If construction is carried out using stones with cement or lime mortar, it is known as stone masonry.
1. Stone masonry
2. Brick masonry
3. Composite masonry
Terms used in Stone Masonry
●Natural Bed: The surface on which the materials was originally deposited in the formation of rock is known as natural bed. Rocks from which tones for masonry is obtained have distinct planes of division along with stone can easily be split. These planes are the natural beds of the stone.
●Bond: The interlocking arrangement of bricks, so as to avoid the occurence of continuous vertical joints is known as bond
●Quoins: The external comer (or) angles of a wall are known as quoins and the stones (or) bricks forming the quoin are known as quoin stones (or) quoin brick.
●Sill level: The bottom surface of a door (or) a window spening is known as a sill level.
●Corbel: It is aprojection provided on the inside face of the wall by projecting stones. The projection is used to serve as a support for root plates (wooded beam) for roof trusses, beams etc.
●Weathering: It is a term to indicate bevelled top surface of the stone. It is sloped so as to allow easy flow of rain water;
●Spalls: Stone chips broken off from large size stone during dressing and shaping are known as spalls.
●Lacing Course: The horizontal course provided to strengthen a wall of regular small stones is known as a lacing course.
●Through Stones: In stone masonry, some stones at regular intervals are placed through the lull thickness of wall to develop bond.
●Cornice. This is a moulded course of masonry hav ing large projections. It may be provided at the junction of the wall and ceiling near the top of the building
●Coping. It is a course of stone, concrete (or) bricks provided at the top of the wall so as to protect the wall from seepage of rain water through joints at the top most course of the wall. This course is generally provided at the top of a parapet wall (ar) compound wall.
●Throating: It is a small groove cut on the underside of aill, coping, cornice und projected chajja to discharge the rainwater without trickling down to the walls
●Course, A layer of stones or bricks is known as a course. The thickness of a course is equal to the thickness of a stone of hrick plus thickness of one mortar joint.
●String Course: It is a continuous horizontal course of masonry, generally provided at every floor level. This course remains projecting from the face of the wall and is intended to improve the elevation of the structure.
General Principles of Stone Construction
◆All the stones used for masonry shall be hard, tough, compact and durable. It should have compact grains and uniform texture.
◆The stones should be laid on their natural beds.
◆The pressure acting on stones should not act parallel to the bedding planes. This shall split the stones.
◆Proper bond should be maintained throughout the masonry.
◆Under the ends of girders and roof trusses larger flat stones should be used.
◆Joints in the stone masonry should not be too smooth to loose friction.
◆ The exposed joints of stone masonry should be proper- ly pointed.
◆The entire masonry work should be properly cured, i.e., it should be kept wet for about two weeks
Dressing of Stones
The process of cutting stones into suitable sizes and shapes is known as dressing of stones
Objects off Dressing
1. To convert the stone pieces in to desired shape and size.
2. To make thin mor- tar joints thereby reducing the mor- tar consumption and to improve the qualities of work.
Hammer Dressing
3. To give the desired surface finish.
4. To make transport easy and economical from quarry.
Types of Dressing
1. Hammer dressing
3. Punched dressing
2. Chisel dressing
5. Combed dressing
4. Furrowed dressing
1 Hammer Dressing: A hammer dressed stone shall have no sharp and irregular corners and shall have comparatively even surface. All the sharp and irregu lar comers of the stone obtained by quarrying shall be knocked off by using the flat face of a scrabbling ham- mer. The surface shall be dressed with the pointed and of the hammer.The projection on the face shall not be more than 40mm on an exposed face.
2. Chisel Dressing: Stones available from the quarry is first dressed with hammer and then smoothly dressed by means of a pointed chisel, so that all the projections are removed and a fairly smooth surface is obtained. In this type of dressing the depth of gap between the surface and a straight edge kept over the surface shall not exceed 1.5mm. This type of dressing is very commonly adopted for ashlar work.
3. Punched Dressing: This is another form of rough dressing usually used for lower portions of the build- ings.punch hole on it at some regular distance (say 25rnm) apart. A25mm wide strip is made around the perimeter of the stone with the help of chisel.
4. Furrowed Dressing: This type of finish is applied to the fillets or flat Hands of cornices, string courses, doors and windows etc. A margin of about 20 mm width is sunk on all the edges of the stones and the central potion is made to project about 15 mm.
5. Combed Dressing: This finish is used only in soft stones. Drags made of steel plates and of different grades are then dragged backward and forward in different directions until the tool marks are eliminated. Fine drags is used at the end, eliminates all the scratches on the stone.
Classification of Stone Masonry
The stone masonry classified as given below.
1. Rubble masonry
2. Ashlar masonry
●Rubble Masonry
In this masonry, stones are not dressed finely. They are used in the masonry as they are available from the quarry (or) stones obtained from quarry may be shaped with the help hammers just by removing excess projection before they are used in the masonry.
Types of Rubble masonry
A. Coursed rubble masonry
B. Uncoursed rubble masonry
C. Random rubble masonry
D. Dry rubble masonry
A. Coursed Rubble Masonry: In this type of rubble masonry, the height of stones vary from 50 mm to 20 cm. The stones are sorted out before the work starta, The masonry work is then carried out in courses such that stones in a particular course are of equal heights
B.Uncoursed Rubble Masonry: In this type of rub- ble masonry the stones arc not dressed. But they are used as they are available from the quarry, except breaking some corners. The courses are not main tained regularly. The wall is brought to a level every 30 cm to 50 cm. This type of rubble masonry being cheaper, is used for the construction of compound walls, godowns, garages, labour quarters etc.
C. Random Rubble Masonry: The stones of irregular sizes and shapes are used for the construction of masonry. The stones arc arranged so as to have a good appearance. More skill is required to make this masonry structural ly stable, This face stones aremchisel dressed and the mortar joints does not exceed 6 mm to 12 mm. This type of masonry is used for the construction of residential buildings, compound walls etc.
D. Dry Rubble Masonry: This is similar in construc- tion of the coursed rubble masonry, except that no mortar is used in the joints. This requires skill in construction. This type of masonry is used in com- pound walls, pitching, bridge approaches, retaining walls etc.
●Ashlar Masonry: In this masonry the entire con- struction is done using square or rectangular dressed stones. The stones used in this masonry are all dressed timely which chiseled. The height of stones varies from 25 cm to 30 cm.
Types of Ashlar Masonry
a. Ashlar fine masonry
b. Ashlar Rough tooled masonry
c. Ashlar Rock masonry
d. Ashlar Chamfered masonry
e. Ashlar block in course masonry
A. Ashlar Fine Masonry: In this type of masonry, the beds, sides and faces are finely chisel dressed. The stones are arranged in proper bond and the thickness
of the mortar joints does not exceed 3 mm. This type of construction gives perfectly smooth appearanes. It is costly in construction.
B. Ashlar Rough tooled masonry: In this type of ash lar masonry, the beds and sides are finely chisel. dressed. This type of work is also known as the bastard ashlar.
C. Ashlar Rock masonry: In this type of ashlar masonry, a strip about 25 mm wide and made by means of a chisel, is provided around the perimeter of every stone exposed for view as in case of rough- tooled ashlar. Only projections on the face, known as the bushings, exceeding & gives massive appearance.
D. Ashlar Chamfered: In this masonry, 2.5 cm chisel, drafting around the face is leveled at an angle of 45° with the help of chisel. Another chisel drafting about 10mm to 12 mm wide is again developed around the perimeter inside the chamfered drafting. The remaining enclosed space is left as such. However, projections of more then 8 cm are removed with the help of hammer.
E. Ashlar Facing or Ashlar Block-in-course: This masonry may be called as combination of rubble masonry and ashlar masonry. The faces of the stones are generally hammer dressed and the thickness of mortar joints does not exceed 6rnm. The depth of course varies from 20 cm to 30 cm this type of construction may be used for heavy engineering works such as retaining walls and sea-walls.
Tools Used in Stone Masonry
Trowel-To lift and spread mortar.
Plumb rule and bob -To check the veiticality wall.
Spirit level -To check the horizontahty of the sur- faces.
Crow bar – To make the stones in quarry.
Hammer – For rough dressing of stones.
Chisels- To dress stones.
Pick axe For rough dressing and to split stones.
Line and pins – To maintain the alignment of the piogtess.
Bevel – To set out angles.
Mallet – it is a wooden headed hammer used for wooden headed chiesels.
