Blue bricks and red bricks are all made of clay, and there is no difference in material. It's just the burning color of blue bricks and wood. Red brick, the color that burns with coal. In ancient times, brick burning was basically wood burning. We went to the Forbidden City to see the so-called red wall pipa. In fact, they are all blue bricks, but they are painted with red paint.

China coal was widely used in Song Dynasty. Not surprisingly, someone must have used it to burn bricks, or had it before.

As for the blue tile, see what tile you mean. I don't know if it is an ordinary gray tile (in China, black is also called cyan). If it is glazed tile, it has been used in architecture since the Southern and Northern Dynasties.

"Biography of Sui Shu He Chou": "At that time, China's glazed works were few and far between, and craftsmen dared not be careless. Thick green porcelain was no different from real porcelain. It shows that it was blue glaze at least in Sui Dynasty.