Concrete blocks are a versatile building material made from cement, aggregate, water, and admixtures. They are manufactured using automated machinery to mix and form the concrete into standardized block sizes. Concrete blocks are classified based on their density and compressive strength, with denser blocks able to withstand more compression. They are also categorized according to manufacturing tolerances. Concrete blocks provide advantages as a construction material such as durability, fire resistance, and recyclability. Proper safety equipment should be used when cutting concrete blocks.

1. Concrete Block
Manufacture and Use
Stonemasonry Department 2011

2. Uses of Concrete Block
*Image courtesy of the Concrete Block Association 2010

3. Advantages of Concrete Block
Versatile, durable and strong
Completely fire resistant
Excellent sound insulation
Ideal background for dry lining wet
finishes and fixings
Inherent thermal mass acts as heat
store
Recyclable
Proven and familiar building method –
no risk
Widely and readily available
Cost effective

4. Materials
Cement Aggregate Water Admixtures
Cement, aggregate, water and admixtures are the materials used in the
manufacture of concrete blocks. To manufacture concrete blocks with specific
properties, the type and ratio of each material is altered.

5. How Concrete Blocks are Made
The video above shows the concrete block manufacture process using
automated machinery.

6. Standard Dimensions
The work size of a standard concrete block is 440mm x 100mm x 215mm

7. Comparable Dimensions
A standard sized concrete block
has the equivalent surface area of
six bricks

8. Terminology
Bed Width
Face
Height
Length
Joint

9. Classifications
Solid Blocks
Blocks which contain no formed voids
Hollow Blocks
Blocks which contain one or more formed
voids which fully penetrate the block

10. Classifications
Cellular Blocks
Blocks which contain one or more formed
voids which do not fully penetrate the
block
Special Blocks
Blocks which are designed and
manufactured for a specific purpose and
which have a shape and size which varies
from standard

11. Compressive Strength
Super
Dense Lightweight
Lightweight
Concrete blocks are classified by their compressive strength. This is their
ability to withstand compression before showing signs of fatigue.
Dense: Compressive strength between 1850kg/m² and 2100kg/m²
Lightweight: Compressive strength between 1000kg/m² and 1500kg/m²
Super Lightweight: Compressive strength between 850kg/m² and 1000kg/m²

12. Tolerances
D1 D2 D3 D4
Concrete blocks are also classified by the tolerances to which they are
manufactured. The table shows what each of the categories mean:
Tolerance D1 D2 D3 D4
Category
Length +3 +1 +1 +1
-5 -3 -3 -3
Width +3 +1 +1 +1
-5 -3 -3 -3
Height +3 +/- 2 +/- 1.5 +/- 1
-5
Limit deviations in millimetres: Source BS EN 771-3:2003

13. Bonding Arrangement
Half block Stop end
Internal return
Closer
Full block
External return

14. Cutting a Concrete Block
Start by marking a cutting line on
the block. Make sure to mark
lines on the top and bottom beds
of the block
Before cutting put your safety
glasses on. Strike a bolster
(holding it vertically) along the
cutting line on the face of the
block.

15. Cutting a Concrete Block
Strike a bolster (holding it
vertically) along the cutting lines
on the top and bottom beds of the
block.
Strike a bolster (holding it
vertically) along the cutting line on
the back of the block. Your block
should now split along all the
cutting lines

16. Health and Safety
Always wear protective
glasses when cutting block.
Wear suitable gloves to
protect your hands
Wash your hands before any
breaks and before you go
home
Always ensure blocks
are stacked safely.

17. References
http://www.cba-blocks.org.uk/index.html
BS EN 771-3:2003 Specification for masonry units – Part 3: Aggregate concrete
masonry units (dense and lightweight aggregates)

18. Developed by The Stonemasonry Department
City of Glasgow College
2011