Effect of Solutions of Humic Compounds on Concrete


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Title: Effect of Solutions of Humic Compounds on Concrete

Author(s): K. R. Robertson and M. A. Rashid

Publication: Journal Proceedings

Volume: 73

Issue: 10

Appears on pages(s): 577-580

Keywords: calcium;chemical analysis;corrsion;humic acids;organic acids;organic compunds;protective coatings;salt water;water.

Date: 10/1/1976

The corrosive effect of humic acid on portland cement concrete was investigated with a 10 ppm concentration of organic matter under conditions simulating fresh and salt water environments. Calcium, the most abundant cation in concrete, was released in the fresh and salt water systems containing humie additions at maximum concentrations of 28 and 96 ppm, respectively. The corresponding controls which were devoid of organic matter contiained significantly lower calcium concentrations the solubility of calcium increased rapidly within the first 4 days of experimental exposure and then leveled off. It was also observed at the end of the experimental period of 15 days that the organic matter formed a protective coating on the surface of the concrete blocks. Considering the concentration of calcium in portland cement concrete the quantity released in the reaction media constituted only a minor fraction of the total solid mass of concrete blocks. Moreover the formation of organic coating on the surface of the concrete appears to have a protective effect from further corrosion. It is therefore concluded that humic compounds present in aquatic or sedimentary environments do not exert any long term adverse effect on concrete structures, but on the contrary may provide a protective coating.