Deep Soil Mixing Technology for Mitigation of Pavement Roughness

The effectiveness of Deep Soil Mixing (DSM) treatment method was evaluated in terms of reducing heave movements of underlying expansive soils. Several binder types were used to treat expansive soils and these methods are considered in a laboratory investigation to select the appropriate binders for field DSM studies. Laboratory studies indicated that a combined binder treatment approach of using lime and cement was the appropriate method for field studies. Two pilot scale test sections were then designed and installed on DSM soil columns. Anchor rods were used to fasten a biaxial geogrid to the DSM columns. Surcharge equivalent to loads from base and surface layers was placed on top of the DSM-geogrid sections through a fill placement. These treated test sections along with control sections on untreated soils were instrumented and monitored. Monitored results showed that soil shrink-swell related movements and pressures in both vertical and lateral directions were considerably less than those recorded in the untreated soil sections. Nondestructive studies using seismic methods showed the enhancements of shear strength in the treated zones. Overall, this research resulted in the development of a design methodology for stabilizing expansive clayey soils at considerable depths using DSM column treatment.