Masonry means construction of buildings utilizing building blocks such as stone, bricks, and concrete blocks, etc.. Masonry is used for the construction of foundation, plinth, walls, and columns. Mortar is the binding material for the building blocks. In this article, different kinds of stone masonry used are explained, and points to be observed while supervising stone masonry works are listed.
What Is Stone Masonry?
The construction of stones bonded together with mortar is termed as stone masonry. Where the stones can be found in abundance in nature, on cutting and dressing to the proper shape, they provide an economical material for the construction of various building components such as walls, columns, tootings, arches, beams, etc..
Stone-masonry being stronger, durable, and weather-resistant, when compared with brick masonry, is used in the construction of piers, docks, dams lighthouse, and other marine structures.
Types of Stone Masonry
Mainly there are three Stone Work Types:
1. Rubble Masonry.
2. Ashlar Masonry.
3. Squared Stone Masonry.
Rubble, composed of natural stone, or stone so dressed as not to permit laying with uniformly thick joints or horizontal joints.
Rubble masonry may be laid coursed or uncoursed. When coursed, the stones are leveled off at specified heights to an approximately horizontal surface.
These courses are not necessarily of the same height but may rise by steps. This work is said to be random coursed.
In uncoursed rubble, the stones are fitted together without regard for courses. Dry rubble is laid without mortar, in low retaining walls and slope walls.
Most of the low retaining walls, slope walls, and miscellaneous structures in part projects are laid up in rubble masonry.
It fits into the surroundings better than more formal kinds of masonry and is usually built of stones found nearby.
For these projects, it is the most attractive masonry when well built, and satisfies all of the requirements of such field structures.
More than that, rubble masonry is a thing of beauty’ when well done, and its composition and. Pattern call for good Judgment and imagination.
One factor in doing a pleasing job Is the choice of stones for size. By observing the rule that headers must be used frequently to tie the wall together, considerable variation in size will be realized.
Smaller stones, chinking irregular spaces between larger stones, also add to the pattern.
The choice of stones for shape is another factor deserving many studies. Since it is unnecessary to hold to courses of uniform height, odd shapes can be used with fine effect.
Occasionally a stone of striking shape and considerable size can be placed to break up too much regularity in the pattern. Long, thin planes give a horizontal effect, which is most pleasing in low structures.
The mortar joints must be kept as uniform in thickness as possible. Many variations in the thickness of the joints will destroy whatever beauty the pattern may have in other respect.
Remember that the wall must be strong, as well as pleasing. So there is more than the pattern on the face to consider.
The pattern need not be sacrificed for strength if stones are chosen for their width extending through the wall, as well as for shape and size, and if care is taken to use a header at every opportunity.
Rubble masonry is one of the best things that an enrollee can learn to handle, for experts in this trade are in demand, and architects and landscape architects always have the need of men who can lay up this type of masonry in an artistic manner.
The thing we find most beautiful is that which satisfies our sense of proportion and of the suitability of materials, and our feeling for good taste in design.
It will be simple and appropriate, in a pattern pleasing in its variety and balance, end having unity, with its surroundings.
Ashlar is stone dressed to permit laying with uniformly thick horizontal joints l/2 inch thick or less. It is divided into two classes:
First, ranged or regular coursed ashlar, also called cut-stone work or dimensioned stone work. This is made of rectangular blocks cut and dressed to prescribed dimensions, and laid in courses of uniform height.
Second, broken ashlar, which is made of rectangular stones cut to dimensions, but not of equal thickness, and laid in the wall in courses which are not continuous throughout. The courses are not always of the same height.
Ashlar is the finest class of masonry. Extreme care is used in setting the stones. The bed for the stone must be thoroughly clean and wetted down.
A thin layer of mortar is then spread evenly. The bed surface of the stone is wetted down. Then the stone is lowered into place on two strips of wood laid in the mortar.
Heart, with a pinch bar, the stone is moved into its exact position and plumbed. The strips of wood are then removed, and the stone settled into place, being leveled by striking with a wooden mallet. The mortar joint should not be over l/2 inch thick.
Each of these three classes of stone masonry is divided into several others. These other classes and combinations of types of arc often used with distinctive names.
Square Stone Masonry.
Square Stone Masonry is laid up with a stone that has been roughly dressed to permit its laying with horizontal joints l/2 inch thick or thicker and is adapted to the same bonds as ashlar.
It is not dressed to as fine a finish as ashlar and therefore, may require joints thicker than 1/2 inch to take up the inequalities of the stones.
It is divided into three classes:
Range masonry, in which all stones are of the same height, and their lengths are fairly uniform.
Broken range, in which the courses are not all of the same height, and two stones are occasionally used to make up the height of the course. The length of the stones may vary a great deal.
Random range, in which the height of courses, the height of stones to make up the courses, and the length of stones may all vary, making an irregular pattern not greatly different from broken ashlar.