Volumetric Swell Prediction of Alkali-Activated Sulfate-Rich Dispersive Clay

Sulfate-rich dispersive clays are a major concern for road infrastructure in South America. The mere application of lime and/or Portland cement has proven to be ineffective. This paper presents an alternative stabilization methodology through alkali-activation concepts that combine the usage of carbide lime [Ca(OH)₂] with a sodium hydroxide (NaOH) solution to stabilize a sulfate-rich dispersive clay. For this, a 2^k factorial design approach was adopted in the definition of the experimental runs to be tested at 1-D swelling. As a reason, the effect of the following variables could be evaluated: NaOH solution concentration, amount of Ca(OH)_2, and dry unit weight (γ_d). Essentially, the usage of a NaOH solution, combined with carbide lime, has shown to be effective in reducing the swelling of the studied mixtures. Moreover, the volumetric strain could be successfully correlated to the porosity/lime index, which enhances the novelty of the approach applied herein and enables the prediction of ε_v for distinct combinations of porosity and amounts of lime.