Masonry

• Masonry


  An assembly or combination of small building units made of clay, shale, concrete, glass, gypsum, or stone that are set in mortar
• Masonry


  • Consists entirely or partially of hollow or solid units laid contiguously in mortar
• Masonry units


  • Concrete masonry units
  • Clay bricks
  • Structural clay tiles
  • Glass blocks
  • Stone

  
• Concrete Masonry Unit (CMU)


  Hollow (or solid) masonry units used for interior/exterior bearing or non-bearing walls, partitions, and backing

  
• Concrete Masonry Unit (CMU)


  • The aggregate used to make the units will determine the weight (25-50 lb. for 8" x 8" x16" stretcher unit)
  • Have good fire-rating, thermal storage capability, good resistance to sound transmission, and are economical

  
• Concrete Masonry Unit (CMU) classes


  • Light weight
  • Medium weight
  • Normal weight

  
• Concrete Masonry Unit (CMU) - Load bearing


  ASTM C90

  
• Concrete Masonry Unit (CMU) - Non-load bearing


  ASTM C129

  
• Determining compressive strength of CMU

  1. Capping the units and applying load in the direction of the height the unit until failure (ASTM C140)

  2. Calculating gross area compressive strength

  3. Calculating net area compressive strength

  
• Absorption of CMU


  • Determined by immersing the unit in water for 24 hours (ASTM C140)
  • Calculated using formulas

  
• Clay Bricks


  • May be solid or hollow core (holes called "cells")
  • Cells should not exceed 25 % of the volume of the unit
  • Composed mainly of silica (grains of sand), alumina, lime, iron, manganese, sulfur, and phosphates, with different proportions
  • Firing temperature varies from 900°C to 1200°C (1650 to 2200°F)
  • Have an average density of (125 pcf)

  
• Absorption of Clay Bricks


  Determined by 24-hour submersion, 5-hour boiling, and saturation coefficient (ASTM C67)

  
• Solid vs. With Holes in Bricks


  • Solid brick used where holes may be unsightly (steps or window sills)
  • Holes help units fire properly, promote bonding with mortar, reduce overall weight, and make units easier to handle
• Classes of Brick


  • Adobe - sun-dried clays and a binder
  • Kiln-burned – natural sand and clay or shale (most widely used)
  • Sand-lime-pearl-grey in color, dolomite lime is mixed with clean sand, pressed, and allowed to harden in closed vessels under steam pressure
  • Concrete - Portland cement and suitable aggregate, formed in molds

  
• Brick Kilns


  1. Water smoking: 400 °F

  2. Dehydration: 300-1800 °F

  3. Oxidation: 1000 - 1800 °F

  4. Vitrification: 1600-2400 °F

  5. Flashing (oxygen reduction) produces different colors or color shading

  6. Cooling down – done in 2-3 days; rate of cooling will affect cracking, and color

  
• Brick Types/Sizes


  • Common (now called Building) - Most widely used, dark orange to deep red color, many finishes & sizes available
  • Meets ASTM C62 grading criteria: SW - severe weathering, MW - moderate weathering, NW - Negligible weathering

  
• Face Brick


  • Made from clay, shale, fire clay, or a mixture, under controlled conditions
  • Meets ASTM C216 standard
  • Types: FBS- general use, FBX- high degree of mechanical perfection, FBA- nonconformity in size, color, & texture

  
• Glazed Face Brick


  • Bricks sprayed with a ceramic glaze and fired at high temperature to fuse glaze to the brick
  • Finishes may appear dull, satin, or glossy
• Fire Brick


  • Made of clays with a large amount of alumina, silica, flint, and feldspar
  • Used in fireplaces, chimney, stacks, incinerators, and many industrial settings
• Paving Brick


  • Burned at much higher temperatures to make them resist water and wear from traffic
• Brick Bond


  • The arrangement of bricks in rows (courses)
  • Designed for appearance and to tie together a structural or outer wall (wythe) to an inner wall
• Brick Walls


  • May be bearing (supports any vertical load) or non-bearing
  • Solid walls- 2 or more wythes bonded together by ties, headers
  • Cavity walls - 2 walls spaced 2 in. apart by metal ties; may fill cavity with insulating material; Weep holes must be in outer wall in order for moisture to escape; not allowed in earthquake zones
  • Faced walls – brick masonry units bonded to a backup wall of another material
  • Veneered walls - facing material is securely tied to a structural wall but NOT bonded to it
  • Reinforced brick masonry reinforcement is placed vertically & horizontally and often grout surrounds it
• Structural Clay Tile


  • Burned-clay units, larger than bricks, with vertical or horizontal cells
  • May be smooth, rough, or scored faced
  • May be non-load or load bearing
  • Terra Cotta, ocher to red in color, is used as a non-load bearing ornamental material

  
• Surface Bonding (BlockBond)


  • CMU is laid dry with vertical steel grouted in place
  • 2 coats of BlockBond are sprayed on inside and outside of walls
  • Surface may be textured and requires no paint
• Gypsum Block


  • Lightweight, used in non-load bearing applications, fire-resistant, interior locations
  • Concern: never use in areas in which moisture exposure could occur

  
• Glass Block


  • Provide controlled light transmission, good insulation, condensation protection, and good sound reduction
  • Formed of 2 cast glass shells that are fused together to form a hollow unit containing a partial vacuum
  • Faces can be smooth, textured, or opaque
• Stone Masonry


  • Rubble - stones as they are collected (fieldstone) or as they come from quarry
  • Ashlar constructed of squared stones set in random or uniform courses
  • Cut stone (dimension)- fabricated and finished at the mill ready to set in place per the specifications
• Causes of Masonry Deterioration


  • Freeze/Thaw Cycle
  • Wet/Dry Cycle
  • Thermal Expansion/Contraction
  • Salt Crystallization

  
• Masonry Cleaning Methods


  • Water Mist
  • Chemical
  • Muratic Acid Solution
  • Abrasive (sandblasting & pressure washing)
• Mortar


  • A mixture of cementitious material, aggregate, and water
  • Used for bonding masonry units together, serving as a seating material, leveling and seating the units, and providing aesthetic quality
• Mortar Properties/Function


  • Have a tendency to shrink very little
  • Have a high degree of resistance to moisture penetration
  • Possess adequate strength to resist the forces applied to it
  • Provide aesthetic qualities to the structure through the use of color and type of joint
• Mortar Basics


  • Brick masonry mortar made of Portland cement, hydrated lime, and sand
  • Retempering – adding water to the mortar mix to maintain consistency
  • Mortar mix should be used within 2 212 hours after initial mix is prepared
  • Efflorescence – the soft white powder appearing on the face of brick; caused by salts in the brick or mortar brought to the surface

  
• Mortar Joints


  • Joint sizes vary: Facing brick - 3/8" to 2", Building brick – 1⁄2", Glazed brick – 1/4"
  • Most weatherproof & recommended are: V-shaped, Weathered, & Concave
  • Joints may be formed by using a trowel, steel rod, or specialized tools
• Grout


  • The water/cement ratio is less critical in grout than in mortar or concrete
  • It is intended to be very "fluid" in order to function in it's "binding" capacity (slump of 8- 11 inches)
  • May be used to fill cavities between masonry walls (often around vertical reinforcement)
  • Purpose is to bond the masonry units, bond the reinforcing steel, increase bearing area, increase fire resistance, and improve overturning resistance
• Plaster


  • A fluid mixture of Portland cement, lime, sand, and water, which is used for finishing either masonry walls or framed (wood) walls
  • Stucco is plaster used to cover exterior walls
  • The average compressive strength of plaster is about 13.8 MPa (2000 psi) at 28 days