How the Stability of Road Pavement is Influenced by Certain Factors

How the Thickness of Pavements is Determined by Several Elements

The following characteristics have a significant impact on road pavement stabilization.

• Factors Influencing Traffic
• Factors in the Soil
• Factors in the Environment
• Factors Affecting Stress Distribution

1. Factors Influencing Traffic

The most significant consideration in road pavement design is traffic. Contact pressure, wheel load, axle configuration, movement loads, load, and load repeats are all important elements.

Contact Pressure

The contact pressure between the wheel and the pavement surface is determined by the tyre pressure, which defines the contact area and pressure. Even though the contact area is elliptical, a circular region is frequently considered for ease of analysis.

Wheel Load

The wheel load is the next crucial consideration, as it defines the depth of pavement required to prevent the subgrade soil from failing. The stress distribution and deflection inside a pavement are affected by wheel designs. Many commercial vehicles use two rear wheels to keep the contact pressure within acceptable limits. To make the analysis easier, it is common to practice converting dual wheel loads to corresponding single wheel loads.

Axle Configuration

The addition of numerous axles to a commercial vehicle increases its weight carrying ability.

Moving Loads

If the vehicle is moving at creep speed, the damage to the pavement is substantially greater. Many studies demonstrate that increasing the speed from 2 km/hr to 24 km/hr reduces the loads and deflection by 40%.

Load Repetition

The impact of traffic on the pavement is determined not only by the magnitude of the wheel load but also by the frequency with which the load is applied. Each load application results in some deformation, and the overall deformation is the sum of all these deformations.

Although the impact of a single axle load on the pavement is minor, the cumulative effect of multiple load repetitions is significant. As a result, the current design takes into account the entire amount of normal axle loads (usually 80 kN single)

2. Factors in the Soil

The soil beneath the pavement base is rarely uniform. Large differences in its qualities are possible. Certain experiments must be carried out to forecast the behavior of the soil under various conditions. Soil strength or soil stabilization varies depending on the kind of soil, bulk density, moisture content, permeability, and internal structure. It also depends on the way the load is applied to the earth.

We know that when the density of the soil increases and the moisture content decreases, the soil strength increases. Due to the low elastic qualities of soil, the supporting power of the subgrade is a critical aspect in the design of flexible pavement. Comprehensive and tensile strength are not significant for evaluating the subgrade's sustaining power. To calculate the subgrade's sustaining power, all of the soil's properties should be set on.

• Shear Strength
• Bearing Capacity
• Penetration Resistance of the Soil

3. Factors in the Environment

Environmental factors have an impact on the performance of pavement materials and can result in a variety of damages in road pavement. Temperature and precipitation are two sorts of environmental elements that affect pavement, and they are detailed below:

Temperature

The temperature has a different influence on asphalt pavements than it does on concrete pavements. Temperature affects the resilience modulus of asphalt layers and causes concrete slab curling. Temperature stresses or frictional stresses emerge in rigid pavements due to temperature differences between the top and bottom of the slab.

The dynamic modulus of asphaltic concrete varies with temperature in flexible pavement. Differential settlements and pavement roughness are caused by frost heave. During the spring break-up period, when the ice melts and the subgrade becomes wet, frost penetration has the most destructive effect.

Precipitation

Rain and snow have an impact on the amount of surface water penetrating the subgrade and the level of the groundwater table. Poor drainage can result in a loss of shear strength, pumping, and support, among other things.

Conclusion

Hope the above mentioned road pavement design guide will be useful for road paving contractors and engineers to determine the road paving cost.