Investigating the pozzolanic reaction of post-consumption glass powder and the role of portlandite in the formation of sodium-rich C-S-H

The use of glass powder (GP) as an alternative SCM offers a viable opportunity to partially substitute OPC, and therefore provides economic and environmental benefits. Moreover, the predominant siliceous amorphous phase provides the required component for its use as pozzolanic material . In this work, the mechanism and the products of the finely ground GP reaction with lime are investigated. The released silica , from glass dissolution, reacts with calcium hydroxide (CH) to form C-(N)-S-H with different compositions depending on the system. In the studied CH-GP binder systems , the fineness of GP ensures a higher surface for silica to react, leaving time for the pozzolanic reaction to take place. However, the glass continues to react even after the consumption of CH, which may lead to the apparition of alkali-silica gels around the particles in the long term.