Performance improvement of Portland-limestone cement by mechanochemical activation

Abstract

This study investigates mechanochemical activation with alkanolamine-based agents for improving the material performance of Portland-Limestone Cement (PLC). By using 0.1 wt% of diethanolisopropanolamine during grinding process, a noticeable improvement of compressive strength (>100 % increase in 28 days) was confirmed for PLC containing 20 % limestone due to the favorable interaction between the diethanolisopropanolamine and limestone. Grinding in the presence of diethanolisopropanolamine (1) enlarges the specific surface area when limestone is added, (2) stabilizes ettringite, (3) enhances hydration of ferrite, and (4) leads to form denser hydration products. The hydration of mechanochemically treated cement lowers the formation of portlandite with preferred orientation in (001) direction and leads to more formation of amorphous and AFm phases, independent of the presence of limestone. The limestone powder in mechanochemically activated PLC enhances the ferrite dissolution and the production of monocarbonate, which contributes to the significant improvement of compressive strength.