An aggregate base course is the layer of soil installed between the surface pavement layer and subgrade (foundation soils) of either flexible (asphalt) or rigid (concrete) pavement. Their purpose is to help transition surface loads from the pavement to the subgrade, evenly support the pavement surface profile, and protect the overall pavement system from water intrusion and deformation. While these objectives of base course layers are applicable to both types of pavements, load transfer is a more focused design consideration for flexible pavement, while moisture control is a priority for rigid pavement designs. Concrete base courses are further discussed in Article 32.11.36.

The main objective of concrete base courses is to regulate moisture, preventing the types of damage common to rigid pavement systems. Load transfer concerns, which can necessitate some base course applications, is less of an issue for rigid pavement.  Aggregate base courses for rigid (concrete) and flexible (asphalt) pavements are discussed in article 32.11.23.

Portland cement concrete paving is also referred to as rigid paving. Concrete pavement is supported by a base layer of compacted aggregates or treated soils, which is in turn placed upon the foundational subgrade soils of the prepared roadbed. If two base layers are utilized, they are referred to as the base and sub-base layers (or courses). Rigid (concrete) pavement differs from flexible (asphalt) pavement in that rigid pavement is designed to carry traffic loads within the pavement layer itself.

Brick unit paving offers an aesthetically pleasing alternative to traditional concrete and asphalt materials, when moderate traffic loads allow its use.  In the most common brick unit paving construction method, individual bricks are abutted on a bed of compacted sand over a granular base course.  These layers (or courses) are constructed upon prepared foundational soils known as the subgrade, and are contained within a framework of edge restraints.

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(As previously published in Modern Contractor Solutions.) Pervious pavement is a green, sustainable strategy that can assist in lowering stormwater runoff, naturally decreasing automobile pollutants, recharging the water table supply and moderating the heat island effect. Similar to other complex construction systems, in order for the sustainable pavement to perform as it was designed, it needs to be installed with precision and maintained with diligence. To drain water effectively on any given site, different geographical areas require special adjustments to the technology as well.

Contractor to Contractor: In this first of a two-part series, contractor-turned-homebuilder Fernando Pages Ruiz introduces permeable pavement, which allows rain and snow to seep into the ground.

What is Pervious Pavement?

Pervious concrete came to the attention of the building community in the United States after Congress passed the Clean Water Act in 1987. With restrictions in the amount of storm water runoff permitted from roads, parking lots and other impermeable surfaces, some developers began to look for environmentally-friendly alternatives. They found it in an exotic, water-sucking concrete first tested in Florida about 30 years ago as a flood-control device. Engineers placed highly porous concrete paving in spots along Florida roadways frequently submerged by heavy downpours. The permeable surface provided a quick-drying roadway that didn’t stay flooded after the storm.

For several years universities in the United States have been looking into the feasibility of using asphalt pavement to collect solar energy, or, more correctly, to harvest the solar energy that asphalt pavement is already collecting. Researchers have found that the technology exists for harvesting this energy, and its implementation may not be that far off.