The American Concrete Institute (ACI) or American Concrete Institute is a non-profit organization in the United States of America that develops standards, norms and technical recommendations with reference to reinforced concrete. It was founded in 1904 and its headquarters are in Farmington Hills, Michigan, USA.[1]​.

At the beginning of the 20th century, there were no standards for the manufacture of concrete blocks in the United States and, as a result, a negative perception of the use of concrete for construction became popular. An editorial by Charles C. Brown in the September 1904 issue of Municipal Engineering even discussed the idea of ​​forming an organization to bring order and standardize practices in the industry. In 1905, the National Association of Cement Users was formally organized and adopted a constitution and bylaws. Richard Humphrey was elected as the association's first president. The first committees were appointed at the 1905 convention in Indianapolis and provided preliminary reports in various subject areas. At the 1907 convention the first complete reports of the committees were offered. The association's first official headquarters was established in 1908 in Richard Humphrey's office in Philadelphia, Pennsylvania. Administrative and editorial assistance led to more effective organization of the institute's conventions and procedural publications. The Standard Building Regulations for the Use of Reinforced Concrete were approved at the 1910 convention and became the association's first reinforced concrete construction code. By 1912 the association had already approved 14 standards. At the December 1912 convention, the association approved the publication of a monthly journal of proceedings. In July 1913, the Board of Directors of what was then NACU decided to change its name to the American Concrete Institute. The new name was considered to be more descriptive in relation to the work carried out within the institute.[3]​.

The Building Requirements Code for Structural Concrete (ACI 318) provides minimum requirements for the design and construction of structural concrete portions of any structure erected under the requirements of a general building code incorporating it.[4]​ This was issued by the American Concrete Institute.[5]​.