And Creative Industries

Recycling is the process by which previously used materials are utilized in producing new products. Finding natural materials for used in construction is getting more and more difficult worldwide. In order to reduce the dependent on natural aggregates (NA) in concrete making recycled aggregates (RA) from demolished structures and roads can be utilized as an alternative if tests proved it is suitability for concrete. Recycled aggregates: Are graded and inorganic aggregates produced by crushing construction and demolition waste (C&DW). Demolished road slabs, concrete and masonry structures are the main sources of this type of aggregates. These are usually demolished due to age, for renovation purposes or in some cases because of wars or naturally disasters like earthquakes. Because of the advances in the manufacturing of stationary and mobile crushing machines and the recycling processes by screening and separation, it has become possible, at accepted cost, to process large quantities of C&DW into crushed graded small sized coarse and fine aggregates suitable for civil engineering infrastructures. Fly ash (FA): Is a by-product resulted from burning coal to produce electricity. Two classifications of FA are produced depending on the type of coal used. Anthracite known as Class C and bituminous coal produces FA classified as Class F (also known as low calcium FA). Fly ash is produced in large quantities worldwide, but unfortunately around 75% is dumped in landfill sites or used for law value applications (Malhotra, 1989). HIGH-STRENGTH CONCRETE (HSC): HSC Is a high performance concrete (HPC) with a high compressive strength, high stiffness and excellent durability. HSC concretes are produced with aid of superplasticizers. The present poor quality concrete, made with a water cement ratio of 0.6 or more, will cease to be used structurally and HPC and ordinary concrete will merge into simply a good quality concrete which will serve the world for a long time to come (Neville. A.M, 2003) . 1. ADVANTAGES OF RECYCLING The advantages of recycling are summarised as follows: RA and FA should be utilised for environmental and technical and economical reasons. The data published by the Office for National Statistics (ONS, 2005) shows that the UK generated an estimated 333 million tonnes of waste. C&DW accounted for 107.5 million tonnes chart (Figure 1) shows the estimated annual waste arisings by sectors in the UK. The chart indicates that more than 60%of the waste materials are generated from construction and mining activities.