Watertight concrete

This is also based on watertight concrete construction but accepts that some seepage may occur through the external concrete wall. The water is kept away from a separate inner-skin wall by an intervening drained cavity. An internal vapor barrier may be applied to the inner-skin wall to limit humidity, but the cavity may then require ventilation to prevent condensation. 

Damp-proofing admixtures and integral water-proofers are a valuable aid to the achievement of watertight concrete but they are not a substitute for good workmanship. 

The plastic plates and terminals are fitted into cast housings inside concrete columns or in built-up areas, in cable junction boxes installed at walls. Belowground test points should be installed in built-up areas only in exceptional circumstances. In this case watertight, flush-mounted test stations are installed under a street-level covering and can be kept dry only by the most careful construction. 

Although the mix design of latex-modified mortar and concrete is done in much the same way as that of ordinary mortar and concrete, properties such as workability, strength, extendibihty, adhesion, watertightness and chemical resistance are controlled by the polymer-cement ratio rather... 

Improved watertight character of the concrete, to prevent the ingress of water containing sulfate and chloride ions. 

The exterior walls, the basin divider partitions, and the heat-exchanger flume are constructed of concrete block on poured concrete footers. The basin was made watertight by placing prefabricated asphalt matting directly on the soil and on the inside surfaces of the walls of the still. Two-inch-thick Foamglass insulation was placed around the perimeter walls so that the edge heat losses would be comparable to those of much larger stills. 

The production room itself should have a minimum ceiling height of 2.5 m and the floors should be watertight and made from concrete with acid brick tiles or other suitable material. The floors should slope appropriately toward drainage points. The walls should be covered with glazed tiles or other suitable material at a minimum height of 1.7 m and the transition between the floor and wall should... 

At the top of the Cone are verbal symbols which are most abstract and at the base are the direct purposeful experiences which are most concrete form of experiences. This is only a pictorial form where all sorts of aids and experiences are arranged in a Cone. The various bands of the cone representing various experiences and aids, should not be considered as rigid divisions or watertight compartments. They overlap and blend with each other. 

The sub-floor plate was constructed as a reinforced concrete one and was made watertight by special additives according to elaborated research on mortars, injection masses, insulation and the protection against corrosion. 

In the construction area, optimal sealing is often required between hardened and fresh concrete, between two pre-cast concrete elements, etc. The special formulated moisture-reactive sealant offers a watertight construction joint in such applications. In contact with water, the sealant swells within 7 days to more than 100% of its original volume and creates a counter pressure between the surfaces that stops water flow (Fig. 107). 

Precast concrete liners have not yet found great use in the United States, except for the OTtouke block used in a number of tunnels in Detroit. They are not watertight and require a secondary lining. Precast concrete segments were designed for a test section of the Baltimore subway tunnels, but were not competitive with steel liners. 

Where a flooding risk exists, cofferdams/caissons may need to be installed with pumps of suitable capacity. A cofferdam or caisson is a watertight box-like iron structure which is normally sunk in the bed of a river. It is pumped dry and filled with concrete and used in the construction of underwater foundations for structures such as bridges or quay walls. Cofferdams must be inspected by a competent person on the same day as it is used by a worker. A permit to work system may also have to be used. 

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