due to its low cost, concrete was a popular replacement for stone as a structural building element. as a building material, concrete was historically consigned to unseen structural positions such as behind a veneer or in the basement, but evolutions in texturing technology produced concrete blocks that could perform aesthetically as well as structurally. rusticated concrete blocks, often referred to as rock-faced concrete blocks, from then on were seen as a cost effective substitute for natural faced stone and from a reasonable distance could pass for the real thing. these rock-faced blocks were valued not only for their low cost but also for their natural fire resistance, sound absorption, and energy efficiency. additionally, installment time was reduced as the irregularity of the faces eliminated the high level of precision needed in placing plain faced blocks.