Sunday, January 27, 2013
Bricks and mortar
In preparation for reconstructing the palace enclosure wall we began today to make the mortar for the bricks. We had to truck in mud, sand, and straw to make it and then mix it all on site. Specialized builders have been called in as construction with unbaked mud brick is a dying art. These days most houses, even in small villages, are made of baked brick and cement mortar, or concrete, or limestone block with cement mortar. Unbaked mud can last a very long time, however, particularly in Egypt where there are mud brick monuments nearly five thousand years old. It is also one of the most environmentally friendly methods of construction.
The mortar for our new mud bricks is made according to a traditional formula of 3 parts mud to four parts sand to one part straw. The Nile mud is a very fine silt and needs these additives to make it more easily worked. It is different from the bricks used in the palace which are almost entirely Nile silt and are very dark, dense, and tough. The ancient mortar also had a much more homogenous composition of silt.
Unlike masonry in ancient Egypt, where very little mortar was used between stones and was more for positioning them rather than cementing them, mud mortar was slathered on in great quantities. This is particularly true at Malqata, where everywhere we see signs of hasty construction, and the mud mortar is used to make up for the often rather sloppy laying of the brick. In the palace, the mortar placed vertically between the bricks can vary between 2 to 8 centimeters thick, while horizontally between the courses it can be as much as 2 to 5 centimeters thick.
Each brick was glued to the one below usually by two circular pads of mortar. They seem to have been balled up in the hand and then pressed into place.
Many of the walls were covered with mud plaster, which did contain a lot of straw to help it hold together, and this was also fairly thick ranging up to about 30 centimeters in depth and we can still see the finger marks of the people who applied it.
Interestingly, the mortar used in the North village is sometimes different, as are the bricks. Along with the Nile mud bricks and mortar, the yellowish desert soil is also used occasionally to make bricks and mortar. I remember seeing the same pattern years ago at Deir el-Ballas, where the palace and official buildings are made of Nile mud while the houses are a mix of mud and desert clay bricks and mortar. This may show that, at least certain aspects of the construction of their homes, were left to the people living in these royal cities, and not everything may have been planned by the government.