Laboratory Study of the Leachate from Crushed Portland Cement Concrete Base Material, MLR-96-04, 1999

(1999) Laboratory Study of the Leachate from Crushed Portland Cement Concrete Base Material, MLR-96-04, 1999. Transportation, Department of

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Abstract

Since the 1980s, the Iowa Department of Transportation has increased its use of recycled Portland Cement Concrete (PCC) as drainable base material below some new pavements. Water flowing out of the longitudinal drains on projects having recycled PCC drainable bases was found to have a high pH value. The high pH water impedes vegetation growth and becomes a contributing factor to soil erosion at the drain outlet. In addition, the high pH water contributes to the growth of crystalline deposits on the drain outlet wire mesh rodent guard and in some cases caused it to become completely blocked. This research determined which of three choices of recycled PCC drainable base material, gradation, and design would give the lowest pH value in the drain discharge water. The drainable base material having its fines separated out and placed as a 2-in. (5.1-mm) bottom layer, below the remaining coarse material, generally gave pH values around 11.2 while other designs tested gave pH values around 11.5.

Item Type: Departmental Report
Keywords: Base course (Pavements), Crystallization, Drainage, Erosion, Leachate, pH value, Portland cement concrete, Recycled materials
Subjects: Transportation > Pavements
Transportation
Transportation > Roads and highways
Transportation > Design and Construction
ID Code: 19954
Deposited By: Iowa DOT Library
Deposited On: 29 Jun 2015 18:04
Last Modified: 29 Jun 2015 18:04
URI: http://publications.iowa.gov/id/eprint/19954