Development of a standard accelerated weathering test for aggregates using dimethyl sulfoxide (DMSO).

PDFTech ReportFHWA-OR-RD 87-02HPR 085-5167AggregatesAccelerated weatheringTestsRocksImmersion testsPetrographyMineralsDeleterious materialsOregonOregon State University. Dept. of Civil EngineeringSzymoniak, TomVinson, Ted S.Wilson, James E.Oregon State University. Dept. of Civil EngineeringOregon. Department of Transportation. Materials and Research SectionUnited States. Federal Highway AdministrationUS Transportation CollectionA standard accelerated weathering test using Dimethyl Sulfoxide (DMSO) was developed to simulate the chemical degradation of basaltic rocks. After a thorough study of the parameters affecting the current procedure, such as container geometry, aggregate particle size, sample weight, and immersion time, a standard test was developed. The recommended procedure consists of immersing a sample of aggregate in the size range between 2.38 mm (#8) and 4.76 mm (#4), weighing 1000g, for a period of five (5) days. At the end of the immersion time the aggregate is re-screened over the 2.38 mm (#8) sieve and the percent weight loss is calculated. The acceptable weight loss limit for the DMSO Accelerated Weathering Test was established by correlating the test results to those obtained through petrographic analysis. The petrographic analysis consisted of determining the percentage of deleterious secondary minerals and their textural distribution within the rock matrix. With these two parameters, a Secondary Mineral Rating for each quarry was calculated and compared to the DMSO test results. In addition, it was found that DMSO may overreact if the minerals analcime and calcite are present in the quarry rock. A second indirect test, the Clay Index, was presented as a simple method to determine the likelihood of DMSO to overreact, since it was found to be insensitive to the type of minerals present in the rock