Johnson set to work trying to discover its composition but because Aspdin's product was protected by explicit patents and extreme secrecy it was impossible to market a copy.
Johnson, a highly moral man, Mayor of Gateshead and a JP, was able to claim that he was the inventor of "true" Portland cement and is generally recognised as such.
He pioneered several innovations, including the production of low-water rawmix slurries, and new designs for kilns and industrial chimneys.
In 1910 on his 100th birthday Johnson was presented with a silver tea service by representatives of the cement industry in Britain and several European Countries.
Johnson was a founding member of Zoar Strict and Particular Baptist Church, Gravesend, where he served as a deacon for many years.