Durability Studies on Native Soil-Based Controlled Low Strength Materials

The Integrated Pipeline (IPL) project - a collaborative effort between the Tarrant Regional Water District (TRWD) and Dallas Water Utilities (DWU) - will supply additional water to the Dallas/Fort Worth area. As part of a sustainability initiative, several studies were conducted to assess the reuse potential of excavated materials along the IPL project. One of these studies involved using the excavated material as an ingredient in a controlled low strength material, often known as CLSM or flowable fill. This flowable fill can be used as bedding and haunch material in pipeline construction. These CLSMs meet the specifications in the short term; however, their long-term performance should be verified in order to be successfully used in the field, especially when these materials are subjected to seasonal changes such as wetting and drying. Hence, durability studies were conducted on CLSMs from two different geologic formations, namely Eagle Ford and Queen City. The variations in retained strength and volumetric strain changes, along with the amount of stabilizer leached out of the CLSM samples at different durability cycles, are presented in this paper. It was observed that Eagle Ford soil CLSM lost more than 50% of its initial strength while Queen City sand CLSM lost approximately 50% of its initial strength when subjected to durability studies. The loss in strength was attributed to both volume change and stabilizer loss in the case of Eagle Ford soil, while stabilizer loss alone caused the loss of strength in the case of Queen City sand.