BLOCK

BLOCKS

Concrete block, sometimes called sandcrete block, are made from a mixture of hard, durable and clean sand, cement and water. On setting and hardening, the blocks attain sufficient strength to be used as walling units.

TYPES OF BLOCK

There are two main types of blocks which are the light-weight and the dense blocks.

The light-weight block are made with light-weight aggregates or with aerated concrete. Lightweight aggregates with which blocks be made include well burnt clinker, wood sawdust, foamed slag, expanded clay. Most of these materials are by-products of industrial production, so the blocks are more popular in nations with greater industrial growth.

The dense block are made from dense aggregates. They include natural sand and crushed rock. Blocks made from such aggregates normally have densities of 1920 to 2080kg/m³. Dense blocks may be solid or hollow. Hollow blocks have a relatively small bearing area and exert up to four times as much pressure on the mortar as lightweight blocks or burnt clay bricks.

CLASSIFICATION OF BLOCK

There are basically three grades of building blocks. These are:

v Dense aggregate blocks which are suitable for general use in load-bearing external walls including works below ground level damp proof course.

v Lightweight aggregates block which are used for load-bearing internal walls including use below ground level damp proof course and inner leaf of cavity and composite walls.

v Non-load-bearing lightweights blocks which are used for non-load –bearing partitions.

Materials used for making building blocks include natural sand and crushed stones, by-products of industrial production such as clinker, foamed or air-cooled slag, sintered pulverized fuel ash, saw dust and wood shavings and expanded clay or shale.

The following are some qualifications of a block, they are:

 

•  A good block must have enough strength in order to carry the weight of the objects in it.
•  It must be durable
•  It must have thermal insulation
•  It must be able to resist fire
•  Sound transmission and absorption must also be made available in it.