"Lime is forgiving and lime is self-healing." Hallock credits lime for the endurance of the centuries-old Tower of Pisa and the ancient aqueducts of Rome.
The lime used to stabilize the clay must be fresh, Hallock said. Lime that has turned gray is old. It has absorbed humidity and won't be as effective.
The exact recipe used to manufacture CEBs will depend on the soil composition of the region. Here in Baja California, Sur, Mexico, the Loreto Bay plant combines:
- 65% clay
- 30% sand
- 5% lime
Later, a smaller mixer (shown here) is used to combine the mortar, which is also stabilized with lime.