Question

Most commercially produced adobe bricks are "stabilized" by adding asphalt emulsion (3 to 5 percent by weight) or Portland cement (5 to 10 percent). These coat the clay particles and reduce their tendency to absorb water and expand. Occasionally (and traditionally) straw is added — why?

Answer

Straw is said to increase the brick's tensile strength and reduce shrinkage cracking during curing.