There is provided an apparatus and process for manufacturing a brick or paver with a high content of coal ash (ranging from 60% to 100% coal ash or fly ash) so that a waste product (coal ash, and more particularly Class F coal ash) from a coal-fired power plant is incorporated into a building product (high content fly ash brick or paver). Also provided is a variable firing tray to support the dried, high content coal ash bricks/pavers as the dried products are sent through a tunnel kiln, to improve circulation around the individual bricks/pavers and thereby result in reduced firing time in the kiln.