，学长论文需要的。灰常感谢
Tree Sap Helps Hold Roadside Shoulders Together
A new technique in upstate New York helps construction crews hold their roadside shoulders together, while saving money and environment.
Lignosulfonates, or lignins for short, are the molecular glue that holds terrs together. During the pulping process at the wood mill, the lignins are removed from the pulp and flushed into tanks or lagoons. This liquid is then sold in a 50％ suspended solid solution for many purposes . Such applications include slurry dispersants in oil well drilling , concrete admixtures , and palletizing formulas.
For several years these lingnins have to been widely used for general dirt and gravel road applications . Top spraving on roads been successful for dust control . They have also been used in conjuncture with base stabilization by grinding the liquid into the road base at a depth of 4 to 8 inches for a hard , permanent fix of an all-gravel road , or subbase for a soon-to-be- paved road .
When mixed with a blend, the lingnins perform even better. adding flexibility and hvgroscopic tendencies to the total product . Sold under several trade names, this liqid has started to take the place of road oils and com-mon brines such as salt brine, calcium chloride, and others.
The newest New York State application has been a cost-effective alternative for use on road shoulders. Highway superintendent Ed-Morgan, from the town of Murray in upstate New York, asw his gravel shoulders disappear-ing year after year with the usual problems caused by washouts, plowing, and general traf-fic. The next season he would reapply addi-tional aggregate with the same negative results.
After successful use of lignins in a stabili-zation project, he thought they might help the situation with his shoulders. “Road Saver stabi-lized my subbase on a previous product, so I thought it would be a natural fit to hold my shoulders in place,” Morgan says.
Morgan brought a pugmill to his work site.This machine mixes aggether in a unifor blend. He mixed about 8 gallons to the ton of 0.625-inch crusher run and laid it down on the shoulders of a newly paved road. The mix was laid down in the 3-foot-wide shoulder-sarea, in a depth of 4 inches at the road sur-face tapered down to 0.5inch. He then took a roller and compacted the mix even with the new hard hard top.
“Two and a half years later , after re-peated heavy farm traffic , plowing , and rain storms the shoulder material is as hard and compact as the day we laid it down ,”says Morgan . “We have had no additional main-tenance or expenditures for that stretch of road in that period of time, which has enabled me to use my aggregate budget elsewhere.”
Other towns and counties have followed suit , including Niagara Country , which was the first agency to include lignin and lignin blends as a single specified bid forms . Carl Allen deputy superintendent of Niagara County noticed his neighbors in Orleans Country using the lignin blends as a bonding agent for their aggregate and became inter-ested in the new concept.
