Fig xA Variation of bulk density and apparent
The mechanical evaluation was performed using specimens 25 mm in diameter × 25 mm in height by cold crushing strength (CCS) tests. A hydraulic press machine (ELE International, model ABR-AUTO) was used, and the reported values 1-NM-PP1 averages of 10 measurements.
Microhardness determination on sintered specimens was done using an HMV microhardness tester (Shimadzu). The loading time was 15 seconds with a loading force set as 9806.65 N. Reported values are the average of 30 indentation measurements performed on the surface area.
For chemical attack tests, sintered specimens corresponding to each composition were ground to below 45 μm. Then the resulting powders were mixed with clinker raw material (see Table 3 for clinker raw material composition) in a mass ratio of 3:1. The mixture was homogenized for 20 min. After that, pellet samples (25 mm in diameter and 10 mm in height) were pressed at 50 MPa. The specimens with clinker raw material concentration were heated up to 1450 °C with a soaking time of 4 h and then, the samples were cooled down within a laboratory electric furnace. Microstructure evaluation was done by a scanning electron microscope (SEM) equipped with EDS chemical microanalysis.