Ana Cristian Magalhães

Bio: Ana Cristian Magalhães is an academic researcher from Laboratório Nacional de Engenharia Civil. The author has contributed to research in topics: Shrinkage & Pozzolan. The author has an hindex of 6, co-authored 9 publications receiving 288 citations.

Lime-Based Mortars: Viability for Use as Substitution Renders in Historical Buildings

Abstract: External renders based on air lime are used in historical buildings as decorative and protective coats. They act as sacrificial layers, particularly exposed to climatic actions and mechanical and environmental impact. They generally present good cohesion and adhesion to the background, although often suffer some degradation as detachments, superficial cracks, or 'lacunae'. Render solutions specified today for old buildings repair are frequently incompatible with pre-existent materials and inappropriate for the specific situation, thus producing new pathology. The choice of adequate materials, formulation, and curing conditions of substitution mortars become crucial for the success of the conservation action. These mortars must meet functional and aesthetic requirements, to fulfill the principles of compatibility, maintaining buildings' integrity and durability. An analysis is presented of ranges of results for different lime-based mortars for old buildings external renders, obtained in several studies car...

Evaluation of mechanical compatibility of renders to apply on old walls based on a restrained shrinkage test

Abstract: When fresh mortars are applied on a substrate they lose water by suction and by evaporation, sometimes very quickly, and they start suffering some shrinkage, while simultaneously hardening and getting stiffer. Because they are adherent to a rigid background—the wall—the deformation is restrained, stresses develop in the render and are partially transferred to the background. These phenomena can generate cracks on the rendering and damage on weak or friable masonry. Air lime renders also suffer these actions, even if they react in a different way compared to cement mortars: they sometimes have high shrinkage, although they have also some ductility (comparatively high rupture energy), developing lower stresses. New␣renders to apply on old walls must be mechanically compatible with old pre-existent materials, namely with old masonry: they should not produce damage and they must be able to␣protect the wall for a reasonable period of time. In this paper a test is described to evaluate the performance of renders concerning restrained shrinkage, results obtained are discussed and conclusions are summarised about compatibility parameters and classification.

Characterization of Historical Mortars from Alentejo's Religious Buildings

Abstract: Alentejo's religious buildings reflect undoubtedly the history and character of this southern Portugal region. Conservation of these buildings requires a deep knowledge of their masonry and renders' lime mortars to evaluate correctly their state of conservation, to avoid progression of pathologic situations, and to plan efficient interventions, with repair and substitution materials with similar characteristics. This article presents a synthesis of the main results obtained in the mortar characterization of religious buildings from Alentejo, which include Evora and Elvas Cathedrals, Mertola Mosque, and the Church of Amieira do Tejo. For each monument, several samples were collected from different sites and a set of tests was carried out, including chemical, mineralogical, and micro-structural tests, as well as physical and mechanical tests. The tested mortars correspond to different phases of construction and interventions on the buildings, comprising mainly origin periods from the twelfth to the eighteen...

Inglesinhos convent: Compatible renders and other measures to mitigate water capillary rising problems

Abstract: In Portugal, conservation and refurbishment interventions on monuments (churches, convents, palaces and fortresses), as well as on historical centers (dwelling buildings), have been assuming increasing relevance. In order to guarantee the present requirements of habitability and aesthetic appearance of the monument without changing its essential character, in conservation interventions, it is necessary to implement wall-covering solutions compatible with the background and the pre-existing materials. In this work, the application to a case study of a diagnosis methodology for the definition of the probable causes of the anomalies and for the evaluation of the state of conservation of renders and plasters is described. The measures adopted for the repair of the anomalies are presented and aim at controlling the causes and minimizing their effects.

Lime-Based Mortars: Viability for Use as Substitution Renders in Historical Buildings

Abstract: External renders based on air lime are used in historical buildings as decorative and protective coats. They act as sacrificial layers, particularly exposed to climatic actions and mechanical and environmental impact. They generally present good cohesion and adhesion to the background, although often suffer some degradation as detachments, superficial cracks, or 'lacunae'. Render solutions specified today for old buildings repair are frequently incompatible with pre-existent materials and inappropriate for the specific situation, thus producing new pathology. The choice of adequate materials, formulation, and curing conditions of substitution mortars become crucial for the success of the conservation action. These mortars must meet functional and aesthetic requirements, to fulfill the principles of compatibility, maintaining buildings' integrity and durability. An analysis is presented of ranges of results for different lime-based mortars for old buildings external renders, obtained in several studies car...

Using fine recycled concrete aggregate for mortar production

Abstract: This research assessed the performance of mortars in which recycled concrete aggregates (RCA) was a component. It replaced natural sand but kept the same particle size distribution. Three mortars were produced with replacement ratios of 20%, 50% and 100% as well as a reference mortar containing no recycled aggregate. The compressive and flexural strength, water absorption by capillarity, drying capacity and susceptibility to cracking of these mortars were analyzed first. Then, based on these results, the most satisfactory replacement ratio was chosen and the following properties were analyzed: water retentivity, shrinkage, adhesive strength, modulus of elasticity, and water vapor permeability. Somewhat surprisingly the best results in the first stage occurred for 20% and 100% replacement ratios, leading to a cautious choice of the 20% ratio for the second stage. Generally the mortar with 20% replacement ratio performed better than the reference mortar, except for adhesive strength and dimensional stability.