A new methodology for assisting quality control of NSM-CFRP systems since very early ages

The performance of NSM systems directly depends on the performance of the adhesive which can only be reached if a proper curing conditions and time are assured. In order to assess the curing process of the adhesives, as well as the corresponding bond behavior, adequate non-destructive testing approaches are required. Nonetheless, scarce information could be found in the literature in concern to this relevant topic. To fill such gap, the present paper proposes a new method for continuous quality control of epoxy adhesives, based on adaptations of an existing technique originally devised for continuous monitoring of concrete E-modulus since casting, called EMM-ARM (Elasticity Modulus Monitoring through Ambient Response Method). This work reports the simultaneous study of the adhesive through EMM-ARM, together with direct pullout tests at several ages on concrete specimens strengthened with NSM CFRP laminate strips using the same epoxy. The tests are described, and the obtained results are presented and discussed, highlighting the potential of applying EMM-ARM for quality control and decision-making assistance of NSM systems.FCT -Fuel Cycle Technologies(undefined

Numerical simulation of the structural behaviour of concrete tetrapods subject to imposed deformations and applied loads

Tetrapods for coastal protection are frequently used in break waters for dissipation of wave energy. During their service, these plain concrete elements usually exhibit degradation signs with frequent premature rupture of one or more of their legs when located in highly aggressive environments subjected to extreme wave action. These ruptures tend to decrease the efficiency of breakwaters as a whole, thus diminishing their capacity to absorb wave energy. The present paper aims to contribute to a better understanding of the stress levels that occur in this kind of mass concrete elements, taking into account imposed deformations (associated with heat of hydration) and applied loads. A thermo-mechanical numerical simulation tool (3D), based on the finite element method, is used for the assessment of heat of hydration induced stresses. After an initial discussion of the temperature development inside the tetrapod, the corresponding residual stresses are presented and discussed, and conclusions are withdrawn with regard to the available capacity of concrete to withstand further applied loads. Finally, the subsequent behaviour of the tetrapod is assessed and compared to alternative solutions with internal reinforcement of the tetrapod legs, such as reinforced concrete (using stainless steel), steel fibre reinforced concrete and reinforced concrete with FRP’s

OBSERVATIONS ON THE PHYSICAL GEOGRAPHY AND AGRICULTURE OF THE RIO NOSARA WATERSHED IN THE NICOYA PENINSULA OF COSTA RICA

OBSERVATIONS ON THE PHYSICAL GEOGRAPHY AND AGRICULTURE OF THE RIO NOSARA WATERSHED IN THE NICOYA PENINSULA OF COSTA RIC

Automatic Understanding and Mapping of Regions in Cities Using Google Street View Images

The use of semantic representations to achieve place understanding has been widely studied using indoor information. This kind of data can then be used for navigation, localization, and place identification using mobile devices. Nevertheless, applying this approach to outdoor data involves certain non-trivial procedures, such as gathering the information. This problem can be solved by using map APIs which allow images to be taken from the dataset captured to add to the map of a city. In this paper, we seek to leverage such APIs that collect images of city streets to generate a semantic representation of the city, built using a clustering algorithm and semantic descriptors. The main contribution of this work is to provide a new approach to generate a map with semantic information for each area of the city. The proposed method can automatically assign a semantic label for the cluster on the map. This method can be useful in smart cities and autonomous driving approaches due to the categorization of the zones in a city. The results show the robustness of the proposed pipeline and the advantages of using Google Street View images, semantic descriptors, and machine learning algorithms to generate semantic maps of outdoor places. These maps properly encode the zones existing in the selected city and are able to provide new zones between current ones.This work has been supported by the Spanish Grant PID2019-104818RB-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. José Carlos Rangel and Edmanuel Cruz were supported by the Sistema Nacional de Investigación (SNI) of SENACYT, Panama

Bond behavior of EBR CFRP systems in concrete: influence of surface preparation

The EBR strengthening technique has been used to improve existing reinforced concrete (RC) structures. In many cases CFRP laminates are used as reinforcing material, whereas epoxy adhesives are used as the bonding agent. In the last decades several investigations have been carried out in order to predict the bond strength of EBR CFRP systems in concrete and, as consequence of that, many analytical expressions can be found out in the literature, including in standards. However, these expressions do not account for the influence of the type of surface preparation, which is a mandatory and critical task in the strengthening application. The present work gives contributions for this lake of knowledge. For this purpose an experimental program composed of single shear lap bond tests was carried out. The main parameters studied were the type of surface preparation and the bond length. The instrumentation included sensors to measure the pullout force and the loaded and free end slips. This paper details the experimental program, presents and analyzes the obtained results. As expected, the results revealed that the bond strength depends on the type of surface preparation. Finally, existing expressions in the literature were upgraded in order to account for the type of surface preparation in the estimation of the bond strength.This work was supported by FEDER funds through the Operational Program for Competitiveness Factors – COMPETE and National Funds through FCT (Portuguese Foundation for Science and Technology) under the project FRPLongDur POCI-01-0145-FEDER-016900 (FCT PTDC/ECMEST/1282/2014) and partly financed by the project POCI-01-0145-FEDER-007633. The authors also like to thank the S&P Clever Reinforcement Ibérica Lda. company for providing the materials.info:eu-repo/semantics/publishedVersio