Stonemasonry

Chapter No.02 Stone MasonryBuilding Construction and GraphicsFALL-2013. By. Engr.Rahat Ullah*

By. Engr.Rahat Ullah

outlineStone and its major types based on formationThe stone masonry and its usesSome pictures from the historyComparison between brick and stone masonryTechnical termsClassification of stone masonryGeneral principles to be followed in stone masonryASSIGNMENT NO.03

By. Engr.Rahat Ullah*


Stone and its major types based on formationBuilding stone is a natural engineering material.Stone is obtained from rock by applying certain disintegration techniques like manual quarrying and blasting etc.Stones obtained from rocks are irregular in shape and size and thus need proper dressing before using for construction purpose.Based on formation of the parent rock it has three typesThe igneous rocksThe sedimentary rocks andThe metamorphic rocks



.continuedIgneous rockformed by the solidification of molten rock such as volcanic activityFor example: GraniteSedimentary formed from silt, marine life, and rocks that have been deposited by running waterFor example: Limestone, SandstoneMetamorphicigneous or sedimentary rock that have been changed by pressure, heat, or moisture For example: Marble, Slate



The stone masonry and its usesStone blocks laid with cement or lime mortar in a systematic manner forming a structural mass which can resist load without disintegration is called stone masonry. Stone masonry is used for the construction of walls, foundation, columns, lintels, arches and other components of structures.If abundantly available it can serve as an economical building material keeping in view the dressing cost and time of construction.Undressed or rounded shape stone masonry with insufficient mortar is disastrous in earthquake hazard areas like Balakot, Abbottabad etc.



Stone masonry, Pictures from the historyBy. Engr.Rahat Ullah*


Roman aqueduct, Pont Du Gard, France (50 AD).By. Engr.Rahat Ullah*


Citadel MycenaeStone masonry corbelled arch and dome. 1350-1225 BC.By. Engr.Rahat Ullah*


Stone masonry at Palace of Knossos, Crete 1350 BCBy. Engr.Rahat Ullah*


As earlier as 700 BC.By. Engr.Rahat Ullah*


Rohtas Fort ,Pakistan(1451AD)By. Engr.Rahat Ullah*


Taj Mahal ,India (1632-1653AD)By. Engr.Rahat Ullah*


Lahore fort, Pakistan (1556-1603AD)By. Engr.Rahat Ullah*


Badshahi Mosque Lahore, Pakistan (1671AD)By. Engr.Rahat Ullah*


Comparison between brick and stone masonryBy. Engr.Rahat Ullah*

Parameter for comparisonStone masonryBrick masonryMaterialNatural material of construction obtained from a quarry.Man made material manufactured by proper moulding and burning.DressingDressing is required to bring stones to the required shape and size.Dressing is not required since bricks are moulded to desired shape/size.BondingDifficult to provide required bond in stone masonry.Easy to provide the required bond in brick masonry. Skill and careHigh level of skill and greater care is required in construction.Less expertise and ordinary labor is required.Lifting and layingInconvenient to handle and place stones without lifting mechanism.Convenient to handle and place bricks without excessive effort.MortarRich and greater quantity of mortar is required to get desired strength.Moderate strength and lesser quantity of mortar is required.Thickness and continuity of mortar jointsThickness of mortar joints is more and irregular and may be continuousThickness of mortar joint is less and uniform, seldom continuous.


continuedBy. Engr.Rahat Ullah*

Thermal resistanceHigh thermal conductivity makes itwarmer in summer and colder in winter.Low thermal conductivity thus have greater comfort level in extreme weathers.Thickness of constructionIt cannot be used for walls less than 12in thick.It can be used for constructing walls having a 4.5in thickness.StrengthIt possess greater strength.Comparatively less strong.Ornamental workCostly and difficult to use in ornamental work.Cheap and can be easily used for aesthetic purposes.AppearanceProvides pleasing appearance increasing with age.Provides simple appearance which deteriorates with age.CostIts cost of construction is more.Comparatively less cost of construction.DurabilityGreater resistance to weathering agents and thus more life.Comparatively less durable.Maintenance costMaintenance cost is less.Maintenance cost is more.


Technical termsBlock in courseThe course of stones provided on the top of cornice to hold down and prevent the cornice from overturning.Corbel A short stone cantilever jutting from the face of a wall toform a bearing.Cornice A projection which crowns a wall, any horizontal division ofa wall, or an architectural feature.Bedding plane The plane along which the stones can be separated into different layers.



CorbelCornice and drip stoneBy. Engr.Rahat Ullah*


.continuedBy. Engr.Rahat Ullah*


.continued Through stone or bond stoneThe stone extending through the entire thickness of a wall to increase its lateral stability is called a through or bond stone.ParapetA low wall constructed around the terrace of a building having flat roof is called parapet wall. Coping A special course provided at the top of wall preventing penetration of rainwater from entering the wall. QuoinsStones larger than those of which the wall is composed, or better shaped, and forming the corners of walls or door and window openings; if they project they are described as raised, and rusticated if having chamfered angles.By. Engr.Rahat Ullah*


..continuedFriezeThe stone course provided below the cornice is called frieze.Spalls The chips of stone used for filling the hollow spaces in stone masonry are called spalls.ButtressThe stepped masonry projections which is intended to provide lateral strength to the wall is called buttress.String course A distinctive course or band continued across a whole facade which may be defined by its position e.g. a sill course.



Identify the defects!By. Engr.Rahat Ullah*


Classification of stone masonryMasonry can be classified according to the thickness of joints, continuity of courses and finish of face. Broadly there are two types of stone masonry, namely: Rubble MasonryAshlar Masonry1). Rubble masonry: This consists of blocks of stones either undressed or roughly dressed and laid in suitable mortar, having wider joints which are not of uniform thickness.b) Uncoursed random rubble masonrya) Random rubble masonry: c) Coursed rubble masonryd) Dry Rubble masonry.



i. Uncoursed rubble masonryBy. Engr.Rahat Ullah*


ii. Random Rubble masonryBy. Engr.Rahat Ullah*


iii. Coursed Rubble MasonryBy. Engr.Rahat Ullah*


iv. Dry Rubble MasonryBy. Engr.Rahat Ullah*


Example of random rubble wall produced from six-sided sawn blocks.By. Engr.Rahat Ullah*


Random rubble uncoursed Random rubble coursed By. Engr.Rahat Ullah*


Square rubble course Square rubble Built to regular courses By. Engr.Rahat Ullah*


2). Ashlar masonry: By. Engr.Rahat Ullah*


Types of Ashlar MasonryAshlar fine or coursed ashlar masonryRandom coursed ashlar masonryRough tooled ashlar masonryRock or quarry faced ashlar masonryChamfered ashlar masonryBlock in course ashlar masonryAshlar facing masonry.



..continuedAshlar fine or coursed ashlar masonry.In this type of masonry stone blocks of same height are used.Every stone is tooled on all sides and thickness of mortar is uniform.A satisfactory bond can be attained due to uniform sizes of stones.Random coursed ashlar masonry. This type of ashlar masonry consists of fine or coarse ashlar but the courses are of varying thickness.Rough tooled ashlar masonry.sides of stones are rough tooled and dressed with chisels. thickness of joint is uniform and not exceeding 6mm.Rock or quarry faced ashlar masonry. Similar to rough tooled type except that there is a chisel margin left rough on the face which is known as quarry faced.



..continuedChamfered ashlar masonry.It is similar to quarry faced ashlar masonry except that the edges are beveled or chamfered to 450 for depth of 25mm or more.Block in course masonry.it is the name given to a class of ashlar masonry which occupies an intermediate place between rubble and ashlar masonry. the stones are all squared and properly dressed. It resembles coursed rubble masonry or rough tooled ashlar masonry.Ashlar facing masonry.Ashlar is the superior but expensive type of stone masonry thus in order to reduce the cost a wall is commonly constructed with a facing of ashlar and backing of rubble or brick masonry, Such walls are also called compound or composite masonry walls.If the backing is of rubble masonry it is called rubble ashlar, if the backing is of brick masonry then it is termed as brick ashlar.



Ashlar fine or coursed ashlar masonry.2. Random coursed ashlar masonry. 3. Rough tooled ashlar masonry.4. Rock or quarry faced ashlar masonry. By. Engr.Rahat Ullah*


Chamfered ashlar masonry.6. Block in course masonry.7. Ashlar facing masonry.By. Engr.Rahat Ullah*


Choice of wall typeThe choice of walling type is influenced by:The design of the building,Technical considerations (whether the wall is load bearing or non-load bearing),Its location,Site exposure, andAesthetic considerations.By. Engr.Rahat Ullah*


General principles and precautions to be followed for stone masonry

The stone used shall be hard, durable and tough. All stones should be laid on its natural bed. The pressure acting on the stones should not act parallel to the bedding planes. This will try to split the stones. Sometimes stones used in corbels are laid with pressure acting parallel to bedding planes. The bond stones and headers should not be of dumb-bell shape. Large flat stones should be laid under the ends of girders, roof trusses, etc. In all slopping retaining walls, the beds of the stones and the plan of the courses should be at right angles to the slope. By. Engr.Rahat Ullah*


continued6) All laid fine dressed stone work should be protected against damage during further construction by means of wooden boxes. 7) Jambs for door and window openings should be made of quoins which are equal in height to the course. They should be in breadth equal to at least 1 times the height of the course and their length should be at least twice the height. 8) All the surfaces should be kept wet while the work is in progress and also till the mortar has set. 9) Double scaffolding will be used wherever it is difficult to fit in the stones later on.



.continued10) All the portions of the masonry should be raised uniformly. Wherever this is not possible, the stone work built earlier should be raked (stepped) so that the new work can be bonded well with the old. 11) Sufficient through stones should be used and they should form th of the area in elevation. 12) The hearting of the masonry should be properly packed with mortar and chips, if necessary, to avoid any hollows or very thick mortar joints. By. Engr.Rahat Ullah*


.continued13) Vertical faces of the masonry walls should be checked with a plumb rule and the battered faces should be tested with wooden template corresponding to the batter and a plumb rule to ensure a constant batter. 14) The stones used in the masonry should be wetted before use to avoid moisture being sucked from the mortar. Masonry should not be allowed to take tension. Through or bond stone should be selected separately from ordinary building stones. Double scaffolding should be used.



Assignment No.03Coursed rubble masonry may be sub-divided into three classes Discuss these three classes of coursed rubble masonry.Write down specifications of stone masonry for different types of stone masonry.Explain in detail cutting and dressing of stones and the tools which are used in this process.





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Stonemasonry

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