Stone masonry: The construction of stones together with mortar is termed as stone masonry were the stones are available in a large amount in nature, on cutting and dressing to the proper shape, they provide a money-saving material for the construction of different building parts/pieces such as walls, columns, footings, arches, lintels, beams etc.
Uses of stone masonry
Stone masonry construction is used in following
(i) Building foundations, dams, monumental structures.
(ii) Building walls, piers, columns, pillars, lighthouses and architectural works.
(iii) Arches, domes, lintels and beams.
(iv) Roofs, flems, paving jobs .
(v) Railway ballast, blackboards, and electrical switchboards etc.
Selection of stone for stone masonry
Selection of stones for stone masonry depends upon different types of the factor.
- Ease of working
- Strength and stability
- Polishing characteristics
|1.||Heavy engineering works Ex: stocks, breakwaters, lighthouses, bridges, piers||Granite, gneiss.|
|2.||Buildings situated in industrial towns||Granite and compact sandstone|
|3.||Pavements, railway ballast, door sits and steps||Granite slabs and slate|
|4.||Electrical switchboard||Marble slabs and slate|
|5.||Fire resistance works||Compact sandstone|
|6.||Carving and ornamental works||Marble and laterite|
|7.||Facework and architectural purposes||Marble, granite closer gained sandstone|
Types of Stone Masonry
Based on the arrangement of the stone in the construction and
Stone masonry can be classified into two category
- Rubble masonry
- Ashlar masonry
General principles in the stone masonry construction
- The stones to be used for stone masonry should be hard, tough and durable.
- The pressure acting on stones should be vertical.
- The stones should be perfectly dressed as per the requirements.
- The heads and bond stones should not be of a dumbbell shape.
- In order to obtain a uniform distribution of load, under the ends of girders, roof trusses etc large flat stones should be used.
- The beds of the stones and plan of the course should be at right angles to the slope in the case of a sloping retaining wall.
- Wood boxing should be filled into walls having finely dressed stonework to protect it during further construction.
- The mortar to be used should be good quality and in the specified faces.
- The instruction work of stone masonry should be raised uniformly.
- The plumb bob should be used to check the vertically of the erected wall.
- The stone masonry section should always be designed to take compression and not the tensile stresses.
- The masonry work should be properly cured after the completion of work for a period of 2 to 3 weeks.
- As per as possible broken stones or small stones chips should not be used.
- Double scaffolding should be used for working at a higher level.
- The masonry hearting should be properly packed with mortar and chips if necessary to avoid hallows.
- The properly wetted stones should be used to avoid mortar moisture being sucked.
1) Rubble masonry: In the category of Rubble masonry, the stones used are either undressed or roughly dressed having wider joints. This can be further subdivided as un-coursed, coursed, random, dry, polygonal and bint.
Uncoursed rubble masonry: This is the cheapest, roughest and poorest form of stone masonry, the stones used in this type of masonry very much vary in their shape and size and are directly obtained from the quarry.
Uncoursed rubble masonry can be divided into the following.
- Uncoursed random rubble
- Uncoursed squared rubble
- Uncoursed random rubble masonry: The weak corners and edges are removed with mason’s hammer. Generally, bigger stone blocks are employed at quoins and jambs to increase the strength of masonry.
- Uncoursed squared rubble: In this type, the stone blocks are made roughly square with a hammer. Generally, the facing stones are given the hammer-dressed finish. Large stones are used as quoins. As far as possible the use of chips in bedding is avoided.
Coursed Random Rubble Masonry
2. Coursed random rubble: This type of masonry is commonly used in the construction of low height walls of public buildings, residential buildings, abutment and piers of ordinary bridges. The stones of 5 to 20 cm size are used in each course.
Coursed Squared Rubble
3. Coursed squared rubble: This type of masonry is made up of hammer squared stones facing with bonded backing of un-coursed random rubble masonry. The stones employed in each course are of equal height. The backing and facing construction should be carried simultaneously. In order to avoid thick mortar joints, small chips may be used.
Built to a regular course
4. Built to a regular course: In this type of stone masonry, the uniform height stones are used in horizontal layers not less than 13cm in height. Generally, the stone beds are hammered or chisel dressed to a depth of at least 10cm from the face. The stones are arranged in such a manner so that the vertical joints of two consecutive curse do not coincide with each other.
Polygonal Rubble Masonry
5. Polygonal rubble masonry: In this type of masonry the stones are roughly dressed to an irregular polygonal shape. The stones should be so arranged as to avoid long vertical joints in face work and to break joints as much as possible. Small stone chips should not be used to support the stones on the facing.
Plint Rubble Masonry
6. Plint rubble masonry: This type of masonry is used in the areas where the flint is available in plenty. The Flintstones varying in thickness from 8 to 15cm and in length from 15 to 30cm are arranged in the facing in the form of coursed or un-coursed masonry.
Dry Rubble Masonry
Dry rubble masonry: This type of masonry is used in the construction of retaining walls pitching earthen dams and canal slopes in the form of random rubble masonry without any mortar. The hollow spaces left around stones should be tightly packed with smaller stone pieces.