Application of recycled aggregate in sprayed mortar and shotcrete

New uses for concrete waste should be investigated to counter the expected increase in its production due to upcoming construction projects. The developed method should be a high-value recycling method that improves resource diversion and environmental preservation. This study was aimed at expanding concrete waste recycling by investigating the feasibility of using low-quality recycled aggregate from demolished office buildings for sprayed mortar and shotcrete, intended for slope protection and cross-section repair, respectively. Additionally, demolished wood chips were incorporated into the sprayed mortar. The study explored mix proportion base mortar and concrete before spraying (prior to adding the quick-setting admixture); confirmed application conditions; and evaluated fresh properties, spraying conditions, and various performances, including compressive strength, static modulus of elasticity, and accelerated carbonation depth using core specimens. Results confirmed that, with appropriate design considerations for performance degradation, low-quality recycled aggregate could meet the required performance criteria as materials for sprayed mortar and/or shotcrete.