Numerical Investigation of the Reaction Kinetics and Expansive Behavior of Sulfate Bearing Soils

The presented study is primarily motivated by observations of significant sulfate induced heaving in cement stabilized soils that have occurred in a number of recent construction projects in Ohio. It is well known that the reaction between the sulfate and alumina in soils and calcium of a lime or cement stabilizer often leads to the formation of ettringite, an expansive sulfate mineral that may contribute to the expansion. This subject has been extensively researched in the past but most of the studies have been focused on the experimental aspects. This paper presents a chemo-mechanical approach to better understand the expansive behavior of stabilized sulfate bearing soils. Numerical simulations are performed in the present study to explore different scenarios characterized by distinct predominant mechanisms. The interplay between different mechanisms is examined in numerical simulations based on recently reported experimental results. The simulation results show that ettringite formation and osmosis swelling can play comparable roles in the heaving process. The kinetics of osmosis is also explored in two distinct theoretical frameworks and the modelling results are consistent with the experimental observations.