Construction and performance of the stabilized base course on U.S. 77 Ponca City, Kay County (FHWA-OK-87-7) 2128

Abstract

This study investigates the field implementation of shale stabilization on an experimental project. A number of test sections were set on the south bound lane of U.S. Highway 77, north of Ponca City, Kay County, Oklahoma. To compare the effectiveness of various stabilizing agents, the base courses of these test sections were stabilized with cement (14%) I quicklime (4.5%), fly ash ( 25%), and an optimum mixture of 8% cement + 3% quicklime + 18% fly ash used conjunctively. Also a control (non-stabilized) section was set as a reference section. Analyses of the samples prepared during construction and those cored from under the pavement after construction showed significant amelioration of the engineering properties of stabilized shale as manifested by their plasticity, compressive and beam strength compared to raw (non-stabilized) shale. Benkelman beam measurements ascertained the improvement in deformation resistance. The microstructure of stabilized shale was studied using X-ray diffraction (XRD). The non basal (hkl) reflections in stabilized oriented specimens suggest that the clay particles in the stabilized shale acquired high resistance to dispersive forces. This, together with the reduction in the integrated intensities of clay minerals help explain the improved stability as a result of stabilization. SEM observations in conjunction with EDS, depicted the presence of .some newly formed hydration products and a rather dense degree of packing. The various data converge to the conclusion that field stabilization is a viable solution to the use of expansive shales.