Bending performance of recycled concrete one-way slabs after pre-soaking in a nano-SiO₂ solution and the subsequent carbonation

Abstract

This study employed a method of strengthening recycled coarse aggregates through pre-soaking in a nano-SiO₂ solution followed by carbonation. The impact of these modified recycled coarse aggregates on the bending performance of one-way recycled concrete slabs was investigated. Five specimens were fabricated and tested, including one one-way natural concrete slab, two one-way recycled concrete slabs, and two one-way slabs with modified recycled coarse aggregate. As a result, the failure of the recycled concrete slabs occurred due to the yield of the longitudinal reinforcement and the maximum crack width at the bottom of the slab, which reached the limit. The maximum load-bearing capacity of the slabs decreased with an increase in the replacement rate of the recycled coarse aggregates. However, one-way slabs containing modified recycled coarse aggregate showed an improvement in the ultimate bearing capacity, with increases of 3.5% and 5.1% when the proportion of modified recycled coarse aggregate used as a replacement was augmented from 50% to 100%. Finally, based on a reasonable material constitutive relationship, a finite element model of one-way slabs under four-point bending was established. The model simulated the loading process of the five types of slabs, further analysing the impact of modified recycled coarse aggregate on the bending performance of the slabs. Moreover, based on the experimental and finite element simulation results, several suggestions were put forward, providing references for similar studies.

Keywords

• recycled coarse aggregate
• carbonation
• pre-soaking in nano-sio2 solution
• one-way slabs
• bending performance