Dating mortar

10-Mar-2020 07:17

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The 14C content of a mortar sample can thus in principle give a measure of the time elapsed since the time of hardening.

However this is fraught with difficulty; the mortar may contain old limestone, either as remains from incomplete conversion into calcium oxide in the burning process or from sedimentary carbonate in the aggregate, yielding apparent ages that are too old due to this form of contamination.

According to Roman Ghirshman, the first evidence of humans using a form of mortar was at the Mehrgarh of Baluchistan in Pakistan, built of sun-dried bricks in 6500 BCE.

The ancient sites of Harappan civilization of third millennium BCE are built with kiln-fired bricks and a gypsum mortar.

Lime and gypsum in the form of plaster of Paris are used particularly in the repair and repointing of buildings and structures because it is important the repair materials are similar to the original materials: The type and ratio of the repair mortar is determined by a mortar analysis.

There are several types of cement mortars and additives. Because of a lack of stone and an abundance of clay, Babylonian constructions were of baked brick, using lime or pitch for mortar.

Mortar is a workable paste used to bind building blocks such as stones, bricks, and concrete masonry units together, fill and seal the irregular gaps between them, and sometimes add decorative colors or patterns in masonry walls.

In its broadest sense mortar includes pitch, asphalt, and soft mud or clay, such as used between mud bricks. Cement mortar becomes hard when it cures, resulting in a rigid aggregate structure; however the mortar is intended to be weaker than the building blocks and the sacrificial element in the masonry, because the mortar is easier and less expensive to repair than the building blocks.

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Dating mortar accurately is very difficult unless it is obviously something like a black ash mortar which was prevalent in the 19th and early 20th century.Thus, artillery pieces that bear little resemblance to howitzers of earlier eras are now described as howitzers, although the British call them guns. military doctrine defines howitzers as any cannon artillery capable of high-angle (45° to 90° elevation) and low-angle (45° to 0° elevation) fire; guns are defined as being only capable of low-angle fire, and mortars only capable of high-angle fire.Most other armies in the world reserve the word howitzer for guns with barrel lengths 15 to 25 times their caliber, longer-barreled guns being termed cannons. In the 18th century, they adopted projectile weight for guns replacing the old naming system of culverin, saker, etc. Mortars had been categorized by calibre in inches in the 17th century and this was inherited by howitzers. The modern howitzers were invented in Sweden towards the end of the 17th century.Howitzers, like other artillery equipment, are usually organized in groups called batteries.

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and houf is in turn a borrowing from the Middle High German word Hūfe or Houfe (modern German Haufen), meaning "heap".The quicklime is then slaked with water to form calcium hydroxide (Ca(OH)2) or building lime, which is mixed with aggregates or filler (sand) and water to form mortar.

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