withstand traffic and the environment. They have a life span of between 20-30years.

 

Functions

One of the primary functions of pavement is load distribution. It can be characterized by the tire loads, tire configurations, repetition of loads, and distribution of traffic across the pavement, and vehicle speed.

 

Type of Pavements

There are various types of pavements depending upon the materials used; a briefs description of all types is given here-

# Flexible Pavement

Bitumen has been widely used in the construction of flexible pavements for a long time. This is the most convenient and simple type of construction. The cost of construction of single lane bituminous pavements varies from 20 to 30 lakhs per km in plain area. Flexible pavement have-

• Have low flexural strength.
• Load is transferred by grain to grain contact.
• Have low completion cost but repairing cost is high.
• Have low life span (High Maintenance Cost).

 

# Rigid Pavement

Rigid pavements, though costly in initial investment, are cheap in long run because of low maintenance costs. The cost of construction of single lane rigid pavement varies from 35 to 50 lakhs per km in plain area, Rigid Pavement have-

• Deformation in the sub grade is not transferred to subsequent layers.
• Design is based on flexural strength or slab action.
• Have high flexural strength.
• Have low repairing costs but completion cost is high.
• Life span is more as compare to flexible.

 

# Types of rigid Pavements

• Jointed Plain Concrete Pavement (JPCP)- does not use any reinforcing steel.
• Jointed Reinforced Concrete Pavement (JRCP)- Reinforcing steel placed at mid height and discontinued at the joints.
• Continuously Reinforced Concrete Pavement (CRCP)- This method is very costly and generally not used in India.
• Pre-Stressed Concrete Pavement (PCP)- Comprises new and innovative construction methods.

 

Mineral Used

# Aggregates

• There are two types of aggregates are used during construction of road i.e. Fine and Coarse Aggregate depending on requirements.
• Maximum size of aggregate should not exceed 1/4^th of the pavement slab thickness.

# Water

• Water used in mixing or curing of concrete shall be clean and free from injurious amounts of oil, salt, acid, vegetable matter or other substances harmful to the finished concrete.
• Portable waters are generally considered satisfactory for mixing or curing.

 

Equipment Used

A list of tools, equipment and appliances required for the different phases of concrete road construction is given below-

• Three wheeled or vibratory roller for compaction purpose.
• Shovels, spades and sieving screens.
• Concrete mixer for mixing of concrete.
• Formwork and iron stakes.
• Watering devices- water Lorries, water carriers or watering cans.
• Wooden hand tampers for concrete compaction.
• Cycle pump/pneumatic air blower for cleaning of joints.
• Mild steel sections and blocks for making joint grooves for finishing purpose.

 

Site Preparation

Before construction begins, the construction site must be carefully prepared, this includes preparing the grade or road base, sub grade and sub base-

• First the site is graded to cut high points and fill low areas to the desired roadway profile elevations.
• Generally, cut material can be used as embankment fill.
• A course of material is placed on the sub grade to provide drainage and stability.
• A course of fairly rigid material, sometimes cement- or asphalt-treated, that is placed on the sub base to provide a stable platform for the concrete pavement slab.

 

Construction Process

After site preparation, construction process consists of various steps, which are describe below

 Form Work

Wooden sheets, battens, plywood, fiber hard board, steel plates, angles, rope etc are generally use for form work.

• Before using form work, it should free from all type material like as dust, cement.
• To placing the concrete in appropriate depth used 2.5-5cm thick and 3mtr long wooden sheeting.
• The depth of wooden block must be same as level of slab thick.
• After 24hrs, form work displaced next length of road.

 

Construction of Joints

• There are three basic joint used in concrete pavement: contraction, construction and isolation.
• Except for some isolation joints, all joints provide a means to mechanically connect slabs. The connection helps to spread a load applied on the slab onto slabs along its perimeter.
• Where it is necessary to provide transverse and longitudinal joints; there wedge of woods, metals fix on level of concrete.
• After setting of concrete it should be pull out.

 

Curing

• After completion of the finishing operations, the surface of the pavement shall be entirely covered with wet hessian cloth, burlap or jute mats.
• Curing is the process of increasing the hydration of cement, after setting the concrete curing process done till 14-28 days.

 

Advantages of Concrete Road

• Durability and maintenance free life.
• Vehicles consume less fuel.
• Resistant to automobile fuel spillage and extreme weather.
• Greener process.
• Saving of natural resources.
• Eco friendly process.