Ashlar masonry is a type of stone masonry which is formed using finely dressed stones of same size, shape, and texture laid together in cement or lime mortar of equal size joints at right angles to each other.
The masonry built using ashlar stones is rectangular where cuboid blocks are laid in horizontal courses or layers. The joints between the stones are very thin, regular, and of uniform thickness, which make the ashlar masonry very strong and sturdy.
It takes quite a long time to prepare the finely dressed stones and then build with them; furthermore, the process of construction is expensive. Therefore, it's usually reserved for large imposing structures like fortification walls, castles, palaces, and churches.
History of Ashlar Masonry
The origin of the use of ashlar masonry is unknown as this dates back to very long time back in history. Ashlar blocks made of local limestone and sandstone form part of the Knossos Palace in Crete, built by the seafaring Minoan civilisation between 2000 and 1500 BC. Later, the Mycenaean's, who lived in the Aegean, used ashlar masonry in citadel and wall construction.
In 15th-century South America, the construction expertise of the Incan civilization used ashlar masonry for building structures at Macchu Pichu and Cusco. The walls were constructed with extreme intricacy and an unimaginable uniformity that it must have taken it months to complete even one section. Today, despite time and earthquakes, they still stand upright without any deformities.
Types of Ashlar Masonry
Factors like the arrangement of the stones, laying of the stones in regular courses with continuous joints, or in broken courses, the height and length of the stones in the layer etc., define these types. Ashlar masonry is broadly divided into 6 types.
1. Ashlar Rough Tooled M
In this type of ashlar masonry, the beds and sides are finely chisel dressed but the exposed face is dressed by rough tooling. This dressing gives the masonry a rough exposed finish to the masonry.
2. Ashlar Fine Tooled Masonry
This is the finest type of ashlar stone masonry. The bed, joints and faces of the stones are chisel-dressed to remove all unevenness and obtain perfectly horizontal and vertical joints. The mortar joints are so thin that they are barely exposed which gives this type of masonry, a very close and packed finish.
3. Ashlar Facing
This type of ashlar masonry is used to give the building an exposed and good aesthetics. The exposed faces of the stones are rough tooled and chamfered.
4. Coursed Ashlar Masonry
This type of ashlar masonry has uniform sized stones with alternating vertical joints which strengthens the wall. The stones are laid in such a way that the joints formed by the lower layer are covered.
5. Chamfered Ashlar Masonry
It is a special type of ashlar rock faced in which the strip provided around the perimeter of the exposed face is chamfered at an angle of 45 degree to a depth of 25 mm.
6. Random Ashlar Masonry
The stone block arrangement doesn't have any specific rule of placement.
It has a general course of alignment, however, the vertical joints need not be one over the other.
The construction of this masonry requires skilled and knowledgeable worker. Although it looks very random, it has an in-built harmony. The variations in height and length have to be in proportion to the overall structure, for strong bonding, and thus, the positioning has to be mindfully crafted.
Great Monuments with Ashlar Masonry
1. Machu Picchu, Peru
The 'dry stone walls' technique is known for its peculiarity of constructing stone walls without binding the stones within with mortar. This Inca site of Machu Picchu has such dry stone walls.
2. Pyramid of Menkaure, Cairo
This is the smallest of the triad of pyramids located on the Giza plateau, on the southwestern outskirts of Cairo in Egypt. It is built from granite and limestone. The mortuary temple complex was constructed using ashlar granite.
3. Royal Tombs, Mycenae, Greece
Ashlar masonry was used in the building of the so-called 'beehive' dome. Hard rocks are the perfect kind for shaping into ashlar stones. Since the rock has to be heavily chiseled, a soft rock cannot be used due to the risk of fractures. Thus, rocks like granite, bluestone, and sandstone are used in ashlar masonry.
Read More : Dressing of Stones with Different Finishes for Masonry Works