Concrete which has set before it can be placed in the forms should not be tempered or softened with water, but should be discarded.
To prevent delay in placing, all forms should be examined before the mixing is begun to see that they are properly braced, that all chips or loose particles are removed, that the surface of concrete which has set has been properly roughened and wetted to assure a bond, as described on page 20, and that all reinforcement, bolts, inserts, etc., are properly located and secured.
At the lunch' period, or at the end of a day's work, the mixing board and equipment should be thoroughly washed, for if this is not done many pounds of heavy concrete are needlessly carried around by the men and the addition of a pound in the weight of tools will lower the efficiency of the workers. Moreover, it will save time and wear and tear of equipment incident to cutting the surplus concrete away with a cold chisel.
Fig. 14.—1592 Showing result of leaky forms and poor placing. The soft cement mortar ran out, leaving areas of honeycombed surface not necessarily harmful but unsightly.
In depositing concrete in the forms care should be taken that the materials do not separate.
If the mixing is done close to the place of depositing, the concrete may be shoveled into the forms directly or through a chute. If it is necessary to lift or transport the concrete, buckets and wheelbarrows are convenient containers. The concrete should be deposited in horizontal layers, preferably not over 6 inches thick, and a spade or paddle should be worked up and down against the forms to push the coarse material away from the surface, as illustrated in [Figure 13]. The object of the spading is to eliminate impounded air that may form pockets in the mass and to insure a smoother and more impervious surface. In addition to being spaded, stiff concrete should be rammed until water flushes to the surface. Tapping the forms with a hammer is a very effective way of securing a smooth surface. [Figure 14] shows the result of improper spading.