l. Basic Physical Properties

1. Moisture content (natural & air-dry)

2. Particle size distribution (sieve analysis & laser particle-size analyzer)

3. Specific surface area (Blaine or BET method)

4. True density / bulk density (pycnometer or paraffin-seal method)

V. Durability & Defect Risk

21. Lime-burst test (GB/T 2542)

22. Efflorescence test (GB/T 2542)

23. Freeze–thaw cycling (-15 °C ↔ +15 °C, 25 cycles)

24. Saturation coefficient (C/B ratio)

ll. Plasticity & Forming Behavior

1. Liquid limit (WL)

2. Plastic limit (WP)

3. Plasticity index (IP = WL- WP)

8. Optimum forming moisture (Proctor-type test)

9. Critical moisture content

VI. Mineralogy & Microstructure

25. X-ray diffraction (XRD) – mineralogical composition

26. Scanning electron microscopy (SEM) – particle morphology

27. Petrographic analysis (thin-section method) – quartz, feldspar, mica, carbonate content

III. Drying Performance

10. Linear drying shrinkage

11. Drying sensitivity index (required<1.3)

12. Drying weight-loss curve (105 °C constant-temperature oven

13. Green-brick flexural strength (three-point bending, MPa)

VII. Particle Shape & Optimization (optional)

28. Aspect ratio (image analysis)

29. Fractal dimension (particle-size vs. surface-area correlation)

IV. Firing Behavior & Properties

14. Differential thermal analysis (DTA)

15. Thermogravimetric analysis (TG)

16. Firing temperature range test (gradient kiln, 850–1150 °C, 30 °C intervals)

17. Firing linear shrinkage

18. Water absorption & apparent porosity (boiling or vacuum saturation)

19. Apparent / bulk density of fired brick

20. Compressive strength of fired specimens (per GB/T 2542)

VIII. On-Site Rapid Checks

30. Field moisture content (portable moisture meter)

31. Field plasticity index (hand-rolling + vernier caliper)

Notes

• Tests 1–31 can be staged as “screening–detailed–trial production”.

• Typical threshold values:

– Plasticity index 9–13

– SiO₂ 55–75 %; Al₂O₃ 10–20 %; Fe₂O₃ 3–10 %; CaO ≤5 %; MgO+SO₃ ≤3 %

– Drying sensitivity index ≤1.3