۱٫ Introduction

۲٫ Experiment descriptions

۳٫ Results and discussions

۴٫ Conclusions

Acknowledgment

References

Abstract

This paper evaluates the feasibility of preparing self-compacting concrete (SCC) by incorporating waste concrete recycling materials (WCRMs). Some or all of the natural materials were substituted with WCRMs, such as recycled coarse aggregate (RCA), recycled fine aggregate (RFA) and recycled powder (RP). Nine SCC mixtures were produced, including eight self-compacting recycled concrete mixes and one control mix without WCRMs. The SCC mixes were designed with four different RCA replacement rates (0%, 25%, 50% and 100%) along with a constant amount of RFA (10%) and varying percentages of RP (10% and 20%). The water/binder ratio was designed as 0.4 for all the SCC mixtures. The workability properties (e.g., flowability, viscosity and passing ability) and mechanical properties (e.g., compressive, splitting tensile and flexural strengths) of self-compacting recycled concrete were investigated. The findings indicate that the substitution ratio of WCRMs will affect the workability and mechanical behavior of SCC. This study demonstrates that the decline in the workability and mechanical behavior of self-compacting recycled concrete results from the cooperation of WCRMs. When natural materials are substituted and the amount of WCRMs is limited, the workability of self-compacting recycled concrete can satisfy the European standard EFNARC (2005). Meanwhile, this study also finds that the selfcompacting recycled concrete can achieve acceptable mechanical performance when compared to the ordinary SCC without WCRMs.

Introduction

In recent decades, the construction industry has faced a series of problems, from a shortage of resources, and energy to environmental pollution. These problems include the consumption of natural resources and energy, emission of greenhouse gas (CO2) and the creation of construction and demolition waste (CDW). Recycling CDW is the most promising solution for reducing the adverse environmental impacts in landfills caused by the construction industry. In 2015, 3.9 billion tons of CDW were produced in China, nearly 30% of which was waste concrete (Fu, 2016; Xiao, 2018). Therefore, utilizing waste concrete recycling materials (WCRMs) in engineering will contribute to protecting the environment and capturing the residual value of waste concrete. The WCRMs include recycled coarse aggregate (RCA), recycled fine aggregate (RFA) and recycled powder (RP). Recycled aggregate (RA), consisting of RCA and RFA, refers to aggregate with a diameter of less than 31.5 mm manufactured by crushing waste concrete. RP is a fine particle produced by collecting dust or finely grinding the CDW (Zhu et al., 2019). In recent years, these WCRMs have become widely accepted as alternative recycled materials that can be used in the construction industry.