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The paper briefly describes the design of a rig capable of testing scaffold towers up to 9 m high and 1.8 m square on plan, for vertical loads up to 100 t, with negligible restraint offered or induced against sidesway (should any naturally occur with loading). The criteria, decisions, omissions and mistakes outlined herein may be useful for other rig designs. The paper concludes with a short description of a “commissioning test” on a Haki “system scaffold” tower.

The main characteristic of this Institute is its configuration, with one body of flat construction; designed for lecture halls and workshops, combined with a 17-storeyed tower which holds the rooms of the residents. The low body consists two storeyed of blocks that are constructed in relation to each other so that the roof of the ground floor becomes the terrace of the second block. Characteristic of the construction is, apart from being entirely of unfaced concrete that is uses large beams which hold up to 17.5 m long splays without supports. The building for the residents has been subdivided into boarding units, each one of which consists of three mezzanine floors. In the middle one are the bedrooms, in the shape of small cubicles, whereas in the other ones are situated the living rooms that complete each unit. The capacity of the Institute is 1,600 people for whom 150 parking places have been provided.La característica principal de este Instituto es su configuración a base de un cuerpo de construcción plano, destinado a aulas y talleres, combinado con una torre de 17 plantas en las que se distribuyen las habitaciones de los residentes. El cuerpo plano lo forman bloques de una sola planta baja, dispuestos entre otros que poseen, además, una planta superior. La relación entre ellos consigue que la cubierta de los primeros sirva de terrazas para la primera planta de los segundos. El conjunto se caracteriza por su construcción totalmente en hormigón visto y por el empleo de grandes jácenas —que alojan alféizares— sin apoyos, de hasta 17,15 m de longitud. El edificio para los residentes se ha subdividido en unidades de internado, de las cuales cada una comprende tres semiplantas. En la central se hallan los dormitorios en forma de celdas, mientras que en las otras dos se han colocado las zonas de estar que completan cada unidad. La capacidad del Instituto es de 1.600 personas, para las cuales se han previsto 150 plazas de aparcamiento.

Not available, El elemento más difícil de analizar por absorción atómica en el cemento portland es el calcio. Los resultados se obtienen por repetición de un gran número de análisis de la misma muestra y suelen diferir entre ellos. La repetición necesaria para obtener una seguridad estadística exige un aumento en el tiempo del análisis. Sin embargo el análisis del calcio, exacto, preciso y rápido, es una necesidad en la industria del cemento. El análisis del calcio exige una gran dilución del problema con el fin de que los resultados cumplan la ley de Beer y eliminar las interferencias ocasionadas por el silicio y el aluminio, para lo cual se añade lantano a la disolución problema.

Synopsis The paper describes the equipment and techniques for applying multiaxial stress states to specimens of concrete, and accurately measuring the deformation at small and large strains. Particular attention is given to inducing uniform and definable states of stress, together with ease and accuracy of control during the various loading regimes. Details of the construction of the apparatus and principles of operation are given.

Not available, No disponible

Effects of various concentrations of thallous carbonate on the hydration of tricalcium silicate have been studied using an isothermal microcalorimeter. The calorimetric results indicate that the hydration reaction is accelerated in the presence of Tl2CO3. X-ray diffraction analysis shows that the concentration of C3S decreases rapidly in the presence of Tl2CO3. Differential thermal analysis of C3S hydrated in the presence of Tl2CO3 indicates the presence of CaCO3. Non-evaporable water content and the degree of hydration of C3S show that the accelerating action of Tl2CO3 is more pronounced only during the early period of hydration. Analysis of the liquid phase in contact with the C3S paste indicates that the concentration of Ca++ and OH− ions are changed considerably in the presence of Tl2CO3.

Not available, Por diversos motivos, tanto de índole legal como científica, puede plantearse la necesidad de distinguir cuantitativamente entre los carbonatos contenidos en un cemento originados por un proceso de carbonatación y los procedentes de adiciones.

Not availableEl actual estudio es el primero de un vasto programa de trabajo destinado a introducir y a actualizar los ensayos de control analítico de los conglomerantes hidráulicos.

Bleeding properties were studied in cement pastes containing a number of different paraffin wax emulsions and clays. Bentonite suspensions and wax emulsions which were unstable in the presence of cement paste filtrate, reduced bleeding rates and capacities more effectively than kaolin suspensions or stable wax emulsions. Additions of calcium lignosulphonate diminished the efficiency with which wax emulsions and bentonite reduced bleeding in cement pastes.

Not available, La Asociación Venezolana de Ingeniería de Inspección, Dirección y Supervisión de Obras (AVIDISO), como parte del Colegio de Ingenieros de Venezuela, organizó, para celebrar en los días 1 al 6 de septiembre de 1975, un ''Curso sobre Tecnología y Control de Calidad en la Construcción de Obras de Concreto".

For the construction of this building, that is situated in a rural environment there were limited financial means available and all the recent norms of the Ministry of Education and Science for Centres of General Basic Education and A-level have been considered. These conditions have fundamentally ruled its construction and its successful architectural composition and it makes this Centre a pilot-model that has been shown to the public at various exhibitions all over Spain.Este edificio, que se halla enclavado en un ambiente rural, tenía una determinada limitación de medios económicos para ser realizado y se tuvieron en cuenta todas las recientes normas del Ministerio de Educación y Ciencia para Centros de Enseñanza General Básica y Bachillerato. Estas premisas han condicionado fundamentalmente su construcción y su acertada composición arquitectónica, haciendo de este Centro un modelo piloto que ha sido mostrado al público en varias exposiciones por toda España.

The effect of copper and steel fibre inclusions on the thermal conductivity of mortar and concrete is investigated. The experimental technique is based on the conventional steady-state method using desiccated specimens. The results indicate that copper fibres significantly increase thermal conductivity while steel fibres have a lesser effect. Vibration of the fresh concrete, during specimen manufacture, produces some fibre alignment. As a result, it is found that theoretical methods based on the assumption of a random fibre distribution under-estimate the experimental values.

The test to failure of two spans of a simple span, prestressed concrete highway bridge is described, and the measured and computed load-deflection curves for the bridge are presented and compared. The calculated load-deflection curve, based on strain compatibility relationships, compares reasonably well with the curve obtained experimentally. Severe dishing of the deck slab led to a separation between the bridge deck and the girders; the result was a loss of composite action and subsequent shear failure of the girders. Questions are raised regarding the state of existing knowledge of the behavior of composite, prestressed concrete, multi-beam bridges.

The design and construction of an elevated urban motorway that was built in the city of Bolzano, Italy, using precast prestressed concrete segmental construction is described. The viaduct consists of 74 spans giving an overall length of 2580 m (1.6 miles). The superstructure is made up of one post-tensioned concrete multi-cell box-section spine beam with cantilever side slabs. The basic construction method of the superstructure is the span-by-span mode using percast segmental units erected on falsework and post-tensioned together. Each of the 34.5-m (113.2 ft) spans is composed of nine segments 2.20 m (72.8 ft) wide by 1.6 m (5.2 ft) deep and weighing 110 tons. The precast elements are connected by a thin layer of epoxy resin adhesive. In the wintertime, the surface to be bonded was electrically heated. The average erection time cycle for the superstructure was one span per week. The viaduct was completed in April of 1974. /Author/

Synopsis From experimental results on a range of mixes made with two lightweight and two normal-weight aggregates and from an analysis of numerous data of other investigators, it is proposed that creep and shrinkage at one year can be predicted from measured values at between 7 and 28 days by means of linear and power equations. Equations for the prediction of longer-term values are also given.

This hospital basically serves the districts of Aubonne and Morges and partly those of Cossonay and Rolle. It comprises a block of six storeys, with the actual hospital, and another one of five storeys with a college for nurses and male nurses; both of them equipped with the latest inventions with regard to technique and comfort. Both centres mutually use the service installations and the rooms that the other building disposes of, for a more rational utilization of the investment made. The complex has a magnificent location in a natural environment. The construction is traditional, the structure being of reinforced concrete and the finishing of high quality., Este hospital atiende fundamentalmente a los distritos Aubonne y Morges y, parcialmente, a los de Cossonay y Rolle. Consta de un bloque de seis plantas, como hospital propiamente dicho, y otro de cinco plantas, para escuela de enfermeras y enfermeros asistentes; ambos dotados con los últimos adelantos de la técnica y el confort. Uno y otro centro utilizan, recíprocamente, los servicios y locales de que disponen, para un más racional aprovechamiento de la inversión realizada. El conjunto está magníficamente ambientado en el entorno natural que lo rodea. La construcción es tradicional, con estructura de hormigón armado y acabados de gran calidad.

MIT HILFE EINES GROSSRECHNERS WURDEN DIE EINFLUSSFLAECHEN FUER DAS EINSPANNMOMENT UND DAS MOMENT AM FREIEN RAND EINES ELASTISCH EINGESPANNTEN, DURCH EINE EINZELLAST BEANSPRUCHTEN KRAGPLATTENSTREIFENS BERECHNET. DABEI WURDE DIE QUERDEHNUNG MIT MY = 0,2 BERUECKSICHTIGT. DER PARAMETER FUER DIE UNTERSCHIEDLICHEN EINSPANNUNGSBEDINGUNGEN IST EINE DIMENSIONSLOSE KENNGROESSE, DEREN ERMITTLUNG AUF EINFACHEN RECHENOPERATIONEN BERUHT. ANHAND VON 3 BERECHNUNGSBEISPIELEN WIRD GEZEIGT, WIE SICH DIE ELASTISCHE EINSPANNUNG MIT HILFE DER ANGEGEBENEN EINFLUSSFLAECHEN BERUECKSICHTIGEN LAESST. (A*)

The prestressed concrete superstructure of the 7,884 m long and 26.6 m wide bridge over the Guanabara Bay, connecting the cities of Rio de Janeiro and Niteroi, in Brazil, was constructed by the cantilever method with the help of precast segments which were glued together with epoxy resin. An experimental investigation of the structural behavior of the glued joints was made in a model of the bridge. Important conclusions resulted from the experiment. It has been shown that the glued joints do not affect the safety of the structure. Several investigations were made during the construction for determination of various important features of the glued joints for erection procedures. The behavior of glued joints was studied with the help of a specially developed concrete test piece.

L'ETUDE DES PROPRIETES DES FILS GALVANISES ELABORES SELON DIFFERENTS PROCESSUS INDUSTRIELS A MONTRE QUE CERTAINS D'ENTRE EUX ETAIENT APTES A L'EMPLOI COMME ARMATURES DE PRECONTRAINTE PAR PRE OU POST-TENSION. LES RISQUES DE FRAGILISATION DE CES ACIERS A HAUTE RESISTANCE PAR L'HYDROGENE LIBERE PAR LA REACTION ENTRE LE ZINC ET LE CIMENT PEUVENT ETRE EVITES, SOIT EN UTILISANT UN CIMENT APPROPRIE, SOIT PLUS GENERALEMENT EN AJOUTANT DU BICHROMATE DE POTASSIUM AUX CIMENTS PORTLAND ARTIFICIELS. L'EMPLOI D'ARMATURES DE PRECONTRAINTE GALVANISEES PRESENTERAIT UN GRAND INTERET DANS TOUS LES CAS OU LES CABLES EN TENSION NE PEUVENT ETRE PROTEGES CONTRE LA CORROSION, TEMPORAIREMENT OU DEFINITIVEMENT, POUR DES RAISONS CONSTRUCTIVES DIVERSES, ET DANS LE CAS OU LA PROTECTION PAR LE BETON D'ENROBAGE OU LE COULIS D'INJECTION RISQUE D'ETRE LOCALEMENT ABSENTE OU DETRUITE.

Thermal expansion of hardened cement paste has been determined within the temperature range of −30°C and +80°C. Mositure content varied from virtually zero to saturaton. Immediate thermal response is followed by time dependnt ration. Immediate thermal response is followed by time dependent partial recovery. A tentative explanation for this behaviour is given.

Due to more restrictive environment legislation, many ready-mix concrete suppliers are often obligated to find adequate means of handling, recycling and marketing their waste solids. This paper discusses the nature, properties and possible uses of the fine fraction of the waste slurry. Chemical, physical and mechanical properties of the slurry solids are presented. The influence of addition of waste solids to mortar and concrete made with three brands of cements are examined. The effects of waste solids on compressive and tensile strength, setting time, shrinkage and sulfate expansion and workability were studied.

This new building has been planned perpendicularly to the old part. The majority of the bedrooms are facing southeast-southwest which gives them a better view and since the natural slope of the ground is followed the various storeys have a different level. The connection of the two blocks has been skilfully made trying to unify the style of the old and the new building by utilizing similar or identical materials, alternating them in a suitable manner.La disposición de este nuevo cuerpo edificado, perpendicular a la parte primitiva, orienta a SE. y a SO. la mayor parte de los dormitorios, les proporciona mejores vistas y, dado que se sigue la pendiente del terreno, se obtienen cambios de nivel en las plantas. La conexión de ambos bloques se ha hecho con maestría, procurando homogeneizar la parte nueva y la primitiva utilizando materiales similares o iguales, si bien diferenciándolos convenientemente.

Les auteurs analysent les differentes notions a considerer pour conduire une etude rigoureuse des correlations entre texture cristalline et proprietes mecaniques des plâtres durcis. Ce sont: 1) les phenomenes decoulant de la croissance cristalline proprement dite (mode de germination et de croissance, vitesse de croissance, taille et forme des cristaux, adherence entre cristaux, croissance cristalline genee); 2) l'influence de certains phenomenes exterieurs: intervention d'effets mecaniques, utilisation de modificateurs de prise et emploi d'adjuvants solides, phenomenes d'absorption, d'humidification, ou de dessication). Cette etude preliminaire est illustree par des observations experimentales de textures et d'evolutions de textures et de proprietes mecaniques en fonction de certains facteurs particuliers etudies.

Precast prestressed segmental construction was used effectively to build two of the world's largest LNG storage tanks for Distrigas Corporation. The author, who was a consultant on this project, discusses the design and construction highlights of these 900,000-bbl LNG tanks. In particular, he describes the fabrication and erection of the precast wall panels and the circumferential post-tensioning of the walls.

The paper begins by mentioning the principles of mechanical similitude which are relevant to the reproduction and testing technique of physical models. It goes on with examining the parameters suitable for defining the characteristics of rocky masses with their complex discontinuities and then with a brief description of the techniques used in respecting the similitude of these parameters in the model.

Conventional tests to determine modulus of elasticity are usually associated with the effects of loadings of very short duration. However, continually increasing load during the early age can produce an increase in the modulus of elasticity due to a form of body compaction by «maturing» creep. The paper compares the results of a test in which a specimen was loaded at 1 day, kept at a constant stress-strength ratio and periodically unloaded and reloaded and a series of specimens were loaded at various ages ranging from 1 day to 29 days. Low temperature tests where hydration was stopped by cooling to −11 °C are also included.

The four works described in this article are: Citizen's Plaza, Lumbermens Mutual Casualty Company, the Northrop Building and Park Plaza. The three first buildings are entirely designed for offices whereas the last one is a commercial complex that includes two big department stores. Although different in shape and architectonic characteristics all these have a number of common factors, among which the most outstanding ones are: the concrete construction and tüe facades of prefabricated panels with alternative use of concrete and glass; the adaptation of the inner sections to subsequent reorganisations, either by using predetermined modules for the installations or by using mobile partitions; its functional ism, by means of the perfect adequacy of the spaces for their given functions; the creation of pleasant rooms by using to as great an extent as possible naturally beautiful materials both with regard to the structural parts as well as to the surfacing; and finally the integration of the inner space with the outside ttirough large windows. Each construction is completed with parking places, gardens and a great variety of services for the needs of the building.Las cuatro obras que se describen en este artículo son: el Citizens Plaza, el Lumbermens Mutual Casualty Company, el Northrop Building y el Park Plaza. Los tres primeros son edificios destinados en su totalidad a oficinas, mientras que el último es un complejo comercial que incluye dos grandes almacenes. Todos ellos, aunque distintos por su forma y características arquitectónicas, presentan una serie de factores comunes, entre los que destacan: su construcción, a base de estructura de hormigón y fachadas de paneles prefabricados en los que alternan el hormigón y el vidrio; la adaptabilidad de los interiores para sucesivas reorganizaciones, bien por el empleo de módulos predeterminados para las instalaciones, o por la utilización de particiones móviles; su funcionalidad, mediante la perfecta adecuación de los espacios a las distintas misiones encomendadas; la creación de ambientes agradables, por el uso, siempre que fue posible, de materiales naturales de gran belleza, tanto en los elementos estructurales como en los de revestimientos; y, por último, la integración de los interiores con los exteriores, principalmente en las plantas bajas, a través de grandes ventanales, y la utilización de materiales idóneos. Cada construcción se completa con aparcamientos, zonas ajardinadas y una variada serie de servicios que satisfacen las necesidades del edificio.

This house has been designed as a series of ascending platforms in a continuous spiral around a central staircase and the various platforms have each been assigned different room functions, such as: living room, master bedroom and children's bedroom, studio, dining room and kitchen, guest room and under the house space has been provided for a garage. The construction is entirely wooden and is lifted above the ground by 9 exposed piles to which are bolted the beams that support the exposed ceiling Joists. For these elements laminated yellow pine wood has been used as well as for the floorings, roofs and deckings. The walls are of panelled cedar plywood whereas the material of the interior doors and cabinetry is mahogany.Esta vivienda se diseñó como una secuencia de plataformas que ascienden, en espiral continua, alrededor de una escalera interior, en las cuales se dispusieron: el cuarto de estar, los dormitorios de padres y de niños, un estudio, el comedor y la cocina, una habitación para los invitados y, debajo del edificio, una plaza de aparcamiento. La construcción, realizada con madera en su totalidad, se levanta del suelo mediante nueve pilares vistos, a los que se atornillan las jácenas que soportan las viguetas, también vistas, de los forjados. Para estos elementos constructivos se empleó madera laminada de pino amarillo, al igual que para los suelos, techos y cubiertas. Los muros laterales se hicieron con un entablado de madera contrachapada de cedro, mientras que para el artesonado, las puertas interiores y las estanterías, se utilizó la madera de caoba.

This interesting bridge across the Danube links the central forest zone with the highway Ceste and contributes greatly to facilitate the intense traffic of this region. It has a total length of 818 m, distributed in nine spans: the two central ones over the river are 190 m each with box girders. A great many problems have bean solved successfully regarding the various foundations, slender beams, processes of concreting, the temperature of concrete, and the most adequate design and realisation all of which makes this work one of the most important ones that have been constructed in Austria during recent years.Este interesante puente sobre el Danubio enlaza la zona boscosa central con la autopista Oeste y contribuye grandemente a aligerar el denso tráfico de esta zona. Tiene una longitud total de 818 m, distribuidos en nueve tramos; los dos centrales, sobre el río, alcanzan los 190 m cada uno, con vigas de cajón. Se han resuelto acertadamente numerosos problemas, relacionados con las variadas cimentaciones adoptadas, esbeltez de canto en las vigas, procesos de hormigonado, temperatura del hormigón y el cálculo y ejecución más adecuados; todo lo cual hace de esta obra una de las más importantes que se han realizado en Austria durante los últimos años.

In the article an ambitious plan is described for solving the problem of how to deal with the sewage water that originates from the flats in the south-east area of the capital and its outlet into the sea. The Himmerfjärden unit consists of a system of tunnels with a total length of 40 km and a depth capacity of 50 m and 100 m. The slope of these sewage tunnels is 1‰, with floor slabs of concrete. An efficient service for 250,000 people is foreseen with a possibility of an increase to 500,000 without the necessity of adding really important works. The construction works, the above mentioned tunels, as well as the pumping station and the mechanical cleaning grids have been carried out by the firm Skanska Cementgjuteriet.Se describe en el artículo un ambicioso plan para solucionar el problema de tratamiento de las aguas residuales que proceden de las plantas existentes en el área suroeste de la capital sueca y su vertido al mar. El conjunto Himmerfjärden consiste en un sistema de túneles, con 40 km de longitud total, dispuestos a profundidades de 50 y 100 m. La inclinación de estos túneles de alcantarillado es de 1‰, con solera de hormigón. Se prevé un servicio eficiente para 250.000 personas, con posibilidad de aumentar hasta 500.000, sin necesidad de realizar obras básicamente importantes, en cuanto a los túneles se refiere. Las obras de construcción, tanto de los citados túneles como de la estación de bombeo y de las rejillas de limpieza mecánica, han sido llevadas a cabo por la empresa Skanska Cementgjuteriet.

This research deals with the possibility of the strengthening of bad quality reinforced concrete columns, in isolated stories, by two usual methods: the increase of the cross section with concrete, ?nd the backing up of rolled steel angles to the edges of the column. The experimental work has consisted in the manufacturing, strengthening and testing of eighteen reinforced concrete columns with a low quality concrete. At a certain height above their bases a widening has been provided to represent the presence of a flat slab. From the compression tests data and conclusions concerning the strength efficiency of the two types of strengthening have been obtained, also information on the distribution of forces between the original columns and the strengthening, as well as on the deformations, cracking and type of failure.La investigación trata sobre la posibilidad de refuerzo en pisos aislados de pilares de hormigón armado de baja calidad, por dos métodos usuales: el recrecido de la sección transversal con hormigón y el adosado de angulares de acero a las aristas del pilar. La experimentación ha consistido en la fabricación, refuerzo y ensayo de dieciocho pilares de hormigón armado de baja calidad. A una cierta altura sobre sus bases se dispuso un ensanchamiento para representar la presencia de un forjado plano. De los ensayos de compresión se han sacado datos y conclusiones referentes a la eficacia de los dos procedimientos de refuerzo, distribución de esfuerzos entre pilar original y refuerzo, deformaciones, agrietamientos y forma de rotura.

The concept of reinforcing materials weak in tension is delight-fully simple. Asbestos fibres are known to have been used almost 4,500 years ago to strengthen clay post. The use of continuous reinforcement is as old as reinforced concrete; the use of short, discrete reinforcing elements is relatively new, although the significance of the fibre geometry and the need to improve the fibre shape to obtain adequate fibre-matrix bond was recognised more than fifty years ago. In spite of these early attempts to apply the ideas of composite action to building materials, the development and practical usage of fibre-reinforced cement composites, like reinforced earth, is barely two decades old. The world-wide interest, however, in the potentialities of these new construction materials has resulted in many meetings in the last five years, and the RILEM International Symposium on Fibre Cement Composites to be held in London from 17–17 September, 1975 is another step forward in consolidating the future prospects of these composites. This paper presents a preview of the achievements to date in this area.

A theory is presented to predict the ultimate shear strength of T-beams of long shear span without web reinforcement. Failure is assumed to occur in the compression zone above the diagonal crack due to the combined shearing and compressive stresses, and is based on Mohr's failure theory. Both equilibrium and compatibility conditions are considered, as well as the shear force due to dowel action of the longitudinal reinforcement. The theory is compared with the test results of the authors and other investigators, and is shown to predict the test results well. The theory is also compared with the ACI-ASCE and the Unified Code methods, and is shown to predict the results better.

The building is situated in the bay of Porto-Pi, serving as a lock for which reason special attention was paid to its exterior. It consist of two floors and a basement, where the activities of the Centre are carried out: a) Research with: laboratories, workshops, office-rooms, etc. b) Public sections, with: exhibitions, objects from scientific expeditions, lecture halls, etc. It has been attempted to give both sections their due independence and yet the appropriate connection between them. The dominating aesthetic criteria are: the BUCKET, the traditional recipient of the island; the PATIO, the characteristic element of the Mallorcan architecture, and the WATER, being the basic reason for the activities of the Centre. Construction of reinforced concrete, unfaced concrete, exterior carpentry of wood, aluminum blinds and double glass panes with venetian blinds in between.El edificio está emplazado en la bahía de Porto-Pí, sirviéndole de cierre, por lo que cuidó especialmente su aspecto exterior. Consta de dos plantas y semisótano, en las que se desarrollan dos actividades a que se destina el Centro: a) Investigación, con: laboratorios, talleres, despachos, etc. b) Zonas de público, con: exposiciones, muestras de expediciones científicas, sala de conferencias, etc. Se procuró que ambas zonas tengan la debida independencia y la adecuada relación. Los criterios estéticos dominantes son: el CUBO, volumen tradicional de la isla; el PATIO, elemento característico de la arquitectura mallorquína, y el AGUA, motivo fundamental de las actividades que se desarrollan en el edificio. Construcción a base de hormigón armado, hormigón visto, carpintería exterior de madera, celosías de aluminio y dobles láminas de vidrio con persianas venecianas intercaladas.

The four new terminals of this airport are low, circular modules, entirely transparent due to the extensive use of glass. The main purpose of the project has been to minimize the walking distance for the passengers, reducing it to one sixth of the normal distance at the present airports. In the centre of the groups of terminals a multifunctional complex has been erected, consisting of: control tower —extension of the previous one— which is 60 m and has become one of the highest in the world: airport administration offices; office complex power plant, situated in the lower part of the unit. In all the buildings concrete has been utilized as basic material in structures and various construction elements; additional features are insulating glass panels on the facades and parquet for the floors. Further constructions at the airport are: a hotel with 600 rooms, shopping centers, exhibition halls, hangars, storage premises and a parking space., Las cuatro nuevas terminales de este aeropuerto son construcciones circulares, de baja altura, totalmente diáfanas gracias al uso masivo del vidrio. El objetivo principal del proyecto fue minimizar las distancias a recorrer por los pasajeros, reduciéndolas una sexta parte de lo normal en los aeropuertos actuales. En el centro del grupo de terminales se ha levantado un complejo multifuncional compuesto por: torre de control —ampliación de la antigua— que con sus 60 m se ha convertido en una de las más altas del mundo; oficinas administrativas del departamento de aviación; central de información meteorológica; y planta técnica de servicios e instalaciones, situada en la parte baja del complejo. En todos los edificios se ha utilizado el hormigón como material base en estructuras y distintos elementos constructivos. Se complementa con los paneles aislantes, de vidrio, empleados en las fachadas, y con el parquet que cubre todos los suelos. Otras construcciones del aeropuerto son: un hotel de 600 habitaciones, centros comerciales y salas de exposiciones, hangares, almacenes y aparcamientos para automóviles.

Some expansion of concrete in overground building, bridge construction and hydraulic structure is due to the reaction of alkalies of the cement with some silica constituents of the aggregates. The elementary reactions and the kinetics of the so called Alkali-Silica Reaction are fairly unknown up to today. Preventive measure to diminish the expansion of concrete is of empiric character only. On a physico-chemical background the authors develop a model for the diffusion and the exchange of alkali ions with silano groups of the silica minerals. The model is checked by numerous experiments such as solubility, ion exchange, micro probe patterns, infrared measurements, and it is in fair agreement with the mathematical calculations.

Synopsis The stress-strain relationships in uniaxial tension for reinforced concrete under short-term static loads are studied by considering results of tests on 110 x 110 x 2000 mm specimens. The variables were the area of main reinforcement, the binder spacing and the concrete core-area. The experimental curves show that the stress-strain relationship is comparatively linear up to about 65 % of the cylinder tensile strength. Empirical expressions are obtained for calculating the elastic modulus of the concrete at the origin. The general stress-strain equation is derived by considering a polynomial modified to take account of the relevant boundary conditions. The derived theoretical curves are compared with experimental curves. It is concluded that the maximum tensile stress attained in the concrete is a function of the variables tested, the tensile strength varying linearly with the area of the main reinforcement.

With the construction of the motor road Barcelona-La Junquera it has become necessary to build a bridge across the National Highway (CN-II, km 773), north of Figueras (Gerona). The special geometric characteristics caused by the crossing of two roads and the favourable conjunction of various factors, have lead to a unique solution that provides both functional, economical as well as aesthetic qualities, a combination rarely to be found in constructions of this type.La construcción de la Autopista Barcelona- La Junquera lia precisado la realización de un puente sobre la CN-II, km 773, al norte de Figueras (Gerona). Las especiales características geométricas impuestas por el cruce de las dos vías de circulación y la favorable conjunción de una serie de factores, han determinado la adopción de una singular solución encaminada a proporcionar ciertas cualidades funcionales, económicas y estéticas que rara vez pueden obtenerse simultáneamente en obras de este tipo.

Not available, La complejidad de la química del cemento es motivo de que aún hoy día permanezcan sin aclarar muchos procesos que transcurren durante el fraguado y posterior endurecimiento de la pasta. La industria de la construcción precisa de un conocimiento técnico más sólido, ya que al saber el modo de actuar de los componentes de la pasta del cemento puede conseguir de este material: facilidad y economía en su empleo, resistencias mecánicas elevadas e inalterabilidad y duración en las obras realizadas. Cualquier nuevo conocimiento sobre la química de la pasta, por ello, suele tener inmediata aplicación o sirve como base para ulteriores investigaciones, que en su día darán nuevas propiedades prácticas al cemento o incluso a otros materiales diferentes. El comportamiento de la pasta durante las primeras 24 horas ha sido el motivo de este estudio. Se efectuaron medidas térmicas, de conductividad, de contenidos de productos solubles en agua, de productos cristalinos y de variaciones de solicitación de agua, por los métodos que veremos a continuación.

Porosity and density changes were measured for a series of mortar specimens and a series of cement paste specimens subjected to various compressive stress histories during desorption and sorption cycles. It was found that hydration is inhibited by compressive stress. Under normal basic and drying creep, the effect of compressive stress is to reduce the porosity and increass the interlayer volume with a corresponding increase in the weight of water retained in the interlayer spaces. For specimens completely dried under load the interlayer volume decreases with load. A model for the creep of concrete is advanced in which, under sustained stress, interlayer volume increases as a result of physical distortion of the solid sheets of cement hydrate.

The two housings are located near the capital, in a small urbanisation of Pozuelo de Alarcón. The planning of both apartments is similar since the families occupying them and their requirements are quite alike. It has been attempted to give «movement» to the storeys, sections and elevations so as to avoid the static impression of a cube anchored to the ground and to give the sides different facets. The materials used are the traditional ones and are easy to maintain and we are of the opinion that the objectives established at the drafting of the project have been fully attained.Ambas están ubicadas en las proximidades de la capital, en una pequeña urbanización de Pozuelo de Alarcón. El programa desarrollado en las dos es similar, dado que las necesidades y familia de sus propietarios son muy parecidas. Se ha procurado dar «movimiento » a plantas, secciones y alzados, a fin de evitar el estatismo del cubo anclado en tierra, tratando de lograr distintas facetas según el punto de vista que se adopte. Los materiales empleados son tradicionales, de fácil entretenimiento, y consideramos plenamente conseguidos los objetivos exigidos al redactar el proyecto.

M any post-tensioning anchorage systems today are using an independent mild steel bearing plate to transmit the prestressing force to the concrete member. The purpose of this plate is to distribute efficiently the high concentrated bearing stresses to the concrete. Unfortunately, though, there is no simple analytical method available whereby the bearing plate stresses can be evaluated accurately. In general, the plate area is governed by the concrete bearing stress, which is easy to establish if the average concrete stress is considered. However, the

Cet article a pour but de presenter certains resultats d'essais effectues au laboratoire «Les polymeres dans la construction» de l'Institut des Ingenieurs du Bâtiment d'Odessa (U.R.S.S.).

Portland cement paste was prepared in the following five ways: (1) cured in fresh water, (2) made with fresh water, cured in sea water, (3) made and cured in sea water, (4) low-pressure steam cured, (5) high-pressure steam cured. The water-cement ratio was 0.4 in all cases. Slow crack growth was studied by the double torsion method, and plots were made of crack velocity versus stress intensity. Fracture toughness and the modulus of elasticity were also measured by flexural beam methods. The steam cured specimens had lower fracture toughness and were somewhat more sensitive to static fatigue than the room-temperature cured specimens. There was evidence that crack growth is aided by the presence of water in the environment or by increased water-cement ratio.

Not availableHasta hace poco tiempo existía todavía la creencia de que solamente con cemento, agua y áridos se podía conseguir cualquier calidad de hormigón, considerándose superfinos los aditivos.

The stress-strain-relations of lightweight concrete published so far differ greatly in shape and ultimate strain. In some cases the curves experimentally obtained are similar to those of normal-weight concrete, in other cases they are very stretched compared to normal-weight concrete. The scatter of the measured values of the ultimate strain of lightweight concrete is greater than the scatter found with normal-weight concrete. It could be shown that the shape of the stress-strain-relation of lightweight concrete also depends on ultimate stress as well as on the type of lightweight aggregate. Furthermore the ultimate strain measured under constant rate of strain is obviously influenced by the type of aggregate and by the strength of concrete. An explanation of the deviation from normal-weight concrete is given.