1. Concrete and Masonry Construction
BSE 2294
Animal Structures and Environment
Dr. Susan Wood Gay

2. Concrete has several properties that make it well suited for a wide variety of agricultural uses.
Advantages:
Plastic when first mixed
Durable
Sanitary
Low maintenance
Disadvantages:
Heavy
Expensive
Low insulation volume

3. Concrete is composed of two components: paste and aggregate.
Portland cement
Entrained air
Water
Disadvantages
Heavy
Expensive
Low insulation value
Cement plant in Iola, Kansas.

4. Stone quarries on the Island of Portland.
Portland refers to the type of cement that is universally produced by all manufacturers.
Carefully controlled mixture of:
Lime
Silica
Alumina
Iron oxide
Burned and ground into fine powder
Stone quarries on the Island of Portland.

5. Portland cement components

6. Portland cement manufacturing

7. Portland cement manufacturing

8. Portland cement manufacturing

9. Portland cement manufacturing

10. Portland cement is available in five types as designated by ASTM.
Description I
Normal cement; suitable for general construction II
Modified cement; low heat-producing for very large concrete structures
III
High-early-strength cement; hydrates rapidly for cold weather application IV
Low-heated cement; lower heat of hydration than Type II for large masses of concrete such as dams V
Sulfate-resistant cement; resists damage due to the high sulfate content of water

11. Entrained air is important for good quality concrete.
Uses less sand and water
Reduces segregation
Improves workability
May be finished earlier
Increases water tightness
Resists freezing and thawing
Resists surface scaling
One cubic yard of concrete can contain
400 to 600 billion air bubbles.

12. Common products for home concrete use.
Normal portland cement is suitable for most farm and general construction work.
1 sack = 94 lbs or 1 ft3
Dry storage is essential
Do not use cement that contains lumps
Common products for home concrete use.

13. Water for making concrete should be clear, free of acids, alkalis, oils, and organic matter.

14. Gravel Quarry in Southern Ontario.
Both the cost and quality of the concrete are affected by the kind of aggregate selected.
Aggregate should be:
Clean
Hard
Strong
Sharp, rough, or flat aggregate requires more cement-water paste
Fractured material severely reduces strength
Gravel Quarry in Southern Ontario.

15. Inclined aggregate screen.
Aggregates size is determined by screening material through a Number 4 sieve.
Number 4 sieve
¼ inch openings
16 openings/in2
Fine aggregate – passes through a Number 4 sieve
Coarse aggregate – does not pass through a Number 4 sieve
Inclined aggregate screen.

16. The use of well-graded aggregates will produce an economical mixture with the least amount of cement.
“Well-graded” – a variety of materials ranging in sizes:
Fine sand
Coarse sand
Small stones
Allows small particles to fill voids between large particles
Use of aggregates from gravel banks not recommended
Well-graded aggregate fit together so
perfectly that a minimum of paste is required.

17. The maximum size of aggregate used depends on the size and shape of the structure and the distribution of rebar.
Structure Type
Aggregate Size
Walls or columns
≤ 1/5 minimum dimension of the member
Slabs
≤ 1/3 slab thickness
Reinforced concrete
≤ 3/4 space between rebar

18. Excessive amounts of silt or organic matter prevents a secure bond between the paste and aggregate.

19. A silt test can determine whether aggregate should be washed.
Glass jar
2 inches of aggregate
6 inches of water
Shake vigorously and let stand for one hour
If more than 1/8 inch of silt has settled at the top of aggregate – wash or abandon
1/8 in
Silt
2 in
Aggregate
The silt layer is only 1/8 in; therefore the
aggregate is useable without washing.

20. An organic matter test can determine whether aggregate should be washed.
Glass jar
½ pint of water
½ pint of aggregate
1 teaspoon lye
Stir and let stand for 3 to 4 hours
Observe color
Clear to light straw – use
Dark straw – do not use
Free of OM
Some OM
Too much OM
The samples on the left and in the middle are
useable; the sample on the right is not .

21. Slump is the measure of concrete consistency.

22. Concrete strength is inversely proportional to the amount of water used.
7000
5 gallons/sack
6000
6 gallons/sack
5000
7 gallons/sack
4000
Compressive Strength (psi)
3000
2000
1000 7d
28d
90d
Moist-cure test at 70 degrees F.

23. The concrete mix depends upon the desired application.
Kind of Work
Water to Cement Ratio
Maximum Size of Aggregate
Mass Ratio (cement: gravel:sand)
Concrete subjected to severe wear, weather, or weak acid and alkali solutions
5 gal/sack
¾ in
1½ in
1:1.9:2.3
1:1.7:3.1
Floors, driveways, walks, septic tanks, storage tanks, structural beams, columns, and slabs.
6 gal/sack
1:2.5:2.8
1:2.2:3.7
Foundation walls, footings, mass concrete, etc.
7 gal/sack
1:3.1:3.3
1:2.8:4.2

24. Use the specific density of materials to determine the masses of materials needed for a specific concrete mix.
A 1:1.9:2.3 ratio mix = ?

25. The specific gravity (γ) of a substance is a comparison of its density to that of water.
1 cup water
1 cup lead
Each glass contains equal volume of material; however, the
glass with lead will weigh more than the glass with water.

26. ρsand/gravel = (2.65)(62.4 pcf) = 165.4 pcf
The density of a material is calculated by multiplying its specific gravity by the density of water.
γsand/gravel = 2.65
ρH2O = pcf
ρsand/gravel = (2.65)(62.4 pcf) = pcf
γcement = 3.15
ρcement = (3.15)(62.4 pcf) = pcf

27. Concrete Volume Example #1
Determine the volume of a one-sack batch of concrete for a
storage tank. The maximum size of aggregate is ¾ inch.

28. Concrete Volume Example #2
Determine the amount of concrete needed for a feeding floor 35
ft by 120 ft by 4 in thick. Include 5% for error.

29. The actual yield of concrete is 60% of the volume of the total volume of materials.

30. Concrete Yield Example
Determine the yield of a 7 gal/sack concrete mixed using a
maximum aggregate size of 1½ inches.

31. Brand new cement mixing truck.
The purpose of mixing is to achieve a uniform distribution of the ingredients and allow for air entrainment.
Mixing times:
One minute for ≤ 1 yd3
One minute plus 15 s/yd3 for large batches
Mixing order (truck mixers):
Water
Little aggregate
Cement
Balance of aggregate
Brand new cement mixing truck.

32. Form for concrete column consisting of
Forms should be ready and in place before the concrete is mixed or before the ready-mix arrives.
Form materials:
Plywood
Steel
Sheathing
Forms should be:
Clean
Tight
Tied together to prevent bulging
Form for concrete column consisting of
plywood and rebar.

33. Before pouring concrete, the job site must be properly prepared.

34. Remove the soft spots and fill them with soil, gravel, or crushed rock.

35. Grade area to approximate slope.

36. Excavate the site about three or more feet then backfill with compact material to prevent foundation sinking.

37. Construct forms for footing, foundation, and/or floor slab.

38. Wood forms should be oiled with form oil or used crankcase oil prior to concrete placement.

39. Immediately after the concrete is in place, it is struck off with a straight edge board, known as screeding.

40. Soon after screeding, the surface may be floated (smoothed) with a darby or bullfloat.

41. Forms may be removed from fittings or foundations in 24 hours; slabs and beams need in four to five days.

42. Curing is the time needed to complete the chemical reaction between portland cement and water.

43. Fresh concrete develops 40% of its potential strength during the first 14 days of curing; 70% during the first 28.
7000
5 gallons/sack
6000
6 gallons/sack
5000
7 gallons/sack
4000
Compressive Strength (psi)
3000
2000
1000 7d
28d
90d
Moist-cure test at 70 degrees F.

44. Plastic film over freshly poured slab.
Curing is a hydration process; therefore, concrete must not be allowed to dry out during curing.
Continuously sprinkle with water
Cover with:
Damp sand
Damp straw
Plastic film
Plastic film over freshly poured slab.

45. Concrete must be protected from freezing or excessive heat during the curing process.
Optimum temperature ~ 75 °F
Process slows down as temperature decreases
Curing stops at 32 °F
Permanent damage if freezing occurs with first 24 hours

46. Placing rebar and wire mesh prior to pouring.
Reinforcing materials improve the strength of concrete structures by carrying tensile loads.
Transfer of tensile forces
Materials
Wire mesh
Reinforcing bars (rebar)
Synthetic fibers
Placing rebar and wire mesh prior to pouring.

47. Wire mesh is a common reinforcing material for concrete.
Advantages:
Can be formed into various shapes
Tensile strength of 60,000 to 70,000 psi
Disadvantages:
Difficult to install
Expensive
High labor
Wire mesh form.

48. Rebar is ribbed steel bars installed in foundation concrete walls, footers, and other poured structures.
Advantage:
Very high tensile strength (70,000 to 90,000 psi)
Disadvantages:
Difficult to install
Expensive
High labor
Cannot weld
Rebar in sealer.

49. Nylon fibers for concrete reinforcement.
Synthetic fibers are replacing welded wire mesh, especially in residential slabs.
Advantages:
Easy to install
Reduce plastic shrinkage cracks
Disadvantages:
Very low tensile strength
Nylon fibers for concrete reinforcement.

50. Construction of concrete block wall.
Walls constructed with concrete blocks bonded together with mortar are described as masonry construction.
Advantages:
Durable
Fire resistant
Low maintenance
Relatively inexpensive
Disadvantages:
More porous than concrete
More subject to cracking than concrete
Construction of concrete block wall.

51. The ASTM has developed a set of specifications for masonry blocks.
Compressive strength:
Type A – 1000 psi (below grade)
Type B – 700 psi (above grade)
Water absorption limited to 15 lb/ft3
Moisture content ≤ 40%
Free from defects
Concrete blocks must meet ASTM standards.

52. Actual sizes of concrete blocks are 3/8 inch less than nominal size in each direction.

53. Setting concrete blocks.
All dimensions should be planned to be in multiples of blocks or half- blocks.
Minimize cutting and fitting
Horizontal dimensions
Half blocks
Whole blocks
Vertical dimensions
Whole blocks only
Setting concrete blocks.

54. Concrete blocks are available in several shapes.
Dimensions
(in x in x in)
Stretcher
8 x 8 x 16
Corner block
Half block
8 x 8 x 8
Sash block
Jamb block
Bull nose
Partition
4 x 8 x 16

55. Stretchers are used for the bulk of the wall.

56. Corner blocks have one square end for wall corners.

57. Half blocks are used in alternate rows at openings.

58. Sash blocks have vertical grooves in one end for metal sashes.

59. Jamb blocks have 2 in by 4 in openings cut out at one end for a door jamb or wooden window sash.

60. Bull nose blocks have one rounded corner for smooth wall openings.

61. Partition blocks are for inside walls subject to small loads.

62. Masonry Block Example
Determine the number of blocks required for the back wall of a
machinery shed. The wall is 40 ft long and 16 ft high.