In 1935, engineers constructed the first experimental soil-cement
pavement. The 1.5-mile (2.4 km) stretch of road outside of Johnsonville,
South Carolina, represented a significant development because it
proved to be a long-sought means to stabilize local soils and provide
good economic road base. More than 70 years later, soil-cement pavements
are still giving good service at low maintenance costs and more
than 100,000 miles (160,900 km) of highway have been built using
also referred to as cement-modified soil and cement-treated aggregate
base, is a dense, highly compacted mixture of soil or roadway material,
portland cement, and water. Soil material can be almost any combination
of sand, silt, clay, gravel, or crushed stone. Granular soils are
preferred, however, because they pulverize more easily and require
less cement to achieve the required strength and durability.
Laboratory tests are performed to determine the proper cement
content, compaction, and water requirements of the soil material
to be used. The soil-cement can be mixed in a central plant or mixed-in-place.
Central plant mixed soil-cement requires a non-cohesive, usually
granular material. For mixed-in-place operations, clay or granular
soils can be mixed.
mixed-in-place construction, contractors follow four basic steps
of soil-cement paving—spreading, mixing, compacting, and curing.
When the roadway has been shaped to grade and the soil loosened,
the proper quantity of cement is spread on the in-place soil. Mixing
machines then thoroughly mix the cement and the required amount
of water with the soil.
The mixture is next tightly compacted
with rollers, shaped to the proper contour and rolled again to achieve
a smooth finish. Finally, the soil-cement is cured by spraying water
and sealing with a bituminous mixture to supply and maintain the
moisture needed for hydration.
Soil-cement's advantages of high strength
and durability combine with low first cost to make it an economical
material. About 90 percent of all the material needed for soil-cement
is already in place, keeping handling and hauling costs to a minimum.
Like concrete, soil-cement continues to gain strength with age.
Because soil-cement is compacted into a tight matrix during construction,
the pavement does not deform under traffic or develop potholes as
unbound aggregate bases. Soil-cement is capable of bridging over
weak subgrade areas and is highly resistant to deterioration caused
by seasonal moisture changes and freeze/thaw cycles.
The use of soil-cement has expanded since its initial development
in 1935. Soil-cement has been used primarily as a base course for
roads, streets, highways, airports, and parking areas. More
on soil-cement for paving.
is also used as slope protection, ditch lining, and foundation stabilization.
Soil-cement is used in every state in the United States as well
as in all the Canadian provinces.
More on soil-cement for water resources.