Laboratorio Central Of Estructuras Y Materiales

Madrid, Spain

Laboratorio Central Of Estructuras Y Materiales

Madrid, Spain
SEARCH FILTERS
Time filter
Source Type

Soriano J.,Laboratorio Central Of Estructuras Y Materiales | La Iglesia A.,Complutense University of Madrid | Garcia Calleja M.A.,Laboratorio Central Of Estructuras Y Materiales | Lopez-Ruiz J.,CSIC - National Museum of Natural Sciences
Estudios Geologicos | Year: 2010

Andesitic rocks produce an alkali-silica reaction with the components of the interstitial phase of concrete. This reaction can be considered as belonging to the slow-kinetic type, since the incongruent dissolution of the rock-forming minerals leads to the late formation of siliceous calc-alkaline gel. As a conquence, the conventional mortar-bar method does not detect such reaction until 90 days later.


Martin A.,University of Burgos | Gadea J.,University of Burgos | Campos P.L.,University of Burgos | Calderon V.,University of Burgos | And 2 more authors.
Estudios Geologicos | Year: 2010

Siliceous aggregates are characterized for presenting certain chemical reactivity opposite to the calcium hydroxide liberated in the hydration of the Portland cement. The consequence of this reaction between the aggregate and the components of the intermediate concrete phase is the formation of gels very eager for water that can generate important disruptive pressures in the deeper structure of concrete. We have assessed the potential reactivity of several siliceous aggregates (granites, gneiss, hornfels, quartzite and serpentine) by means of the accelerated method in concrete bars (normalized method) and the superficial reactivity method, observing by scanning electron microscopy (SEM) the formation of silica calcium alkaline gels. On the other hand, we explore the way of minimizing this disruptive reaction employing ground clay bricks and cement type CEM IV UNE-EN 197-1.


Campos P.L.,University of Burgos | Gadea J.,University of Burgos | Soriano J.,Laboratorio Central Of Estructuras Y Materiales | Martin A.,University of Burgos | Calderon V.,University of Burgos
Estudios Geologicos | Year: 2010

This paper presents a study of the reactivity of the slates with alkali hydroxides released by the cements in concretes and mortars. For this purpose several essays were performed under different conditions to a selection of slates of different origins and composition. It has been shown that all the tested slates are susceptible to alkali-silica and alkali-silicate reactivity with the alkalis of the cement and that not all the tests routinely performed to detect such reactions are reliable. Verified the reactivity of these rocks, the causes of observed behaviours and the possibilities to minimize or eliminate this reactivity are studied so that the slates could be in use in contact with cement in composite materials. The use of pozzolanic cements turns out to be effective for the elimination of this type of reactions.


Lanza V.,Laboratorio Central Of Estructuras Y Materiales | Alaejos P.,Laboratorio Central Of Estructuras Y Materiales
Dam Maintenance and Rehabilitation II - Proceedings of the 2nd International Congress on Dam Maintenance and Rehabilitation | Year: 2011

Alkali silica reaction is an expansive pathology of concrete frequent in dams. Methodologies developed nowadays to detect reactive aggregates are too long in order to detect also slow reactive aggregates. This paper describes other rapid tests developed in Laboratorio Central de Estructuras y Materiales of CEDEX to accept or reject aggregates (3 days maximum). These tests are useful to select the aggregates among several options for construction of new dams or hydraulic works in a short period of time. A new test based on Gel-Pat Test has been developed for detecting reactive aggregates and identify the reactive components in three days. Modified Gel Pat test becomes easy and quick to classify aggregates as innocuous or potentially reactive. Also, domain size measured with X Ray diffraction has been applied to detect reactive forms of quartz. Lastly, after analyzing limitations of chemical tests for detection of reactive aggregates, soluble silica has been used to classify quartzites, quartzarenites, and siliceous sands as reactive or innocuous. © 2011 Taylor & Francis Group, London.


Gadea J.,University of Burgos | Soriano J.,Laboratorio Central Of Estructuras Y Materiales | Martin A.,University of Burgos | Campos P.L.,University of Burgos | And 4 more authors.
Materiales de Construccion | Year: 2010

The aim of this work is to contribute to the knowledge of the interactions between aggregates and the components of the interstitial phase of concrete and to determine whether those aggregates that are subsequently used in the manufacture of concrete are reagents and are therefore likely to undergo a progressive deterioration of their initial properties. An initial petrographic study of each aggregate is performed in order to be able to determine its subsequent behaviour and reactivity under the influence of various factors. The potential reactivity of different silicaceous aggregates (slates, gneiss, hornfels, granites, quartzite and serpentine) is then determined by a chemical method for evaluating the potential reactivity of aggregates and an accelerated method in mortar specimens, and finally the surface reactivity is investigated. The results of these studies suggest that some aggregates are able to react with the components of the interstitial phase of concrete. The existence of this kind of interaction is confirmed by the results of the surface investigations before and after the basic reaction.

Loading Laboratorio Central Of Estructuras Y Materiales collaborators
Loading Laboratorio Central Of Estructuras Y Materiales collaborators