A Study of Concrete Made with Fine and Coarse Aggregates Recycled from Fresh Concrete Waste

This paper deals with the possibility of using fresh concrete waste as recycled aggregates in concrete. An experimental program based on two variables (proportion of fine aggregates replacement and proportion of coarse aggregates replacement) was implemented. The proportions of replacement were 0%, 50%, and 100% by mass of aggregates. Several mechanical properties were tested as compressive and tensile strengths. The results show a good correlation between aggregates replacement percentage and concrete properties. Concerning mechanical properties, a gradual decrease in compressive, splitting, and flexural strengthn with the increase in recycled aggregate percentage is shown. 1. Introduction The intensive use of aggregates in constructions is a very important environmental concern. In the region of Aquitaine in France, the availability of aggregates becomes a serious problem. In order to reduce the use of natural aggregates for natural resources and energy preservation, the use of recycled aggregates in concretes is an interesting solution. Numerous studies show the potential of recycling aggregates such as ceramics [1], rubber [2, 3], glass [4], and demolition wastes (bricks and concrete). Due to the high amount of concrete from demolition wastes, this material was studied as substitution of natural aggregates by several authors [5–8]. However, these aggregates are highly porous, and contain a high amount of impurities [8, 9]. Limited studies were conducted on the potential of fresh concrete waste (FCW). These aggregates are mainly composed of overordered fresh concrete. The advantage of this waste is that it contains limited amount of impurities in comparison with other recycled aggregates. Every day, a concrete batching plant receives from several construction sites a huge amount of overordered fresh concrete. This is caused mainly by the uncertainty in the exact quantity of the required concrete for construction projects. In France, 2.6 million tons of fresh concrete is considered as waste and should be recycled. Currently, the practice of managing overordered fresh concrete is to use it in road or to dump it into landfill, which is considered as a nonbenefit solution. Moreover it will be of high cost in the close future because of the saturation of landfill areas [10]. Recycling this material is of particular interest because its use can considerably reduce the problem of waste storage, and simultaneously it helps in the preservation of natural aggregate resources. Recent successful studies on the use of FCW as aggregates in concrete have been