Ultrafine Alkali Activated Slag (AAS) and Portland/Slag (P/S) cements have been commercially available in the United States for 2 and 5 years, respectively. Ultrafine cements have been the subject of research at Northwestern University for 6 years.
Particle size of the ultrafine slag cement is characterized by 98% passing at 7 microns and a D50 at 3 microns in contrast to the ultrafine portland/slag cement which has 98% passing at 10 microns and a D50 at 4 microns.
The chemical composition of the slag used in these cements is 35% SiO2, 16% Al2O3, and 43% CaO. The composition of the portland/slag cement, which is a 25/75 blend, is therefore between the bulk composition of portland cement and the slag.
Both of the ultrafine cements permeate fine sands when formulated at high
water-to-cement ratios. Viscosity plays an important part in the permeation mechanism, and both cements exhibit viscosities below 10 cps at water-to-cement ratios of 2. This low viscosity is obtained through the use of superplasticizing with naphthalene sulfonate and acrylic acid polymers.
Applications of the ultrafine cements include dam grout curtain rehabilitation, consolidation grouting, and nuclear and hazardous waste containment. One hundred and twenty metric tonnes of the portland/slag cement have been used for hazardous waste containment at Niagara Falls, New York.