STONE MASONRY

Masonry Masonry may be defined as the construction of

building units bonded together with mortar. The building units may be stones, bricks, or precast blocks of concrete. When stones are used as the building units we have stone masonry. Masonry is normally used for the construction of foundations, walls columns and other similar components of the building. It performs variety of functions such as (i) supporting loads (ii) subdividing space (iii) providing thermal and acoustic insulation. Etc.

Definition of terms 1. Course: A course is a horizontal layer of masonry

units. Thus, in stone masonry , the thickness of course will be equal to the height of the stones plus thickness of one mortar joint. 2.Header: A header is a full stone unit or brick which is laid that its length is perpendicular to the face of the wall. Thus , the longest length of a header lies at right angles to the face of the work. 3. Stretcher: A stretcher is a full stone unit or brick which is so laid that its length is along or parallel to the face of the wall. Thus, the longest length of stretcher lies parallel to the face of the work.

4.Natural Bed: Stones are obtained from rocks

which have distinct planes of divisions along which the stones can easily be split. This plane is known as natural bed. 5. Through stone: A through stone is a stone header. Through stones are place at regular interval. If the thickness of the wall is small, through stone may be of length equal to the full width of the wall. 6. Sill: The bottom surface of a door or window opening is known as Sill. 7. Lintel: It is a horizontal member of stone, brick , wood, steel or reinforced concrete, used to support the masonry and the super-imposed load above an opening.

8.Plinth: Plinth is the horizontal projecting

course of stone or brick, provided at the base of the wall above the ground level. 9.Plinth Course: It is the uppermost course of the plinth masonry. 10.Column : It is a vertical load bearing member of masonry, which is constructed in an isolation from the wall and whose width does not exceed four times its thickness. 11.Pier: Pier is an isolated vertical mass of stone or brick masonry to support beams, lintels arch etc.

Classification of Stone masonry Depending upon the arrangement of stones in the

construction, degree of refinement used in shaping the stone and finishing adopted, stone masonry can be classified as follows: (a). Rubble Masonry (b). Ashlar Masonry In the rubble Masonry , the blocks of stone that are used are either undressed or comparatively roughly dressed. The masonry has wide joints, since stones of irregular sizes are used. Rubble masonry are of following types.

(a) Random Rubble -----------(i) Uncoursed

(ii) Built to course (b) Square Rubble -------------(i) Uncoursed (ii) Built to courses (iii) Regular Coursed (c ) Miscellaneous types --------(i) Polygonal walling (ii) Flint walling (d) Dry Rubble masonry

Random Rubble Masonry: Uncoursed This is the roughest and cheapest form of stone walling. In this type of masonry , the stones used are of widely different sizes. Since the stones are not of uniform size and shapes, 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 the same time long continuous vertical joint are avoided.

Random Rubble: Built to courses The method of construction is the same as above except that the work is roughly leveled upto form courses varying from 32 -45 cm thick All the courses are not of same height. This form of masonry is better than Uncoursed Random Rubble Masonry. For the construction of this type of masonry,quoins are built first and line is stretched between the tops of quoins.

Square Rubble: Uncoursed Square Rubble Masonry uses stones having straight bed and

sides. Stones are usually sqaured and brought to hammer dressed. This also known as square snecked rubble. The stones with straight edges and sides are available in different sizes. They are arranged on face in several irregular pattern. Good appearance can be achieved by using risers( a large stone, generally through stone) , leveller (thinner stones) and sneck or check (small stone) in a pattern , having their depths in the ratio 3 : 2 : 1

SQUARE RUBBLE: BUILT TO COURSE THIS TYPE OF MASONRY ALSO USES THE SAME STONES AS USED FOR UNCOURSED SQUARE RUBBLE. BUT THE WORK IS LEVELLED UP TO COURSES OF VARYING DEPTHS. THE COURSES ARE OF DIFFERENT HEIGHTS. EACH COURSE MAY CONSISTS OF QUOINS, JAMB STONES, BONDERS AND THROUGHS OF SAME HEIGHT ,WITH SMALLER STONES BUILT IN BETWEEN THEM UPTO 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 heights, but the height of stones in one particular course is same.

Polygonal wallingIn this type the stones are hammer finished on face to an irregular polygonal shape. These stones are bedded in position to show face joints running irregularly in all directions. 2 types of polygonal walling may be there. In the first type the stones are only roughly shaped, resulting in only rough fitting. Such a work is known as rough picked.

In the second type the faces of stones are more

carefully formed, so that they fit more closely such a work is known as close picked work.

FLINT WALLING STONES USED IN THIS MASONRY ARE FLINTS OR COBBLES WHICH VARY IN WIDTH AND THICKNESS FROM 7.5 -15 CM. AND IN LENGTH FROM 15 -30 CMS. THE STONES ARE EXTREMELY HARD BUT THEY ARE BRITTLE AND THEREFORE MAY BREAK EASILY. THE FACE ARRANGEMENTS OF THE FLINTS MAY BE EITHER COURSED OR UNCOURSED OR BUILT TO COURSES.

Dry Rubble Masonry Dry Rubble Masonry is that rubble masonry, made to courses in which mortar is not used in the joints. This type construction is cheapest and requires more skill in construction. This may be used for non load bearing walls such as compound wall etc.

Ashlar Masonry Ashlar masonry consists of blocks of accurately dressed

stone with extremly fine bed and end joints. The blocks may be either square and rectangular shape.the height of stone varies from 25-30cm. The height of blocks in each course is kept equal but it is not necessary to keep all the courses of the same height. ashlar masonry may be subdivided into the following categories. 1) Ashlar fine tooled 2) Ashlar rough tooled 3) Ashlar rock,rustic or quarry faced 4) Ashlar chamfered 5) Ashlar block in course 6) Ashlar facing

ASHLAR FINE TOOLED This is the finest type of stone masonry

work. Each stone is cut to regular and required size and shape so as to have all sides rectangular. The beds, joints and faces are chisel dressed such that all waviness and uneveness is completely removed and a fairly smooth surface is obtained. Headers and stretchers are laid alternatively in each course. Thickness of the mortar joint should not be more than 5mm.

Ashlar rough tooled In this type of masonry the beds and sides of each

stone block are finely chisel dressed just in the same manner as for Ashlar fine tool. Thickness of the mortar joint should not be more than 6 mm

Ashlar rock faced In this type of masonry the exposed face of a stone

is not dressed but is kept as such so as to give rock facing. Each stone block is maintained true to it s size, with perfectly straight side faces and beds and truly rectangular in shape. Thickness of mortar joints may be upto 10mm

Ashlar Chamfered This is special form of rock faced

Ashlar masonry in which the strip provided around the perimeter of the exposed face is chamfered at an angle of 45 degrees by means of a chisel to a depth of 25mm due to this a groove is formed in between adjacent blocks of stones. Around this bevelled strip another strip of 15 cm is dressed with the help of chisel.

Ashlar Block in course This type of masonry is intermediate between

rubble masonry and ashlar masonry. The faces of each stone are hammer dressed and the height of blocks is kept the same in any course. depth of courses may vary from 15-30 cm

Ashlar Facing Ashlar facing masonry is provided along with brick or concrete block masonry, to give better appearance. The sides and beds of each block are properly dressed so as to make them true to shape. The backing of the wall may be made in brick masonry.