Try to keep the sides of the hole as clean and vertical as possible. Except for relatively small posts the posthole should be at least 300-400mm across and provide for a minimum clearance between the posts and the side of the hole of no less than three times the maximum aggregate size. For a rotating clothesline allow for a hole of 450-550mm across.

The Right Mix for the Job
Conventional Concrete or the fast setting Quikcrete? Read on to establish which is the right mix for your job.

Conventional Concrete
One of the golden rules of concrete practice is to ensure that the initial mix contains no more water than is necessary to produce a concrete of sufficient workability to do the job. Using more water yields a greater volume of concrete but lowers the strength and increases shrinkage.

Good concrete or mortar mixes for setting posts and poles should not have high levels of workability. The aim is to produce a stiff mix with just enough water to allow satisfactory compaction. Such a mix will tend to look more like a moist soil than a conventional wet concrete. While the use of a relatively dry mix requires more effort to compact the result is a densely packed material that offers strength and support even before setting and hardening of the concrete.

If the water content is kept to a minimum the amount of cement required is reduced. Concrete mixes for the setting of posts and poles normally comprise 1 part cement to 8 parts total aggregate (sand and coarse) by volume. If the sand and coarse aggregate are mixed separately as distinct from an all in "Builders Mix", use equal quantities of each. if you do not have a concrete mixer the concrete or mortar may be hand mixed in a barrow or bucket.

Easicrete, (Ready-to-use Concrete to which you simply add water) is a convenient and economic alternative for the volume of concrete necessary for bedding posts and poles.

Setting of Posts and Poles
Compact the soil in the base of the hole. Place the post in the hole to check that the final height above ground is correct. It the hole is too deep fill and compact concrete to the desired level. Hold the post in its intended position using temporary supports (timber props or guy wires at right angles.) When the post is secure ram concrete into the gap around the post making sure that each layer is well compacted before adding any more concrete. It is common to finish the concrete level slightly below ground level and to overlay with damp soil. This hides the concrete foundation from view while also helping "cure" the concrete by preventing premature drying.

The Quikcrete option
Quikcrete is a fast vsetting concrete consisting of a special blend of Ultracem Cement, graded dry quality sand & aggregate, and selected additives. Only water is required. QUIKCRETE achieves a set in minutes and a 28 day strength of 15Mpa.

Quikcrete is most suitable for applications involving placement of posts - from erecting fences to securing clotheslines and mail boxes. Concrete the post and carry on with the job.

For structural concretes and/or concretes requiring a smooth trowel finish, use EASICRETE ready-to-use concrete. QUIKCRETE is not recomended for these requirements.

Quantities
Quikcrete
As a guide: For posts up to 1.8m in length use 1 bag of QUIKCRETE, for larger posts use 2 bags. Generally, the diameter of the post hole should be twice the diameter of the post. Use packed earth above the QUIKCRETE base to ground level. For extra strength use more QUIKCRETE.
Water:
A measured water supply is required.

Quikcreting Guide

1. Thoroughly wet hole to compensate for any ground drainage which may soak up water required for the QUIKCRETE. (In sandy soils line the post hole with plastic to slow water loss.)
2. Place and position post in hole.
3. Pour 3 litres of water per bag of QUIKCRETE into the hole, when measuring allow for any ground water present.
4. Immediately pour one bag of QUIKCRETE evenly arround the post - do not mix!
5. Re-check the posts positioning, and sparingly add water to any dry QUIKCRETE visable and level the surface stright away if necessary.

1. If using more than one bag of QUIKCRETE repeat steps 1-5. Then layers of QUIKCRETE may be separated by a layer of compacted earth.
2. After a minimum of 15 minutes, the hole can be topped up with compacted earth, and drilling and nailing can occur. If left for an hour, the post will withstand more substantial pressure such as wire straining.

Disclaimer:
While the information presented within this web site is offered in good faith, Holcim (New Zealand) Ltd disclaims any and all responsibility for the application of the principals and procedures discussed.