Concrete Pouring in Hot Air and Cold Weather

Abstract Concrete production and placement in hot air and cold water and the various problems that emerge in the concrete cure may affect the strength and durability of concrete adversely. In this article presented, various points to be considered and some actions that can be taken while pouring concrete in hot air and cold weather … Read more

Quality Control When Pouring Concrete in Hot Weather

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Quality Control in Hot Weather As you have discovered, during hot weather temperature is not the only hindrance to quality concrete. We have to be very concerned with relative humidity and wind velocity. In order to establish good quality control procedure, we need to know when the conditions are detrimental to the production of quality … Read more

Methods of Prestressing

There are two methods of prestressing: • Pre-tensioning: Apply prestress to steel strands before casting concrete; • Post-tensioning: Apply prestress to steel tendons after casting concrete. Pre-tensioning This is the most common form for precast sections. In Stage 1 the wires or strands are stressed; in Stage 2 the concrete is cast around the stressed … Read more

Basic Principle of Prestressing

The classic everyday example of prestressing is this:  A row of books can be lifted by squeezing the ends together: The structural explanation is that the row of books has zero tensile capacity. Therefore the ‘beam’ of books cannot even carry its self weight. To overcome this we provide an external initial stress (the prestress) which compresses the books together. Now they can only separate if the tensile stress induced by the self weight … Read more

Suggestions for Design

Economy of concrete structures begins in the design development stage with designers who have a good understanding of formwork logic. Often, two or more structural alternatives will meet the design objective equally well. However, one alternative may be significantly less expensive to build. Constructability, that is, making structural frames faster, simpler, and less costly to … Read more