Joints in Masonry Wall
Masonry is the art of construction of building units ( stones, bricks, precast concrete blocks ) which are bond together with mortar. In stone masonry, only stones are use which are obtain from rocks that may be igneous, sedimentary ( sandstone and limestone ) or metamorphic ( states and marbles ). For building purposes, mainly limestones and sandstones are use. Joints in Masonry Wall are provide in masonry are :
Joints in Masonry wall in building construction
Butt or Square joint
It is form by placing the square surface of one stone against that of another.
Rebate or Lap joint
It prevents movement between the arch voussoirs. It is adopt to secure a water-tight joint.
Tongue and Groove joint
Groove joint is not commonly use. It consists of a tongue or projection that works along one edge of a stone which fits into the corresponding groove in the adjacent stone. It in some cases, is adopt as an alternative to the rebate joint in flat arches and between the horizontal slabs forming the landings of stone staircases. Groove joint is also known as joogle joint and should not be confuse with mortar joggle joint.
Lower storeys of buildings, plinths and quoins are, in some cases, emphasis by the use of stone blocks which have their edges sunk below the general face. The word rusticate is use for such a type of masonry. It gives massive appearance to the structure.
It is use in cornices and at such places where water is to be divert away from the joint. The saddle in this case is bevel backward from the front edge.
The mortar joggle joint is use for the end joints of ashlar when the stone blocks have a small bed and for cornice stones.
Dowels are provide at the joints in those stones that are liable to become displace. These are either of slate or gun metal ( alloy of copper and tin ). The length is 2t or 3t where t is the thickness of end section is square, the size of which varies from 25 mm to 50 mm.
In this, the joints are reinforce with either metal or slate cramps. Cramp is a piece of non-corrosive metal e.g. gunmetal, 22.5 cm to 45 cm long, 6 mm to 13 mm thick and 25 mm to 50 mm wide with ends that are turn down from 2 cm to 4 cm. It must be fit in tightly, after which it is grout and cover with either asphalt or cement.
It is not use now-a-day. in this, a hole is sunk of dovetail shape in the sides of adjacent stones and after placing the adjacent stone, a common space for the plug is form. It is fill with cement grout to form a cement plug. Molten lead was poured in early stages to form a lead plug and is not now use.
Bed joint or Tables joint
In this a joggle is form in the stone bed to prevent lateral movement of stones. The height of the projection varies from 3 cm to 4 cm and the width is 0.34 times the breadth of the stone.
Detail in Substructure and Superstructure in the construction of the building https://civilcrews.com/substructure-and-superstructure/