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It is necessary to ensure the properties of recycled aggregate concrete (RAC) can meet the requirements of those for the corresponding natural aggregate concrete (NAC), since only in such cases recycled aggregates (RA) may be accepted for structural use. This study aims to propose a modified design method of RAC based on aggregate gradation readjustment (AGR). It tries to maintain the effective amounts of both the coarse and fine aggregates of RAC similar to that of the NAC after concrete mixing as it is well known that due to the weakness of the old attached mortar to RA, the gradation of the aggregates would be undesirably changed. Two series of concrete mixtures were conducted. One was to examine the variations of the compressive strength and porosity along with the aggregate adjustment ratio using a single RA source; while the other one was used to verify the effect of the proposed AGR method through the investigation of concrete properties made with RAs obtained from different sources. The results show that the proposed method was beneficial to improving all the properties of RAC investigated.

Three-dimensional (3D) printing has recently been introduced into the field of chemistry as an enabling tool employed to perform reactions, but so far, its use has been limited due to material and structural constraints. We have developed a new approach for fabricating 3D catalysts with high-complexity features for chemical reactions via digital light processing printing (DLP). PtO2-WO3 heterogeneous catalysts with complex shapes were directly fabricated from a clear solution, composed of photo-curable organic monomers, photoinitiators, and metallic salts. The 3D-printed catalysts were tested for the hydrogenation of alkynes and nitrobenzene, and displayed excellent reactivity in these catalytic transformations. Furthermore, to demonstrate the versatility of this approach and prove the concept of multifunctional reactors, a tungsten oxide-based tube consisting of three orderly sections containing platinum, rhodium, and palladium was 3D printed.

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