Studies focusing on materials used in Cultural Heritage conservation projects are becoming increasingly important. In this paper, pore structure and mechanical

ABSTRACT:Lime mortars to be used in restoration works of Cultural Heritage are being more and more studied. The knowledge on the lime pastes allows to understand the behaviour of the binder fraction. The aim of this work is to study the influence of the kneading water on two critical aspects of the lime-pastes: pore structure and capillary porosity, because both of them are related to the service life of the material, particularly with the moisture transport. Mercury intrusion porosimetry has been performed to establish the pore size distribution: one pore range has been checked in the different pastes tested, setting linear relationships between the pore diameter and the water/lime ratio.Fractal geometry has been used from the MIP results in order to evaluate the pore surface complexity, as a function of the kneading water. From the results, it can be concluded that kneading water is only responsible for a swelling of the structure, but it does not change the pore surface (keeping constant the surface fractal dimension). DIA analysis has been carried out, confirming the previous results. Finally, the correlation obtained between the capillary coefficient and the water/lime ratio confirms the postulated pore structure for the different amount of kneading water in lime-pastes.

ABSTRACT:Carbonation, as a reaction of the curing process of both, cement and lime binders, modifies the microstructure. Several microstructure properties, namely, porosity, pore size distribution, surface fractal dimension and specific surface area have been investigated in this study to describe the effect of carbonation on microstructure. Both carbonated and non-carbonated pastes of lime and blended pastes of lime and cement having varying W/B (water/binder) ratios are studied. Results show that carbonation decreases the porosity, but not with the same intensity in all pore size ranges. The highest modification is between 0.03 and 0.01 µm in lime pastes and between 0.2 and 0.02 µm in 50% lime pastes, while in 80% lime pastes the modification is very small. It is also observed that carbonation is a function of the binder composition but not of the W/B ratio. Moreover, surface fractal dimension decreases during the carbonation process, while the specific surface area varies depending of the binder composition.

Microstructure of blended pastes of lime and cement were studied in this paper. An increment of complexity of the microstructure was found when pastes increase their percentage in cement. Microstructural characteristics as porosity, morphology of the pores, pore size distribution and surface fractal dimension were evaluated in the different pastes studying the modification with the variation of composition. The capillary water absorption is also evaluated obtaining higher capillary coefficients values for the pastes with higher amounts of lime. The increase of complexity of the microstructure, due to the cement in the pastes, leads to slight deviations of the parallel tube model.

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