Zhong, Zhen, Tao, Pan, Zhang, Hao, Jin, Huijun, Lou, Rong, Cui, Yuhang, Huang, Qian, and Liu, Jie
Rapid urbanizations impose increasing challenges on safety decompositions of those buildings that reached service life, so there is an urgent call for eco-friendly demolition methods. As a green demolition method, the technique of soundless cracking demolition agents (SCDAs) can effectively eliminate dust and noise pollution commonly encountered in conventional methods, and thus attract rising attention in light of increasing concerns for sustainable and low-carbon developments. Herein, this paper provides a state-of-art review of SCDAs and associated applications. SCDA, a powdery material, mainly consists of quicklime (CaO), which tends to expand significantly when mixed with water. The expansion properties of SCDAs are susceptible to internal and external factors, such as compositions, ambient temperature, mixing water temperature, and water/cement (W/C) ratio, restraint conditions, among others. Therefore, substantial efforts have been made to improve the expansion performance of SCDAs by regulating the abovementioned factors. The resulting expansion force from SCDA expansion can effectively crack brittle materials, e.g., concrete and rocks, the cracking process of which can be measured using strain gauges and Acoustic Emission (AE). More recently, digital image correlation and computed tomography have been employed to monitor the SCDA-induced cracking process, and the implementation of those new techniques promotes the observations of crack developments and underlying mechanisms. To gain a cost-effective application of SCDAs, extensive efforts have been undertaken to optimize the design in hole parameters. Accordingly, several empirical equations have been proposed for determinations of optimal hole parameters, but the application of the equations is restricted to particular conditions where they are proposed. Despite the successful usage of the SCDA technique in demolitions of construction structures, mining, unconventional gas and oil recovery, some limitations, namely hard rock fragmentation, precise numerical works and blowout, still need to be addressed for further applications. Overall, this paper gives a brief review of SCDAs, covering scopes of compositions, expansion properties, applications, inadequacies and prospects, deepening our understanding of SCDAs, and providing recommendations for future research priorities. • Factors influencing the expansion characteristics of SCDAs are analyzed. • Some new technologies for observing the process of crack development are presented. • The optimum usage of SCDA related to the hole design parameters is summarized. • Further work in the research and application of SCDA is proposed. [ABSTRACT FROM AUTHOR]