Cob and reclaimed building materials go hand in hand.
This is a great article in Mother Earth News in which they mention using reclaimed concrete (Urbinite) as a perfect material for cob building foundations.
Photo By Chris McClellan
Today, building your own house is the exception to the norm, and it is almost unheard of to build with local materials. Instead, houses are built by specialists using expensive tools and expensive, highly refined materials extracted and transported long distances, often at great ecological cost. Industrial materials have many benefits — performance, predictability, speed and ease of installation — but they have in common that they must create a profit for the companies that manufacture them. The average number of members in U.S. households has dropped by more than half in the past 50 years. Yet, over the same time period, average home sizes have more than doubled. We are more comfortably housed than at any point in history, but practically enslaved by the payments (the word “mortgage” is French for “death contract”). Fortunately, we have other choices.