Dear all,
Adding a stabilizer (such as Alkali-activated materials (AAMs), Geopolymer, lime, cement, etc.) in order to increasing the strength of loose soil, mostly change the maximum dry density (MDD) and optimum water content (OWC). My researches have shown that adding AAMs to a weak clay could reduce the OWC from 20 to 15%. Although it is because of interaction between the water and alkaline activator, in the most researches it is recommended to use OWC for preparing all samples (with all dosage of stabilizer). In other words, as the OWC decreases, I prepare the natural clay and stabilized clay at the same water content, and the stabilized clay has been prepared with 5% higher OWC in comparison with natural soil.
my question is why in the most soil stabilization researches this has been recommended?
Dear Mohamad,
Stabilized soil samples normally prepared at OWC because the engineering properties of stabilized soil at OWC is much better in other wc. Also, the shear strength of soil is much higher as compared to any other water content. so, the problem in which shear strength is more focused in that case stabilized soil sample with OWC is the best..the problems in which the volume of soil is more important in that case slightly higher or lower than the OWC is decided.ok all the best..
The optimum moisture content provides the maximum dry unit weight that can be obtained. The increase in the dry unit weight means improving the soil properties; increased strength, decrease in permeability and compressiblity. So it is better to use the optimum moisture content.
It is recommended to carry out an OMC test for chemically (e.g. lime, cement etc.,) stabilized soil samples. The stabilized samples will have a different OMC. In your case, the samples will be wet of optimum. This value is also strictly dependent on the expansive nature of the clay mineral.
Please refer to the attached document that illustrates the protocols for lime treated samples.
Dear Mohammed,
If you perform several mechanical tests (in saturated conditions-avoiding the suction effects) by varying the water content and leaving the molding density fixed, you will notice that the mechanical properties of the soil-stabilizer mixtures improve when they are closer to the optimum water content of compaction.
In the OWC the voids are reduced to a minimum, that is, the porosity is reduced and the contact areas between the soil particles and the stabilizer are increased, promoting better interaction between them and subsequent chemical/geopolymer reactions.
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