Plain bricks spall away fairly soon. I used them sideways in 4 places to hold the grills in the fireplace I made in Baton Rouge. They kinda fell apart by the end of about 5 years.
The fire bricks held up for around 18 years in the fireplace made out of field stone with firebrick in the chimney and fire pit area, similar to what we put out back in the pics I posted. They were still good when I sold the house in 1990 and moved to Singapore.
Ralph