Development of Equipment for Compacting Soil-Cement into Plastic Molds for Design and Quality Control Purposes

Abstract

In current soil–cement practice, a disconnection exists between laboratory mixture design, pavement layer thickness design, and construction quality control. A device was developed to integrate all three of those aspects by allowing compaction of soil–cement into single-use plastic cylinder molds. The device was a metal split-mold design that surrounded the slightly modified plastic mold to prevent distortion of the specimen during compaction. Compaction was performed by use of two methods: a custom-built compaction frame (similar in concept to the ASTM D-1632 device) and a manual modified-Proctor hammer. This paper's objectives are (a) to demonstrate the feasibility of using the new device to produce suitable specimens and (b) to discuss possible applications. More than 750 soil–cement specimens were compacted under laboratory conditions with the new device. Specimens were analyzed for final dimensions (e.g., diameter and height), variability in unconfined compressive strength, and elastic modulus. Analysis showed that the device could produce acceptable test specimens with variability in unconfined compressive strength similar to that of traditional Proctor specimens and that values of specimen elastic modulus were similar to those found in literature. Currently, the Mississippi Department of Transportation is working toward incorporating this new compaction device into its soil–cement practices.