PROJECT TITLE Project No; 12

Lightweight Block Wall, Incorporating Opening Spanned by CORE

Internal Lintel 1 of 6

Blocks Uses, Basic Properties and Size.


Blocks were originally introduced for the building of lightweight internal partitions. They were of poor quality and would often crumble when the bricklayer attempted to cut them.

Since the introduction of Pulverised Fuel Ash (PFA) blocks in the 1960s the wide range of blocks meet the thermal and load bearing requirements of modern day construction.

Partition of Blockwork in modern dwellings


  1. Internal leaf of cavity wall, load bearing insulation blocks.
  2. Foundation blocks for cavity walls, 250mm thickness and upwards
  3. Foundation blocks of appropriate thickness Load bearing quality.
  4. Load bearing blocks in sizes from 100mm to 230mm.
  5. Standard blocks in sizes ranging from 75 to 230mm

Concrete blocks Solid, Cellular and Hollow.

Concrete Blocks

Concrete blocks are manufactured under three headings:






Manufactured in the following sizes: 450 x 225 x 100, 125, 150, 225mm.

They are widely used in industrial and agricultural buildings, providing a hard wearing load-bearing structure.



Manufactured in the following sizes: 450 x 225 x 100, 125, 150mm.

They provide a lightweight block for partition walls.




Manufactured in the following sizes: 450 x 225 x 225mm.

They are widely used in industrial and agricultural buildings to provide external and partition walls that may be subject to lateral movement.

Filling voids with concrete and vertical reinforcement can strengthen walls.

Blocks Site Practice.

Storage of Blocks on Site

  1. Blocks should be stored on a dry level surface.
  2. Protect blocks from severe weather conditions by sheeting down.
  3. On hard standings blocks can be stored four packs high. This should be reduced to two packs high on uneven ground.
  4. If blocks have absorbed excessive moisture they should be allowed to dry out before use to minimise the risk of drying shrinkage in finished blockwork.

Pulverised Fuel Ash (PFA) blocks.

General Information

There is a wide range of PFA blocks available, and each one is designed for a specific purpose. To provide identification for each type companies vary the V keyed surface markings on the face of the block or provide a colour code brand on the end of the block.
















As each type is designed to meet specific requirements, it is essential that blocks are correctly used.

Bridging Openings.


The horizontal beam that spans an opening is called a lintel.

In early stone buildings this would take the form of large blocks of stone or timber beams. In modern buildings stone and timber has been replaced by concrete or steel.

As the load is applied to a lintel there is a tendency for it to sag. This creates stresses within the lintel as shown in the drawing below.














Where concrete is used to form lintels it will adequately cope with the compressive stresses but will require steel rods to be cast into the lower section of the lintel to resist the tensile stresses.

Steel reinforcement should be positioned 25mm from the bottom of the lintel. This will provide maximum resistance to tensile stresses. It will also protect steel from corrosion by exposure to the elements and from possible damage in the event of a fire in the building.


Internal Lintels Concrete.

Pre-cast Concrete Lintels

Cast to the width of the wall and to a depth depending upon the span














Plank Lintels.

The reinforcement within a plant lintel is stretched before the lintel is cast. Once it has been hardened the steel is released placing the whole lintel in compression. This allows for the depth of the lintels to be reduced by 65mm.


Internal Lintels Steel