CONCRETE-WORK ON THE FARM.

New Zealand Journal of Agriculture, Volume XXX, Issue 2, 20 February 1925, Page 96

CONCRETE-WORK ON THE FARM.

A. W. HUDSON,

B.Ag., Assistant Instructor in Agriculture, Christchurch.

The advantages of concrete-structure on the farm are now generally recognized, but practical knowledge of the technique of the work is often lacking among farmers. In a series of articles —now commenced. the writer proposes to give sufficient detailed information to enable any handy man to undertake the simpler, structures or operations. The present instalment deals (i) with the general subject of materials, and (2) with the making of concrete posts. In subsequent articles it is proposed to treat similarly some other uses to which concrete can be put on the farm. 1. MATERIALS AND THEIR PREPARATION. The materials used in making concrete are the “ aggregate/’ cement, and water. The aggregate may be natural shingle, broken shingle, crushed rock, sand, or a combination of these. It should consist of well-graded material that is, material of all sizes between the largest stones allowed and sand. The material most commonly used is pit, river-bed, or beach shingle, and great care must be taken that there is neither clay nor vegetable matter present. If the shingle contains any soil or plant debris it must be washed free of these. A convenient form of trough for this purpose is shown in Fig. 1. The aggregate is placed in the trough and stirred thoroughly while water is run through. The lighter clay or soil particles or vegetable matter are carried out at the overflow notch. The maximum size of stones allowed in the aggregate will depend on the nature of the work. For ordinary fencing-posts and troughs the largest stones should pass .through a f-in. mesh screen. For posts above 8 in. by 8 in. larger stones may be allowed, but should not be. larger than will pass through a screen of .i| in. mesh. Floors . and.

paths permit the use of large shingle if their thickness is greater than about 2 in., but in general large material is not to be recommended. Where pit or river-bed shingle is used it will generally be necessary to screen the material. This may well be done' at the pit or other place where the shingle is obtained, and the type of screen shown in Figs. 2 and 3 will be found very useful It may be propped up on the tailboard of a dray so that the material passing through the meshes of the screen will fall into the dray and the coarse stones back to the ground. Carting of unneeded material is thereby avoided. The wire for such (a screen is obtainable already prepared at wireworking establishments. Cement. This must be of good quality, and must not have suffered exposure to damp. Since it. is often difficult to store any quantity under the driest of conditions, it is advisable to get only, as much as may be used up in a few months. Water. — It is necessary that water should be free from acid, alkali, clay, or vegetable matter. PROPORTIONS OF MATERIALS. A weaker mixture than 1-6 one part of cement to six of aggregate —should not be used, except where the work is not likely to be subjected to severe strain or wear, such as in the case of bulky walls, where 1-8 can be safely employed. When washed shingle or crushed stone is used, clean, coarse sand in the proportion of about one of sand to two of stone must be added. This will not -increase the space occupied by the stone very much, as it must be borne in mind that the sand goes to fill up the spaces among the coarse material. Measuring of Quantities. — On the farm, measurement of quantities is most conveniently done with a kerosene or petrol tin, which holds about two-thirds of 1 cubic foot of material. A bag of cement contains 1 j cub. ft., and therefore about two kerosene-tinfuls. The volume of the work '■ should be measured ; this will be the measure of the quantity of aggregate required (the addition of the cement to the shingle does not increase the total bulk, as the cement goes to fill up the finer spaces in the material). Suppose the volume of concrete required is 4 cub. ft. : since a kerosene-tin holds about two-thirds of 1 cub. ft., six tins of aggregate will'be required. (In practice it is generally found

that in a case similar to the foregoing about six and a half tinfuls will be required. This is due to the fact that the material does not become completely packed when just thrown into the tin. A little practice will allow a very accurate estimate of the required quantity to be made.) Having measured the shingle or other aggregate, a measured quantity of cement is then emptied on the top of the heap so that it runs evenly all over it. In the example six tinfuls of the aggregate were taken, and therefore, if the mixture is to be 1-6, one tinful of cement will be required. .

Mixing. — A mixing-board 8 ft. by 8 ft. square is suitable for anything up to eight tinfuls at a time. It should be made of tongued-and-grooved Oregon-pine boards, this timber being most suitable for all concrete moulds, &c., as it is less liable to warp than others. Where there is no need to shift the mixing-board a smooth concrete floor makes a very good substitute. Mix thoroughly before and after adding the water. The best mixing is obtained by having a man on each side of the k heap. Shovel from the bottom, and throw the material away from the heap with a turn of the shovel, at the same time imparting a ' spreading movement. Turn the material in this manner at least three times before adding water. A drag with flattened tines is a very useful tool for mixing, and if its use is alternated with that of the shovel the work will be made easier. Repeat the turning operations, at the same time splashing water carefully over the new heap being formed, or using a watering-can. The water must not be added so quickly as to cause streamlets to run away from the heap, as a large amount of cement may be lost if this happens. The quantity of water necessary depends upon the wetness of the aggregate before mixing. Excess of water must be avoided, and when the concrete is so wet as to require a slight shake to dislodge it from the shovel the wetness will be right for most purposes. ' So that the concrete can be used immediately, the mould must be got in readiness before mixing. 2. CONCRETE POSTS. . . ORDINARY FENCING-POSTS. Making the necessary moulds is, of course, the first step in connection with concrete posts. Drawings of a mould suitable for making tapering posts, 6 ft. long, 5 in. by 5 in. at the bottom and 5 in. by 3 in. at the top, are given in Fig. 4. This type of boxing can be used equally well for the post with parallel sides similar to that made in the mould shown in Fig. 5, or a two- or six-post mould may be preferred. If it is considered preferable to make the posts singly — when larger posts, say, 8 in. by 8 in. in cross-section, are being prepared — then the Figs. 6 and 7 type is extremely useful. Instead of the dowels, strips may be fastened on the base-board to keep the sides from bulging ; or two iron pins passing through holes in a cross-piece which rests on the top of the mould, fitting into holes in the base-board, make a very convenient... arrangement for this purpose (Fig. 6). Since the dowel-holes tend to become filled with cement, this method of holding the mould in position is probably the better one. '

' Method of Preparing and Filling Moulds. Cover the base-board with a sheet of plain galvanized iron, or with paper, or paint with any one of the following : (i) Waste oil (such as that from the crank-case of an engine) ; (2) clay and water made into a pasty solution ; (3) whitewash. The portion of the mould comingin contact with the concrete must then be painted with any of these materials and placed in position on the base-board. Wet the mixture, and mix it thoroughly. Lay about 1 in. of concrete in the bottom of the mould, and tamp with a wooden rammer similar to that shown in Fig. 8. Next place two reinforcing-rods (previously prepared) with about 1 in. or 2 in. of their ends bent at right angles, and extending to within about | in. of the ends of ’the mould, on the thin layer of concrete (for position of reinforcing-rods see Fig. 9 —important). Now

fill the moulds to within about f in. of the top, being careful to tamp thoroughly as the concrete is put in in thin layers. Place two other reinforcing-rods in position with the bent-over ends turned towards the centre of the post, fill in to the top of the mould, and finish the surface with a trowel. The next operation is to fix in the wire staples shown in Fig. 10, so that the end with the double loop protrudes about | in. This must be done immediately the concrete is in position, and fine material carefully tamped around the staples. A rod of wood marked with the required spacing will serve as a guide to the position of the staples. In addition to the wire staples, holes 'through the post should be provided, because the life of the staples is limited, and when they rust away the post is likely to be better than ever. These holes may be made in the desired position by placing | in. iron rods through the mould

from side to side before the concrete is put in. The rods must be removed before the. concrete hardens, usually about two hours after placing it in the moulds. This method cannot be adopted in making tapering posts unless no more than two posts are made in the one mould.

Removal of Moulds.

The moulds may be removed about three or four hours after the concrete has been laid. The method adopted at Lincoln College, where the type of boxing shown in Fig. 4 is used, is as follows : The end boards and blocks and outside boards are first removed ; then two parallel boards attached by iron hoops (Fig. 11) are placed so that they lie along the edges of two adjacent posts and astride the dividingboard of the mould. The boards are held firmly, but without undue pressure, and by means of a tool such as a screwdriver the ends of the dividing-board is levered up just a sufficient amount to allow a hooked iron rod. to be placed under it. Keeping the parallel board firmly in position, the dividing - board is then lifted right up and removed. If this operation is not performed at about the time'stated it will be necessary to leave the dividing - boards of the mould in

position until the posts themselves can be moved. .On no account must the posts be moved until four or five days have elapsed. They may then be lifted carefully, supported in the middle as well as at' the ends, and should be laid carefully on sand or loose earth unti ! . mature. A stout plank makes a convenient carrier for the posts, and prevents any tendency for them to sag in the middle. STRAINERS. For a good strainer, which can be used also as a gate-post, the following is recommended :• Type of mould as in Fig. 7 ; dimensions, 8 ft. by 8 in. by . 8 in. ; reinforced with j in. or J- in. round iron. When the post is required as a strainer a notch to take the ends of the stays is made by bedding a wedge-shaped piece of wood of the required size into the face of the post as soon as it is moulded. LARGE GATE-POSTS. The mould for making these is shown in Fig. 12, and the method adopted in building one is as follows : The position in which the post is to stand is carefully determined. A hole, 3 ft. to 3 ft. 6 in. deep and about 16 in. square, is dug. The base of the mould is then set in position over the hole and carefully levelled. Reinforcing-rods of Jin. or fin. iron, long enough to reach from the bottom of the hole to the top of the post, and which may be held at the correct distance apart by a wooden frame or by strong wire (the latter can be left attached to the rods) twisted round them, are next placed in the hole, and the concrete filled in to the top of the base. The mould proper is then placed in position and fastened to the base by means of the brackets and thumbscrews shown in the diagram : it is carefully plumbed and held firmly in position by two temporary stays connecting the .mould with pegs firmly driven into the ground. While the mould is being filled the concrete should be well tamped with an oar-shaped rammer, especially around the sides. If this is done and there, is sufficient sand in the aggregate a very smooth surface will result. As soon as the mould is filled the cap is put on. This may be of any desired shape. The small drawing annexed to Fig. 12 gives dimensions for a pyramid-shaped cap, which is made two or three days before the post. Short wires are inserted into it, and when the cap is put in position these serve to tie it to the post.» The cap-mould shown consists of a square frame with, a pyramid-shaped mould (shown in section) within it. An alternative method of putting on the cap is to prepare a strong mixture (1-2 or 1-3) of cement and sand,,which is made fairly stiff, and simply placed on top of the post and moulded into the desired shape. This is- a slower method than the one first described. The post-mould may be removed with safety in about two days, and if the post is then painted over with . pure cement mixed into a paste with water a very good finish will result. z A pure-white cement may be procured for such work as this if a better appearance is desired. The hinge fasteners which have given best results at Lincoln consist of a three-sided bracket with the ends rounded and threaded. The fourth side has two holes bored in it, and carries the hanger for the hinges. The threaded ends of the three-sided piece pass through

the holes, and the whole is fastened securely by nuts (Fig. 13). The type of gate-fastener to be used should be decided on beforehand, and a hole made in the boxing for its insertion. STAYS. Stays may be made any size. Those used at Lincoln are 8 ft. long and 4 in. by 2 in. in cross-section, and reinforced with two pieces of No. 6 wire near the top and bottom edges. Two are used, placed side by side and | in. apart. The fence-wires pass between them and are then fastened round the post (see Fig. 14). It is a good plan to have a few old kerosene-tins on hand whenever mixing is being done. - If there is any surplus material it can be put into such tins, and the blocks formed used to butt the stays against. . x - BEVELLING. It is good practice to bevel the corners of posts, so that if they are struck the possibility of a piece being chipped out is lessened, and a heavy blow, unless striking the post squarely, would more easily glance off? Bevelled strips can be placed in the mould for the bottom corners of the post, and a trowel may be used to bevel the corners lying uppermost. SEASONING OF POSTS. Posts, and indeed any concrete - work, should be dried slowly. Therefore keep posts covered with wetted bags or other material 'for about two weeks, and even after this the drying must be slow. From three to six months must be allowed before the posts are used. Concrete-work must be protected from extremes of heat and cold. If protection cannot be provided no attempt should be made to work in very hot or in frosty weather. : . • v ' REINFORCING. Reinforcing-material may be used as follows Tapering posts (Figs. 4 and 16) . . ' Four rods of No. 6 wire or J in. round iron. 6 in. by 6 in. posts (Figs. 6 and 15) Four rods of 4 in. or f in. round iron. 8 in. by 8 in. post . . . . Four rods of f in. or | in. round iron. 12 in. by 12 in. gate-post . . Four rods of | in. or f in. round iron. The reinforcing-rods must run nearly the full length of the posts. FENCES. The fence shown in Fig. 15 is constructed of 6 in. •by 6 in. posts placed about 1 chain apart. Wooden droppers are fastened to the wires about every 6 ft. The spacing of the wires is approximately as follows : From the top of post to barbed wire, 3 in. ; from barbed wire to first plain wire, 10 in. ; from first plain wire to-second plain wire, yin. ; from second plain wire to third plain wire, 6 in. ; from third plain wire to fourth plain wire, 5 in. ; from fourth-plain wire to fifth plain, wire, 5 in. ; from fifth plain wire to sixth plain wire, 5 in.'; from sixth plain wire to ground-level, 5 in. This fence may be considered. suitable for holding any kind of ordinary .stock. The droppers are hung so as to clear the ground, and the fence swings on any attempt being made to get through it. This is generally sufficient to frighten stock away. ‘

The tapering posts (Fig. 16) are placed much closer than in the fence just'described. Their distance apart is from 5 yards to 6 yards, with droppers between. They cannot be recommended for horse or cattle fences unless more strongly reinforced. Half a chain should not be too great a distance between such posts where the fence is intended for sheep.

In estimating ..quantities it will be seen that in the case of material for mould Fig. 4 standard sizes of timber have been allowed for : e.g., instead of 5 in. by i|in. for the long boards and ends of mould, 6 in’ by i| in. is reckoned on. Tongued-and-grooved boards are not sold by the superficial foot, but' by the “ running ” foot. This will affect the calculation of cost very slightly.. COST OF TAPERING POST AS MADE IN MOULD SHOWN IN FIG. 4. Mould. Dressed Oregon pine (first class) costs at the present time about £3 per 100 superficial feet. . , £ s. d. ■SB sup. ft. at £3 per 100 . . . . .. .. .. . . 1.14 10 Four iron brackets and bolts, with thumb-screw and wood screws . . 010 o (Dost of labour for making. . . . . . ... . . . . o 10 o j Total cost of boxing .. .. .. .. .. 14 10 i Assuming that such a mould can be used one hundred times, the cost allocated to each post will be 545. divided by 400, or just over 1 Id., A mould well cared for and kept under cover when not in use will give considerably more service than the figure given. At Lincoln some moulds have been in use off and on for a period of twelve years. Concrete-work. . ■ It is here assumed that shingle costs the farmer ios. per yard. Considering that such work, as carting can. be done when horses cannot

be used on the land, it . seems hardly fair to charge even this amount. In any case a little consideration will show that even if the cost of shingle is twice the amount stated the increase in the cost of the post will not be great. Cement and shingle : I yard of shingle is sufficient for making thirty-two tapering posts. Cement costs about 7s. 3d. per bag at main centres. S. d. i yard shingle .. .. .. .. ..0100 3 1 bags cement (1-6 mixture) . . ' ...."I's'4 For thirty-two posts .. . .. ..£1154 The cost of cement and shingle for one post equals is. i|d. Reinforcing : 1 cwt. No. 6 galvanized wire costs 255. There are about 383 yards in 1 cwt; ; therefore 1 ft. costs about |d., and 24 ft. (amount required for one post) 6d. Labour : With three sets of six-post moulds three men can make eighteen posts in half a day. Allowing 12s. per day per man, the cost of labour per post is is. . . . Summary of Cost. Mould, to be charged per post, i|d'. ; cement and shingle, is. i|d. ; reinforcing, 6d.; labour, is : total cost per post, 2s. Bf-d. This does not allow for removal and clearing of moulds, which involves ’ only • a small amount of labour. • cost of 6 ft. by 6 in. by 6 in. post (fig. 7). Mould. ■ • • f j i. S. d.

22j sup. ft. at per 100 . . . . . . ..0138 Iron plates and bolts . . . . .. ..0 76 Labour for making . . . . .. ..050 Total cost of mould .. . .

If used one hundred times, the cost to be charged per .post is 3d. Concrete-work. Cement and shingle : 1 yard of shingle will make eighteen of these posts.. £ s. d. .

i yard shingle .. .. .. .. . . o io o 3j- bags cement .. .. . . . . ..154 For eighteen posts . . ... ... £1 15 4

Cost of cement and shingle for one post, 2s. Reinforcing : j in. round iron, 245. per cwt. ; 1 cwt. approximately 300 ft. ; therefore cost of 1 ft. is id. approximately, and 24 ft. costs 2s. Labour : Three men can make twelve posts in half a day ; at 12s. per - day per man, the cost of labour per post is is. 6d. Summary of Cost. Mould to be charged, per post, 3d.; cement and shingle, per post, 2s. ; reinforcing, per post, 2s. ; labour, per post, is. 6d. : total cost of post, ss. qd.

COST OF 8 FT. BY 8 IN. BY 8 in. STRAINER-POST. - Mould. . ' Z s. d

331 sup. ft. at £3 per 100 . . . . ..<lOO Iron plates and bolts .. ... .. ..076 Labour for making . . . . . . . . 050 Total cost of mould .. ■. .. .. £1 12 6

If used one hundred times, cost to be charged per post is qd. ■ Concrete-work. . Cement and shingle : i yard of shingle will make about seven and a . half posts, i yard shingle and 3| bags cement cost Zi 15s. qd. ; therefore cost of cement and shingle per post is 4s. pd. approximately. Reinforcing : | in. round iron at 225. 6d. per cwt. ; 1 cwt. = 171 ft. ; therefore cost of 1 ft. i-jd., and 32 ft. = 4s. 3d. Labour : Three men can make six posts (probably more) in half a day. The cost of labour per post is thus 3s. Summary of Cost. Mould, per post, 4d. ;• cement and shingle, 4s. pd. ; reinforcing,. 4s. 3d. ; labour, 3s. : total cost of post, 12s. 4d. COST OF 12 IN. BY 12 IN. GATE-POST (FIG. 12). Mould. This cost must necessarily be approximate only, because onlyjone or two such moulds would be required, and for the purchase of small quantities of timber of suitable dimensions the cost would undoubtedly be greater in proportion than if a large amount was ordered.

. , £ s. d. About 30 sup. ft., say .. . . . . .. 10 0 Iron straps, hinges, &c. . . ■. . . . • • 10 o Labour .. .. . - .. .. ..0150 Total . . . . . . . . ..£2150

Concrete-work. In this case the position in which the post will stand must determine the labour required in getting material to the spot. Therefore only the actual cost of shingle, cement, and reinforcing is shown. must be remembered that the post is built in position, so that the labour of placing it occurs during the making. If a hole 3 ft. 6 in. deep and 18 in. square is made, about | yard of shingle is necessary.

£ s. d. | yard shingle .. .. .. .. ..050 About if bags cement at 7s. 3d. . . .. ..0120 Four reinforcing-rods, 9 ft. long, f in.'diameter .. 074 £* 4 4

(To be continued.)

Portion, of Mould for which required. of Cross-section. Number Pieces required. of each Piece. Total Number of Superficial Feet. (i.) For Mould shown in Fig. 4. Inches. Ft. Bearers of base-board and brace (not neces3x2 ! 5 2 9 14 7 7 sarily dressed) Long boards of mould . . . . 6 x i| 5 6 0 4° 3° End boards and blocks (off-cuts here will 6 x i| 4 2 6 make stops for ends of brace) . Tongued-and-grooved base-boards 6x1 6 7 0 .42 ■ 21 Total superficial feet .. 58 58 (2.)' For Mould shown in Fig. 7. ■ ■ > Side boards and end blocks ■ 6 x 11 2 8 ;■ 16 12 Base-board ... .. .. • IO X l| 1 7 7 1 of Total superficial feet . .' 22f (3.) For Single Mould to make 8 in. by 8 in. Strainer or Gate Post Side boards and end blocks 8 x i| 2, '■ 20 20 20 Base-board . . ... 12 X l| 1 9 9 I3i' Total superficial feet . . . . 1 33i

TIMBER REQUIRED FOR MOULDS.