Reusing waste clay brick powder for low-carbon cement concrete and alkali-activated concrete: A critical review

The utilization of the waste clay brick powder (CBP) as an alternative binder in cementitious materials is an effective approach to recycling clay brick waste. Many research articles have been published on concrete containing CBP, but a systematic review on the performance of CBP and its blended concrete has been lacking until now. Therefore, the purpose of this article is to provide a comprehensive review of the utilization of CBP for low-carbon cement concrete and alkali-activated concrete, offering readers an effective pathway to understand its performance. This review article provides a detailed introduction on the preparation technology of CBP, as well as the micro-macro properties of cement concrete and alkali-activated concrete incorporating CBP. The results showed that CBP with irregular micro-structure is rich in silicon, aluminum, and oxygen elements, and exhibits good pozzolanic activity and micro-aggregate filling effect. Optimizing CBP particle size, replacement rate and curing condition can prepare the cement concrete with good micro-macro properties. Besides, there is an optimal CBP replacement rate, alkali concentration, Na/Si and Si/Al molar ratios for the alkali-activated concrete containing CBP. The mix of CBP in concrete obviously reduces the CO2 emission and energy consumption, showing an excellent environmental benefit. The mechanical activation treatment, active admixture and nano-particle modification can improve the properties of CBP blended concrete. In the future, CBP can be widely used in 3D printed concrete, high performance and ultra-high-performance concrete, lightweight concrete, fully recycled concrete and CO2 sequestration concrete.