## 1 Introduction  
Concrete structures are aging quickly owing to abnormal climate caused by global warming and other external factors, which reduce the strength of such structures and result in damage. The concrete damage detection method currently used poses a risk of different interpretations of the evaluation results depending on the concrete material, structure, external environment, and craftsmanship of the workers. To address this problem, a new concrete damage detection method based on the mixing of nanomaterials is investigated in this study. Nanomaterials are widely used because of their extremely small size and diameter 0.1 (100 nm), which provide them with a large surface area per unit volume and various advantages [1, 2]. Nanomaterials can be used in the construction field by introducing nanotechnology to existing construction materials [3, 4, 5, 6, 7]. The introduction of nanotechnology is expected to convert cement-based materials into new construction materials with various advantages such as mechanical, electrical, and thermal functions. Among the various nanomaterials, carbon nanotubes (CNTs), which are carbon-based materials, have a high electrical conductivity of 6000-10,000 S/cm, which is similar to that of copper, and a high thermal conductivity of 3000-6600 W/m\(\cdot\)K, which is similar to that of diamond. The mixture of existing cement-based materials and CNTs has been extensively researched both domestically and internationally in the development of new construction composite materials with diverse performances [8, 9, 10, 11, 12, 13, 14]. Studies on cement composites mixed with CNTs with mechanical, electrical, and thermal properties have been conducted to enhance the strength, electrical conductivity, and heating ability and to measure the degree of damage. Among the studies on electrical conductivity and heating properties, [PERSON] et al. [15] formulated the relationship between the CNTs and the thermal conductivity of a cement composite mixed with such components. [PERSON] et al. [16] studied the electrical resistance and pressure sensitivity of a CNT-cement composite mixed with sulfuric acid and nitric acid. The dimensions of the cement composite were 40 \(\times\) 160 \(\times\) 40 mm, and the mixture ratio of sulfuric to nitric acid was set as a parameter. The field emission scanning electron microscopy (FE-SEM) analysis results showed that the CNTs were uniformly distributed in both the CNT composite mixed with sulfuric acid and nitric acid and an unmixed CNT composite, thus confirming the formation of a CNT network. The electrical resistance of the CNT-cement composite decreased significantly owing to the effect of the CNT network, and the pressure sensitivity was higher in the CNTs mixed with both sulfuric acid and nitric acid. [PERSON] et al. [17] studied a road de-icing system using the heating property of a cement composite mixed with multi-walled carbon nanotubes (MWCNTs) by conducting ice-melting experiments at subzero temperatures. When 3 wt% MWCNT is added, a road de-icing system can be achieved by generating a layer with a thermal conductivity of 2.83 W/mK. In addition, [PERSON] et al. [18] inspected the electrical properties according to the MWCNT concentration of a cement composite mixed with fly-ash-based geopolymers and MWCNTs. The MWCNT concentration was relative to the cement weight, and the electrical properties improved as the concentration increased, although the MWCNTs agglomerated at 1.0 wt%. [PERSON] et al. [19] explored the compressive strength and resistance properties of a cement composite mixed with silica fume and CNTs. The composite was fabricated with dimensions of 25 \(\times\) 26 \(\times\) 150 mm, and the silica fume and CNT concentrations were set as parameters. The experimental results showed that the aggregated CNTs decomposed to small sizes owing to the effect of the silica fume in the cement composite mixed in small amounts along with the CNTs. Accordingly, their compressive strength and electrical resistance properties were improved.