Evaluation of Chemically Stabilized Clay Soil Embankments with Accelerated Pavement Testing

Abstract

The Midwest States Accelerated Pavement Testing Pooled Fund Program, financed by the highway departments of Missouri, Iowa, Kansas, and Nebraska, has supported an accelerated pavement testing project to compare the performance of stabilized clayey embankment soil when portland cement, fly ash, lime, and a commercial product were used as stabilizing agents. The project aimed to determine if lime stabilization, the most common method used in Kansas for the chemical stabilization of embankment soils, is the optimum method. The experiments were conducted at the Civil Infrastructure Systems Laboratory of Kansas State University. The test program consisted of constructing four pavement structures and subjecting them to full-scale accelerated loading. The study indicated that cement and lime are the most effective stabilizers. These stabilizers resulted in lower vertical compressive stresses at the top of the subgrade and lower rut depth at the pavement surface than the stresses and depth resulting from fly ash–treated soil. After more than 2 million axle load repetitions, the pavement with cement-stabilized embankment soil exhibited much less surface cracking than did the pavement with fly ash–stabilized embankment soil. The commercial product proved ineffective in stabilizing the nonsulfate clayey soil used in this experiment, when the embankment was constructed at the same moisture content and compaction level as for the other three chemicals. The unconfined compression strength measured on laboratory-prepared samples of soil stabilized with the commercial chemical compound was very similar to that of the untreated soil.