Fig. 6: Macroscopic and microscopic observations of samples after salt weathering test.

a Macroscopic and microscopic observations of sample N-35. b Macroscopic and microscopic observations of sample S-35. c Macroscopic and microscopic observations of sample N-25. d Macroscopic and microscopic observations of sample S-25. e Macroscopic and microscopic observations of sample N-15. f Macroscopic and microscopic observations of sample S-15.