CONCLUSION
When the red tropical soil is treated with hydrated calcium hydroxide (lime), reactions take place, and the soil’s index and engineering properties are modified resulting in strength increase of the soil-lime system.
There is an initial rapid reaction between the amorphous, colloidal non-crystalline fractions of the soils and the lime. This reaction probably leads to the improvement in soil’s properties and workability referred to as amelioration. A second much slower reaction occurs between the lime and probably the crystalline and non-crystalline clay components of the soils as noticed in the plotting of lime reacted versus time of reaction.
Well graded red tropical soils from Nigeria with significant colloidal fines generally produced greater strength when stabilized with lime.
The mechanisms of the reactions and strength development in the soil-lime system follow mostly Jander’s equation and as such are diffusion controlled processes.
These red tropical soils are pozzolanas. They react with hydrated lime in the presence of water and form cementitious substances that improve the strength in the soil-lime system as seen in the higher UCS developed after stabilization.
Most of the reactions that occur in the red tropical soil-lime mixture occur within the initial seven days of reaction.
Thompson’s reactivity parameter has been found to have good statistical correlations with the fines and the strength of the stabilized red tropical soils in this research.
A simple theory based Activity index computed for these soils has shown high correlation with Thompson’s lime reactivity parameters. This, to a great extent has alleviated the problem of treatment and curing of the soils for 28 days and crushing as required before obtaining Thompson’s lime reactivity figures for these soils.
