Admixture makes concrete stronger and more durable

View of an off-ramp from Parker road to southbound I225 in Denver, Colorado. This structure used a ternary mix that included 6% silica fume, 20 percent Flyash class F and less than 500lbs of cement with 56-day strength of 4500 psi.  

One of the most widely used supplementary cementitious materials (SCMs) in the production of high-performance concrete (HPC) is silica fume. Also known as microsilica, silica fume is a byproduct of producing silica metal or ferrosilicon alloys. As an admixture in HPC, it makes concrete stronger and more durable.

Silica fume consists of very fine particles about 100 times smaller than the average cement particles. The extreme fineness of the silica fume particles allows it to fill the microscopic voids between cement particles