Carbon nanotube foam concrete (CNFC) is a low-carbon and sustainable lightweight backfill material. In this paper, the cracking evolution characteristics and the damage patterns of CNFC during uniaxial compression were monitored by the acoustic emission (AE) technique, and the microscopic pore structure of CNFC was analyzed by fractal theory. The results demonstrated that the flowability of CNFC was within 163–176 mm, respectively. With 0.05 wt.% carbon nanotubes (CNT), the 7d and 28d compressive strengths of foam concrete (FC) increased by 33.04% and 27.74%, respectively. The microstructural observation revealed that CNT can improve foam stability and optimize the pore spatial distribution and size. The AE responses reflected the excellent bridging effect of CNT effectively suppressed the crack development during compression and enhanced the performance of FC. CNT increased the cost of CNFC from 169.78 RMB/m3 to 423.72 RMB/m3. The cost per unit of intensity of CNFC0.05 increased by 17.44% and the CO2 emission per unit of intensity decreased by 21.69%. The results are expected to provide a reference for the preparation and research of nanocomposite foam concrete.
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