Please note! This essay has been submitted by a student.
Recently, the tests regarding use of concrete with recycled aggregates (RAC) presented in different countries were concentrated on properties of material. Very few tests were prepared on structural reinforced-concrete members made of such kinds of concrete. Such tests are essential because it is difficult to predict the influence of differences in particular properties on the overall behaviour of reinforced concrete members made of various mixtures of recycled aggregate concrete. The purpose of the tests presented in the report was to govern differences in behaviour of simple reinforced concrete members made of RAC in comparison with members made of normal concrete with natural aggregate. On the basis of before material tests ten series of beams have been selected for tests. Flexural performance by taking partial replacement of Natural Coarse Aggregate (NCA) with Recycled Coarse Aggregate (RCA) at 0%, 30%, 50%, 70% and 100%. Full scale test were performed on ten simply supported beams having two point load at L/3 from the face of the support until the failure load had reached. In general, the comparison of the results showed related bearing capacity of members in the series, and significantly greater deformations of concrete in members with recycled aggregate concrete.
Aggregate is one of the main elements in making concrete, it covers 75% of the total for any concrete mix. The strength of concrete produced is dependent on properties of aggregates used. Recent data showed that the increasing demand of construction aggregate reach to 48.3 billion metric tons by 2015 with maximum consumptions in Asia and Pacific. Due to greater demand for new buildings, the demolition of old buildings would occur which would cause large amount of construction and demolition waste. The most common way of disposal to the construction and demolition waste is landfill. Without proper sorting and treatment of it, as the time passes landfill cause many environmental problems such as air and water pollution. The constant mining and use of resources is causing lack, hence resource scarcity and environmental issues caused by this waste made each country to start thinking about a sustainable path to achieve both economic and social win situation.
In order to achieve this goal, the process of recycling concrete waste was initiated. Recycling is the act of processing the used material in making new product. Recycled aggregates contained of crushed, graded inorganic particles processed from materials that have been used in construction. The materials are generally from buildings, roads, bridges, and sometimes even from disasters such as wars, floods and earthquakes. Of course, recycling of waste concrete is not the aim in itself, it representing a new technology of waste processing that has potentially environmental and economic advantage Hence keeping concrete debris out of landfills, saves space of landfill sites. Also, recycling concrete drags down the cost for buying raw materials and transporting waste to landfill sites. Conservation of natural resources by reducing the need for gravel mining.
In third world countries like Pakistan, most of construction organizations do not have the purchasing power of buying expensive recycling equipment. Therefore, techniques are proposed to be developed and research institutes should be organized in this context. It is also observed that due to lack of research skill, most of the construction organization are uninformed of these techniques. To cope up with this problem, Government and research organizations should hold seminars and workshops on regular basis involving construction organizations. Government is advised to stop the construction organizations involved in dumping of the construction waste in open atmosphere. Instead disposing off the waste must be regulated, especially when construction sites are producing toxic wastes, e.g. asbestos. Further transport of hazardous materials for disposing off should be properly carried out by the companies having a permit or license obtained from an environmental protection agency.