Tensile strain sensitivity of steel fiber reinforced cement matrix composites tested by split tensile test

Structural health monitoring is crucial to protect the lives and for asset management. Classical sensors have low durability, low sensitivity and high cost which limit their use. Development of smart cement based materials for construction industry is an important task. In this study, six different cement based mixtures were designed. Five of the mixtures have 6 mm steel fiber inclusions. Three samples from each mixture were cast and cured, thus, 18 samples were prepared. The samples were tested with split tensile test. Simultaneous to the split tensile test, electrical potential measurements were conducted. The use of split tensile test for determining self sensing properties of cement based composites has been achieved for the first time in this study. The correlations between the electrical resistance change and tensile strain were determined. The performance measures of gage factor and linearity for a strain sensor were investigated for the cement based composites. Gage factors as high as 5195 were obtained. This is the highest gage factor reported in the literature. The gage factor of cement based composite is almost 2600 times the gage factor of metal strain gages which has a gage factor of 2. The variations of electrical resistance, gage factor, linearity, correlation coefficient of best fit line to the electrical resistance change versus strain data, with respect to fiber volume fraction were discussed. The observations are encouraging further research for development of smart cement based materials which can sense its strain and damage.