How to Begin Concrete Masonry by Jimmy Cox

The truth about an amateur concrete masonry project is that the results can be every bit as good as a job done by a professional. Both in appearance and structurally, the job you do can rate A-l on the building inspector's card. There will be a difference in time due to the fact that the pro can work faster, but the amateur need not worry about speed - the end result is more important than the time needed to accomplish it.

Mixing in wheelbarrow is good system for amateur mason. A good batch can be mixed this way and a deep barrow easily contains the wet ingredients.

The mixture for concrete, actually an artificial stone, consists of a blend of fine and coarse aggregates, each piece of which is completely surrounded and held to its mates by hardened Portland cement paste. A chemical reaction, which occurs ideally due to favorable temperatures and the presence of moisture while curing, causes the paste to harden.

The most important rule is to be ready when the ready-mix truck arrives. Have grading done, forms in and friends around to help you.

Concrete mix lacking in finer particles will be hard to handle and place. It will be rough to finish and deep pours will have honeycombed surfaces.

Light troweling fills all spaces between coarse aggregates with finer particles with correctly proportioned mix. Such a workable mix also produces most concrete for a given amount of cement.

The water to cement ratio is probably the most important factor as far as the strength of mix is concerned. Too much water will result in a thin, diluted cement-paste that will be weak and porous when it hardens. It will not bond the aggregates nor will it be watertight.

The correct water-cement paste, and this is important, produces a mix with maximum strength. The amateur will often use more water than necessary because it makes a more fluid mix that flows easily into the forms. Such a project may look O.K. to begin with (although there will probably be finishing problems due to excess moisture), but it will eventually be discovered to lack strength and durability.

Actually, too little water is much better than too much. The less water you use (and still come up with a workable mix), the stronger the mix will be! Ideally, the proportions suggested should be exactly followed by measuring precise quantities of perfectly dry aggregates.

Since this is difficult to do under normal conditions, a good procedure to adopt, after aggregates and cement have been thoroughly mixed, is to add a small amount of water at a time (mixing as you go) until the concrete is pliable and yet can be compacted in your hand and placed so it will stand without crumbling. When a more fluid mix is required add more water and more cement to keep a correct proportion.

Pour the concrete where it's most needed. If there's room available, a truck can move from spot to spot. Spread and tamp pour with hoe or rake.

A shovel is also useful for spreading the concrete mix. Boots should be worn by workman - a good idea since you'll probably have to walk in topour.

Aggregates can be fine or coarse. Fine aggregate is usually sand although other materials may be substituted. The ideal sand for concrete contains particles that vary uniformly in size from very fine grit up to 4 in. The gradation from fine to coarse is important because the finer particles fill the spaces between the larger pieces.

With these tips you should be ready to start your project.

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