Use of clean coal combustion by-products in highway repairs

A dry flue gas desulfurization (FGD) by-product was used to reconstruct the failed portion of a highway embankment. A wall was constructed through the failure plane to stop further slippage. To evaluate the suitability of FGD by-products in this type of project, the site of the repair was divided into three test sections. In the first section, the soil removed from the slide area was recompacted and replaced according to standard construction practices. In the second section, the embankment consisted of a field-compacted mixture of soil and FGD ash in approximately equal proportions. The third section was constructed of compacted FGD by-product. All three test sections were capped by a layer of compacted boiler ash or crushed stone to provide a temporary wearing surface. Measurements of slope movement as well as water quality and levels are being made at the site to evaluate long-term embankment performance. The completion of this experiment should lead to increased acceptance of FGD by-products in construction projects. Monetary savings will be realized in avoiding some of the disposal costs for the material, as well as in the reduced reliance on alternative engineering materials. (C) 1997 Elsevier Science Ltd.