Pre-cast concrete

Figure4.9 Standard pipe installations for water sluice valve up to 10 inches or 250 millimeter diameter. Notes (1) If a valve extension spindle is required, a galvanized centering support must be provided. (2) Flanged valves with appropriate adapters must be used. (3) Unless otherwise directed, pre-cast concrete units shall be bedded on well-compacted granular material Type A brought up from the base of the trench...

Figure4.10 Standard pipe installations for a double air valve. Note Unless otherwise directed, pre-cast concrete units shall be bedded on well-compacted granular material Type A brought up from the base of the trench.

Figure 4.15 Pre-cast concrete indicator and marker posts...

Example 26.1 A building wall is made up of pre-cast concrete panels 40mm thick, lined with 50mm insulation and 12mm plasterboard. The inside resistance is 0.3 (m K)/ W and the outside resistance 0.07 (m K)/ W. What is the 1/ factor ... 

OTHER COMMENTS used in the manufacture of mortars for building blocks, bricks, stone and pre-cast items also used as a moisture sealant for exterior of concrete blocks used in concrete on highway paving, domestic and commercial building construction, and in pre-cast concrete articles useful in light-weight concrete, terrazzo, stucco, asbestos cement products, interior surfaces, and exterior surfaces. 

In recent years, epoxy resin systems have been utilized for special applications on the exteriors of buildings. One of these systems involves the use of an epoxy plaster, which is troweled onto the surface of an exposed wall, into which are set stone aggregates. This surfacing resembles a pre-cast concrete panel with an exposed aggregate facing. This method is utilized, not only in new construction, but in re-surfacing deteriorated areas. 

Pre-cast concrete has achieved a recognized position in the construction industry. Quite often, it is necessary to provide a decorative surface to these panels. Ti common method is to produce an exposed aggregate finish. Many architects now specify concrete panels having a veneer of marble, granite, limestone or other decorative natural stone. These veneers are applied in sections no thicker than 3/4 inch. Epoxy adhesives are used to bond the concrete to the veneer. 

Recogriising the need to improve the standard of w aste w ater treatment, Techrete, a major pre-cast concrete manufacturer... 

A total of 11 machines is used for heading, 6 on the British side and S on the French side. Both railway tunnels in a distance of 15 m each from a central service tunnel of 4.8 m diameter are headed with a diameter of 7.6 m. Pre-cast concrete or cast-iron segmental linings are installed immediately behind the excavation. 

Uses Hydrophobing agent, water repellent for masonry, primers for min. substrates, facade impregnations based on styrene-acrylic, acrylic, and other polymer emulsions (concrete, artificial limestone pre-cast concrete, roadways, and bridges... 

Epoxy sensitivity has been observed with relatively high frequency. Bricklayers and workers engaged in pre-cast concrete building component factories are exposed to products containing epoxy resins (van Putten et al. 1984 Avnstorp 1992 Conde-Salazar et al. 

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). 

Siporex. Trade-name A lightweight (0.5 kg/1) pre-cast concrete made from Portland cement, fine sand, A1 powder and water. The set aerated blocks are autoclaved. (Costain Concrete Co. Ltd., London.)... 

British Standards Institution (BSI). BS 2028 1968. Pre-cast concrete masonry units. Specification for pre-cast concrete masomy units. BSI, London, 1968. 

The handling of kerb stones is one of the main causes of back problems and other musculoskeletal disorders. Standard kerb stones weigh approximately 67 kg and are made of pre-cast concrete. Thus the main hazards associated with the manual handling of kerb stones are the weight of the stones, unsuitable body posture and the frequency and repetitive nature of the work. The risk, therefore, of injury to workers who lay kerb stones by hand is high and employers must address all three hazards. HSE recommends a hierarchy of control measures in their information sheet, CIS No 57, as follows ... 

Typical Use Fixing steel fixtures (inserts) into concrete. Pre-cast concrete elements. External reinforcements. Repair of honeycombed ... 

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