SME archive recycling
Regarding the limit value for the rate of incorporation of recycled aggregates, it may be higher than those indicated in standard NF EN 206/CN:2014 for type 1 and 2 gravel, and for recycled sand "presenting an absorption of limited water". It will depend on the exposure class of the concrete and the Eeff/Lequi ratio. Recybéton adds: " These limit values will be valid regardless of the compressive strength of the concreteIt should be noted that the concrete obtained will present lower performance in certain aspects: potentially stronger absorption and humidity, lower resistance to attrition and fragmentation. récupération de béton The use of recycled aggregates will also require some adjustments in the manufacturing process. , such as the storage of additional cuts or the use of pre-mixers.For the development of formulations , the experts recommend applying the usual general approach, while taking greater safety margins, and checking certain properties (elastic modulus, tensile strength, shrinkage, creep).The adjustment of the effective water must be made according to the proportion of recycled aggregates and the nature of the new aggregates. When placing concrete , specialists recommend that the density be checked at the same time as the compressive strength. For higher recycling rates, “ project-critical mechanical properties will also need to be monitored by an appropriate program .” The delivery note for the ready-to-use material must mention the substitution rate adopted. On the dimensioning of the worksin reinforced concrete or prestressed concrete, the Recybéton players plan to use the current calculation rules defined in Eurocode 2 when the rate of incorporation is low, then to set up certain models on a flat-rate basis for intermediate rates. Finally, for the highest dosages, it will be wise to set up procedures limiting the variability of the critical properties of the concrete and to control them experimentally. In order to enhance the eco-friendly nature of recycled aggregate concrete, Recybéton suggests that life cycle analysis (LCA) be carried out according to the EN 15804/CN standard using validated data from the sector, pending the publication of rules and requirements described in the Product Category Rules. This LCA will be supplemented by the evaluation of other impact indicators: savings in natural aggregates, increase in the recycled share of the waste generated by deconstruction, etc. The transport aspect of materials must be taken into account. Finally, regarding the complete insurability of materials, the sector notes: "For the works company, the use of concrete containing recycled aggregates falls within the scope of the compulsory ten-year insurance linked to certain structures. It should be noted that the use of concrete containing recycled aggregates beyond the practices recognized as common techniques absolutely requires the prior information of the insurer .