Mitsubishi Materials and Ube Industries have announced their joint development of a ultrahigh strength silica fume cement called Silica Fume Cement Super. By increasing the quantity of silica fume and optimizing the composition and manufacturing method for the cement, the partners have to realized an ultra-high strength of 150N/m2, a compressive strength not possible with silica fume cement of the past. It has also enabled concrete pumping which was impossible in the past.
Another feature is that the cement can be used in the same way as ordinary cement in ready-mixed concrete factories. The two partners intend to commercialize the product in the first half of this fiscal year, and sales will take place through Ube Mitsubishi Cement, a joint venture of the two companies.
The shift to high-strength concrete is progressing along with the increasing number of ultrahigh rise collective housing projects being constructed in major metropolitan areas. In order to achieve concrete with a compressive strength of 100 N/m2, JIS standard cement is inadequate, and the current silica fume cement is limited to 120 N/m2.
In addition, for a strength of 150 N/m2 or more, as the water-to-cement ratio drops below 15% viscosity rises considerably, so it becomes difficult to produce and work with concrete, and in particular concrete pumping was impossible.
Silica fume comprises ultra-fine particles with a diameter of 0.1 micrometers and having non-crystalline silicon dioxide as its main component. It increases the strength and fluidity of concrete.