The following article concerning the history of concrete and reinforcing steel was taken in part from the ironworkers reinforcing manual.

“Concrete is essentially an artificially made rock, and is one of the most important and lasting of building materials.

Historical proof of concrete’s importance and durability can be found in the Pantheon at Rome which was built about 117-124 B.C. — over 2,000 years ago. This ancient structure was built with circular walls about 20-feet thick and a hemispherical dome spanning 142-feet. The concrete used was a mixture of lime, an aggregate of soft volcanic rock, and a local earth or clay called “puzzolana” found in the vicinity of Rome.

A timeline of interesting facts about cement and reinforcing steel:

• 1756 (approx.) — English engineer John Smeaton makes the first true hydraulic cementing material (a material that hardens under water). Today this product is known as “hydraulic lime”.
• 1824 — Portland cement patented by Joseph Aspdin of Leeds, England. The name Portland was chosen due to the remarkable resemblance of the hardened cement to the building stone quarried on the Isle of Portland.
• 1850 — A Frenchman named Lambot constructs a small boat using reinforced concrete.
• 1854 — W.B. Willkinson of England patents a true reinforced concrete floor slab.
• 1861 — Francis Goignat publishes a statement of the principals of this new construction method.
• 1861 — Joseph Monier, a Parisian gardener, employs the use of metal frames as reinforcement for garden tubs and pots.
• In 1897, two German engineers, Wayss and Bauschinger, investigate a report on the “Monier System.” Prior to this time, there was comparatively little construction of this type.

Austrian Engineers made great developments in theory and practice in the 1890’s, and the use of structural steel shapes as reinforcement was developed. During the same time frame, François Hennebique of France and Ernest L. Ransome in the United States were the first to use reinforced concrete in building construction. Ransome, in his early experiments, originated the twisted square bar from which numerous patterns of deformed bars have evolved. The success of these two men encouraged further study on the subject, resulting in several methods of reinforcement being introduced both in Europe and North America.

A.P. Turner of Minneapolis devised a girderless or flat slab called the “Mushroom Slab” in 1906. By that time the use of reinforced concrete was becoming quite prominent and has increased from year to year up until the present day.

Concrete by on its own has very little tensile strength. Therefore, it must be reinforced in some manner that will ensure against rupture or breakage. When the construction is such that tension can occur, reinforcing steel is embedded into the concrete to withstand that tension. The use of concrete and steel together constitutes what is called “Reinforced Concrete.” Reinforced Concrete is a combination of both steel and concrete using the best properties of each, namely the crush resistant strength of concrete and the tension, or pull resistance of steel.

Combination structural members of concrete and reinforced by steel bars, placed so as to carry the tensile stresses are sturdy and reliable. The concrete, besides supplying compressive strength, also supplies the steel with protection from corrosion and fire. Qualified Engineers design reinforced concrete structures, and drawings are made to show the size and location of the reinforcing steel.

It was early in the 1900’s when the Iron Workers established jurisdiction over the unloading, handling and installation of reinforcing steel for concrete construction. It wasn’t too long until Iron Workers were skilled in laying reinforcing steel. Companies, therefore, found the most efficient way to perform a job requiring the use of this material was to hire members of the International Association of Bridge and Structural Iron Workers. And as we know, the name of the union was later changed to the International Association of Bridge, Structural, Ornamental and Reinforcing Ironworkers.

As the demand for more buildings grew, and construction increased throughout the United States and Canada, so did the demand for more skilled ironworkers. Although many buildings were constructed of steel, many others were of reinforced concrete. The number of skilled workers in this branch of the iron working trade has increased and today, many buildings, structures and bridges are designed, not only to withstand tremendous weight, but also to conform to modern day Architecture.”