Specifications for Waterproofing Floors of Steel and Concrete Bridges

The solid bituminous cements are made in varying degrees of melting point, penetrative power, etc., to meet varying conditions. They are claimed to be especially adaptable to work in which there is danger of settlement, heavy vibration, contraction, and expansion. Their method of application is, in principle, that of enclosing the structure in a continuous, elastic, waterproof membrane composed of layers of fibrous felt or burlap cemented together with the bituminous product.

The floor finish, applied like paint, is claimed to prevent the continual formation of dust, and to protect concrete floors from staining.

The liquid waterproofing is a transparent waterproofing applied with a brush. It is adapted to interior or exterior surfaces whose physical appearance is desired to be left unchanged.

The foundation black is a heavy hydrocarbon coating for foundation work. It is applied cold, and is claimed to be effective under severe pres sure conditions.

Protective Paints and Finishes.

Simul taneously with the extended use of cement and concrete in construction, there has arisen the problem of specially prepared finishing mate rials. Most of the large paint manufacturing houses have attacked the problem, and in some cases have placed their products on the market under special names, such as S-W Concrete and Cement Weather-Proof Coating, a clear liquid, which, it is claimed, without weakening the bond of the cement, seals up and damp-proofs the porous surfaces and affords a satisfactory ground for the application of subsequent coats of paint; S-W Concrete and Cement Finish, a paste-like compound furnished in various colors, to be thinned for use with raw linseed oil and turpentine; Duck Brand Weather-Proof Colors, for stone or concrete, which penetrate the sur face to a depth of about one-quarter inch and are claimed to serve as an efficient waterproof filler and an artistic finish combined, etc. De scriptive literature regarding any special fin ishes on the market is furnished by their pro prietors on application.

Waterproofing a Problem of Design.

The special method of waterproofing a concrete building of any class should be considered in the original design of the structure. To post pone consideration of such necessary details as provision against dampness, or the method of applying the plaster to smooth interior surfaces, until the structural walls are in place, is to invite extremely annoying and costly conse quences.

Some interesting side lights on this aspect of the waterproofing problem are found in the following extracts from an article in the "Ce ment World," relating to the case of a very large reinforced structure.

The walls and floors of the building having been erected, and the time having arrived for interior plas tering, it became imperative to decide upon some method of applying the plaster to the smooth interior of the concrete walls, and at the same time provide against the penetration of dampness from the outside walls to the plaster, and the injurious, sometimes disastrous, conse quences that result from damp walls.

The owner and contractor of the building had in mind the application of a damp-proof compound to the interior of the wall, and the application of the plaster directly upon the surface so treated.

This method has been employed in a large number of brick buildings with very successful results, and, although it is of comparatively recent origin, it is taking the place of furring and lathing to a considerable degree, owing to its efficiency, cheapness, and ease of application. While extensive experience has demonstrated that this method is successful in the case of brick and stone walls, the fact should not be overlooked that the conditions in the case of a smooth concrete wall free from mortar joints are somewhat different, and waterproofing contractors are too prone to guarantee that the bond between the damp-proofing and concrete and that between the plaster and the damp-proofing will be permanent. While some work of this kind has given satisfactory results for short periods of time, the experience has not been altogether uniform, nor sufficiently convincing to warrant the fur nishing of a guarantee that no separation of the plaster will take place in the course of several years.

Whether the porosity of the brickwork or the un evenness of surface created by the mortar joints is the principal element that produces an efficient adhesion of the plaster to the waterproof film, is still a disputed question, but such adhesion in the case of brick walls is beyond dispute. The lack of sufficient experience in case of the dense and opaque concrete walls placed the builder of the structure above referred to under the necessity of adopting this method of damp-proofing at his own risk, or of adopting some other method of damp proofing and plastering the building. Some of the other methods available were : 1. The use of metal furring against the concrete.