Portland cement mortar (often known simply as cement mortar) is created by mixing Ordinary Portland cement (OPC), hydrated lime, and aggregate (or sand) with water.
It was invented in 1794 by Joseph Aspdin and patented on 18 December 1824, largely as a result of various scientific efforts to develop stronger mortars than existed at the time. It was made popular during the late nineteenth century, and owing to the First World War, it had by 1930 superseded lime mortar for new construction. The main reasons for this were that Portland cement sets hard and quickly, allowing a faster pace of construction, and requires fewer skilled workers. However, as a general rule, Portland cement should not be used for the repair of older buildings constructed in lime mortar, which require the flexibility, softness and breathability of lime if they are to function correctly.
In the United States (and other countries), one of five standard types of mortar (available as a dry premixed product) are generally used for both new construction and repair. The ratio of cement, lime, and sand included in each mortar type produces different strengths of mortar. The formulations for each type are specified by the ASTM standards organization. These premixed mortar products are designated by one of the five letters M, S, N, O, and K, with Type M mortar being the highest strength and Type K the weakest. These type letters are taken from the alternate letters of the words "MaSoN wOrK".
Read more about this topic: Mortar (masonry)
Famous quotes containing the words portland, cement and/or mortar:
“It is said that a carpenter building a summer hotel here ... declared that one very clear day he picked out a ship coming into Portland Harbor and could distinctly see that its cargo was West Indian rum. A county historian avers that it was probably an optical delusion, the result of looking so often through a glass in common use in those days.”
—For the State of New Hampshire, U.S. public relief program (1935-1943)
“It is fair to assume that when women in the past have achieved even a second or third place in the ranks of genius they have shown far more native ability than men have needed to reach the same eminence. Not excused from the more general duties that constitute the cement of society, most women of talent have had but one hand free with which to work out their ideal conceptions.”
—Anna Garlin Spencer (1851–1931)
“For the first time I’m content to see
What poor mortar and bricks
I have to build with, knowing that I can
Never in seventy years be more a man
Than now a sack of meal upon two sticks.”
—Philip Larkin (1922–1986)