Filler for bituminous concrete - by grinding montmorillonite containing free silica and calcium and magnesium carbonates, obviating undesirable swelling in water

摘要

The filler is made by heating to 150-800 degrees C and grinding, to fine particles whose porosity is 50% volume of voids, a crude or broken-up natural rock of the montmorillonite type contg. 35-70% silica and 5-40% CaO3 and/or MgCO3, the rock opt being mixed with other rocks supplying known fillers, e.g. limestone, chalk, porphyry, sand, schist, flyash, dolomite, or industrial slag.