Concrete blocks; important things to note before using concrete blocks in masonry work

Articles > Concrete blocks; important things to note before using concrete blocks in masonry work

Introduction to concrete blocks:

Concrete block construction or concrete manufacturing units / CMUs are very common in simple and easy construction. Their reduced weight has many advantages over the stone and bricks-based construction. A hollow-block is much lighter than a brick and stone block. In multi-story buildings, their use is very common, due to their lightweight. They rarely place additional load and burden on reinforced columns, roofs, and walls. A concrete block can have a hollow cavity from the inside, as well as it can have a solid (internally filled) state. Unlike the kiln burnt bricks, the concrete blocks save the cost of heating and compressing cost. It is simply prepared by mixing the sand, coarse gravel, fine gravel, and sand with any type of cement to make a mixture of concrete. Any type of cement can be used in preparing the concrete mixture of the blocks. An ordinary Portland cement is very economical in almost all the countries of the world. However, the Pozzolana Portland Cement can also be used. The extra advantage of the pozzolana Portland cement is, that is successful in damp, and waterlogging areas. In case of sulfate attack or seashore regions, an SRPC (Sulfate Resisting Portland Cement) can be used in order to protect the structure from sulfate attack. The common composition of the concrete for making a block is as follows.

Composition of concrete blocks:

Concrete blocks are available in two types based on their weight and composition. A block with a higher density is manufactured from the mixture of Portland cement, sand, aggregate, coarse gravel, and fine gravel. While a block with lightweight is cast by home recycle material, slag cement, post-consumer glass, recycled aggregate and industrial waste materials, like bottom ash and fly ash. Aerated concrete is another easy and fast means to construct a lightweight concrete block.

Benefits of using empty concrete blocks:

The following are the main advantages of hollow concrete blocks:

Because these blocks have holes in them, therefore, they do not need any kind of redress. The mortar piled up inside the holes easily mixes them up. The construction work is very fast while using these blocks.
Handling concrete blocks is very easy because of their small weight.
There is a great saving of cost while using concrete blocks.
Due to their large size, there is a reduced number of joints, as compared to brick construction. A minimum quantity of mortar is used in this type of construction.
In case that the concrete blocks are hollow, the holes in the blocks act as a bad conductor of heat. They appear to be poor heat conductors. Weather conditions do not affect the internal temperature of the room.
The cost of concrete blocks is lower than that of stone and brick, thus proving to be very economical.
As a bare concrete surface has no effect on efflorescence, therefore, maintenance costs are small for this type of construction.
As the ingredients of these blocks can be replaced by waste products such as fly ash, which makes the use of these blocks more economically.

Disadvantages of Concrete Blocks:

Besides the advantage and benefits, there are some demerits of the concrete-made blocks. Keeping in view these disadvantages, many construction experts do not recommend the use of the blocks. Some of the most prominent demerits of these blocks are as follows.

The porous structure of the blocks is permeable to water. Thus easily penetrating water can harm the durability and strength of the structure.
The structures made of these blocks are vulnerable to sulfate. Therefore, in the areas with a sulfate concentration, the use of these types of bricks is not favorable.
The strength of these blocks is, if compared to that of bricks and stones, is not satisfactory. However, their strength can be increased by using steel bars among the blocks to create stress within the structure.

Types of Concrete Blocks:

Keeping in view the shape and form of the concrete blocks, they can be divided into the following two types. Out of these two types, the blocks are further classified into many types, which are being discussed in the upcoming lines.

Two Types of concrete blocks:

There are two basic types of concrete blocks based on their design and construction.

Hollowed-concrete-blocks/bricks
Solid-concrete-blocks/Bricks

(1). Hollowed-Concrete Bicks/blocks:

Unlike the solid blocks, the hollow-concrete-blocks are never completely filled with concrete materials. There is an empty large space, or more than one space in the inner side left. The formation of cavities in these blocks aims to reduce their dead weight. The deadweight of a building can cause the building to be in danger of collapse. These blocks are available in different sizes and sizes, depending on the manufacturer's requirement. The most common size of hollow-concrete blocks is 7.8740 in X 11.8110 in X 5.90551 in.

(2). Solid-Concrete-Blocks:

Solid concrete blocks are blocks, which are filled entirely with concrete materials. These blocks have no empty space on their inner sides. This type of block is used for the construction of walls, which are designed to carry an internal load. They are also widely used in columns and low-rise buildings. It is used for internal load walls and beams and floor blocking systems.

Seven Types of Hollow Concrete block:

Stretcher blocks(3core)
Channel bond beam or lintel concrete blocks
Concrete End blocks
Low web bold beam block
Control joint blocks
Corner blocks
Double corner blocks

(1) Double-Concrete Blocks:

For reinforced construction, double concrete blocks are used. The stainless steel bar and grout form an inner column of reinforced concrete inside a series of block cavities.

(2) Concrete Corner Concrete:

A corner block is a block made of concrete used in the corners and edges of a wall to create a functional bond pattern.

(3) Low Web Bold Beam Block:

The hole inside this type of block provides space for a horizontal reinforcing bar and grout. It is used to tie the wall together in critical areas to make a bond beam.

(4) Stretcher Blocks (3 core):

It is the most widely used method of construction from concrete blocks. These blocks are needed to join the corner of the masonry structure. They are used to connect the ends of two walls in a corner.

(6) Manage Joint Block:

This type of block is used to make expansions of the type of stocks standing in construction. A sealant is used between the connecting units.

(7) Complete Block:

Used when the end of the unit will be displayed.

(8) Channel Bond Beam or Lintel Block:

These blocks provide spaces to increase the horizontal strength of the masonry structure. These blocks are used above the door bands and upper horizontal beams to tie the whole wall in a consolidated structure.

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