Disclosed herein are low density fiber cement articles, such as fiber cement building panels and sheets, comprised of multiple overlaying fiber cement substrate layers having small and uniform entrained air pockets distributed throughout. Also disclosed herein are air entrainment systems and methods for manufacturing aerated low density fiber cement panels or sheets with consistent air void content and uniform air void distribution. Also disclosed herein are air entrainment technologies adapted to work in conjunction with the Hatschek process to produce aerated fiber cement articles having controlled air void content and distribution.