Types of Pavement

A pavement is a durable surface material used to cover roads or airstrips. Its primary function is to distribute the applied vehicle loads through different layers. It should also provide an acceptable riding quality, good skid resistance, and favorable light-reflecting characteristics.

The pavement should withstand geographic, seasonal, and diurnal variations in temperature. This will ensure its long design life.

pavement

Asphalt is a versatile, affordable paving material that can be used for a wide range of road, highway and parking lot construction projects. It is also a cost-effective option for resurfacing existing pavements. Asphalt is also an environmentally friendly material that can be produced using a variety of sustainable practices. The Federal Highway Administration (FHWA) is currently testing full-scale highway sections that utilize recycled materials and low-temperature warm-mix production technologies to determine the optimal pairings of these two sustainable technologies.

One of the primary benefits of asphalt is its durability. This quality, combined with its high strength, makes it a good choice for long-distance highways and arterial roads. The material’s durability also translates into reduced maintenance costs. The ability to withstand heavy traffic loads and climatic conditions also helps make asphalt an ideal material for resurfacing roads that carry a significant amount of vehicle traffic.

Another benefit of asphalt is its water drainage capabilities, which help to prevent the buildup of water underneath the pavement surface. This can lead to heaves, which are caused by the movement of moisture through the subgrade or base layer of the roadway. Asphalt can also be designed to direct stormwater runoff into grassy areas or other suitable locations, which helps to reduce pollution.

However, the disadvantage of asphalt is its susceptibility to disintegration, which can lead to potholes and other problems on roads. These issues are usually the result of poor design and installation or a lack of maintenance. The most common type of disintegration is longitudinal cracking, which are long fractures that extend from end to end down the centerline or slightly off-centre in the direction of the original construction.

A less severe, but still problematic, form of disintegration is transverse cracking. This cracking develops perpendicular to the longitudinal cracking and is often caused by inadequate or uneven loading. This type of cracking can be repaired by filling the affected area with a cold mix asphalt mixture.

Cold mix asphalt stays soft in cold temperatures and is a great temporary solution for potholes. It is made by emulsifying the asphalt binder in water before mixing it with the aggregate components. This process allows the mixture to remain fluid while being transported to the job site and mixed with the aggregates.

Concrete is a popular road construction material because it offers safety and durability. It can be used as a base, sub-base and surface course in the road building process. The material is easy to work with and can be placed quickly. It also has a long service life, even when subjected to repeated heavy loads. However, concrete has some limitations that need to be addressed in its construction.

Concrete is manufactured from raw materials and prepared for paving with special equipment. The proportions of the ingredients are different for each type of pavement. The mix is then poured into a form or cast on the road surface. The concrete is then smoothed and textured before it hardens.

It is important to use the proper amount of concrete for each section of the road. The thickness of the concrete is also affected by temperature, weather conditions and the curing procedures. These factors are all important to the longevity of the road.

Cement is the primary ingredient of concrete. It is a very strong material that is very resistant to corrosion. However, it is not a very flexible material, especially in three dimensions. The magnitude and frequency of vehicle loads affects the amount of stress the pavement can handle before fatigue failure occurs. To prevent premature distress, the concrete should be tested and pre-cast to verify that it meets design assumptions.

The quality of the aggregates in concrete is another factor that affects its performance. A good aggregate is free of clay, silt and other contaminants. In addition, the aggregate must have sufficient angularity to allow the pavement to transfer the load.

In addition, the concrete must be properly poured and placed to achieve the desired surface qualities. The contractor should ensure that the pavement is level, and that it has proper longitudinal and transverse joints. It is recommended that a minimum of 0.6 percent steel reinforcement be used, with the reinforcing bars having tensile strengths specified in AASHTO specifications.

The contractor should also check that contraction joints are constructed as shown on the plans. These are designed to control cracking and provide relief for expansion of the concrete due to changes in temperature and moisture.

Grass pavement, also known as green pavement, is another type of permeable paving that uses open pore pavers or plastic grids to allow precipitation to penetrate the surface and infiltrate into the soil below. This type of paving reduces the amount of water that runs off the site and into local aquifers, where it can cause flooding and erosion. It is a more environmentally friendly solution because it allows stormwater to return to the ground naturally and re-establish a natural hydrological balance. It also helps to reduce pollution, as the aquifers will naturally filter out the pollutants that are carried away by stormwater.

Using open pore pavers or plastic grids, the paving system is designed to be planted with grass or low-growing herb plants that grow through the pore spaces. The look is similar to a traditional gravel parking lot and the pavers or grids are placed in a pattern to create an attractive surface that is well-suited for pedestrian and bicycle traffic, service and emergency access lanes, long term parking slots and private driveways. This is a cost-effective alternative to standard concrete and asphalt pavement that can have the same longevity as these types of pavements, but with the added advantage of being more appealing visually.

Research shows that porous pavements can significantly reduce contaminant loads in stormwater runoff, which may help to protect backwater refuges and prevent down-cutting of streams and inter tidal areas. They also provide a natural hydrological cycle that replicates the natural hydrology of soils, reducing the erosive power of stormwater and moderating fluctuations in water flows in waterways. They also allow stormwater to infiltrate into soils and natural aquifers, where microorganisms naturally break down and reuse water and soil nutrients, removing the need for chemical treatment of water and other contaminants.

Despite these advantages, there are still some limitations that need to be addressed before this type of paving can be used. In cold climates, road salts can migrate through the pore space and into groundwater, which could cause problems. Also, infiltrating stormwater can freeze below the pavement and cause frost heave, which requires proper design to reduce the risks.

Dirt pavements are a common option for rural roads that don’t need to support as much traffic. However, they require more maintenance and upkeep than paved options, as dirt is susceptible to erosion from rain, snow, ice, and even traffic. When left unattended, this can lead to a muddy mess that’s difficult to drive through and can even pose safety risks for pedestrians and vehicles.

In addition, dirt can stain concrete over time and cause it to break down and crumble. This can be expensive to repair as the cracks and stains can spread quickly and become bigger over time.

A dirty pavement can also scare off customers and potential tenants for a business, as it doesn’t give a good impression of the company. Investing in a professionally cleaned pavement can increase foot traffic and create a positive image for the business.

When it comes to residential property, a dirty pavement can be a real eyesore and can lower curb appeal. It can also depreciate the value of the home, which can make it harder to sell in the future.

Although there are several soil stabilization treatments that can help with this problem, it’s generally more cost-effective to pave a road or sidewalk rather than spend time attempting to save a worn out and dirty dirt path. The advantages of paving are that it is much easier to clean and it’s more durable than grass or gravel. In addition, paved surfaces are more resistant to erosion and weather changes, and can handle a variety of vehicle weights and traffic conditions.

Types of Excavating Work

Many types of excavation work are suited to specific construction projects. Here are the main ones:

Level Ground Excavation helps create foundations for buildings below ground level.

The processes involved in building roads, railways, and canals include adding or removing large masses of dirt and stone. These additions and removals are commonly referred to as cut and fill excavation. These processes are usually carried out using heavy machinery such as excavators and bulldozers. The type of mass being added or removed depends on the construction project.

For example, earth excavation is typically used when building a foundation, as it strips the layer of soil underneath the topsoil for construction purposes. Another common excavation type is rock, used to clear rocky surfaces that hinder the building process. Rock excavation is challenging, requiring special equipment, such as drilling or blasting.

One of the main considerations in cut-and-fill excavation is calculating how much material will need to be moved between different sections. This is determined by measuring the existing topography of a plot of land and determining how much space is required for construction. The remaining area is then split into cut and fill sections, with the former section having a lower elevation than the latter. Calculating how much material will need to be removed from a site before construction begins is important, as this helps minimize the amount of hauling required for the job.

This type of excavation also considers the field shrink and swell factor for the material being transferred between the cut and fill sections. The amount of material that shrinks or swells as it is relocated will impact the time it takes to build the project and ultimately influence the cost.

The cut-and-fill process needs to conserve as much mass as possible. Having more cut than fill will result in project managers needing to find somewhere to dispose of the excess dirt. Having more fill than cut means that additional mass will be brought in from elsewhere on the site, increasing labor and equipment costs. For this reason, cut-and-fill excavations are designed to keep the cut-and-fill mass relatively equal.

Trench excavation involves digging a narrow cut, cavity, or depression in the earth’s surface that is deeper than it is wide. It can be found on construction sites and is the most common form of excavation. According to OSHA, trenching is the leading cause of workplace fatalities and requires high worker safety training and protective systems.

This type of excavation focuses on removing material, usually dirt and rock, to clear surfaces like rocky areas that impede building structures. It may also be used to dig drainage ditches that funnel water away from habitation, infrastructure, and agriculture or to remove sediment deposits in waterways to make them passable.

A trench can be any length and depth, although deep trenches typically have a length that greatly exceeds their width. This type of excavation is commonly used to lay foundations for buildings or bury services such as pipes, and it often requires specialty equipment and procedures.

Identifying the soil types related to a specific trench or excavation is important before beginning work. This information helps determine the proper excavation, support, and backfilling methods. Additionally, it is helpful to identify if the trench will have underground utilities or other hazards that must be avoided.

The type of soil, its consistency, ease or difficulty in excavating, appearance, and water seepage are some of the characteristics that influence the best methods. Sometimes, a single trench can contain soil types that vary widely from one end to the other.

A competent person must review the site before starting work, identifying and marking all buried services appropriately. It is also important to know the location of nearby vehicles, equipment, and structures that could put pressure on or undermine the trench walls. Finally, the competent person should check the area for signs of hazardous gas, vapors, or dust and ensure all equipment is de-energized before entering the trench. Remember to complete and share a job hazard analysis, update your written accident prevention program, and conduct routine equipment inspections.

Once a site is identified, the archaeological team must decide which excavation method to use. The choice is usually based on the natural geography of the site, the strata, and cultural layers, and how much time the archaeologists have to complete the excavation.

Shovel test surveys, shovel test pits, probes, and trenches are all common excavation types. Each type allows the archaeologists to explore different areas of a single layer while enabling them to record their findings.

Once the archaeologists have selected their excavation method, they must map the site. This includes establishing a grid system, or datum, to make all future measurements. The datum can be a specific location or feature on the site, such as a boulder, building, or fence post. Alternatively, it can be a point in space, such as a GPS coordinate.

The next step is to establish the phasing of the site, which helps determine the chronology of the layers of the site and provides the context for the interpretation of artifacts and features. Phases are usually arranged chronologically and can be grouped into domestic, commercial, or industrial categories.

When the phasing is completed, the archaeologists can begin excavation. This often involves digging in the order that the phases were deposited, which ensures that the artifacts are removed from the soil in an order consistent with the sequence of human activity at the site.

Rebar is vital in construction projects such as skyscrapers, highways, and bridges. It adds great strength to concrete and helps prevent cracking that might destroy a project. Rebar is almost always made of steel, which provides excellent tensile strength. It is sometimes coated with zinc or another metal to help prevent rusting. Alternatives to steel rebar include glass fiber-reinforced polymer (GFRP) and carbon fiber.

Footing excavation is digging and removing dirt, rocks, or other materials that make up the foundation of a building or different structure. This type of excavation is often done to prepare for construction, install utilities, or create basements. It can also be used to create slopes or level uneven terrain. It is usually performed with heavy machinery like excavators and backhoes and power tools such as jackhammers and concrete cutters.

Stripping is a type of excavation that is focused more on clearing a large area than digging a pit or trench. This excavation method removes wide swaths of topsoil, gravel, or other materials to prepare the site for construction or engineering projects. It can also be used to clear out contaminated or otherwise undesirable areas.

This type of excavation is generally related to the construction of a bridge. It involves removing any materials that might interfere with the construction of the foundations, substructures, and so on needed to support a bridge. This is a complex operation that requires different types of equipment than other forms of excavation.

During tunnel excavation, workers dig and remove soil, rock, or other material to create a passage through the ground. This is often done for infrastructure, including roadways, subways, canals, or sewage systems. This type of excavation is typically done under the direction and approval of a professional engineer.

In addition to being used in constructing skyscrapers, bridges, and other structures, rebar is also widely used for more esoteric purposes, such as minimalist art and coffee tables. Rebar is most commonly made from steel, which has excellent tensile strength and doesn’t easily bend. Alternatives to steel rebar include GFRP, which offers good tensile strength but isn’t as strong as steel.