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This paper presents the study of the nature and conservation state of different stuccos and Roman concretes from the Roman city of Baelo Claudia (Cádiz). The chemical, mineralogical and microstructural compositions of the said materials have been established. Different causes of their decay have been found, among which we should emphasize the loss of the binding material (lime), basically due to the processes of partial solubilization; the lack of bond between the stuccos and the support stone, due to the different characteristics and properties of these two materials; and finally, the biological-type attack with the proliferation and colonization of different organisms in the said materials.

This paper constitutes a compilation as well as an interpretation of the present state of knowledge about the different microstructures developed in the interface areas of concrete, that is, the cement paste-aggregates, the cement paste-reinforcement, the cement paste-fiber, etc. The Chemical reactions taking place in interface areas, the development and morphology of such areas and their strength ^since interfaces are taken as the weakest points of concrete) are the aspects dealt with in some detail in this work.

The effect of a small quantity of CaF2 on the capacity of reaction of raw mixes has been studied in this paper; and for this purpose the thermal behaviours of a commercial raw mix without the addition of CaF2 were compared at different ages of clinkerization. The times required to complete the reactions at different temperatures are estimated. The mineralizer effect of fluorspar has a maximun at temperatures of clinkerization of about 1.200ºC and ages of cinkerization of about 10 minutes.

Five different compositions belonging to the equilibrium system CaO-Al2O3-Fe2O3 were dopep with a fixed quantity of MgO (6,5% wt). The compositions, which lie in different primary fields of crystallization and in different triangles of compatibility, were submitted to several thermal treatments. Each composition, which had previously been melted, originates in its solidification the aluminates and ferrites which are usual in the interstitial phase of clinker Portland, although they are in different microstructural arrangements. The effect of MgO on the generated microstructures has been shown. Also, the solubility of MgO on the aluminic and ferritic phases has been measured.

In this research the process of formation of a low energy clinker is studied, when fly-ashes (rich in sulphates and lime) and fluorspar are used as raw materials (fly-ashes replaces to the tradicional raw mix partially). The availability of those fly-ashes is shown since clinker at 1.340 °C is obtained. The mineralogical composition, mineralizer capacity and temperature of formation of the new liquid phase is studied.

A preheater with fluidized bed is planned on a pilot scale, capable of being fitted to a rotatory furnace, also of a pilot nature, for the manufacture of Portland clinker. With this it is intended to design a system of dynamic simulation of clinkerization, to obtain clinker of similar characteristics to those which are obtained industrially.