Masonry1

Masonry1

1. Sundried Mud Brick

   • Oldest building material
   • Neglible
   • used 8,000 BCE in Egypt
   • Strength depends on quality of manufacturer and expertise

2. Clay brick and Mortar

   • Extensively used in Rome
   • Manufacturing disappeared with decline of Empire.
   • Resurgence 14th c. with use of klin firing
     • More stronger and durable.

3. Molded Brick

   • Brick made with molds
     • by f.dropping individual lump of wet clay into brick
   • Excess clay: scraped off and green brick removed
   • clay must have a greater amount of water to allow it to work into the mould
     • Molded brick is generally weaker and softer
   • depression called frog
     • frog faces downwards
   • frog take various shapes

4. Extruded Brick

   • forcing wet clay through a die in an extruder
   • die: conical rods, create core holes in column help drying and firing of the bricks.
   • Core holes improve mortar bond.
   • cross-sectional dimensions determine the length & width

5. Extruded Brick Manufacturing

   • Surface texture applied wet clay column with rotating textured drums.
   • wire cutter: parallel wires cuts the column into individual bricks
   • dried in a drying chamber then fired in the kiln

6. Free-Thaw Cycles

   • Wetdry cycles, capillary actionexceed the strength of the masonry.
   • Moisture in masonry freezes it expands causing to spall and surface to break way
   • Molded brick is too porous to withstand
   • extruded brick density been improved over time to withstand

7. Brick dimensions

   • width stated first the h x l
   • bricks and concrete blocks contain voids
   • hollow masonry unit is 25%
     • bricks have core areas <25% technically solids
       • bricks without cores = top of wall 100%solid

8. Mortar

   • made from bitumen and then clays.
   • used: sand, lime and water
   • lime allowing walls absorb more movement without cracking.
   • porous faster drying of the wall through the mortar joints
   • bond masonry units into an integral wall.
   • Mortar moulds itself to the surface profile
   • also:
     • compensates for size variations
     • Embeds reinforcement in place
     • surface character shadow lines at masonry joints, and colour

9. Contemporary Mortar

   • Consists of: binder Portland cement and hydrated (Type S) lime
     • filler (Mason’s sand manufactured or natural sand
       • Water
   • Grading gives 30% voids,Voids filled by binder.

10. Mortar type:

    • N is the general-purpose, non-load bearing, masonry veneer walls, load-bearing walls
    • O least amount of Portland Cement, max. lime. weak
    • M less workable, less elastic, exhibits more shrinkage less lime.
      • parapet walls & interior masonry floors. greater strength & abrasion resistance.
    • S: ext. load-bearing or nonload-bearing walls in seismic or high-wind regions higher bond strength, less water resistant.
    • M, S & N pre-blended mix for mortar in bags that contain 1 cubic foot
      • one bag of Type S masonry cement with 2-1/4 to 3 ft3 of sand.

11. H. Mortar Joint profile

    • aesthetics and w resistant
    • Weathered, struck, beaded & extruded
    • Weathered greatest water resistance

12. C.Joint profile

    • exterior masonry, concave joint is recommended.
    • tooled concave joints more resistant to water and freeze-thaw damage.
    • interior masonry, raked and flush joints
      • raked =dust
      • flush- plastered or paint

13. Mortar Admixtures

    • Accelerators" for cold, reduce time to be protected
    • Air-entraining increase mortar workability and impede freeze/thaw deterioration
    • Coloring agents limited to finely ground metallic oxides, quantities do not exceed 10%

14. White & Coloured Mortars

    • white used as provide greater control

15. Re-tempering

    • prepared immediately prior to use.
      • addition of water to unused mortar, reduces strength
    • Mortar prepared more than 2-1/2 hrs prior to use should be discarded