Various Joints in Construction.

8/13/2019 Various Joints in Construction.

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1)EXPANSION JOINTS

•

The concrete is subjected to volume change dueto many reasons.

• So we have to cater for this by way of joint to

relieve the stress.

• Expansion is a function of length.

• The building longer than 45m are generally

provided with one or more expansion joint.

• In india recommended c/c spacing is 30m.• The joints are formed by providing a gap

between the building parts.



EXPANSION JOINTS

•

Is basically controlling the slenderness ration ofthe shape/ form

• It can be vertical or horizontal

• Ex. Rcc column L/d= Slenderness ratio

(L=effective length and d=least lateral dim.)

• 12< SR (slender col.) 12> SR ( short col.)

• Expantion joint are given @ 30-40 M. interval

• Construction Joint---when vast area of conc. Isdone in phases

• Extension Joint---when construction is done

phases over longer time period/ gaps



EXPANSION JOINTS

•

Tounge andgroove joint• Filling should takethe compression.•

40-50 mm widegap• Filling material=PVC, thrmocol ,• Dowel bars to

embed in other wall• It gives continutyof the surface

•



EXPANSION JOINTS

Floor Conditions• Since building expansion joints are designed to isolate sections of a building, they inevitably cutthrough floors.• Copper and copper alloys can be used in floor expansion joints in two ways: as trim andcover plates, or to prevent the flow of water through the expansion space.• Copper waterstops are used to prevent the flow of water. They run continuously from one endof the building to the other.• Adjacent waterstops are joined with 3/4" soldered lap joints. Water stops are designed toaccommodate movement by flexing. The recommended minimum weight for c opper waterstops is16 oz.• As cover plates are not required to stop the flow of water, their technical requirements are notas strict.• The main criteria is that the material used must be strong enough to bridge the expansion spaceunder given loads. Brass and bronze are used to provide the required strength.



EXPANSION JOINTS

A. Building Expansion Joint at Concrete FloorThis detail shows a continuous cast-in-place copper waterstop bridging the space

between concrete floor slabs.

The detail also shows the use of brass or bronze cover plates. An insert is cast into the

edge of each floor. The actual cover plates are then attached to one side of the insert

and allowed to slide freely over the other side. This is also true for cover plates in the

ceiling, as shown..



EXPANSION JOINTS

C. Building Expansion Joint at Concrete Garage Floor Slab

Exterior concrete structures, such as garages, are exposed to a much greater volume ofwater. It is often impossible or impractical to completely prevent water from gettingthrough an expansion joint. Under these circumstances, a copper gutter can be usedto catch the water and direct it to a drain or spill. The gutter is supported by copper orbronze lock strips that allow it to accommodate expansion and contraction movement.

above.



2) CONSTRUCTION JOINTS

• They must be designed in order to allow

displacements between both sides of the slab but, atthe same time, they have to transfer flexural stressesproduced in the slab by external loads.• Construction joints must allow horizontaldisplacement right-angled to the joint surface that isnormally caused by thermal and shrinkagemovement.•

Tappered @ 45 degrees



CONSTRUCTION JOINTS

• Construction joints are placed in a concrete slab to

define the extent of the individual placements,• Construction joints are placed as per thepredetermined joint layout.• They must be designed in order to allow

displacements between both sides of the slabbut, at the same time, they have to transferflexural stresses produced in the slab by externalloads.• Construction joints must allow horizontaldisplacement right-angled to the joint surface thatis normally caused by thermal and shrinkage

movement.• At the same time they must not allow vertical or

rotational displacements



3) CONTRACTION JOINTS

• A contraction joint is a sawed, formed, or tooled

groove in a concrete slab that creates a weakenedvertical plane.•It regulates the location of the cracking caused bydimensional changes in the slab.•Unregulated cracks can grow and result in anunacceptably rough surface as well as water infiltration

into the base, subbase and subgrade, which canenable other types of pavement distress.• Contraction joints are the most common type of jointin concrete pavements,•Contraction joints are chiefly defined by their spacingand their method of load transfer. They are generallybetween 1/4 – 1/3 the depth of the slab and typically

spaced every 3.1 – 15 m



4) ISOLATION JOINTS

• Joints that isolate the slab from a wall, column or

drainpipe• Isolation joints have one very simple purpose—theycompletely isolate the slab from something else.•That something else can be a wall or a column or a drainpipe.•Walls and columns, which are on their own footings that aredeeper than the slab subgrade, are not going to move thesame way a slab does as it shrinks or expands from drying ortemperature changes or as the subgrade compresses a little.•Isolation joints are formed by placing preformed jointmaterial next to the column or wall or standpipe prior topouring the slab.•Isolation joint material is typically asphalt-impregnatedfiberboard, although plastic, cork, rubber, and neoprene arealso available.

Various Joints in Construction.

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