The bitumen content in bituminous materials can usually be determined quickly and accurately by Method No. 1. In the case of certain natural asphalts containing finely divided mineral matter, the mineral residue is not easily retained by the filter and it is necessary to resort to Method #2 to obtain accurate results. This method will not be used unless the filter becomes unduly clogged or the mineral matter passing through the filter exceeds 0.5%.
NORMA 59-P-1947 history
1947NORMA 59-P-1947 Interim Standard for Measurement of Bitumen Composition in Asphalt Raw Materials