Ferrocement

Ferrocement is used to construct relatively thin, hard, strong surfaces and structures in many shapes such as hulls for boats, shell roofs, and water tanks.

The inventors of ferrocement are Frenchmen Joseph Monier who dubbed it "ciment armé" (armored cement) and Joseph-Louis Lambot who constructed a boat with the system in 1848.

The outer layer was sculpted to mimic rustic logs and timbers, thereby also ushering faux bois (fake wood) concrete.

When used in house construction in developing countries, it can provide better resistance to fire, earthquake, and corrosion than traditional materials, such as wood, adobe and stone masonry.

It has been popular in developed countries for yacht building because the technique can be learned relatively quickly, allowing people to cut costs by supplying their own labor.

In the 1930s through 1950s, it became popular in the United States as a construction and sculpting method for novelty architecture, examples of which are the Cabazon Dinosaurs and the works of Albert Vrana.

Over this finished framework, an appropriate mixture (grout or mortar) of Portland cement, sand and water and/or admixtures is applied to penetrate the mesh.

Steps should be taken to avoid trapped air in the internal structure during the wet stage of construction as this can also create cracks that will form as it dries.

Modern practice often includes spraying the mixture at pressure (a technique called shotcrete) or some other method of driving out trapped air.

Its big attraction was that for minimum outlay and costs, a reasonable application of skill, an amateur could construct a smooth, strong and substantial yacht hull.

Using the example of the Mulberry Harbours, pre-fabricated units could be made for ports (such as Jamestown on St Helena) where conventional civil engineering is difficult.

The disadvantage of ferro concrete construction is the labor-intensive nature of it, which makes it expensive for industrial application in the western world.

In modern practice, the advent of liquid acrylic additives and other advances to the grout mixture create slower moisture absorption over the older formulas, and also increase bonding strength to mitigate these failures.