Influence of fine aggregates on the microstructure, porosity and chemico-mechanical stability of inorganic polymer concretes

• Reinforcement of the interfacial zones with Al–Si Fines improved the chemical stability and strength of IPC concretes.
• Reactions at the interfacial zones contributed to pores refinement with the decrease in the pores threshold.
• Semi-crystalline Fines provide a very limited degree of reactions (at the surface of the solid particles) essential for the quick and effective setting within a short period of setting.

This work investigates the effects of the structure, the bulk chemical composition and amount of the aluminosilicate fines on the strength development, pore refinement, water permeability, moisture control capacity and the microstructure of inorganic polymer concretes (IPC). The amorphous fines, one from pumice and another from recycled glass, presented sponge-like microstructure with tortuous pore network that maintained the presence of fine capillary pores while semi-crystalline feldspar sludge, the third type of fine aggregates used for this study, showed more dense and compact microstructure that explain the higher strength enhancement. Both amorphous and semicrystalline fines contributed to decrease the porosity, improve the strength and microstructure. However, based on the moisture control capacity and the durability indicators, the fine aggregate derived from semicrystalline feldspar was found to be more appropriate and efficient for the development of IPC at short time scale of curing. Pumice fine aggregate was found to be effective only with a long term curing.