Description
Recently there is a growing interest in how to decrease the environmental impact of concrete and how to increase its durability. As concrete is mostly unsaturated during its service life, measuring unsaturated flow (through imbibition or diffusion) can provide information to assess its durability. Additionally, permeability values are often used to describe concrete’s ability to withstand the ingress of aggressive agents. However, it is not known whether the measured performance is representative of service-life behavior. In this research, the results obtained via 2 unsaturated flow methods (imbibition and diffusion) and 2 permeability tests (CEMBUREAU and Torrent method) were compared. In order to do this, 6 concrete mixes with 3 different cement types (CEM I, CEM II and CEM III) and two water to cement (w/c) ratios (0.4 and 0.7) were tested after 28 days and 120 days of curing. First of all, capillary imbibition was tested on specimens with a diameter of 100 mm and a height of 100 mm for 1 week. Furthermore, water vapour diffusion through the concrete was measured using the cup method, which consists of creating a moisture gradient, using a hygroscopic salt, with a concrete slice as a barrier. The results showed that for concrete with a w/c of 0.4 all test methods indicated that CEM III performed worse in comparison to CEM I and CEM II, which had a similar performance. However, for a w/c of 0.7, CEM III performed superior in comparison to CEM I and CEM II in the capillary imbibition test and the water vapour diffusion which can possibly be explained by an increased tortuosity. In the gas permeability tests, CEM III performed worse in comparison to CEM I and CEM II.
