Recycling aggregate from concrete, properties and possibility for using in ready Mix Concrete

Abstract

Many requests for different types of concrete, in general are depends of the aggregates. One of the aim of this paper is to analyses the possibilities of using the recycling aggregate, from part of existing concrete such a raw materials and during the technological process for production of aggregate. Recycling of concrete is a relatively simple process. It involves breaking, removing, and crushing existing concrete into a material with a specified size and quality. In this paper the main target is to compare the properties of fresh concrete and the hardening concrete for the mix design with crashed aggregate and recycling aggregate from parts of concrete after the demolition process.Nowadays large amount of demolished concrete are available on construction sites which are now posing a serious problem for transport in urban areas. Day by day this amount is larger and the reasons are that:- Many old buildings, concrete sidewalks, bridges and other structures have exceeded their age limit use due to structural deterioration.- Other possible structures for use are in ruin, because they are not serving the needs of today's society.- Structures have become waste resulting from natural disasters like cyclones, earthquakes,floods etc.As a result of greater demand for concrete, taking into account the fact that aggregate isthe component with the largest participation in concrete. Decreasing the source of natural aggregate we should explore the use of recycled aggregate. Recycled aggregate has goodquality especially in resistance to pressure when the content of brick is not more than 0.5%, it presents the potential for use in a wide range of applications, for the case when it meets the test and performance requirements. However the quality of the concrete which is made with recycled aggregate is lower compared to concrete which is made with natural aggregate.Nowadays, the application of recycled aggregate in construction areas is extensive. It's application is different from country to country, in the sense that each state sets the criteriafor use depending on it's quality.Based on the experience of use, recycled aggregate can be used for: production of concrete, in concrete roads, for production of concrete domes, as padding of the embankment,for construction of pipes, production of concrete blocks etc. Almost in all cases where natural aggregate is used.Based on laboratory analysis Recycled aggregate compared with natural aggregate: absorbsmore water, it has less density in many cases, it has lower specific weight, lower resistance to abrasion, it's more easily to destroy it, it contains more dust particles etc. Due to these results to gain the desired work ability of concrete obtained from the recycled aggregate is necessaryto add a certain amount of water to saturate recycled aggregate before or during mixing with other ingredients of concrete, if not previously used any additional reducing the rate of water absorption. On the other hand it is very important to use the concrete with recycling aggregate for the concrete which offer very good properties in thermo insulation, such a very important request in efficiency of energy.