Most of today’s “concrete houses” have concrete walls, but a wood roof. This wood roof can become the weak link when natural disasters, such as hurricanes and earthquakes, strike an area. In contrast, all-concrete houses, such as those constructed with insulating concrete form (ICF) walls and reinforced concrete roofs, comprise very strong box shell structures that have been shown to be resistant to several types of natural disasters.

Concrete mixtures are almost always characterized by their water-cement ratio w/c. Unfortunately, the w/c is an abstract number without any particular meaning and is inversely related to concrete strength: the lower w/c, the greater the concrete compressive strength. As demonstrated in this article, the w/c also has a hidden meaning that helps explain its relationship to compressive strength and makes this relationship easier to understand.