Abstract: A partially hydrophobic precipitated silica having a methanol wettability of 10 to 49%, in particular with a DBP uptake on a dry basis of greater than 250 g/100 g and a mean particle size of 1 to 12 &mgr;m and/or a carbon content of 0.3 to 1.85% and/or a loss on drying of 2.6 to 10.0% and/or a pH value of 5.5 to 10.0, is prepared by mixing the amount of water-repellent agent with the precipitated silica suspension at very short residence time and low pH value, filtering off the solid substance, washing free of salt, drying, post-treating thermally and milling. The partially hydrophobic precipitated silica can be used in active substance formulations and active substance formulations of hydrolysis-sensitive substance and in defoaming agents.

Abstract: There is provided a process for improving mineral asphaltic coatings for streets and roadways comprising preparing a mixture to be used as the base mineral asphalt coating material, homogeneously mixing in 0.1 to 10 weight % of silica which is either (1) a precipitated silica, (2) a precipitated and spray dried silica or (3) a pyrogenically produced silica and further working this mixture into a mineral asphalt coating for streets and roadways.