"We Specialize in Cutting Doorways and Windows in Concrete Foundations"
We Service Stow MA and all surrounding Cities & Towns
A pail having a mean inside diameter of 10 inches arid a height of 14 inches is filled with broken stone well shaken down; a similar pail filled with water to a depth of 8 inches is poured into the pail of stone until the water fills up all the cavities and is level with the top of the stone; there is still 21 inches depth of water in the pail. This means that a depth of 5 inches has been used to fill up the voids. The area of a 10-inch circle is 78.54 square inches and therefore the volume of the broken stone was 78.54 X 14 = 1,099.56 cubic inches. The volume of the water used to fill the pail was 78.54 x 5.75, or 451.6 cubic inches. This is 41 percent of the volume of the stone, and is in this case the percentage of voids. The accuracy of the above computation depends largely on the accuracy of the measurement of the mean inside diameter of the pail. If the pail were truly cylindrical, there would be no inaccuracy. If the pail is flaring, the inaccuracy might be considerable; and if a precise value is desired, more accurate methods should be chosen to measure the volume of the stone and of the water.
It is invariably found that unscreened stone or the run of the crusher has a far less percentage of voids than screened stone, and it is therefore not only an extra expense, but also an injury to the concrete, to specify that broken stone shall be screened before being used in concrete, unless, as described later, it is intended to mix definite proportions of several sizes of carefully screened broken stone. Since the proportion of large and small particles in the run of the crusher depends considerably upon the character of the stone which is being broken up, and perhaps to some extent on the crusher itself, these proportions should be tested at frequent intervals during the progress of the work; and the amount of sand to be added to make a good concrete should be determined by trial tests, so that the resulting percentage of voids shall be as small as it is practicable to make it. It is usually found that the percentage of voids in crusher-run granite is a little larger than in limestone or gravel. This gives a slight advantage to the limestone and gravel, which tends to compensate for the weakness of the limestone and the rounded corners of the gravel. Broken stone is frequently sold by the ton, instead of by the cubic yard; but as its weight varies from 2,200 to 3,200 pounds per cubic yard, an engineer or contractor is uncertain as to how many cubic yards he is buying or how much it costs him per cubic yard, unless he is able to test the particular stone and obtain an average figure as to its weight per unit of volume. Cinders for concrete should be free from coal or soot.
Usually a better mixture can be obtained by screening the fine stuff from the cinders and then mixing in a larger proportion of sand, than by using unscreened material, although, if the fine stuff is uniformly distributed through the mass, it may be used without screening, and a less proportion of sand used. As shown later, the strength of cinder concrete is far less than that of stone concrete; and on this account it cannot be used where high compressive values are necessary. But on account of its very low cost compared with broken stone, especially under some conditions, it is used quite commonly for roofs, etc., on which the loads are comparatively small. One possible objection to the use of cinders lies in the fact that they frequently contain sulfur and other chemicals which may produce corrosion of the reinforcing steel. In any structure where the strength of the concrete is a matter of importance, cinders should not be used without a thorough inspection, and even then the unit compressive values allowed should be at a very low figure.
Cutting and/or enlarging door, window and bulkhead openings in concrete foundations.
Cutting 1" to 24" diameter perfectly round core holes for electrical, plumbing or vents in concrete floors and foundations.
Cutting and dicing concrete floors, concrete walkways, concrete patios or concrete pool decks for easy removal and/or neat patching.
Cutting trenches in concrete floors for plumbing, electrical, sump pumps, French drains or other utilities.
We cut and remove concrete, stone or masonry walls, floors, walkways, patios and stairs.