Browsing by Author "Urreta, J. I."
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Item Efficiency of short steel jackets for strengthening square section concrete columns(1997) Ramírez, J. L.; Bárcena, J. M.; Urreta, J. I.; Sánchez, J. A.; Centros PRE-FUSION TECNALIA - (FORMER); Infraestructuras y Servicios CorporativosFollowing other short length square concrete column strengthening methods which have been studied and published before by the authors (polymeric concrete, steel angles and prestressed bolts jackets), two different additional methods will be presented in this paper. In one of this methods the steel jacket is formed by two bent plates L shaped welded longitudinally in the two common corners, leaving a small clearance with respect to the original column surface that is injected with a polymeric grout afterwards. In the other, the jacket is made by adhesion of steel plates to the complete four faces of the column, closing the jacket by narrow bent plates L shaped joined also by adhesion to the steel plates at the column corners. Complete loss of strength of the original concrete column has been assumed, in centered compression, and a method of calculation for load transfer between column and jacket in the smallest length possible will be presented. A good experimental behaviour and correspondence between calculation and results has been obtained for the welded and injected jacket but these results have been poor for the jacket built up by adhesion. Problems caused by the quality of adhesive and mastics have also been detected, and finally some observations concerning the price and conditions of execution have been made.Item Los finos del árido calizo de machaqueo en la fabricación de hormigones de altas prestaciones: Datos para un tema en discusión(2000) Etxebarria, A.; Ramirez, J. L.; Urreta, J. I.; Gorbeña, J.; Centros PRE-FUSION TECNALIA - (FORMER); Infraestructuras y Servicios CorporativosThis paper deals with the use of crushed limestone aggregate, fine and coarse, in High Performance Concrete (H.P.C.) manufacturing. Firstly, different international research projects about this subject are presented and following, a focus on the Spanish experience is made. In addition the paper provides a list of works made in Spain with HPC from crushed limestone aggregates and a complete bibliography section about the subject in discussion.Item Proposal for limitation and control of fines in calcareous sands based upon their influence in some concrete properties(1990-07) Ramirez, J. L.; Barcena, J. M.; Urreta, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); Infraestructuras y Servicios CorporativosThe development and final conclusions of a research programme which has gone on for four years are explained here. The products of Basque Country quarries have been analysed, studying also the influence of calcareous and clay fines in mortars, as well as in crushed calcareous aggregate concretes, this being the objective of the present article. 42 different concrete mixes in duplicate, with the same workability, have been made, taking the contents of fines and clay in sand and the cement content as variables. This process has involved handling a total of 14 tonnes of aggregate and the manufacturing of more than 900 standardized cylinders. It is concluded that up to 15% of fines in calcareous and ground sand are admissible, provided that the proportion of clay fines is controlled by means of a sand equivalent sight test and, even better, by the methylene blue test method. This research work has been the basis for the new text of the corresponding paragraphs in the recent Spanish Concrete Standard EH-88, but could be, a reference for others with a similar type of aggregate.Item Reuse and valorization in civil works of electric arc furnace (EAF) slag produced in C.A.P.V.(1999) García, C.; San José, J. T.; Urreta, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); Infraestructuras y Servicios CorporativosThe steelworks produced annually in the Basque Country is in the range of 700,000 tons of EAF slags (oxidizing). One of the possible reuses for these waste materials could be derived from their reutilization in civil works, partially substituting raw materials in roads, concrete and cement. The aim of this paper is to carry out a study about several properties regarding the EAF slag, produced in the 11 factories considered for this work, in order to determine the valorization of this waste materials through its potential application to: bituminous mixes, granular bases, aggregates for concrete and raw material in the production of cement. This paper aims to suggest recommendations which should lead to a safe use of EAF slag in civil works from a technical point of view. Nowadays, the 38% of the total steelworks of Spain is being produced in the Basque Country (CAPV), with a production of 5.2 × 106 tons per year. The different waste materials produced in CAPV are shown on the table 1. The European administrations are giving priority to the reuse of waste materials, in order to minimise dumping in local landfills. For this reason, the future for the steelworks factories, considering economical issues, is the reuse of all their by-products if this was technically possible.Item Sables calcaires à fines calcaires et argileuses: influence et nocivité dans les mortiers de ciment(1987-05) Ramirez, J. L.; Barcena, J. M.; Urreta, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); Infraestructuras y Servicios CorporativosOn a réalisé un programme de recherches assez exhaustif dans le but de rassembler des données pour une prochaine révision de la Norme Espagnole du Béton sur la teneur en fines des sables, actuellement fixée, sans exception, à 5%. On présente les résultats de l'influence des différentes teneurs en fines calcaires et argileuses sur les propriétés mécaniques des mortiers, prélablement à l'étude de cette influence sur des bétons confectionnés avec des granulats calcaires de broyage. Cette phase est en cours d'exécution à l'heure actuelle. Avant de se livrer à ces travaux expérimentaux, on a réalisé une prospection générale de toutes les carrières de broyage de calcaire dans la zone nord-est de la péninsule correspondant au Pays Basque. D'après les résultats obtenus, il semble que la limite pourra s'élever jusqu'à 12 à 15%, à condition d'assurer la présence d'argile à un taux défini par des essais.