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CMJ Engineering Research
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One option for stabilizing existing soils below pavements consists of adding hydrated lime to cause both a chemical and physical reaction to improve the qualities of our clays soils.
In certain geological formations, soluble sulfates are present in variable amounts, and, when in contact with lime, can form a volatile reaction, forming ettringite, and forcing swells in excess of 50 to 100 percent.
Studies have shown that such reactions can cause the pavement subgrade to bulge upward and actually overlap itself because of the radial and axial swelling.
Concern exists regarding soluble sulfates in soils occurring in areas where the Eagle Ford geological formation outcrops. It is extremely impossible to predict the presence and concentration of soluble sulfates, since the concentrations vary significantly with vertical and lateral extent.
In addition, where fill materials are obtained from areas of sulfates, the filling operation can spread these sulfates along great lengths of pavement subgrades, thereby potentially causing long sections of pavement with significant heaving.
Recent studies have been developed to give guidelines for successful application of hydrated lime in areas with high sulfate concentrations.
CMJ presently is performing a research study to test the pre-stabilized condition of the soils and application rates/curing periods to help reduce these problems.
Our test sample has soluble sulfate concentrations on the order of 18,000 to 20,000 parts per million.
Generally speaking, soluble sulfate concentrations above 2,000 parts per million present significant concerns in the industry. CMJ's remolded samples are presently in the test phase and we expect to have these results completed within the next two months.
The results of these tests will provide positive guidance to a local city in formulating an appropriate design/construction procedure to mitigate soluble sulfate heaving problems.
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