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Safety First!
Mixing Concrete
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Exercise these safety precautions when using a concrete
or mortar mixer.

1. Read all operating and maintenance instructions before operating or servicing the mixer. You should test run it empty prior to actual use.

2. Give complete and undivided attention to the operation of the mixer.

3. Know how to stop the mixer and the motor/engine instantly.

4. Always have all guards and safety devices attached and in place before operating the mixer.

5. Keep inexperienced and unauthorized people away from the mixer at all times.

6. Never leave the mixer unattended when it is running.

7. Shut off the engine or disconnect the electric motor before making any adjustments or putting hands or tools in the drum. NEVER REACH INTO THE DRUM WHILE THE MIXER IS RUNNING.

8. Do not over-fill. Avoid exceeding the mixer's capacity.

9. Do not refuel the engine when it is hot or running, or while you are smoking. Avoid spilling fuel.

10. Block the mixer wheels or legs when operating on a slope so that the mixer is level and will not move.

11. Use safety chains when towing on the highway.

12. Lower the frame stabilizers if the mixer is equipped and lock them in place before operating the mixer. If the ground is soft, place boards under the stabilizers and wheels.

13. Keep the mixer clean and in good operating condition. Loose or damaged parts are dangerous.

14. Do not wear loose clothing that could get caught in the moving parts or on control levers. KEEP HANDS AND FEET AWAY FROM MOVING PARTS.

15. Never charge or fill the unit prior to starting, as the overload initially encountered could damage the motor/engine.

 

 

Mixing and using concrete is well within the means of a do-it-yourselfer. It requires planning and muscle, plus an understanding of the material to produce the best results. Concrete is a mixture of:

1. Portland cement (this is a type - not a brand name)

2. Sand, gravel, or other aggregates

3. Water

Suggested Concrete Mixes.
USE OF CONCRETE
U.S. Gal. of Water Per Sack of Cement Average Sand Moist
Sand & Gravel
Per Sack Cement
Sand
CU. FT.
Gravel
CU. FT.
Largest Size of Gravel
Most farm construction such as floors, steps, basement walls, walks, yards, pavement, silos, grain bins and water tanks.
5
2-1/4
3
1-1/2 in.
Concrete in thick sections and not subject to freezing. Thick footings, thick foundations, retaining walls, engine bases.
5-1/2
2-3/4
4
1-1/2 in.
Thin reinforced concrete such as milk cooling tanks, fence post, thin floors, most uses where concrete is 2 to 4 inches thick.
5
2-1/4
2-1/2
3/4 in.
Very thin concrete such as top course of 2-course floors and pavements, concrete lawn furniture, most uses where concrete is 1 to 2 inches thick.
4
1-3/4
2-1/4
3/8 in.

If you're tackling a concrete project, you'll need to decide how you will begin. Your choices are:

Buy the dry ingredients separately and mix them.
Small batches can be mixed in a wheelbarrow. For larger batches, use a large mixing box/pan or powered cement mixer. These items are readily available from your equipment rental company. This method is the least expensive.

Buy the dry ingredients conveniently premixed in bags.
You just add the right amount of water and you're ready to go. This is a more expensive option because the yield from a typical 80-pound bag of mix is 2/3 cubic feet. The upside of this option is that bagged material is excellent for small projects such as anchoring mailbox posts, basketball hoops and clothesline posts.

If you're planning on a project which requires pouring a concrete slab, the following chart will be helpful.

Cubic Feet of Concrete in Slabs.
Area sq. ft.
(length x width)
Thickness, in.
4"
5"
6"
50
17
22
26
100
33
41
50
200
68
84
100
300
100
124
150
400
135
168
200
500
168
208
250

 

 

Air-entrained concrete vs. Normal concrete

Air-entrained concrete is necessary in areas where concrete must withstand freezing and thawing temperature shifts and de-icing treatments. Air-entrainment is the process of introducing millions of microscopic air bubbles into the concrete to permit enough space for the absorbed water to expand when water freezes; preventing the concrete from breaking or cracking.

Air-entrained concrete is actually easier to pour and finish than regular concrete. You can buy air-entrained Portland cement in specifically marked bags, or add an air-entraining admixture.

To be effective, air-entrainment agents need to be thoroughly blended with the concrete mix. A power-mixer is a must for this application.

Below you will find a chart of proportions for both air-entrained and normal concrete.

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Table 1. Proportions by weight to make 1 cubic foot of Concrete.
 
Air-entrained concrete
Concrete without air
Maximum-size coarse aggregate in.
Cement, lb.
Sand, lb.
Coarse
Aggregate, lb.
Water, lb.
Cement, lb.
Sand, lb.
Coarse
Aggregate, lb.
Water, lb.
3/8
29
53
46
10
29
59
46
11
1/2
27
46
55
10
27
53
56
11
3/4
25
42
65
10
25
47
65
10
1
24
39
70
9
24
45
70
10
1-1/2
23
38
75
9
23
43
75
10
If crushed stone is used, you should decrease coarse aggregate by 3 lb. and increase sand by 3 lb.
Table 2. Proportions by volume.
 
Air-entrained concrete
Concrete without air
Maximum-size coarse aggregate in.
Cement, lb.
Sand, lb.
Coarse
Aggregate, lb.
Water, lb.
Cement, lb.
Sand, lb.
Coarse
Aggregate, lb.
Water, lb.
3/8
1
2-1/4
1-1/2
1/2
1
2-1/2
1-1/2
1/2
1/2
1
2-1/4
2
1/2
1
2-1/2
2
1/2
3/4
1
2-1/4
2-1/2
1/2
1
2-1/2
2-1/2
1/2
1
1
2-1/4
2-3/4
1/2
1
2-1/2
2-3/4
1/2
1-1/2
1
2-1/4
3
1/2
1
2-1/2
3
1/2
You will find that the combined volume is approximately 2/3 of the original bulk.
 

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Mixing Mortar
 

When mixing mortar, you should exercise the same safety precautions as you would for mixing concrete.

Because mortar mixes are designed for bonding bricks together, they do not use coarse aggregate. You can purchase mortar in premixed bags or mix it yourself.

1 cubic foot of mortar mix is enough to lay 25 bricks, and we have given formulas below that you can use for mixing Portland cement or masonry cement.

Portland Cement. Mix 16 pounds of Portland cement with 8-1/2 pounds of hydrated lime and 100 pounds of dry sand. Carefully add between 2 and 3 gallons of water to make a fluid smooth mixture. Check the consistency as you go.

Masonry Cement. Mix 31 pounds of masonry cement with 100 pounds of dry sand. Carefully add between 2 and 3 gallons of water to make a fluid smooth mixture. Check the consistency as you go.

 

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