PSI - Issue 64

Antonella D’Alessandro et al. / Procedia Structural Integrity 64 (2024) 1160–1167 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

1162

3

the material, of the electrical setup, and of the electronic measurement systems are crucial. For these purposes, scalable smart mortar, with an electrical setup consisting of a 1D arrangement of electrodes along mortar joints is specifically analyzed. The research presented here aims to preliminary investigate the conductivity and strain sensitivity of mortars with various aggregates to develop smart, self-monitoring, masonry capable of both strain-sensing and damage detection. Future work will involve producing larger masonry samples using the most promising mortars identified in this study and evaluating their monitoring capabilities on full-scale elements. To enhance the electrical properties of materials for smart sensing applications, it is essential to evaluate the percolation transition zone. This zone represents the range of inclusion content where there is a significant increase in electrical conductivity due to the formation of conductive pathways between adjacent inclusions. This connected network significantly affects the material's electrical behavior (Chen et al., 2004). Moreover, the percolation threshold typically delineates the transition from strain-sensing to damage (crack) sensing. The sensitivity to strain and damage can also be influenced by the presence of fine and coarse aggregates, which produce double and triple percolation effects (Wen and Chung, 2007; Baeza et al., 2010) 3. Materials and samples 3.1. Components A blend of Portland cement type 42.5R, quarry aggregates (sized 0 ÷ 4 mm), and water are chosen for constituting the reference mortars and the matrix of the carbon-doped samples. Due to the higher compatibility with water and for avoiding special dispersion process needed for nano-sized fibers, 6-mm chopped CMFs (type SIGRAFIL® type C C6-4.0/240-G100), manufactured by SGL Carbon, are adopted in the experimentation. The microfibers are incorporated at relative amounts ranging from 0 to 0.25% by weight of the cement. Sand is added at a ratio of 7/2 to the cement volume, as common mortar compositions used in construction. A consistent water-to-cement ratio of 0.5 is maintained throughout all mixes. Table 1 reports the mix designs of the samples, including both normal and doped ones with CMF.

Table 1. Mix designs of normal mortar and composites with CMF Components

Reference mortar (g)

Doped mortars (g)

Cement c

172 602

172 602

Sand s

Water w

86

86

CMF

0

0.043/0.172/0.43

Ratio w/c

0.5

0.5

Fig. 1. Sample s’ preparation.