EFFECT OF pH OF WATER ON MOISTURE SUCEPTIBILITY OF ASPHALTIC MIXTURES

Raheem, Haydar

	EFFECT OF pH OF WATER ON MOISTURE SUCEPTIBILITY OF ASPHALTIC MIXTURES
journal of kerbala university
Article 1, Volume 6, Issue 3, 2010, Pages 60-71 PDF (0 K)
Author
Haydar Raheem
Abstract
Moisture damage of asphaltic mixture is a term used to refer to the distress due to the effect of water presence between aggregate surface and asphalt binder. Water at this interlayer alter the pH to high value reaching 10 leads to splitting or breaking bonds between aggregate and asphalt which is known as stripping. Water can enter the pavement from external sources like poor drainage systems, broken or floating sewer conduits or high water table of the ground. Also, water can be enter the pavement through using wet aggregate in the production of asphaltic mixture. In this research, Iraqi aggregate were classified according to the resistance to water damage effect taking into account the mineral composition and texture. The results obtained refers that crushed aggregate had less resistance than uncrushed aggregate nevertheless, asphaltic mixture without additive for improving resistance to water damage effect, had been failed in boiling water test, where, in the presence of water (pH about 10) the retained asphalt coated aggregate were 45%. Lime was used as additive in three ways: dry method, wet aggregate and slurry lime method. Slurry lime method was improved water damage resistance where coated aggregate after conducting boil test were 85% for uncrushed aggregate and 78% for crushed aggregate. Quartzite compose 80% of aggregate which reflect acidic surface properties, where with the presence of water, high pH values were recorded (about 11). The main conclusions were moisture damage is a serious problem and there is a need to use treatment for elimination water damage through using slurry lime.

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