concrete yield is term used to describe actual volume of freshly mixed concrete form known quantities of ingredients. Usually concrete is sold on volume basis i.e m3 and batched by weight basis.If the mixture proportions for concrete mixtures are not established for the required unit volume or if concrete ingredients are not batched accurately, the combined … Read more
Following field test can be done on cement for quality checks. However if cement satisfy the field tests requirements, does not really indicate that cement is of good quality. This field tests can be perform for quality check purposes for the using cement for less important works such as plastering, block work OR temporary works. For … Read more
Curing of concrete – an introduction Presence of water is important to complete chemical reaction between cement and water. The setting and hardening of concrete largely depends on presence of water for hydration process. While mixing the required quantity of water is generally added to concrete ingredient and theoretically no additional water is required. However water … Read more
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 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
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
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
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