Concrete Volume 8 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916 Excerpt: ... that it is practically impossible to introduce any filler into the seams. Even when this is done the alternate opening and closing of the fracture, due to changes in temperature, lowers and in time destroys the effectiveness of such repairs. On the other hand, joints in concrete lining constitute a weak feature. In strength, durability and watertightness the best formed joint is inferior to the continuous lining. For these reasons, to which may be added that of extra cost, the distance between joints should be as great as possible consistent with changes in volume due to temperature and the adoption of suitable forms and proper methods of construction. When forms are used their length is usually limited to the size and weight which can be readily shifted by hand without the aid of special equipment. Even when the forms are of the simplest kind the methods of construction commonly employed place other limitations on the distance between joints. Again, in lining curves, the frequency of the joints depends upon the degree of curvature, the sharper the curve the shorter the distance between joints. Notwithstanding these limitations, the tendency in the past has been to insert too many joints, particularly on straight portions of canals. The subject of joints in concrete lining is also closely related to the manner in which the lining is laid, whether continuously or in alternate sections. Joints which are adapted to one of these methods may be a misfit when applied to the other. In using either method it is advisable to break joints between the floor and the sides, as indicated in Fig. 2, a. Kinds of Joints--Various kinds of joints are used to prevent cracks in concrete linings: (1) One of the most common is the plain abutting joint. This joint is sim-le, ..