Nominal size: _ x _ x __ unit Actual size: ___ x ___ x _____ inches ASTM C55 Concrete Brick ASTM C90 Load-Bearing Block Most units are _ in. high and __ in. long; block is then referred to by thickness. ASTM C140 Sampling and Testing CMU 5 Thus, a 12 in. block is 12 in. _____ (actual 11 /8 in. ______) ASTM C426 Drying shrinkage
Nominal Width Minimum Face Shell of Unit (in) Thickness (in) Minimum Compressive Strength of CMU, net area 3 and 4 3/4 _____ psi (average of 3); _____ psi (individual) 61 81 1/4 Sash/Corner Unit 10 1 1/4 12 1 1/4 ______
Stretcher Units Solid Unit
http://www.oneontablock.com/ Concrete Masonry Units 1 Concrete Masonry Units 2
Web Requirements Concrete Block Shapes and Types
• ¾ inch minimum web thickness 2 2 •6.5 in./ft minimum normalized web area 144 2 2 • Practical minimum is about 12 in. /ft Header Block Double Open End = normalized web area 135° Return Bullnose https://www.lowes.com/pd/Block-USA- http://www.rcpblock.com/block_ to avoid excessive breakage Header-Concrete-Block-Common-16-in-x-8- precision-shapes.html in-x-8-in-Actual-16-in-x-8-in-x-8-in/3599430 = total web area • New block shapes being developed = nominal length of unit • Help with laying block around = nominal height of unit reinforcement • Increase thermal resistance of wall Pilaster Units A Block Lintel Block http://www.rcpblock.com/block_precision-shapes.html
Knock-out Bond Beam Rebar Unit L Corner https://www.youtube.com/watch?v=CECM474_uck theproblock.com http://www.oneontablock.com/ Concrete Masonry Units 3 Concrete Masonry Units 4 Architectural Shapes Concrete Block Manufacturing
• Batching and mixing of concrete • Generally automatic • Very dry, no-slump concrete • Forming of units with block machine • Concrete mix enters the machine • Vibrated and compressed using molds and dies • Two or more units per machine cycle •Curing • Steam kilns at atmospheric pressure • 120° to 180° • 18 hours • Packaging and shipping • Cubers • Splitters
Concrete Masonry Units 5 Concrete Masonry Units 6
Block Machine Joint Reinforcing
Truss Type Ladder Type
4.5 Horizontal reinforcement required for masonry not laid in running bond of 0.00028Ag , placed at a maximum spacing of 48 in. o.c. in horizontal mortar joints or in bond beams. 0.00028(7.625)(16) = 0.034in2 Use 9 gage (W1.7) at 16 in. o.c.
Rebar Positioners
Placed in mortar joints Placed in cells Concrete Masonry Units 7 Concrete Masonry Units 8 Movement of Masonry Movement of Concrete Masonry
4.2.5.1 Shrinkage coefficient, km 4.2.3.2 Coefficient of Thermal km = 0.5sl Expansion
-6 ° Block Shrinkage Block Shrinkage sl Total linear drying shrinkage kt = 4.5x10 in/in/ F
Aggregate sl Aggregate kt Sand and gravel 2.3x10-4 Dense Aggregate 5.2x10-6 /°F Cinders 4.2x10-4 Cinders 3.1x10-6 /°F Expanded Slag 3.4x10-4 Expanded Slag 4.3x10-6 /°F Expanded Shale 3.1x10-4 Expanded Shale 4.6x10-6 /°F Brick Expansion Brick Expansion Mean value 3.3x10-4 Pumice 4.1x10-6 /°F Maximum (C 90) 6.5x10-4
Concrete Masonry Units 9 Concrete Masonry Units 10
Control Joints Control Joint Spacing: Empirical Method
Control Joint: Non-elastic joint that allows in-plane movement but transfers out-of-plane loads across joint. Empirical Method Control Joints for Concrete Masonry Walls – Empirical Method, NCMA TEK 10-2C
Distance between joints not to exceed lesser of Length to or ft height ratio 1 ½ : 1 25 • Minimum horizontal Michigan Joint reinforcement of 0.025 in2/ft. • W1.7 (9 gage) joint reinforcement at 16 in.
Sash blocks
Tongue and Groove Gasket Joint Joint reinforcing across http://www.imiweb.org/masonrydetails/pdf/02.010.1301.pdf control joint Joint Concrete Masonry Units 11 Concrete Masonry Units 12 Control Joints: Engineered Method Elimination of Control Joints with Reinforcement
Engineered Method: Engineered Method: Control Joints for CMU Walls – Alternative Engineered Method, NCMA TEK 10-2C Control Joints for CMU Walls – Alternative Engineered Method, NCMA TEK 10-2C
Strain, in/in • Control crack width with reinforcement 0.0010 0.0015 • Keep reinforcement in elastic range Maximum Wall Panel Length (ft) 25 20 • As ≥ AnFt/fy Dimensions Length/Height Ratio 2½ 2 • Ft is tensile strength of a vertical section. For running bond, crack will Minimum horizontal reinforcement ratio, As/An 0.0007 0.0007 alternate through a unit and a head joint • Tensile strength of unit: 200 psi
Drying shrinkage 0.00065/2 = 0.00032 An = net area of vertical • Tensile strength of head joint: 25 psi cross-section Carbonation Shrinkage 0.00025 • Average: 112 psi irreversible reaction between • A ≥ 0.0019A cementitious materials and carbon Partially grouted wall: s n dioxide in the atmosphere 2 • An needs to include area of grouted bond beams An = 2(1.25in)(12in/ft) = 30in /ft Temperature (70°F) 4.5x10-6(70) = 0.00032 2 0.0007An = 0.021in /ft • #4 at 24 in., #5 at 40 in. for 8 inch CMU wall TOTAL 0.00089
W1.7 (9 gage) joint reinforcement at 16 in. (0.0255in2/ft)
Concrete Masonry Units 13 Concrete Masonry Units 14
Control Joint Detail at Bond Beam Control Joint Detail at Openings 24 inch min. Bond beam Move the control joint outside the reinforced section
V-joint; crack will form at root of V and be less visible Control joint 24 inch min. • Allow control joint to go through ELEVATION reinforcement Raked joint; fill with sealant Debond bar • Move vertical bar for 12 inches Debond bar on one TOP VIEW outside of control side for 12 inches joint • Optional jamb bar besides opening Concrete Masonry Units 15 Concrete Masonry Units 16 Wall Weights (psf), ASCE 7-16: Light weight units Wall Weights (psf), ASCE 7-16: Medium weight units
Grout Spacing Wythe Thickness (in) Grout Spacing Wythe Thickness (in) 4681012 4681012 Density of Unit: 105 pcf (Light weight units) Density of Unit: 125 pcf (Normal weight units) No grout 22 24 31 37 43 No grout 26 28 36 44 50 48 in o.c. 29 38 47 55 48 in o.c. 33 44 54 62 40 in o.c. 30 40 49 57 40 in o.c. 34 45 56 65 32 in o.c. 32 42 52 61 32 in o.c. 36 47 58 68 24 in o.c. 34 46 57 67 24 in o.c. 39 51 63 75 16 in o.c. 40 53 66 79 16 in o.c. 44 59 73 87 Full Grout 55 75 95 115 Full Grout 59 81 102 123 Solid Units 32 51 69 87 105 Solid Units 38 60 81 102 124
These weights are slightly different than in NCMA TEK 13-B Concrete Masonry Wall Weights, particularly for 4 inch units
Concrete Masonry Units 17 Concrete Masonry Units 18
Wall Weights (psf), ASCE 7-16: Normal weight units Section Properties: Net Area
Grout Spacing Wythe Thickness (in) Nominal Wythe Thickness (in.), with 4681012 actual wall thickness below (in.) Grout Spacing Density of Unit: 135 pcf (Normal weight units) 4 6 8 10 12 No grout 29 30 39 47 54 3.625 5.625 7.625 9.625 11.625 48 in o.c. 36 47 57 66 Net Area (in2/ft) 40 in o.c. 37 48 59 69 32 in o.c. 38 50 62 72 No grout 18 24.0 30.0 30.0 30.0 24 in o.c. 41 54 67 78 48 in o.c. 31.5 40.7 44.9 49.1 16 in o.c. 46 61 76 90 40 in o.c. 33.0 42.8 47.9 52.9 Full Grout 62 83 105 127 32 in o.c. 35.3 46.0 52.4 58.7 Solid Units 41 64 87 110 133 24 in o.c. 39.1 51.3 59.8 68.2 16 in o.c. 46.6 62.0 74.8 87.3 Full Grout/Solid Units 43.5 67.5 91.5 115.5 139.5
NCMA TEK 14-1B Section Properties of Concrete Masonry Walls Based on face shell bedding, minimum dimensions, and 8-5/16 inch grouted cell (half of a 15.625 inch block plus half of a 1 inch web)
Concrete Masonry Units 19 Concrete Masonry Units 20 Section Properties: Moment of Inertia Section Properties: Section Modulus
Nominal Wythe Thickness (in.), with Nominal Wythe Thickness (in.), with actual wall thickness below (in.) actual wall thickness below (in.) Grout Spacing Grout Spacing 4 6 8 10 12 4 6 8 10 12 3.625 5.625 7.625 9.625 11.625 3.625 5.625 7.625 9.625 11.625 Moment of Inertia (in4/ft) Section Modulus (in3/ft) No grout 38.0 130.3 308.7 530.0 811.2 No grout 21.0 46.3 81.0 110.1 139.6 48 in o.c. 138.6 332.0 593.1 943.8 48 in o.c. 49.3 87.1 123.2 162.4 40 in o.c. 140.2 336.7 605.7 970.3 40 in o.c. 49.9 88.3 125.9 166.9 32 in o.c. 142.7 343.7 624.6 1010.1 32 in o.c. 50.7 90.1 129.8 173.8 24 in o.c. 146.8 355.3 656.2 1076.3 24 in o.c. 52.2 93.2 136.3 185.2 16 in o.c. 155.1 378.6 719.3 1208.9 16 in o.c. 55.1 99.3 149.5 208.0 Full Grout/Solid Units 47.6 178.0 443.3 891.7 1571.0 Full Grout/Solid Units 26.3 63.3 116.3 185.3 270.3
NCMA TEK 14-1B Section Properties of Concrete Masonry Walls NCMA TEK 14-1B Section Properties of Concrete Masonry Walls Based on face shell bedding and minimum dimensions Based on face shell bedding and minimum dimensions
Concrete Masonry Units 21 Concrete Masonry Units 22
Section Properties: Radius of Gyration Section Properties: Example
Problem: Find section properties for 8 in. CMU, face shell bedding, grout at 48 in. o.c. Nominal Wythe Thickness (in.), with actual wall thickness below (in.) Grout Spacing in
4 6 8 10 12 5.125 3.625 5.625 7.625 9.625 11.625 7.625 in 8 in Radius of Gyration (in) 48 in No grout 1.35 2.08 2.84 3.55 4.28 1.25 in 48 in o.c. 1.96 2.66 3.33 3.99 40 in o.c. 1.94 2.63 3.29 3.95 2 2 2 An 48in. 7.625in. 40in. 5.125in 161in An 161in / 4 ft 40.3in / ft 32 in o.c. 1.91 2.59 3.24 3.88
24 in o.c. 1.87 2.53 3.16 3.79 3 3 16 in o.c. 1.79 2.43 3.04 3.64 48in. 7.625in. 40in. 5.125in 4 4 4 In 1324in In 1324in / 4 ft 331.1in / ft Full Grout/Solid Units 1.05 1.62 2.20 2.78 3.36 12 12
4 In 1324in 3 3 3 NCMA TEK 14-1B Section Properties of Concrete Masonry Walls Sn 347.4in Sn 347.4in / 4 ft 86.9in / ft Based on average properties of assemblage per Code 4.3.2 t / 2 7.625in./ 2
Concrete Masonry Units 23 Concrete Masonry Units 24