—On a clean flagged or wooden floor spread three barrow-loads of ashes, then about one barrow-load of lime, and so on until the whole of the dry materials (or one mixing) has been spread; then throw over them about three bucketfuls of tar, and before mixing it with them add (say) six bucketfuls of water; then mix as for concrete, and when the liquids are pretty well absorbed add a similar quantity, mix again, and so on until all the liquids have been absorbed; the mass will then be something of the consistency of ordinary mortar. Next pass the whole three times at least through a pug mill: if this be not done the concrete will be a failure. An ordinary hand pug-mill will not be sufficient; the knives are not strong enough, nor will it incorporate the materials thoroughly, but an upright pug-mill, worked by steam power where practicable, or by at least one horse, should be used.
It will be found that as the mass emerges from the pug-mill a large proportion of the water will run from it; means should therefore be provided for allowing the water to escape freely from the floor.
Method of Laying.
—Prepare the path for a layer of concrete 3 inches in thickness, on a hard dry bottom, inclining from the inside to the kerb, at the rate of ¹⁄₂ an inch to a foot for pathways not more than 6 or 7 feet wide, but for wider pathways an inclination of ³⁄₈ of an inch to a foot will be sufficient.
A template the full width of the path having been provided, lay concrete with a shovel on the inner side of the path for a length of (say) 15 feet and a width of 1 foot, at such a height that when it has been well rammed and patted with shovels it shall be the exact height intended for the path; this is to form a resting-place for one end of the template, the kerb forming that for the other end; then fill the intervening space with concrete up to the template, treading and ramming it solidly for about twenty minutes, and as it gets into shape, patting it with shovels and smoothing with a trowel; then, with an iron (not stone) roller weighing about 5 cwts., roll for two hours, trimming and filling up hollows where necessary; then go on with another length, and occasionally roll the first for half-an-hour, and so on. Experience alone will decide the quantity of rolling necessary after the first day or two, as weather and other causes tend to a more rapid solidification of the concrete at some times than at others.
On the third day, sprinkle a small quantity of sea or other very fine sand on the concrete, and allow it to remain for two or three days after the path has been in use—it should then be removed.
General Remarks.
—The ashes should not be those from a saw-mill or other place where wood ashes would be mixed with them. All ashes, spar or grit, and lime, should be passed through a screen of ³⁄₈-inch mesh. The lime should be the best blue lias, slaked under cover; it should be allowed to lie for at least four days, but not more than six days, before it is used. The spar or grit should be sharp and angular.
Great care should be taken to keep the concrete free from mud or dust; it should be tipped from the carts or barrows, either directly into place, or, if this cannot be done, a few slabs or boards should be laid down, on which it may be tipped.
The path should not be used until the concrete is sufficiently solid to bear a man’s weight without taking the impression of his boots.