The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique.

The use of construction and demolition waste in concrete manufacture allows the concept of sustainability to be included in the construction industry and helps to alleviate both the large consumption of natural resources and the high generation of waste. The present research assesses first the suitability of two different mixed recycled aggregates as coarse aggregates for concrete according to the code on structural concrete (EHE-08), and subsequently evaluates the effect of their use as a partial (50%) replacement of natural coarse aggregate (gravel) on the mechanical properties (compressive strength, splitting-tensile strength, flexural strength, stress–strain curves and modulus of elasticity) in concrete mixes of 25 MPa strength grade. The secondary material characterisation shows that, although presenting promising properties in terms of granulometry, particle size, density and shape, the recycled aggregates should be pretreated in order to comply with the quality of fines and water absorption, and their resistance to fragmentation limits their application in concrete mixes with a strength grade below 30 MPa. Regarding the results of the tests performed on the hardened concrete, the values obtained suggest that the use of mixed recycled aggregates is feasible, but at the expense of minor losses of the mechanical characteristics.

The construction sector comprises a number of activities that may result in environmental impacts of considerable magnitude, waste generation being one of the major negative effects of this industry due to the large streams generated. Proper knowledge of the environmental problem caused by the sector is of great importance in order to achieve an effective waste management. Thus, this paper analyse the Spanish situation regarding construction and demolition waste (CDW) compared with other European Union countries; which sets out the current figures of the CDW scenario (legislation, generation, composition, treatment and market) as well as the difficulties encountered when handling this residue.

The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.