Sustainable synthesis of soundless chemical demolition agents from industrial by-products for non-explosive rock fracturing

Abstract

Blasting remains the dominant rock fracturing method, yet its use is increasingly constrained by safety and environmental concerns. Soundless chemical demolition agents (SCDAs) offer a non-explosive alternative, yet conventional products are costly, rely on non-renewable raw materials, and require long fracturing times. Here, this study explored the use of two industrial wastes, calcium carbide residue (CCR) and drinking water sludge (DWS), to synthesize sustainable SCDAs (CCR-DWS SCDAs). CCR, which is rich in Ca-bearing phases, served as the precursor for CaO, the primary expansive component, whereas DWS provided Al-, Fe-, and S-bearing constituents that helped regulate the reaction process and improved the expansion performance. Results demonstrated that the optimal formulation (6% DWS and 30% water content) reached 37.11±1.42 MPa at 4 h and 50.45±2.55 MPa at 24 h, outperforming four commercial SCDAs. Microstructural characterization identified portlandite as the dominant phase responsible for crystallization-induced expansion. An appropriate DWS addition enhanced the expansive pressure by regulating the hydration kinetics, whereas excessive DWS suppressed the hydration reaction and impaired pressure development. Granite fracturing experiments further confirmed the superior efficiency, showing that the optimal CCR-DWS SCDA achieved crack penetration much earlier, within only 1.4 h at a borehole diameter-to-side length ratio of 1:5 and 8.8 h at 1:10, compared with 10.8 h and 18.8 h for the commercial SCDA. Fracture-surface characterization further revealed that the higher loading rate induced by the CCR-DWS SCDA produced smoother macroscopic fracture planes, supporting more controlled and predictable directional fracture propagation. Overall, this work establishes a waste-to-performance pathway for producing high-efficiency SCDAs with clear sustainability and engineering benefits.

Keywords

Non-explosive rock fracturing / Drinking water sludge / Calcium carbide residue / Soundless chemical demolition agents

References

[1] Tian YY, Tsendbazar NE, van Leeuwen E, Fensholt R, Herold M. A global analysis of multifaceted urbanization patterns using Earth Observation data from 1975 to 2015. Landsc Urban Plan 2022; 219:104316.

[2] Al—Bakri A, Hefni M. A review of some nonexplosive alternative methods to conventional rock blasting. Open Geosci 2021; 13(1):431—42.

[3] De Silva R, Pathegama Gamage R, Anne PM. An alternative to conventional rock fragmentation methods using SCDA: a review. Energies 2016; 9(11):958.

[4] Hao C, Dong L, Fan F, Li X, Ma J, Zhang Y. Tensile—shear collaborative fracturing in hard rock induced by a controllable free surface: Mechanism and application. Int J Min Sci Technol 2026; 36(4):725—42.

[5] Hao Q, Zhong Y, Liu X, Zhang Q, Yin T, Li Z. Unveiling the regulatory mechanisms of rock fracture behavior and catastrophic failure predictability: The key role of porosity. Int J Min Sci Technol 2026. in press.

[6] Jiang ZS, Zheng WZ, Wang Y, Li S, Sun LQ. Green demolition technology of reinforced concrete slab: Application of soundless chemical demolition agents and its evaluation system. Struct Concr 2023; 24(4):4549-64.

[7] Huynh MP, Laefer DF, McGuill J, White A. Temperature—related performance factors for chemical demolition agents. Int J Mason Res Innov 2017; 2(2/3):220.

[8] Zheng W, Li R, Xu L. Review and analysis on research and application of static crushing technology. Joural of harbin institute of technology 2021; 53:5.

[9] Xu JZ, Zhai C, Ranjith PG, Sun Y, Qin L, Ma HT, et al. Investigation of non—explosive expansion material in roof caving field application. Int J Rock Mech Min Sci 2019; 120:50-7.

[10] Hao B, Hu S, Cheng J, Huang H, Kang K. Mechanism analysis of rock breaking using static cracking agent SAC. Electron J Geotech Eng 2014; 19(Z6):17759-79.

[11] Tang W, Zhai C, Xu JZ, Sun Y, Cong YZ, Zheng YF. The influence of borehole arrangement of soundless cracking demolition agents (SCDAs) on weakening the hard rock. Int J Min Sci Technol 2021; 31(2):197-207.

[12] Li RS, Zheng WZ, Xia ZH, Tian WC. Destruction extent of reinforced concrete shear walls demolished by soundless chemical demolition technology: Improvement by structural and parameter design. Constr Build Mater 2024; 440:137295.

[13] Dexpan U. Dexpan: Non—Explosive Demolition Agent for Concrete and Rock Removal: Dexpan USA Official Website; 2025. Updated 2025. Available from: https://www.dexpan.com/.

[14] Australia N. ECOBUST: Naturally Innovative Demolition and Quarrying without Explosives: Neoferma Australia Official Website 2025. Updated 2025. Available from: https://neoferma.com/ecobust/.

[15] De Silva VRS, Ranjith PG, Perera MSA, Wu B, Rathnaweera TD. Investigation of the mechanical, microstructural and mineralogical morphology of soundless cracking demolition agents during the hydration process. Mater Charact 2017; 130:9-24.

[16] Akinyemi BA, Orogbade BO, Okoro CW. The potential of calcium carbide waste and termite mound soil as materials in the production of unfired clay bricks. J Clean Prod 2021; 279:123693.

[17] Pourabbas Bilondi M, Toufigh MM, Toufigh V. Using calcium carbide residue as an alkaline activator for glass powder—clay geopolymer. Constr Build Mater 2018; 183:417—28.

[18] Zhao YX, Gao BY, Shon HK, Cao BC, Kim JH. Coagulation characteristics of titanium (Ti) salt coagulant compared with aluminum (Al) and iron (Fe) salts. J Hazard Mater 2011; 185(2—3):1536-42.

[19] Liu XR, Wu YX, Xu QX, Du MT, Wang DB, Yang Q, et al. Mechanistic insights into the effect of poly ferric sulfate on anaerobic digestion of waste activated sludge. Water Res 2021; 189:116645.

[20] Xu B, Qin JD, Yang MQ, Yi YL. Characterization of freshwater sludge generated in Singapore: Exploring opportunities for a circular economy. Waste Dispos Sustain Energy 2024; 6(4):589-602.

[21] Xu B, Tan JW, Yang MQ, Yi YL. Using freshwater sludge and carbide sludge to produce expansive agents for civil engineering applications: a feasibility study. J Water Process Eng 2024; 67:106131.

[22] Yang MQ, Xu B, Tan JW, Yang EH, Yi YL. Production of concrete expansive agents from freshwater sludge and carbide sludge. Case Stud Constr Mater 2025; 23:e05033.

[23] Xu B, Zhu XY, Ren L, Wu W, Yi YL. Rock fracturing using soundless cracking agents produced from freshwater sludge and carbide sludge. J Rock Mech Geotech Eng 2026.

[24] Du G, He T, Xu Z, Liu L. Study on properties of calcium oxide in SCA under different calcination conditions. Inorganic Chemicals Industry 2023; 55(10):35-41.

[25] Zhu XY, Zhai C, Yu X, Xu JZ, Zheng YF, Tang W, et al. Effects of anhydrous CaCl₂ on flocculation characteristics, rheological properties and blowout inhibition mechanism of non—explosive expansive cement. Constr Build Mater 2024; 456:139167.

[26] Xu S, Hou PY, Li RR, Suorineni FT. An improved outer pipe method for expansive pressure measurement of static cracking agents. Int J Min Sci Technol 2022; 32(1):27-39.

[27] Habib KM, Vennes I, Mitri HS. Methodology for the estimation of expansive cement borehole pressure. Int J Min Sci Technol 2023; 33(1):73-81.

[28] Harada T, Idemitsu T, Watanabe A, Takayama SI. The design method for the demolition of concrete with expansive demolition agents. Fracture of Concrete and Rock. New York, NY: Springer New York; 1989:47-57.

[29] Natanzi AS, Laefer DF, Connolly L. Cold and moderate ambient temperatures effects on expansive pressure development in soundless chemical demolition agents. Constr Build Mater 2016; 110:117-27.

[30] Zhou HW, Xie H. Direct estimation of the fractal dimensions of a fracture surface of rock. Surf Rev Lett 2003; 10(5):751-62.

[31] Bieniawski Z, Hawkes I. International Society for Rock Mechanics Commission on Standardization of Laboratory and Field tests suggested methods for determining tensile strength of rock materials. Int J Rock Mech Min Sci 1978; 15(3):99-103.

[32] Barton N, Choubey V. The shear strength of rock joints in theory and practice. Rock Mech 1977; 10(1):1-54.

[33] Serris E, Favergeon L, Pijolat M, Soustelle M, Nortier P, Gärtner RS, et al. Study of the hydration of CaO powder by gas—solid reaction. Cem Concr Res 2011; 41(10):1078-84.

[34] Baur I, Keller P, Mavrocordatos D, Wehrli B, Johnson CA. Dissolution—precipitation behaviour of ettringite, monosulfate, and calcium silicate hydrate. Cem Concr Res 2004; 34(2):341-8.

[35] Chen JN, Yang XM, Su H, Cui J, Xie JF. Evaluating and enhancing heat storage in a Ca(OH)₂/CaO shell—tube reactor: a numerical study on key factors and performance optimization. Energy 2024; 309:133161.

[36] Evju C, Hansen S. The kinetics of ettringite formation and dilatation in a blended cement with b—hemihydrate and anhydrite as calcium sulfate. Cem Concr Res 2005; 35(12):2310—21.

[37] Zhong Z, Zhang H, Hu YJ, Lou R, Tao P, Liu J. Experimental and numerical explorations on the optimized applications of SCDA in cracking concrete blocks. Measurement 2023; 206:112335.

[38] Ghasemi S, Khamehchiyan M, Taheri A, Nikudel MR, Zalooli A. Crack evolution in damage stress thresholds in different minerals of granite rock. Rock Mech Rock Eng 2020; 53(3):1163-78.

[39] Zhu ZM, Mohanty B, Xie HP. Numerical investigation of blasting—induced crack initiation and propagation in rocks. Int J Rock Mech Min Sci 2007; 44(3):412-24.

[40] Kang SH, Kwon M, Kwon YH, Moon J. Effects of polycarboxylate ether (PCE)—based superplasticizer on the dissolution and subsequent hydration of calcium oxide (CaO). Cem Concr Res 2021; 146:106467.

[41] Chatterji S. Mechanism of expansion of concrete due to the presence of dead—burnt CaO and MgO. Cem Concr Res 1995; 25(1):51-6.

[42] Xie HP, Wang JA, Xie WH. Fractal effects of surface roughness on the mechanical behavior of rock joints. Chaos Solitons Fractals 1997; 8(2):221-52.

[43] Zhang Q, He MC, Wang J, Guo S, Zhu C, Tao ZG, et al. Investigation of a non—explosive directional roof cutting technology for self—formed roadway. Int J Min Sci Technol 2022; 32(5):997-1008.

[44] Simoni M, Hanein T, Woo CL, Provis J, Kinoshita H. Effect of impurities on the decarbonization of calcium carbonate using aqueous sodium hydroxide. ACS Sustain Chem Eng 2022; 10(36):11913—25.

[45] Massoumi Nejad B, Enferadi S, Andrew R. A comprehensive analysis of process—related CO₂ emissions from Iran’s cement industry. Clean Environ Syst 2025; 16:100251.

[46] PriceWatch. Bauxite Price Trend, Forecast and Pricing Analysis: PriceWatch Official Website; 2026. Updated 2026. Available from: https://www.pricewatch.ai/bauxite—prices/

[47] Davis D, Müller F, Saw WL, Steinfeld A, Nathan GJ. Solar—driven alumina calcination for CO₂ mitigation and improved product quality. Green Chem 2017; 19(13):2992-3005.

[48] Tan JW, Xu B, Yang MQ, Yi YL. Treatment of drinking water sludge through co—calcination with calcium carbide residue. J Water Process Eng 2025; 70:106929.

[49] NEA. Refuse Disposal Facility: National Environment Agency of Singapore. Updated 31 August 2025. Available from: https://www.nea.gov.sg/our—services/waste—management/waste—management—infrastructure/refuse—disposal—facility.