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Mortar. This may be divided into two classes—mortar for building purposes, and mortar for pointing, the latter being called by practical men“pointing stuff.”
Building mortar may again be divided into two classescement mortar and lime mortar, the first being distinguished as compo, from the latter, which is generally called mortar only.
The decision as to the quality of the mortar will depend upon where it is to be used. Thus, for work under water, footings, piers receiving heavy weights, etc., Portland cement or Blue Lias would be used; for ordinary purposes, fairly hydraulic, such as grey stone lime. Fat or poor limes should never be used for building brickwork.
The proportions recommended are as follows: Above ground: Fairly hydraulic lime, one part to three sand; eminently hydraulic lime, one part to two sand; Portland cement, one part to five sand. For footings: Eminently hydraulic lime, one part to one sand; Portland cement, one part to two sand. For work washed by water, such as river walls, etc., Portland cement and sand in equal proportions.
A greater proportion of sand than the above is often used with eminently hydraulic lime and Portland cement, and a good hard mortar results, but the ultimate strength is not attained.
Sand, as already stated, serves the purpose of admitting carbonic acid gas to the lime, and is also used for the sake of economy.
Mode of Mixing.--A clean site or platform having been chosen, the lime and sand should be measured out in a yard measure. In the case of fairly hydraulic lime, which is supplied in lump, the screened sand is formed into a ring, the lime shot into the middle, and sprinkled with just sufficient water to slake it. Some of the sand is then turned over the lime, and it is left in this state till the lime has become thoroughly slaked. Water is then added, the remaining sand gradually pulled in, and the whole mass carefully incorporated with a larry and shovel.
For hydraulic limes and cements, which are supplied in a powdered state, the lime and sand are again measured and shot upon a platform, the sand first and the lime upon the top of it. These are mixed together, first in a dry state, and then with just sufficient water to form a fairly stiff paste, in order that the lime or cement may not escape with the water. With the latter mortar small quantities only should be mixed at a time.
The mortar-mill is now frequently used, but, though a finer mortar may be turned out, it is often not so good as that made by hand. This applies more especially to cement mortar. The mill is also a means of using materials that are really not fit for making mortar.
Mortar for Pointing.—Yellow pointing stuff, sometimes called stopping. One of the most objectionable modes of treating old and sometimes new brickwork, is to rake out the joints, colour the work as a poor imitation of new malm bricks, fill in the joints with stopping, rub over, in the case of old work, with a piece of sacking, and new, with a brick, and then joint with either a white or black tuck joint. In stock, or yellow malm facings, in which yellow stopping is used, the brickwork is coloured with a solution of copperas and water, sometimes with a little yellow chrome added to give a brighter colour; experiments being made upon an old brick, or a portion of the work hidden from view, so as to hit upon the desired tint.
The yellow stopping is composed of fairly hydraulic lime one part, fine washed sand three parts, and sufficient yellow ochre to make the stopping of the same tint as the copperas-washed brickwork.
For red brickwork, the colouring solution is made up of Venetian red and Spanish brown, in the proportion of about 2 lbs. of each to 3} gallons of water, according to the desired tint, 1 lb. of copperas, and sometimes beer, to set the colour. The mortar will be similar to the above, with the exception that the colouring matter is Venetian red, with a small amount of vegetable black.
Putty for pointing is made of silver sand and stone lime, two of the first to one of the latter. The lime, being dry slaked, is mixed with the sand, passed through a very fine sieve, mixed with sufficient water to form a very hard paste, oil sometimes added to make it work better, and then well beaten with a club hammer or other heavy instrument. For black putty, vegetable black is added to the above, the quantity being about 1} cwt. to 1 cubic yard.
There are several other fancy-coloured mortars, such as pink, chocolate, etc., the object being to make a contrast between the brick and the joint. Thus a deep chocolate blends well with red facings, etc.; but being too numerous to deal with individually, the colouring must be left to the judgment of the practical man.
THE METHOD OF MEASURING BRICKWORK, CONCRETE, POINTING, ETC.
Most bricklayers know how to use the foot rule in measuring ordinary work, but, having attained the measurement, the difficulty arises as to how to square or cube the quantities thus obtained. Another difficulty also met with is how to take the measurement of awkward shapes, e.g. gables, arches, etc. This chapter, therefore, is intended to help those who have no knowledge whatever of the subject.
In the building trades, measurements are taken as foot run, foot super, or square, and foot cube.
Foot run relates to length only; for instance, drains, tilecreasing, cutting under 6" wide over circular arches, cement fillets, etc., are taken and priced at the foot run. In this there are 12" to a foot, and 3' to a yard.
Foot super, or square.—Here length is multiplied by width or height; a paved floor, so many feet long by so many feet wide, will have so many feet super, or square, of paving. In a square foot there are 144 square inches. To make sure that this is so, draw a square 12" long by 12" wide, and divide up into inches; it will be seen that there are 144. But in the building trades, both with square and cube measurements, twelfths of feet are reckoned upon. So 6 square feet 72 square inches would be written as 6'6"
super. There are also 9 square feet in a square yard. This may be proved by laying down a square 3' long by 3' wide, and dividing into squares 12" by 12", when nine squares will have been formed. Foot super is used in measuring facings, paving, tiling, etc.
Cube measurement is length x (multiplied by) thickness x depth or height. Thus, in finding the cubic contents of an 18" square pier, say 6' high, it would be stated, as 6' x 1'6" x 1' 6". In the cubic foot it will be seen (Fig. 211), that there are 1728 cubic inches. That is to say, that 1728 wooden cubes 1" x 1" x 1" may be built up to form a cube 12" long, 12". broad, and 12" deep. Here again, instead of reckoning 1728 inches, the cubic foot is divided into twelve cubes, and 6 cubic feet 864 cubic inches is written as 6' 6" cube. There are 27 cubic feet in a cubic yard, as may be seen by making twenty-seven cubes 12" X 12" X 12", and piling them together to form a cube 3' x 3'x3'. Cubic measurement is used for excavations, concrete, etc.
Before squaring dimensions, a perfect mastery of the multiplication tables up to 12 times is necessary. A thorough knowledge of these tables will also be sufficient for division when needed. Thus, knowing that 12 times
Fig. 211. 9 are 108, then 12 into 108 = (equals) 9, and 12 into 112 = 9 and 4 over, or 9 into 108 = 12, and 9 into 112 = 12 and 4 over, etc. A constant practice in this will be invaluable in squaring dimensions.
There are several arithmetical methods of squaring dimensions, but for those who are not expert it would be better to adopt one system only. An easy and accurate method is that known as cross multiplication, or duodecimals. By duodecimal is meant multiplication by twelves. Take as an instance 5' 7" X 2'4", or, as it is written
5' 7" 2 4" 11' 2''
1' 10" 4"
13' 0" 4'"" Here, start to multiply 5' 7" by the 2, and say twice 7 are 14; 12 into 14 = 1 and 2 over; place the 2 under the 4, and carry 1. Next, twice 5 are 10, and the 1 carried = 11; place this under the 2. Proceed with the multiplication by 4", and say 4 times 7 are 28; 12 into 28 = 2 and 4 over; place the 4 in the line under 11' 2", but one place to the right of the 2", and carry the 2. Then 4 times 5 are 20, and the 2 carried make 22; 12 into 22 = 1 and 10 over; place the 10 under the 2", and 1 under the 11'. Add these two lines, starting with the first figure to the right : so 4, with nothing added = 4, bring it down in its place; 10 and 2 (or 10 + 2) are 12; 12 into 12 = 1 and none over, place 0 under the 10, and carry 1; the 1 carried + 1 + 11 are 13, place the 13 under the 1; and the answer will be 13'. Whenever in the place twice removed to the right of the feet (or where 4 appears in the last result), the figure is 6 or over, reckon this as one more to the place to the right of the feet (or where 0 appears in the last result), but when under 6 discard it. Thus, if the last answer had been 13' 0" 7'', call it 13' 1", but, being 13' 0" 4" only, it should be taken as 13'.
Cubing.-Let 6'4" X 2' 11" X 3' 6" be the dimensions, written
6' 4" 2' 11" 3' 6''
Proceeding as before (see below), begin by multiplying 6' 4" 2', and say twice 4 are 8; this cannot be divided by 12, so place it under the 11. Twice 6 are 12; place this under the 2'. Then multiply by the 11"; 11 times 4 are 44; 12 into 44 = 3 and 8 over; place the 8 under the 12' 8", but one place to the right of 8, and carry the 3. Then 11 times 6 are 66, and the 3 carried make 69; 12 into 69
Place the 9 under the 8, the 5 under the 12, and add the two lines : 8 and 0 = 8, write it in its place under the 8; 9 and 8 are 17, 12 into 17 = 1 and 5 over, place the 5 under the 9 and carry the 1; 1 and 5 are 6, and 12 are 18, place the 18 in its proper position as feet; and the result so far is 18' 5" and 8'". Multiply this by 3' 6", placing the 3 under the 18, and the 6 under the 5. As before, first multiply by the feet, and say 3 times 8 = 24; 12 into 24 = 2; carry the 2 and place 0 in the line, under the 3' 6", but to the right of the 6. 3 times 5 = 15; and 2 = 17; 12 into 17 = 1 and 5 over; place the 5 under the 6 and carry 1. 3 times 8 are 24, and the 1 carried makes 25 ; place the 5 under the 3 and carry 2. 3 times 1 are 3 and 2 = 5; place it to the left of the last 5, making 55. Then multiply by the 6", and say 6 times 8 are 48; 12 into 48 = 4 and 0 over; again place the 0 under the 55' 5" 0, but one place to the right of the 0, and carry the 4. 6 times 5 are 30, and the 4 carried, 34; 12 into 34 = 2 and 10 over; place the 10 under the 0, and carry 2. Then multiply 18 by 6, adding on the 2, and making 110; 12 into 110 = 9 and 2 over, place the 2 under the 5, and the 9 under the
5 and 9 over.