Repair of structures in concrete is still a challenge, especially when access and environment offer a difficult context such as the case of wharves. Concerning the repair of concrete for marine structures, European standards give the requirements in predefined and standardised conditions. However, repair of wharves is performed in harsh conditions such as access, humidity and operator position. These conditions do not enable the direct application of standards. By accounting for these requirements, the repair technique consists in rebuilding the concrete cover and in some cases using protective coating for some beams. In this paper, we focus on the concrete repair techniques. The aim of MAREO project (French project of the National competitive cluster in Civil Engineering and Eco-Building) is to compare several repair techniques carried out in the most complex area for repair: the tidal zone. The project deals with initial performance, sustainability, cost of durability and concrete properties monitoring by destructive testing (DT) and non destructive testing (NDT) techniques. The studied NDT techniques are: impact-echo, surface waves, multi-offset radar, and capacitive method. Both, beams placed in natural exposure and slabs specimens placed in accelerated conditions in laboratory are considered. For all the beams, the contaminated concrete was removed using high-velocity water jets (hydro-demolition). The selected techniques are wet shotcrete, dry shotcrete, formed concrete and manual repair. This paper focuses on the ability of NDT techniques to evaluate the changes of properties related to the chloride ingress in concrete both on site and in laboratory accelerated conditions. The interest of each technique and its sensitivity to several physical factors are highlighted. The need of NDT-combination is illustrated.