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News Archive 2001 - 2010

TxDOT Testing Recycled Reinforcers for Roadway Shoulders

June 13, 2003

Researchers in the Civil Engineering Department of The University of Texas at Arlington’s College of Engineering have begun field tests on two unusual mediums - manure compost and biosolids compost - to determine their effectiveness in mitigating shrinkage cracks on unpaved shoulders. Both reinforcing methods were already evaluated in laboratory conditions.

Unpaved shoulders are subject to cracking during high temperatures. When it rains, these cracks allow moisture to penetrate deep within the soil and under the pavement. This moisture causes the soil to greatly expand, resulting in pavement heaving. This reduces the life of the pavement and causes a bumpy ride. The composts should stabilize the moisture content of the shoulder soil and reduce cracking and heaving.

The tests are funded by the Texas Department of Transportation (TxDOT) and are being conducted along a 1300-foot section of State Highway 108 near Stephenville. Both compost materials are readily available in the Stephenville area, known for its abundance of dairy farms. The manure compost is recycled from solid cattle wastes and the biosolids are come from sludge produced from the treatment of wastewater. The sludge is subjected to a composting process to produce biosolids compost. Both materials contain phosphorous and nitrogen (nutrients for plant growth) and other chemicals.

Civil Engineering Professor Anand Puppala was the principal investigator during the development stage of the project, which was funded by TxDOT. Drs. Syed Qasim and Laureano Hoyos were Puppala's co-investigators. Initial findings from the test site show that both materials are performing satisfactorily in encapsulating the surface. Field monitoring through the summer and the next fifteen months will provide better explanations on the effectiveness of these materials.