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Self-sensing cementitious composites can enable structures that are capable of carrying the loads applied on them while monitoring their condition. Most of earlier research has focused on the incorporation of nanofillers or microfibers into cement paste or mortar composites. However, there have been very limited number of studies on the development of steel-fiber-reinforced cementitious composites with self-sensing capabilities. This study explores strain sensitivity of concrete mixtures that include coarse aggregates up to 15 mm diameter and steel fibers with a length of 13 mm and a diameter of 0.25 mm. Five different concrete mixtures with steel fibers at 0%, 0.2%, 0.35%, 0.5%, and 0.8% volume ratios were fabricated. Compression tests with simultaneous measurement of strain and electrical resistance were conducted on the cubic specimens. Gauge factor and percent linearity that is a measure of error in strain sensing were calculated. Concrete mixtures with 0.5% steel fibers possess a strong linear relationship between applied strain and electrical resistance change with a gauge factor over 20 times larger than that of traditional metal strain gauges. Phenomenological models for different resistivity and gauge factors of cement paste/mortar with respect to concrete with large aggregates and short–long fiber cement composites were presented.

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Earthquakes, material deteriorations and other environmental factors challenge the structural safety. In order to protect the lives, structural health monitoring is crucial. The metal foil strain gages have low durability, low sensitivity and can get point wise measurements which are disadvantages. In this study six different concrete mixtures were designed; one without any copper powder, the rest five having different copper powder volume fractions. Three cube samples from each mixture were cast and cured. Simultaneous measurement of electrical resistance and strain were conducted during the compression tests. A strong linear relationship between strain and electrical resistance change was obtained for copper powder reinforced concrete. The results are contribution to the development of “Smart Concrete” which can sense its strain and damage.