Preparation and characterization of one-part non-Portland cement

This work aims at enhancing the mass production and commercial viability of non-Portland cement (NPC) by preparing one-part-NPC (just add water). NPC is an eco-efficient material compared to Portland cement (PC). It was prepared by mixing of blast-furnace slag (BFS) with 2, 4, 6, 8 and 10% sodium hydroxide (SH) by total weight of BFS, and then mixing it with water. The homogeneous slurry is immediately dried in an oven at 80 °C for 24 h, followed by pulverization to a fixed particle size. Two main compositional factors were examined: first is the increase of SH wt%, while the amount of water to slag (W/BFS) ratio is kept maintaining constant, and the second includes increasing of W/BFS ratio at constant SH dosage. One-part NPC was mixed with water at W/NPC ratio of 0.25, and then cured. A conventional two-part NPC, containing SH solution (liquid part) and BFS (solid part), was prepared for comparison. The results showed that, the amount of NPC hydration products increase with SH wt% and W/BFS ratio. The compressive strength values of hardened cements proved that, the activation of slag continues after the addition of water to NPC. After 90 days of curing, the compressive strength of one-part NPC mixture decreased by 10% compared to that of the two-part-NPC containing the same activator content. Some selected hardened pastes were analyzed using FTIR, TGA/DTG and SEM techniques. The results of the different analyses are in a good harmony with those of mechanical properties and prove that; one-part NPC can be beneficially used as an alternative to PC.