CHAPTER-16

CONCRETE BLOCK MASONARY AND

COMPOSITE WALLS

CONCRETE BLOCK MASONARY Solid and hollow concrete blocks are manufactured to

meet the growing requirement of building blocks in towns and cities.

They are manufactured with lean mixes of cement , sand and aggregates of size less than 12mm.

The size of solid concrete block is 400x200x150 mm (normal size).

The minimum strength prescribed is 4N/MM.SQ. The block should have sharp edges and right angled corners.

Hollow block of normal sizes 400x200x190mm and 400x300x190mm are manufactured.

The net area of hollow block is 55-60% of the gross area. They should have sharp edges and right-angled corners.

CONCRETE BLOCK MASONARY

Hollow concrete blocks

Advantages of using concrete block is:

1. Construction is fast, as the size of the block is large and the mortar required is less.

2. To build a 1m.sq. and thickness 200mm, only 10 blocks are required as against 115clay bricks. It needs only 13 liters of cement mortar as against 45 liters required in brick masonry.

Concrete blocks may be given the following surface finishes

a) Coarse texturedb) Glazed finishc) Slumped finishd) Specially faced finishe) Colored finish

Construction of walls with concrete bock masonry

The construction method for concrete block walls is exactly the same as that for brick masonry.

First, corners or ends are built to a few courses, followed by the middle portion.

Vertical joints are broken. The final closing block needs to be

fitted carefully.

The following points need to be observed in concrete block masonry

Blocks should be dry before use.Vertical joints should be broken.Mortar used should not be stronger than the block itself.

The preferable mortar is 1:1:10 cement-lime-sand mix.The joints should be 5-10mm thick.The blocks used for external walls should have

absorption less than 10%. For internal walls, adsorption up to 15% may be permitted.

Solid concrete blocks or hollow blocks filled with site concrete should because in the junction of walls and also in the middle of long walls to avoid cracking due to expansion

Concrete blocks used in building construction

STONE COMPOSITE MASONRY

Stone composite masonry is constructed with stone and one or more combinations of materials, like stone facing and brick backing or stone facing and concrete backing.

Stone composite masonry is of different types, each having its own properties.

To make use of both ashlar and rubble, composite masonry may be used. In such masonry, the facing is with ashlar masonry, while the backing is with rubble masonry

STONE COMPOSITE MASONRY

FIELD STONE (RUBBLE) STONE COMPOSITE MASONRY

BRICK-STONE COMPOSITE MASONRY

RUBBLE-BACKED BRICK MASONRY

BRICK-BACKED ASHLAR MASONRY

BRICK-BACKED STONE SLAB MASONRY

RUBBLED-BACKED BRICK MASONRY The facing is of brick masonry, while

the backing is of rubble stone masonry.

This type of composite masonry is commonly adopted in locations where stone is available locally in large quantities.

BRICK-BACKED ASHLAR MASONRY In this type the facing is of ashlar

stone masonry, while the backing is of brick masonry. It is used where skilled labor and beautiful stones are available.

The stones thickness should be such that multiple layers of bricks match it.

Care should be taken to break vertical joints. Cement mortar is preferred for such masonry.

BRICK-BACKED ASHLAR MASONRY

BRICK-BACKED STONE SLAB MASONRY

The facing is granite or marble and the backing is of bricks. It is preferable to use metal cramps to connect the facing and backing.

REINFORCED BRICK MASONRY

Ordinary brick masonry cannot take tensile stresses because bricks get pulled apart at the mortar joints. In such situations brick masonry is reinforced by steel bars or expanded bars.

Reinforced brick works are commonly used in lintels, retaining walls, walls built on soil that is susceptible to large settlement and in seismic zones.

Sometimes, brick columns are strengthened with bars to increase their compressive load-carrying capacity.

REINFORCED BRICK MASONRY

TYPES OF MASONRY BONDS

Reinforced brick works may be grouped into:

REINFORCED BRICK LINTELSREINFORCED BRICK COLUMNSREINFORCED BRICK WALLSREINFORCED BRICK SLABS

REINFORCED BRICK LINTELS

The reinforcement consists of 6-12mm diameter while vertical stirrups are 6mm in diameter.

The vertical stirrups are at every third joint.

REINFORCED BRICK LINTELS

REINFORCED BRICK LINTELS

REINFORCED BRICK COLUMNS

By reinforcing the load carrying capacity of the column is increased. For this construction special type of bricks are used which have grooves for vertical reinforcement.

At every fourth course, they are provided with horizontal steel plates of 6mm thickness.

Vertical steel bars are fixed in the foundation concrete block.

REINFORCED BRICK COLUMNS

REINFORCED BRICK WALLS Walls that are likely to be subject to tensile are

reinforced. The reinforcement required is horizontal and vertical.

Horizontal reinforcement is provided at every third or fourth course. It consists of steel mesh spread flat on the cement mortar and pressed uniformly.

It consists of 20-30mm wide steel flats of thickness 1.5-2.0mm.

These flats are dipped in molten tar to increase their resistance against rusting and then immediately sanded.

Generally one strip is provided for every thickness of half a brick.

REINFORCED BRICK WALLS Reinforcement in vertical direction is

provided by using special bricks that have grooves to pass the bars.

Mild steel bars of 6mm diameter are used as vertical reinforcement.

They are tied at suitable intervals with fine wires

Bricks with grooves

REINFORCED BRICK SLABS If bricks are to be used for the construction of

slab, they should be reinforced with steel. In such construction a wooden platform is built

which is covered with well beaten earth. Then fine sand is sprinkled over which mortar

layer is spread and reinforcement is embedded. Specially bricks with grooves are then laid in one

or two courses. The joints are filled with mortar. The slab is cured for three to four weeks. The top

and bottom surfaces are suitably finished.

REINFORCED BRICK MASONRY

THANK YOU

PREPERD BY,

AKHIL

ALTHAF

ANAND

SREEJITH

SHAN