FILLING THE JOINTS.
The joints between the bricks or blocks should be filled to keep the brick in the proper position, to lessen the chipping of the edges of the brick, and to prevent water from penetrating to the cushion coat and to the foundation. Three farms of filler are in common use, viz.: Sand, tar and hydraulic cement.
Sand Filler—Sand was the first filler employed for brick pavements, and in the Middle West is even yet almost exclusively used. The sand should be fine and dry, and should be worked into the joints by sweep ing it over the pavement, which also should be dry. Although the sand is nominally always swept into the joints, it is usually simply spread upon the surface and left to be worked in by traffic, which is un desirable since the joints are eventually filled with manure and street dirt. The sand can be swept into the joints effectively and economically with a revolving machine sweeper. The cost of sweeping the pavement preparatory to filling the joints and the filling of the joints, including the cost of sand, is usually about two cents square yard.
The advantages of a sand filler are: 1. It is cheaper than any other form of filler. 2. The pavement may be thrown open to traffic as soon as the bricks are laid. 3. The pavement may be taken up easily and without breakage of the brick. 4. It is practically watertight, particularly after being in service a short time.
The disadvantages of a sand filler are: 1. It does not protect the edges of the brick from chipping. 2. It may be washed out on steep slopes. 3. It is removed from the top of the joints by the street sweeper.
Tar Filler—Tar is occasionally used as a filler for the joints_ of a brick pavement pavement. The grade ordinarily used is that known to the trade as No. 5 or No. 6 coal-tar distillate. The bricks should be dry, and the tar should he applied at a temperature of 300° to 320° Fakir. by being poured into the joints with a vessel very much like a sprinkling pot without the nose. The success or failure of the tar filling depends on the efficiency and care of the person in charge of heating the tar. If the tar be too hard, it pulverizes in very cold weather; if it be too soft, it runs and becomes sticky in very hot weather. The cost of a tar filler depends upon the locality and upon the closeness of the joints. Usually tar costs from 6 to 8 cents a gallon; and one
gallon is generally sufficient for one square yard of pavement. The total cost of the filler varies from 10 to 12 cents per, square yard of pavement.
Tar is superior to sand in that it makes a perfectly watertight joint; and it is superior to hydraulic-cement grout in that it is not so rigid and therefore makes a more quiet pavement. Tar costs more than sand, and does not protect the edges of the brick as well as hydraulic-cement grout.
The objections to tar are: 1. In summer it is likely to. melt and run out of the joints; and in winter it is brittle and likely to chip out of the joints. 2. The heating of it makes unpleasant odors on the street.
Cement filler—The most common joint filler, other than sand, is a thin mortar composed either of neat Portland cement or of 1 part cement and 1 part fine sand, the latter proportions being the more common. The pavement should be copiously sprinkled immediately before the grout is applied. The sand and the cement should be mixed in batches say of not more than 40 to 50 pounds of each at one time, in a tight mortar box. The box for this purpose should be to 4 feet long, 27 to 30 inches wide, and 12 to 14 inches deep, and should have legs of different lengths, so that the mixture readily flow to the lower edge of the box, which should be 8 to 10 inches above the pavement.
The sand and the cement should first be mixed dry; and when the dry mixture assumes an even and unbroken shade, water should be added in- a sufficient quantity to form a grout of the consistency of thin cream. The grout should be removed from the box to the pavement with a scoop shovel, and not by overturning the box; since by the last process the sand, cement, and water are separated and are deposited on different portions of the pavement. While the box is being emptied the grout should be constantly stirred to prevent a separation of the sand from the cement; and after the grout has been applied to the pavement, it should be quickly swept into the joints with steel brooms. It is better that the joints should be only about half filled at the first application, since then there is a less depth of grout in the joints and consequently less liability of the separation of the sand, the cement, and the water.