Pointers for pathways

Press, 6 August 1987, Page 27

Pointers for pathways

Many of the recommendations for a concrete driveway will apply equally to a path, but there are a few points, however, which should be considered separately. Obviously the dimensions will be different as will acceptable gradients and surface finishes. The width will be selected to suit the application. The main approach to the house may well be Im wide, or more, whereas 0.5 m may be considered adequate for around the garden. In general the limiting gradient for comfortable walking will be somewhat flatter than the limit for safe driving. A slope of 1 in 10 is generally accepted without question, but 1 in 6 can be decidedly uncomfortable. At some point between these two limits you should consider introducing a few steps. A more positive guide can be obtained by walking over a few existing surfaces and measuring the slope of those which appear about the limit of comfort. Remember too that the

limit for a path on the shaded side of the house with possible dampness, etc., may be a little less than would be satisfactory in a more open situation. Disposal of surface water is essential for safety and comfort. A minimum slope of 1 in 50 is essential, either as longitudinal gradient or as cross fall.

Side forms can be 100 x 25mm timber on edge supported by pegs at approximately Im spacing. Soil placed against the outside of the forms will provide additional rigidity. Curves can be formed where desired with strips of hard-board. Shrinkage cracking is normally avoided by restricting the length of individual slabs to about 2.5 m. It is quite common to find a crack developing from the inside corner of a junction where two sections of path meet. For site mixing the materials required will be about 1 1 / 3 cubic metres of builders mix and 6 bags of cement for each cubic metre of finishd concrete. The proportions used will

be one part of cement with six parts of builders mix and just enough water for workability. Aim for consistent proportions from batch to batch and ensure each one is thoroughly mixed. Remember there is no such thing as over-mixing. Ready mixed concrete will simplify this part of the project and will ensure much faster progress since your effort is confined to placing and finishing. You must have good truck access and be sure you are able to handle the volume of concrete within a reasonable time. Ask the supplier to include a retarder if you need an extended working period. Many good jobs are ruined through trying to finish the surface too soon. Once the concrete has been compacted in the forms it should be levelled off then left alone until all signs of surface moisture have disappeared. Wait until it is quite firm then work it up with a wooden float to give a coarse sand-paper texture. If floating brings

back signs of moisture it is too early. A smoother finish can be achieved by using a steel trowel but, since it> tends to be more slippery, it is not recommended for paths. If a really good non-slip finish is desired, perhaps on a steep section of path, the surface can be lightly broomed after wood floating. This must be the most under-rated aspect of all home concreting. By the stage of final finishing you have put in all the work and spent the money on materials. The one remaining step will cost virtually nothing, but it can double the quality of concrete in terms of strength and durability. All that is necessary is a periodic hosing with water over the next 3 or 4 days to prevent premature drying. The side forms can be removed any time after about 24 hours and it is usually safe to walk on the concrete after about 3 days. Initially this must be done with some care, but it can be in full service after about 5 or 6 days.