27-08-2014, 12:29 PM
Concrete is the basic engineering material used in most of the civil engineering structures, it is the premier construction material used widely across the world in most types of engineering works. According to research, concrete stands second to water on volume consumption basis Concrete is a composite material made up of cement, fine aggregates, coarse aggregates and water mixed in desired proportion based on strength requirement. Concrete solidifies and hardens after mixing with water and placement due to a chemical process known as hydration. The water reacts with the cement, which binds the other components together, eventually creating a robust stone-like material. Concrete is used more than any other man-made material in the world. Concrete like other engineering materials needs to be designed for properties like strength, durability and workability. Concrete mix design is the science of deciding relative proportions of ingredients of concrete, to achieve the desired properties of concrete. Use of mineral admixtures like fly ash, slag, metakaolin and steel fibre have revolutio
Now a day, construction and demolition industry is one of the country’s largest waste producers. The waste produced by demolition can be minimized and could be utilized again. Concrete recycling is an increasingly common method of disposing of dismantled concrete structures which was once routinely shipped to landfills for disposal. But recycling is now increasing due to improved environmental awareness, government laws and economic benefits. In India, about 14.5 MT of solid wastes are generated annually from construction industries, which include waste sand, gravel, bitumen concrete bricks, masonry, & concrete. However, some quantity of such waste material is being recycled and utilized in building materials. Most of the waste materials produced by demolished structures disposed of by dumping them in land fill. Dumping of wastes on land is causing shortage of dumping place in urban areas. Therefore, it is necessary to start recycling and re-use of demolition concrete waste to save environment. Concrete recycling gains importance because it protects natural resources and eliminates the need for disposal by using the readily available concrete as an aggregate source for new concrete or other applications. Large-scale recycling of demolished concrete will help conserve natural resources, and solve a growing waste-disposal crisis. The future for recycled aggregates will be driven by reduced landfill availability, greater product acceptance, continuing government recycling mandates, and the continuing decay of a large stock of existing infrastructure, as well.concrete as is well known is a heterogeneous mix of cement, water and aggregates. The admixtures may be added in concrete in order to enhance some of the properties desired specially. In its simplest form, concrete is a mixture of paste and aggregates. Various materials are added such as fly ash, silica fumes, admixture and with using steel fiber to obtain concrete of desired property. The character of the concrete is determined by quality of the paste. The key to achieving a strong, durable concrete rests in the careful proportioning, mixing and compacting of the ingredients. The detailed experimental investigation is doing to study the effect of partial replacement of cement by FA and SF with using Steel fiber in concrete. Numerous tests are performed on wet concrete such as workability tests such as compaction factor test and slump test. The tests on hardened concrete are destructive test while the destructive test includes compressive test on concrete cube for size (150 x 150 x 150) mm,In actual practice, test on workability of wet concrete are carried out to ensure uniform quality concrete only. Strength is not a measurable at that stage with the available technology. Therefore the concrete samples are to be cured for 28 days in normal method to arrive at the compressive strength and for necessary follow up action. It is not only difficult to dismantle the suspected portion of concrete at such a stage but also expensive in terms of time and money. Predicting the strength at the manufacturing stage, however, is yet to receive due attention of engineers.
Objective
To study the workability property of fresh concrete.
To study the compressive strength property of the hardened concrete