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Frequently Asked Soil-Cement Questions
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vs. Lime
Which product is better—portland cement or
hydrated lime—in stabilizing clay soils?
In 2003, an investigation was completed that evaluated the performance
of portland cement and hydrated lime in stabilization and in improving
engineering properties of several soils. Three soils were examined
that had Plasticity Index (PI) values of 25, 37, and 42. The following
general conclusions can be drawn based upon the investigation performed:
1. For the soil with a PI of 25, portland cement performed better
than lime even at dosages as low as 3%. For the soils with a PI
of 37 and 42, the performance increased significantly when the cement
dosage was increased to 6% or more.
2. The maximum dry density of all three soils stabilized with portland
cement attained higher maximum dry density than the lime-stabilized
soils.
3. The unconfined compressive strength (UCS) of the soil with a
PI of 25 stabilized with portland cement was almost always higher
than that of lime-stabilized soil.
4. Strength of cement-stabilized soil is generally higher than
lime-stabilized soil at all ages.
5. California Bearing Ratios (CBR) measured for all three soils
stabilized with 6% and 9% portland cement or lime, clearly indicate
that cement-stabilized soils have superior load bearing capacity.
6. For all three soils, stabilized with 6% and 9% portland cement,
there was a significantly higher strength than lime-stabilized soils
after vacuum saturation tests.
7. The physiochemical nature of cement-stabilized soils results
in better wet-dry durability.
8. Hydraulic conductivities of the soil with a PI of 25 stabilized
with portland cement were significantly lower than lime-stabilized
ones at all dosage levels.
9. The concentration of calcium ions in leachates from lime-stabilized
soils is generally higher than those from cement-stabilized soils.
For the complete findings contained in this investigation, please
see PCA publication RD125
– Comparative Performance of Portland Cement and Lime Stabilization
of Moderate to High Plasticity Clay Soils.
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