Civil Engineering Principles of Pavement and Site Grading

14 September 2020

Civil engineering is an important field when it comes to engineering design and construction. This field deals with the overall design, construction, and maintenance of the physical structures in a naturally built environment such as roads, bridges, dams, airports, structural components of a building, pipelines, and railways. 

Two major principles that are known in civil engineering are pavement and site grading. These two principles possess features and applications that are deemed very helpful and useful in the field of modern engineering design and construction.


In civil engineering, pavement is a durable hard surface that is laid down and constructed on an area where vehicular or foot traffic usually occurs. It transfers and distributes applied loads from the surface to the sub-base and the subsequent layers underneath the surface. Aside from load distribution, the whole structure of the pavement must also effectively provide the needed skid resistance, proper riding quality, light-reflecting characteristics, and low noise pollution in the area.

To date, there are two classifications of pavements based on their overall structure and material. One of which is the flexible pavements. Modern flexible pavements are usually made from sand and gravel or crushed stone that is compacted with bituminous materials like asphalt, tar, or asphaltic oil. The way flexible pavement is constructed follows the concept of a layer theory, allowing it to distribute the load by grain-to-grain transfer and sustain maximum compressive stress.

Another classification of pavement is the rigid pavement. Rigid pavements are usually made from concrete, coarse and fine aggregate, and Portland cement that is reinforced with steel rod or mesh. This type of pavement can transfer surface loads to sub-grade soil through the flexural strength of the pavement. Rigid pavement does not have numerous layers of materials as it only depends on plate theory. However, its flexural strength allows it to hold a shape against difficult environmental conditions.

Site Grading

Another key principle that civil engineering utilises during the construction of structures is site grading. It entails the needed slope and topography adjustments of a specific area before proceeding to the construction of the property foundation, base course for a road or railway, or landscape. Site grading is also utilised for surface drainage and other utility works necessary for the property.

The main purpose of site grading is to level out the ground so that the land surface and underneath it can be stabilised for various construction purposes. Another reason why site grading is important as it can help direct the flow of runoff water and facilitate proper drainage, which can prevent erosion, foundation damage, and basement flooding that can all form when there is too much water build-up.  Before site grading is performed, professional engineers must assess certain crucial factors first. They would typically assess soil composition and the moisture levels of the surface. Once they have concluded that the surface requires further site grading, they will now hire an excavation services team to initiate the work. Heavy-duty equipment such as excavators and bulldozers will be brought to the site to effectively level the surface. To keep the water flow away from the property, the slope must be built at least 5%, which translates to a six-inch drop in height. A grader is then needed to create an even finish on the site.

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