Engineering presented on October 16th, 1986. Title: Development of A Standard Accelerated Weathering Test for

Some basaltic rocks common in Oregon when incorporated into a pavement structure as the base course aggregate or in the surfacing layer degrade and disintegrate owing to the minerals contained within the rock and the environment in which it is placed. To simulate the chemical degradation of basaltic rocks an accelerated weathering test using Dimethyl Sulfoxide (DMSO) was developed. The objective of the research reported herein was to: 1) study the interaction of DMSO with clay standards, 2) develop a reliable method of determining clay type and content In basalt rocks, 3) study the parameters influencing the current test and develop a standard procedure, and 4) determine acceptable weight loss limits for untreated basalt aggregates after immersion in DMSO. By investigating the electro-static interaction between clay standards and DMSO it was found that the DMSO molecule has a preference for cations and it is able to donate hydrogen ions. Both factors allo