Fig. 294.—Diagram Illustrating Details of Mold Construction.
Fig. 295.—Example of Poor Wall Form Construction.
This matter of making provision for the swelling of the forms is another point to be watched. Referring again to Fig. 294 it will be seen that the swelling of the lagging, even if the cornice instead of being under cut at A were straight cut on the line c d, is liable so to crowd the lagging into the corner A and B that the concrete is cracked along the lines e f or g h. A suggested remedy for this danger is shown by Fig. 296. At a distance of every 3 or 4 ft. insert a narrow piece of lagging a and behind these lagging strips cut notches b in the studs. When the concrete has got its initial set pull back the lagging strip a into the notches b, leaving an open joint to provide for expansion due to swelling.
Fig. 296.—Notched Studding for Removal of Lagging Board to Permit Swelling.
Fig. 297.—Form for Concrete Facade Shown by Fig. 298.
Fig. 298.—Concrete Facade for Plate Girder Bridge.