Design of a non-shrinking silica fume high-performance concrete with recycled ceramic tile aggregate

Internal curing (IC) process introduced via a water-entraining agent using lightweight and porous aggregate has become an essential component in designing high and ultra-high-performance concrete (HPC/UHPC). This paper presents experimental results demonstrating the effectiveness of using recycled ceramic tile aggregates (RCTA) derived from waste ceramic tiles as an IC agent for high-performance structural elements. Previous studies by the author have confirmed the efficiency of both the pre-saturated recycled porous ceramic coarse aggregate (RPCA) as an IC and shrinkage compensating agents in mitigating autogenous shrinkage and the induced internal self-stress in HPC mixtures. The main objective of this study is to investigate the effect of two different curing systems (internal curing using the waste ceramic aggregate combined with shrinkage compensating agents) on silica fume (SF) HPC behavior. The shrinkage compensating agents include a combination of shrinkage-reducing agent (R) and expansive additive (E). The influence of this combined ternary curing system on the mechanical properties, including compressive, flexural, and splitting tensile strengths, modulus of elasticity, autogenous shrinkage, and internal self-induced tensile stress, were investigated. The obtained results indicate a substantial reduction in the autogenous shrinkage strains magnitude and, consequently, the internal self-induced tensile stress in the HPC mixtures designed with these two curing systems. It was also found that this combination of the two curing systems resulting in a hybrid curing system, performs much better than the single incorporation of shrinkage-compensating agents. Besides, a long-term strengths improvement was recorded for mixtures designed with the RPCA. Incorporating recycled aggregate in the design and production of HPC could further promote concrete sustainability by reducing the amount of virgin extracted non-renewable minerals, reducing the energy required to extract and process natural aggregates and the CO₂ generated, and also reducing solid waste materials disposal.