Cement Sidewalks

Street Signs.

It has been proposed to indicate the names of the streets by inserting colored letters in the cement walk at the corner of the block. This may be done by. placing wooden or metal letters of a thickness equal to the wearing coat in the proper position and laying the wearing coat around them, and then remov ing the letters and filling the space with colored cement-mortar.

Slipperiness.Ordinarily cement walks are not slippery, though occasionally one is seen that is somewhat slippery. There is considerable difference of opinion among contractors as to the cause of the slipperiness, some claiming that it is due to too much troweling, others to too rich mortar, and still others to one or another particular brand of cement. Apparently a slippery walk occurs only when the wearing coat is rich in a very finely ground cement, and is troweled excessively long. The long continued troweling seems to work an excess of very fine cement to the surface of the walk. If the sand is coarse and sharp, such a walk will cease to be slippery when the film of neat cement has worn away; but if the sand is very fine, the walk may always be slippery.

" If a cement walk is so hard that one may strike fire with the shoe heel, it is nearly certain to wear slick." Walks made with granite screenings are usually smoother than those made of sand, since the angular fragments of granite are not so easily displaced as the rounded sand grains and consequently the surface is not roughened by the depressions left by the dislodged particles.

Precautions.Since cement walks are very common and are often built by inexperienced workmen without adequate super vision or inspection, a summary will be given of some of the precau tions to be observed if first class work is desired. 1. Use clean sand, particularly in the wearing coat. 2. Use the same brand of Portland cement in base and top. 3. Thoroughly mix the sand and cement dry. 4. Use a minimum amount of water, i. e., only enough to make the mortar the consistency of moist brown sugar. 5. Mix the mortar and the broken stone until each fragment of stone has mortar adhering to every point of each face. 6. Con solidate the concrete, particularly at the edges, by thorough tamping. 7. Avoid long blocks, and also broken joints. 8. Under no consideration, attempt to place the top coat if there is a film of dirty water on the top of the concrete base. 9. Apply the wearing coat as soon as the base is in position. 10. Tamp the wearing coat or use heavy pressure in troweling it. 11. Finish the surface of each block to a plane, and be very careful that it is not low in the center. 12. Keep the walk damp for several days after it is finished. 13. The thickness of the concrete base and also of the wearing coat should conform to the specification, and each should have the specified proportions of sand and cement.

Cement Walk Across Driveway.

Cement walks fre quently cross private driveways, and often the driveways them selves are paved with what is practically a cement walk, except that the construction may be a little heavier. The surface of the driveway should be roughened to give a good foot-hold for horses. One method of doing this is to form V-shaped grooves, about 1 inch wide and + inch deep and 4 inches apart, across the driveway. These grooves may be made with a tool some what like that shown in Fig. 157, page 607, but can be most

easily made by the use of the tools hown in Fig. 160. When a cement sidewalk is carried across an unpaved driveway, the foundation and also the walk itself should be made heavier; and in addition the crossing should be widened, the added portion being constructed with an inclined surface to assist the wheels in mounting and to prevent them from crushing the edge of the walk. In the South Side Parks of Chicago, at intersections of unpaved streets and alleys, the edge of the walk is carried down 18 inches from the surface of the walk to form a curb. This curb or header is 6 inches thick and is faced the same as the surface of the walk, and its upper corner is finished with a radius of inches.

Cost of

Cement Walks.Materials. One barrel of Port land cement will lay about 35 square feet of walk having a 3-inch concrete base composed of one part cement and two parts of sand, about half of the cement being required for the base and half for the top. If gravel is used instead of sand and broken stone, the above proportions will still be approximately true. One yard of gravel will lay about 80 square feet of concrete base. One yard of sand will make 250 square feet of wearing coat. One yard of cinders will cover about 72 square feet 4 inches thick after being tamped.

Gravel and sand can usually be had at $1.00 per cubic yard, delivered. Cinders cost from 15 to 50 cents per cubic yard at the furnace, and will usually cost 50 cents per cubic yard to haul. Granite chips that will pass a 1-inch mesh and be caught on a j-inch mesh will usually cost about $4.00 per ton or about $5.60 per cubic yard ( = 2,800 lbs.). Screenings of undecayed granite will usually cost $5.50 per ton or about $7.70 per cubic yard.

Labor.The amount of labor required to lay cement walks varies greatly with the organization of the gang, and also with the energy and skill of the superintendent. A man can do the excava tion for 250 to 300 square feet per day, assuming that the excava tion is to be only 10 or 12 inches deep, and assuming that the earth is simply cast to the side, and assuming further that the earth is in good spading condition. Under the conditions assumed above and with wages of common labor at $1.50 for 10 hours, the exca vation will cost only about a cent per square foot; but most contractors estimate that under average conditions. it will cost l cent per square foot. Wheeling, grading, and tamping the cinders will cost about a cent per square foot. One finisher and five common laborers should on the average lay 800 square feet of walk in 10 hours, exclusive of the preparation of the foundation; but apparently some contractors with 6 men put in 1,200 square feet in 9 hours, while others lay only 600. A well organized gang should lay 100 square feet of walk per man. If common labor receives $1.50 per day, a form setter will receive $2.00, and a finisher $3.50 or $4.00.

Total Cost. The following represents the average expe rience of a prominent contractor in Central Illinois, for a walk 5 feet wide having a concrete base 3 inches thick composed of one part cement and six parts of gravel and having a wearing coat 1 inch thick composed of one part cement and two parts of sand.