Permeability of Expansive Soils Modified/Stabilized with lime (Review Paper)

Abstract

The aim of this paper was to review the mechanism of the expansive soil-lime reactions: short term and long-term reactions in both lime modification and lime stabilization. The focus of the study was the effect of curing time for a certain centigrade 25C curing temperature in both lime modification / stabilization-expansive soils on the coefficient of permeability. Peer reviewed articles published between 2000- and 2019 were collected and relevant data were extracted. Results of this review study showed that the coefficient of permeability of expansive soils modified with lime increased during the first 7 days of curing time at curing temperature 25C and it remains constant or slightly decreased for longer curing time periods. However, for expansive soils stabilized with lime, it was found that the coefficient of permeability increased during the first 7-day curing time at curing temperature 25C, then decreased during the longer curing time periods (pozzolanic reaction). It is also noted that even though the coefficient of permeability decreased during pozzolanic reaction, it remains higher than that of the untreated soils. Conclusions Based on the data selected from previous works, the following conclusions can be driven from this review paper: • For lime modification, the initial consumption lime (ICL) is added to the expansive soil sand caused to increase the coefficient of permeability (k) during the first 7-day curing time at 25C curing temperature. Beyond the 7 days curing time, the coefficient of permeability may remain constant or slightly decreased. • For lime stabilization, adding lime content to the expansive soils must be more than ICL. This percent of lime will attribute to increase the coefficient of permeability (k) for the first 7 days curing time. After that (longer curing time), the pozzolanic reaction will develop. The coefficients of permeability decreased and continue decrease as long as the pozzolanic reaction has been developing. But the final magnitude of the coefficient of permeability remains higher than that of the untreated soils even at very long curing time. • High technologies such as Scanning electron microscopy (SEM) showed that the inter-particle pores are in charge of the change in the coefficient of permeability of lime modification/stabilization of expansive soils. • An average value of increasing permeability for all studies at curing time 7 days and 28 days can be determined and its ratio to initial average value can be quantified to assess the amount of increasing in soil permeability at different stage.

Keywords

• Permeability
• Lime modification / stabilization
• Expansive soils