Innovative Hybrid Sensor for Rapid Assessment of Sulfate-Induced Heaving in Stabilized Soils: Fid-Bau Portal

Innovative Hybrid Sensor for Rapid Assessment of Sulfate-Induced Heaving in Stabilized Soils

A. Puppala

Heaving has been observed in sulfate soils when they are treated with lime or cement additives. This heaving is attributed to the formation of an expansive mineral known as Ettringite. Ettringite is known to form from reactions of calcium ions from the chemical additives, sulfates in soils and free reactive alumina released from treated clayey soils and stabilizers. Since chemically-treated bases have been used to support the pavement infrastructure, this type of heave has distressed the pavements and as a result, it became necessary to develop alternate stabilization techniques to treat sulfate soils. Evaluation of the sulfate heaving requires long laboratory-based mix designs, since it is important to perform the long term swell tests on treated soils. Hence, it is important to develop a faster and reliable device and test method to assess and evaluate sulfate heaving in chemically-treated sulfate soils in a short time frame. The intent of the present research was to devlop an innovative hybrid sensor, BM sensor comprised of Bender Element (BE) and moisture based Time Domain Reflectometry (TDR) technologies to assess the sulfate heave in treated soils in a quick time frame. This hybrid sensor was successfully used in the laboratory for quick assessments of soil stiffness and moisture content variations in cement and lime-treated sulfate soils. After succesful and quick assessments of the heaving, the sensor was used in the field test section to monitore stiffness and moisture content changes. Both laboratory and field studies showed that this sensor can be used in the field to assess sulfate heaving. More field studies will further enhance and promote the use of this sensor for quick evaluation of sulfate heaving.