Goliad County Solves Basic Problem with Simple Solution
By Donald H. Taubert
Director, Promotion & Technical Service
Capitol Cement
Ted
Long, Construction Foreman for Goliad County in South Texas, recently solved
a distressed pavement problem with portland cement. During a routine road examination
earlier in the year, Long noticed some "soft spots" on Manahuilla
Road, in northwest Goliad County. There were several options for repair, including
removal and replacement of the base and asphalt surface, patching soft spots,
or recycling the entire base and pavement with portland cement, a more durable
and economical repair technique. Long chose the recycling because it did not
require removal and disposal of the road bed materials. All the materials are
recycled in place, hence no hauling and disposal costs are necessary.
Portland cement works to stabilize all kinds of base materials
found in Texas. It binds and hardens caliche and pit-run materials as it creates
a soil-cement base for the surface course. It can also be used to create a permanent
working platform by stabilizing granular and plastic soils underneath. When
the failed flexible pavements are pulverized, mixed, and compacted with cement,
the mixture provides a road base with strength and long-lasting durability.
The process is simple. The surface is scarified to a depth of six to eight inches,
and portland cement is placed over the surface at the prescribed amount and
blended with standard mixers.
The
project on Manahuilla Road required twenty-three pounds of cement per square
yard, six inches deep (about 4.5 percent by weight of material). Goliad County
doesn't have a rotary mixer, so their experienced motor-grader operator did
all the blending and mixing. This was the same process that was used in projects
that were built in the U.S. as early as 1938.
After the mixing, the material was bladed off to the shoulder
and then placed back on the roadway and compacted in two lifts using normal
watering to achieve optimum moisture. The base was compacted to standard density
with tractor drawn pneumatic and sheepsfoot rollers. The road stayed 18 feet
wide, but shoulders were added with this "new" base material.
"Pre-cracking"
is a new technology recently developed that inhibits typical soil-cement crack
patterns that might reflect through the asphalt surface. The following day,
Long rolled the completed road base several times with the pneumatic roller
to induce "micro-cracks", which ultimately prevent reflective cracking
yet maintains the base's structural integrity. He also rolled the roadbed one
to two hours before seal coating. Bad weather and holidays prevented the county
from shaping and crowning the road for several days, but Long felt that the
situation did not cause a problem.
The road was chip-sealed with CRS-2 oil at 0.45 gallon per
square yard and PB4 natural asphalt rock for chip seal at 120 tons per mile.
The entire process was then repeated for a second coat, ensuring a durable surface
treatment.
Long
said, "I like that fact that we were able to complete this repair with
portland cement at less than one half the cost of usual procedures. I also feel
that we now have a better product than we would have had by adding additional
or even other base material to the existing pavement without a stabilizer, as
we have done it in the past. We were also able to do it with our own road crew."
©2005 Road Recycling Council
P.O. Box 17362 - Cambridge, MA 02141
phone: (857) 998-0119 fax: (617) 547-0042