Strength of compacted earth: Linking soil properties to stabilizers

The influence of stabilizers and soil properties on the strength of stabilized, compacted earth is investigated. This is achieved by establishing relationships between natural soil properties (two measures each of gradation and plasticity and one of shrinkage), stabilizer treatments (0-6% of lime and/or cement and/or asphalt), and stabilized unconfined compressive strength (UCS). A total of 219 strength tests were performed on 104 different soils. The soils can be categorized into two groups according to whether single soil properties or combinations of them are "favourable or "unfavourable in their predisposition to stabilization. The mean UCS for favourable soils ranges from 2.98-3.25 MPa (90%≥2 MPa) and for unfavourable soils from 2.32-2.48 MPa (60%≥2 MPa), having controlled for stabilizer treatment variation. Soil linear shrinkage is the best single discriminator of stabilization suitability based on the categorization results. In linear modelling (analysis of covariance), the UCS of favourable soils is a function of variation in soil properties but not of variation in the quantity of cement or lime used. Conversely, the UCS of unfavourable soils is a positive function of the quantity of stabilizer used. The results of the study stress the importance of selecting a soil whose characteristics are favourably predisposed to stabilization in order to attain satisfactory strengths of compacted earth. Future research should be aimed at developing a system that uses key soil properties to predict the likelihood of successful stabilization.