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  • Talk about tolerances
  • Talk about tolerances
  • Talk about tolerances
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  • Blockwork

    1. 1. Concrete BlockManufacture and Use Stonemasonry Department 2011
    2. 2. Uses of Concrete Block *Image courtesy of the Concrete Block Association 2010
    3. 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. 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. 5. How Concrete Blocks are Made The video above shows the concrete block manufacture process using automated machinery.
    6. 6. Standard Dimensions The work size of a standard concrete block is 440mm x 100mm x 215mm
    7. 7. Comparable Dimensions A standard sized concrete block has the equivalent surface area of six bricks
    8. 8. Terminology Bed Width Face Height Length Joint
    9. 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. 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. 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. 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. 13. Bonding Arrangement Half block Stop end Internal return Closer Full block External return
    14. 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. 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. 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. 17. References EN 771-3:2003 Specification for masonry units – Part 3: Aggregate concretemasonry units (dense and lightweight aggregates)
    18. 18. Developed by The Stonemasonry Department City of Glasgow College 2011