Reinforcing bars in masonry construction have been used since at least the 15th century (2,500 meters of rebar was used in the Château de Vincennes). During the 18th century, rebar was used to form the carcass of the Leaning Tower of Nevyansk in Russia, built on the orders of the industrialist Akinfiy Demidov. The cast iron used for the rebar was of high quality, and there is no corrosion on the bars to this day. The carcass of the tower was connected to its cast iron tented roof, crowned with one of the first known lightning rods. However, it was not until the mid-19th century that rebar displayed its greatest strengths with the embedding of steel bars into concrete, thus producing modern reinforced concrete. Several people in Europe and North America developed reinforced concrete in the 1850s. These include Joseph - Louis Lambot of France, who built reinforced concrete boats in Paris (1854) and Thaddeus Hyatt of the United States, who produced and tested reinforced concrete beams. Joseph Monier of France is one of the most notable figures for the invention and popularization of reinforced concrete. As a French gardener, Monier patented reinforced concrete flower pots in 1867, before proceeding to build reinforced concrete water tanks and bridges.
when did they start using rebar in concrete
the mid-19th century