This document describes the reference method for the determination of the methylene blue value (VBS) in soils and rocks for earthworks. The test is based on measuring the quantity of methylene blue that can be adsorbed by the material suspended in water. This quantity of absorbed methylene blue is reported by direct proportionality to the 0/50 mm ground. The soil blue value is directly related to the specific surface area of the soil particles or rocky material. NOTE The VBS test uses common equipment and calibration as the methylene blue test MB for aggregates (EN 933-9), but the test applies to another granular fraction (5 mm for VBS and 2 mm for MB, respectively). Thus, the results obtained between the two tests cannot be compared in the general case.