De-calcified palaeozoic limestone as filter - for bitumen

摘要

The filler is naturally occuring de-calcified palaeozoic limestone with SiO2 from organic sources. The residue is pref. used alone or mixed with inorganic additives such as limestone, porphyry, slate, iron slag, fly-ash, or at most 10% Portland cement. This allows the bitumen absorption number or porosity to be adjusted as required.