Performance Studies On Rigid Pavement Sections Built On Stabilized Sulfate Soils

Soils of Southeast Arlington are highly expansive and rich in sulfates. They undergo sulfate induced heaving when traditional calcium based stabilizers are used for soil stabilization (Puppala et al. 1998). Traditional stabilizers do not provide effective solution since they are known to induce heaving, termed in the literature as sulfate induced heaving (Hunter, 1988). Both swelling and softening of these soils rich in sulfates induce considerable damage to overlying pavement infrastructure. Typically, high sulfate soils treated with calcium based stabilizers form ettringite mineral. Ettringite undergoes heaving when hydrated (Hunter, 1988; Puppala et al. 2001). Since this sulfate-induced heave is caused by soil stabilization with calcium-based stabilizers, it is regarded as a manmade or post treatment expansive soil problem (Puppala et al. 2005). These problems are further aggravated by seasonal temperature disparity typical to North Texas and may eventually damage the pavement (Chen, 1988; Nelson and Miller, 1992). Constant maintenance problems on the existing pavement infrastructure resulted in the initiation of a research study to explore and investigate new methods for subgrade stabilization. The study has been conducted in University of Texas at Arlington as a part of research for City of Arlington. The research work conducted aims at selection of an ideal stabilization method or methods for stabilizing sulfate rich soils of Southeast Arlington. This research study was conducted to evaluate the stabilization potentials of Sulfate Resistant Type V Cement, Class F Fly ash with Type V Cement, Ground Granulated Blast Furnace Slag, Lime with Polypropylene fibers and Lime. Rigid pavement test sections were constructed on the five sections of stabilized subgrade soils and these sections were instrumented and monitored for twenty six months. Instrumentation data obtained from strain gauges and pressure cells as well as elevation surveys were analyzed to address any heave related movements and load carrying potentials of treated subgrades. DCP tests were also conducted to monitor the strength characteristics of stabilized soils. In addition, chemical tests and mineralogical tests were conducted on the stabilized samples collected from the test site to address the formation of Ettringite mineral. Overall, based on the long term analysis, Cement-Fly ash treatments proved to be the most effective treatment which for stabilizing sulfate bearing soils with no heave distress was followed by Type V Cement and GGBFS treatments.