ASTM C55 ASTM C90 ASTM C ASTM C Concrete Masonry Units Concrete Brick Load-Bearing Block Sampling and Testing CMU Drying shrinkage Nominal size: _ x _ x unit Dimensions Actual size: x x inches Most units are _ in. high and in. long; block is then referred to by thickness. Thus, a in. block is in. (actual 11 5 / in. ) Minimum Compressive Strength of CMU, net area psi (average of ); psi (individual) Report from one East Tennessee manufacturer: Average of blocks from sets: 570 psi, 00 psi, 0 psi Some manufacturers still report based on gross area instead of net area. Nominal Width of Unit (in) Minimum Face Shell Thickness (in) and / 1 1 1/ 1 1/ 1 1/ Concrete Masonry Units 1 Concrete Masonry Units Concrete Block Shapes and Types Architectural Shapes Concrete Masonry Units Concrete Masonry Units
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 0 to 10 1 hours Packaging and shipping Cubers Splitters Concrete Block Machine Concrete Masonry Units 5 Concrete Masonry Units Joint Reinforcing Movement of Concrete Masonry Truss Type Rebar Positioners Ladder Type.5 Horizontal reinforcement required for masonry not laid in running bond of 0.000A g, placed at a maximum spacing of in. o.c. in horizontal mortar joints or in bond beams. 0.000(7.5)(1) = 0.0in Use 9 gage (W1.7) at 1 in. o.c...5.1 Shrinkage coefficient, k m k m = 0.5s l s l Total linear drying shrinkage Aggregate Sand and gravel.x - s l Cinders.x - Expanded Slag.x - Expanded Shale.1x - Mean value.x - Maximum (C 90).5x -... Coefficient of Thermal Expansion k t =.5x - in/in/ F Aggregate Dense Aggregate Cinders Expanded Slag Expanded Shale Pumice k t 5.x - / F.1x - / F.x - / F.x - / F.1x - / F Placed in mortar joints Placed in cells Concrete Masonry Units 7 Concrete Masonry Units
Control Joints Control Joint: Non-elastic joint that allows in-plane movement but transfers out-of-plane loads across joint. Control Joint Spacing Empirical Method Control Joints for Concrete Masonry Walls Empirical Method, NCMA TEK -C Michigan Joint Tongue and Groove Joint Distance between joints not to exceed lesser of Length to or ft height ratio 1 ½ : 1 5 Minimum horizontal reinforcement of 0.05 in /ft. W1.7 (9 gage) joint reinforcement at 1 in. Sash blocks Gasket Joint http://www.imiweb.org/masonrydetails/pdf/0.0.1.pdf Joint reinforcing across control joint Concrete Masonry Units 9 Concrete Masonry Units Control Joints with Horizontal Reinforcement Engineered Method: Control Joints for CMU Walls Alternative Engineered Method, NCMA TEK -C Strain, in/in 0.00 0.0015 Maximum Wall Panel Length (ft) 5 0 Dimensions Length/Height Ratio ½ Minimum horizontal reinforcement ratio, A s /A n 0.0007 0.0007 Drying shrinkage 0.0005/ = 0.000 Carbonation Shrinkage 0.0005 irreversible reaction between cementitious materials and carbon dioxide in the atmosphere Temperature (70 F).5x - (70) = 0.000 TOTAL 0.0009 A n = net area of vertical cross-section Partially grouted wall: A n = (1.5in)(in/ft) = 0in /ft 0.0007A n = 0.01in /ft Horizontal Reinforcement Only Engineered Method: Control Joints for CMU Walls Alternative Engineered Method, NCMA TEK -C Control crack width with reinforcement Keep reinforcement in elastic range A s A n F t /f y F t is tensile strength of a vertical section. For running bond, crack will alternate through a unit and a head joint Tensile strength of unit: 00 psi Tensile strength of head joint: 5 psi Average: 1 psi A s 0.0019A n A n needs to include area of grouted bond beams # at in., #5 at 0 in. for inch CMU wall W1.7 (9 gage) joint reinforcement at 1 in. (0.055in /ft) Concrete Masonry Units 11 Concrete Masonry Units
Control Joint Detail at Bond Beam Wall Weights (psf), ASCE 7- Bond beam Control joint ELEVATION V-joint; crack will form at root of V and be less visible Raked joint; fill with sealant TOP VIEW Wythe Thickness (in) Density of Unit: 5 pcf (Light weight units) Full Grout Solid Units 9 0 0 55 51 1 0 5 75 9 7 7 9 5 57 95 7 55 57 1 7 79 115 5 Concrete Masonry Units 1 Concrete Masonry Units 1 Wall Weights (psf), ASCE 7- Wythe Thickness (in) Density of Unit: 5 pcf (Normal weight units) Full Grout Solid Units 9 59 0 5 7 51 59 1 1 5 5 5 7 50 5 75 7 Wall Weights (psf), ASCE 7- Wythe Thickness (in) Density of Unit: 15 pcf (Normal weight units) Full Grout Solid Units 9 1 0 7 1 9 7 50 5 1 7 7 57 59 7 7 5 1 5 9 7 7 90 7 1 Concrete Masonry Units 15 Concrete Masonry Units 1
Section Properties: Net Area Section Properties: Moment of Inertia.5 Net Area (in /ft) 1.5 5.5.0 1.5.0 5. 9.1. 7.5 7.5 0.0 0.7..0 51..0 91.5 9.5 0.0.9 7.9 5. 59. 7. 115.5 11.5 0.0 9.1 5.9 5.7. 7. 19.5.5 Moment of Inertia (in /ft).0 7. 5.5. 1...7 1. 155.1 17.0 7.5 0.7.0.7.7 55. 7.. 9.5 50.0 59.1 05.7. 5. 719. 91.7 11.5 11. 9. 970..1 7. 0.9 1571.0 NCMA TEK 1-1B Section Properties of Concrete Masonry Walls Based on face shell bedding and minimum dimensions Concrete Masonry Units 17 NCMA TEK 1-1B Section Properties of Concrete Masonry Walls Based on face shell bedding and minimum dimensions Concrete Masonry Units 1 Section Properties: Section Modulus Section Properties: Radius of Gyration.5 Section Modulus (in /ft) 1.0. 5.5. 9. 9.9 50.7 5. 55.1. 7.5 1.0 7.1. 90.1 9. 99. 11. 9.5 1.1. 5.9 9. 1. 19.5 15. NCMA TEK 1-1B Section Properties of Concrete Masonry Walls Based on face shell bedding and minimum dimensions 11.5 19. 1. 1.9 17. 15. 0.0 70. Concrete Masonry Units 19.5 Radius of Gyration (in) 1.5 1.05 5.5.0 1.9 1.9 1.91 1.7 1.79 1. 7.5....59.5..0 9.5.55..9..1.0.7 NCMA TEK 1-1B Section Properties of Concrete Masonry Walls Based on average properties of assemblage per Code.. 11.5..99.95..79.. Concrete Masonry Units 0
Section Properties: Example Problem: Find section properties for in. CMU, face shell bedding, grout at in. o.c. 5.5 in 7.5 in A n I n in in in. 7.5in. 0in. 5.5in 11in in. 7.5in. 0in. 5.5in 1in 1.5 in A n 11in / ft 0.in / ft I n 1in / ft 1.1in / ft S n In 1in 7.in t / 7.5in./ S n 7.in / ft.9in / ft Concrete Masonry Units 1