Cement was a substance used in construction that hardened and was used to bind other materials together.
Subsequently, the term could refer to anything that kept a way of life from falling apart. A Vulcan phrase originated by T'Plana-Hath was "Logic is the cement of our civilization with which we ascend from chaos using reason as our guide". (ENT: "The Forge")
In 1930, when a cordrazine-affected Dr. Leonard McCoy believed that his 20th century surroundings had been faked he was impressed with the perfection, "right down to the cement beams." (TOS: "The City on the Edge of Forever")