Abstract

The objective of this research was to compare the efficacy of portland cement to that of lime for improving the strength and durability of plastic clays. The scope of work associated with this research involved laboratory strength and durability testing of three plastic clays treated with portland cement or lime. To ensure a broad application of the work, the clays were obtained from three different regions of the United States, specifically from project sites near Bloomington, Indiana; San Antonio, Texas; and Monticello, Utah. Laboratory testing included evaluation of selected properties of the three clays in the untreated condition and in the treated condition. For the untreated condition, testing included measurements of soluble sulfate concentration, analysis of particle-size distribution, determination of treatment concentration using the Eades and Grim test, determination of Atterberg limits, development of moisture-density relationships, and measurement of California bearing ratio. In the treated condition, each clay sample was treated with either portland cement or lime, and testing included determination of Atterberg limits, development of moisture-density relationships, measurement of unconfined compressive strength (UCS), evaluation under wet-dry cycling, and evaluation under freeze-thaw cycling. For each of the three clay types, statistical analysis was performed to compare the strength and durability of the cement-treated specimens and the lime-treated specimens at each treatment concentration. Across all three clays, lime-treated specimens exhibited greater reductions in the plasticity index when compared to cement-treated specimens. In general, increased treatment concentrations corresponded to increased strength and strength retention. Percent strength retention of the cement-treated specimens was higher, on average, than that of the lime-treated specimens for the Indiana and Texas clays at low and medium concentrations. Similar strength retention was observed for cement-treated specimens and lime-treated specimens at high stabilizer concentrations across all three clays. In general, similar or significantly higher strengths were observed for specimens treated with cement than specimens treated with lime after 7 days, 28 days, and freeze-thaw cycling. Cement-treated specimens retained similar or greater mass after wet-dry cycling than lime-treated specimens. Cement-treated specimens also retained similar or greater strength after freeze-thaw cycling than lime-treated specimens, except for the Texas clay treated at the high concentration and the Utah clay treated at the medium concentration.

Degree

Rights

https://lib.byu.edu/about/copyright/