Chemical Base Stabilization

Portland cement is spread evenly over the surface of the existing asphalt in the amount of 2-4% of the total depth to be recycled and mixed in.

Water is added usually by water truck or by hose if necessary.

A grader then mixes the material and rebuilds the crown.

The mixture is rolled with a roller or multi-wheel roller and left to cure for a couple of days. After curing, surface can be chip-sealed or paved.

When mechanical stabilization does not increase the reclaimed materials loadcarrying capability sufficiently, other additives can be used in conjunction with the granular materials or on their own. The addition of these additives is referred to as chemical stabilization. The more common additives are Portland cement, lime, and fly ash.

Portland Cement
Portland cement has proven to be a very good method of base stabilization. Although there is no nationally accepted method for undertaking an FDR mix design, it is generally recognized that a mix of Portland cement between 2% to 6% of the dry aggregate weight produces the desired results.

Lime
Lime is another common stabilizing additive but is used mainly for subgrades and soils with a high PI

Fly Ash
Fly ash is a by-product of coal-fired power production and can also be a very cost effective stabilization additive where it is available at a reasonable price. There are basically two types of ash product in coal-fired power plants: a lightweight, fine ash called fly ash and a coarser ash called bottom ash.