Lightweight concrete obtained with special admixtures producing bubbles throughout the mass shows lower resistance, which makes it less suitable for … - Eduardo Torroja

Before a man can successfully plan a structure... he must study, from every possible angle, the ultimate purpose of his building. Attention must be directed to the basic structural concept before the mathematical process of calculation is undertaken.

Adobe (sun-dried clay bricks) is a material usable in regions where sandy clays suitable for fabrication are found. Adobe masonry, is, however, useful only for walls and structural elements subjected to lower values of tension and compression, and is, therefore, of little interest as a structural material.

If you lean on a straight stick... [it] can resist your weight, despite its slenderness, as long as it remains straight; once it starts to bend, it will easily break. The danger of breaking increases with the deflection... [T]he danger of failure will diminish with the increased of the cross section, or if the same are of cross section should be maintained, by distributing the material in a hollow section.