High activity agent for concrete N90 TOPFILL® N90 is a new type of reinforcing material, its main component is modified Silica. The particle size distribution is 60nm~500nm, the aggregate structure is a single sphere, with irregular groove surface and relatively lower structure. The smallest structural unit is spherical. With extremely low surface activity, structural units could not be agglomerated. The smallest structural unit has uneven surface, with certain reinforcing performance. Nano grade structural unit has a very low degree of structure. Good dispersion in rubber, with addition amount increasing the rolling resistance of tread rubber decreased.