New Concretes Incorporating Recycled Ceramic Aggregates

摘要

This line of research pretends to analyze the possibility of reusing waste material coming from the ceramic industry in substitution of conventional aggregates when producing structural concrete, with the subsequent economic and environmental benefits. At a first stage the material has been crushed, sieved and washed in order to obtain the proper recycled aggregate (>4 mm). At a second stage, these aggregates have been classified according to their physical - mechanical properties, so that compliance with the EHE-08 could be verified. Results obtained after this process were satisfactory. All requirements contained in the specification were achieved. It was also observed that other properties as porosity and water absorption coefficient were very similar to those of standard aggregates, which represents a significant advantage. Once that the possibility of using this type of material in concrete production was verified, different design mixes for concrete were elaborated by substituting the conventional aggregate partially and progressively by recycled material (20 and then 25%). These concretes were subject to several tests (mechanics, pressured water penetration, microstructural and freeze-unfreeze cycle resistance). Results obtained in the mechanical tests (compressive and splitting tensile strength tests) are higher when using recycled materials. An increase in strength resistance between 5 and 25% has been observed as the percentage of substitution grows. Regarding the study of the microstructure, it has been specially focused on the analysis of the aggregategrout transition area. This analysis concludes that the interfacial transition zone (ITZ) recycled aggregate-grout is smoother and more compact than in the case of uncrushed aggregate-grout. This means that a better behavior of these concretes should be expected against external physical, mechanical and chemical aggressive agents. Finally, the rest of test previously mentioned followed the same trends and therefore recycled concrete can be considered adequate for structural usage.