The effect of carbon nano- and microfibers on strength and residual cumulative strain of mortars subjected to freeze-thaw cycles

Abstract

The strength and development of residual strain of normal strength mortars subjected to freeze-thaw cycles incorporating carbon nanotubes (CNTs) and carbon microfibers (CMF) were studied. The workability was influenced by the fiber type, the dispersion method, and the amount of fibers. The obtained results showed that the measured flexural strength increased only in the case of mortars incorporating CMFs. The compressive strength remained unchanged in the case of mortars containing CMFs and was slightly lower when CNTs were present. The residual strain due to freeze-thaw cycles was lowered in comparison with reference mortar only when incorporating CMFs. The obtained results confirmed that in order to utilize the outstanding mechanical properties of CNTs the binder matrix must be very homogenous to provide sufficient contact area for stress transfer. The used water to binder ratio was sufficiently low only for long CMFs, which were able to bridge numerous weak inclusions present on the binder matrix. © 2013 Japan Concrete Institute.