Stone is one of the best and most ancient construction materials. The construction of a Stonemasonry wall is very much better than any other structure. In ancient times many buildings are constructed using stone masonry. Stone and mud joint building is a powerful structure at such a time.
Today I will explore the stone masonry wall in construction, the Technical terms of the stone, and the principles of stone masonry. If you are a civil engineer and overseer working in the construction field this basic information is necessary. I hope this article is very helpful for you. Please read this post till the end to increase your knowledge.
What is a Stone Masonry wall?
Stone is used to construct walls with mortar joints called Stone masonry walls. Stone is a construction material that is used in different structures. Like Building walls, Retaining walls, bridges, Tunnels, roads, railways, and many more structures. The stone masonry is divided into ashlar masonry and rubble masonry. That will be discussed below for stone masonry wall details.
The technical term for Stone Masonry wall
what are the technical terms of stone masonry walls? if you are a technical person then technical terms of construction materials are also necessary for your job. So I have attracted some important terms used in stone masonry wall construction.
Natural Bed
This term is used in stone masonry only. We already know that stone is obtained from the rocks. The stone is formed by the plane of division of rocks. A natural bed is a particular plane part of the rock where the stone is easily split. In stone masonry, a natural bed of stone should be kept perpendicular to the direction of the pressure.
Course
A horizontal layer of stone is known as a Course. In stone masonry thickness of course cannot be standardized as stones are not available in any one size.
Bed
The lower surface of stones on which the rest in a course is known as a bed.
Hearing
The space of the wall between facing and backing is known as hearing.
Joint
- The place where two or more stores meet is called a joint.
- The joint between the successive course of stones is known as the bed joint.
- The joint between various units in a course is known as a vertical joint.
Through stone
- Some stones at regular intervals are placed right across the wall. Such stones are known as through stones or bond stones and sometimes only through. These stones keep both the faces of the wall securely held together.
- If the thickness of the wall is considerable, two through stones with suitable overlap are provided.
- The area covered by the through stones should be about 1/4 to 1/2 of the area of the wall surface in the plan. Through stone should be nonporous to prevent any moisture from getting into the wall.
Plinth course
The topmost course of masonry to attain a plinth is known as the plinth course.
String course
It is a continuous horizontal course of masonry generally provided at every floor or sill level. This course remains projecting from the face of a wall and is suitable weathered and throated to through off rainwater, clear off the wall face.
Corbel
It is a projection provided on the inside face of the wall by the projection of one or more courses of stones. The projection is used to serve as a support for wall plates for roof trusses, beams, etc. The collet stones should rest at least 2/3rd of their width into the wall to prevent their overturning before trusses make it to rest on them.
Cornic
This molder course of masonry heaving large projection may be provided at the junction of a wall and ceiling or near the building. Cornice stone should have sufficient bearing on the wall and also sufficient weight on it to prevent its overturning.
Weathering
is the term used to indicate the level to the surface of the stone, sills, cornices, and coping stones bevel at the top surface in a sloping way to allow easy flow and rainwater.
Throating
It is a term that applies to the groove formed on the underside of a cornice, sill, and coping stones. This groove helps to throw away rainwater and clear the wall surface.
Coping
It is a course of stone, concrete, or brick, provided at the top of the wall to protect the wall from seepage of rainwater through the joints of the topmost course of the wall.
Block in the course
This is a course of stone masonry, provided above the cornice to hold down the cornice against the tendency of overturning. It also adds to the appearance of the structure.
Frieze
it is a course of the stone provided immediately below the cornice. It is gradually kept flush with the wall and may have architectural moldings from the appearance point of view.
Spalls
Stone chips broke off from large-sized stones during dressing and shaping known as spalls. Spalls are used to fill up the empty spaces in the stone masonry with mortar. Spall is known as snecks.
Template
It is a block of stone used under the bearing ends of beams. It distributes the concentrated load transferred by beam reaction over a large area of a load-bearing wall.
Molding
Their ornamental features give constructional members to their aesthetic appearance.
Material Required for Stonemasonry Wall
Now I am going to give a brief information about what we need to do while installing stone masonry walls. Also, we need mortar for the stone and joints.
Stone
The stone used for masonry should be hard, durable, tough, sound, and free from weathering, decay, or defects like cracks, sand holes, injuries, patches of loose or soft materials, etc.
The stones should be obtained only from the approved quarry.
The stone unit should be obtained by quarrying large massive rocks and not by breaking small boulders having rounded faces. Rocks from which building stones are divided into three groups.
- Igneous
- Sedimentary
- Metamorphic
Mortar
Do we know what mortar is? Mortar is a bonding agent for any masonry wall. In which two or more stones help to be connected. Cement mortar, Lime mortar, and Mud Mortar are used in the stone masonry. Cement mortar is the best mortar for stone masonry wall construction.
What are the objectives of mortar use?
- Load intensity
- Increase load caring capacity
- Improve the durability of the wall
- Binding stones each other
- Fire Resistance
- Increase the rate of setting and hardening
Safe Permissible load on stone masonry
The strength of stone masonry depends upon the following factors:
Stone ( i.e sandstone, limestone)
Masonry (i.e coursed rubble, ashlar, etc)
Mortar (i.e lime mortar, cement mortar, mud mortar)
The basic stresses are based on the compressive strength of stone units and various types of mortars.
Ashlar masonry in 1:3 cement mortar
Granite = 1600 KN/m2
Sandstone = 1100 KN/m2
Limestone = 700 KN/m2
Ashlar masonry in lime mortar
Granite = 1100 KN/m2
Sandstone = 800 KN/m2
Limestone = 500 KN/m2
Coursed rubble masonry in 1:3 cement mortar
Granite = 1200 KN/m2
Sandstone = 1000 KN/m2
Limestone = 600 KN/m2
Coursed rubble masonry in lime mortar
Granite = 900 KN/m2
Sandstone = 700 KN/m2
Limestone = 400 KN/m2
Random rubble masonry in 1:3 cement
Mortar = 600 to 1200 KN/m2
Random rubble masonry in lime mortar = 400 to 600 KN/m2
Classification of stone masonry
Stonemasonry can be classified into main two types. Which is listed below. The classification of stone masonry is in the construction used of the arrangement of stones, shaping of stones, and finishing of stone masonry.
- Rubble masonry
- Ashlar masonry
Rubble Masonry
In the rubble masonry, the blocks of stone that are used are either undressed or comparatively rough-dressed. The stone masonry has a wide joint, till the irregular size and shape of the stone should be used. Rubble masonry is also categorized into the following types:
Random Rubble course
This is the roughest and cheapest form of stonewalling. In random rubble masonry, the stones should be used in widely different sizes and shapes.
Since the stones are not of uniform size and shape, greater care and ingenuity have to be exercised in arranging them in such a way that they adequately distribute the pressure over the maximum area, and at some time long continuous vertical joints are avoided.
Random Rubble Built to course
This method of construction is the same as non-course except the works are roughly leveled up to form a course varying from 30 to 45 thick. For the construction of this type of masonry, quoins are built first and the line is stretched between the tops of quoins. The intervening walling is then brought up to this level by using different sizes of stones. This type of masonry is better than non-course random rubble masonry.
Square Rubble Uncoursed
Square rubble masonry user stones have straight beds and sides. The shape of stones is usually squared in shape and brought to hammer dressed or straight cut finish of the stone. In the course, of square rubble also sometimes known as square snacked rubble, the stones with straight edges and sides are available in different sizes. They are arranged on the face in several irregular patterns.
A good appearance can be achieved by using a (riser) large stone, (leveler) thinner stone, and ( sneck) small stones in a pattern having a depth of 3:2:1 respectively.
R= Riser : 3
L= Leveller: 2
S= Sneck: 1
Square Rubble Built to course
This type of masonry also uses the same stones as used for non-course square rubble. But the work is leveled up to the course may consist of quoins, jamb stones built in between them up to the height of the larger stones to complete the course.
Square Rubble Regular Coursed
In this type of masonry, the wall consists of various courses of varying height, but the height of stones in one particular course is the same.
Polygonal rubble masonry
In this type of stone, the hammer finished the face to an irregular polygonal shape. These stones are bedded in the partition to show face joints running irregularly in all directions.
Two types of polygonal walling may be there. The first type of stone was only roughly shaped, resulting in only rough fitting, such work is called a rough pick. In the second type, the faces of stones more carefully form so that they fit more closely. such work is called close-pick work.
Flint walling (Flint rubble masonry)
The stones used in this masonry are Flints or cobbles, which vary in width and thickness from 7.5 to 15 cm and in length from 15 to 30 cm.
There are irregularly shaped nodules of silica. The stones are extremely hard. But they are brittle and therefore may break easily. The face arrangement of the cobbles may be either course or non-course or built to course strength of the Flint wall may increase by introducing backing courses of either thin long stones.
Dry rubble masonry
Dry rubble masonry is rubble masonry made to the course in which mortar is not used in the joints. This type of construction is the cheapest and requires more skilled construction. This may be used for non-load-bearing walls such as compound walls etc.
Ashlar Masonry
Accurately dressed stone blocks with found stone beds and end joints called ashlar masonry.
The block of stone should be square and rectangular shape in this masonry. The height of stones varies from 25 to 30 cm. The height of blocks in each course keep equal but it is not necessary to keep all the courses of the same height. Ashlar masonry may be categorized into the following.
- Fine tooled
- Rough tooled
- Rock, rustic, or quarry-faced
- Chamfered
- Block in the course
- Facing
Ashlar Fine tooled
This is the finest type of stone masonry work. Each stone is cut to the regular and required size and shape to have all sides rectangular so that the stone gives a perfectly horizontal and vertical joint with adjoining stone.
The thickness of courses is generally not less than 15 cm.
The width of the stone should not be less than 15 cm.
The thickness of the mortar joint keeps uniform throughout and it should not be more than 5 mm. The exposed joints finely point.
Ashlar Rough Tooled
In this type of masonry, the beds and sides of each stone block are finely chiseled dressed first in the same manner as for ashlar fine, but the exposed face is dressed by rough tooling.
The thickness of the joint in this masonry doesn’t exceed 6 mm.
Ashlar Rock Faced ( rustic or quarry-faced)
In this type of masonry, the face of the stone in the exposed face is not dressed but the stone gives in to the rock facing.
However, a strip of about 25 mm wide, made using a chisel, provides around the perimeter of the exposed face of every stone.
The projection on the face exceeding 8 cm was removed with the help of a hammer. Such projection (exceeding 8 mm) is also called bushing.
The height of each block may vary from 15 cm to 30 cm.
Ashlar chamfered
In this masonry 2.5 cm, chisel drafting around the face, not left plane but it chamfers or bevels at an angle of 45° with the help of a chisel.
Another chisel drafting about 10 mm to 12 mm wide again develops around the perimeter inside the chamfered drafting.
The remaining enclosed space is left as such. However, a projection of more than 8 cm is removed with the help of hammers.
Ashlar block in the course
This masonry is intermediate between rubble masonry and ashlar masonry.
The faces of each stone hammer dress and the height of the blocks remain the same in any course, though it is not necessary to keep a uniform height for all the courses.
This type of masonry is adopted in heavy works such as retaining walls bridges etc.
Ashlar Facing
This facing masonry is provided along with brick or concrete block masonry to give a better appearance.
The sides and bed of each block are properly dressed to make the truck shape.
The stone exposes the face’s rough tool and chamfered.
The backing of the wall may be made of brick masonry.
General principles that should be observed in the Stone Masonry wall
The stone used should be strong, tough, and hard, and should be confined to the specification of work. The stones should be free from defects like cracks, flaws, cavities, etc.
The stones should be well-watered before use so that they do not observe water from the mortar.
All the stones should lay on their natural bed.
Stones to use should dress properly according to the type of masonry.
A proper bond should be maintained. Formation of the vertical joint should be avoided.
No tensile stress should allow development in the masonry.
Masonry work should be raised uniformly so that the nonuniform distribution of load on the foundation is avoided.
Broken stone, small pieces, and chips should not be used for facing and backing.
However, this may be used in hearting for proper packing with mortar.
The facing and backing of the wall should be well-bound by stones. The through stones should lay staggered in the successive courses. The center-to-center distance between them should not exceed 1.5 m.
The mortar to use for the work should be of proper quality and proportion. Masonry work may be done in mud mortar, lime mortar, or cement mortar.
Quoins used to form the joints for windows, doors, and other openings should be of the full height of the course. The breath and length of quoin should at least be 1.5 times and twice its depth respectively.
The vertical surface of the wall should be constructed perfectly is plumb. They should frequently check.
The joint in the stone masonry wall should be properly filled with mortar and stone chippings.
Where it requires raising new construction over the old or dry one it should be well cleaned and wetted before starting construction.
Double scaffolding should be adopted to carry out the stone masonry construction at a high level.
The exposed joint of the masonry should properly point by cement mortar or lime mortar, by racking them first up to a depth of about 2 cm.
Stone Masonry Wall Joints
The junction of adjacent units of stones is known as a joint. Parallel to the bed of brick or stones is the bed joint. Bet joints are thus horizontal mortar joints upon which stones are laid.
Joints perpendicular to the face of the wall are known as cross joints or vertical joints.
Butt joint or square joint
- Most commonly used.
- The dressed edge of two adjacent stones is placed side by side.
Rebated or lapped joint
This type of joint is provided in arches copings etc.
The length of the rebate or lap should not be less than 70 mm.
Tongue and groove joint or joggle joint
This type of joint prevents sliding along the side joints
Tabled or bed joint
This joint is used to prevent lateral movement of stones such as in sea walls where the lateral pressure is heavy.
The height of the projection is 30-40 mm and the width is equal to 1/3rd of the width of the stone.
Cramped joint
- The joint uses a mental cramp.
- Cramps are usually non-corrosive metals.
- Cramp dimension
- Length =20-30 cm
- Width =2-4 cm
- Thickness =5-10 mm
- Cramp prevents the tendency of the joints to open out.
Dowelled joint
The joint is formed by cutting rectangular holes in each stone and inserting dowels.
Conclusion
The wall of the building should be made with the help of Stone which is a stone masonry wall. I hope this post is very helpful for you. If you like and are helpful please share this post with your friend and comment in the comment section.
