Ana Paula Ferreira Pinto

University of Lisbon | UL · Department of Civil Engineering Architecture and Georesources

This research aims to develop a multifunctional, water-based product for protecting and consolidating stone materials. A new synthesis strategy using water-diluted silane formulations, composed of TEOS and an alkyl monomeric silane (ETES) or a polymeric siloxane (PDMS), homogenized by ultrasonic irradiation was followed to produce hybrid networks a...

Products designed to form continuous inorganic networks from alkoxysilanes frequently include organic solvents because of the necessity to turning the precursors miscible with water and because dilution is required for certain applications. Thus, there is a demand for efficient mixtures employing eco-design strategies. This study explores the feasi...

This paper evaluates the influence of water content and mixing conditions (mixing time and sequence of addition of the constituents) on the fresh state properties of lime-based materials and their impact on the hardened state properties. Higher water contents allowed an increased fluidity and lower torque, yield stress and plastic viscosity values....

Consolidation improves the cohesion of stones and preserves stone-built heritage. However, consolidation also modifies other characteristics that have an important role in stone vulnerability to salt crystallization, something especially important in porous limestones. This study evaluates the potential ability of alkoxysilanes and phosphate-based...

This study aims at assessing the role of stone porous network and mineralogy on the behavior of three partially condensed alkoxysilane-based consolidants, catalysed by different routes. Consolidants were applied on two porous stones of similar strength and with significant presence in built heritage (limestone and sandstone). The potential of the c...

This work aims at investigating and comparing the ability of novel products to act as consolidants for carbonate stones and how the lithotype and testing conditions influence the perception of their initial efficacy. Novel consolidants based in alkoxysilanes and ammonium phosphate can penetrate deeply, and have initial efficacy on porous limestone...

Assessing the suitability of a treatment to be applied to a stone surface with severe loss of cohesion is always a major challenge; few satisfactory options have been proposed and sufficiently demonstrated, and the guiding principles on how to test, evaluate and decide on a stone consolidation treatment are still insufficient to be of real help to...

This study aims at preparing novel composite materials for the consolidation of damaged stone in built heritage from tetraethoxysilane(TEOS)based sols with nano-sized hydroxyapatite (HAp) with high crystallinity and high aspect ratio. Synthesis of nanostructures of hydroxyapatite (HAp) was carried out using hydrothermal precipitation methods at dif...

Soft limestones are widely present in noteworthy constructions, but they are prone to decay due to their specific characteristics. In this paper, soft Ançã stone possessing a wide range of properties are analyzed to explain the degradation patterns and degradation rates that can be found in monuments and to estimate decay susceptibility. Experiment...

The effects induced by diammonium hydrogen phosphate (DAP) on coarse marble varieties susceptible to granular disintegration as consolidation material is still poorly addressed. The work aims at investigating the behavior and efficacy of diammonium hydrogen phosphate(DAP)-based consolidant prepared in laboratory onto weathered coarse-grained marble...

This paper intends to evaluate the short- and long-term effects of high-range water-reducing (PCE and PNS) and viscosity-modifying (potato starch) admixtures when used alone or together in the formulation of lime mortars. Results showed that PCE and PNS led to a moderate decrease in porosity, a slower and lower water intake and a significant improv...

This work aims at evaluating the influence of curing conditions on the carbonation process of lime-based mortars and pastes and on the resulting mineralogical, macro- and microstructural properties. To this end, lime-based materials (mortars and pastes) were subjected to natural (0.05 % CO2) and accelerated (5 % CO2) carbonation. The influence of f...

Despite many existing solutions and the research effort to produce tetraethyl-orthosilicate(TEOS)-based products with improved properties for the consolidation of carbonate stones in built heritage, there are still many open questions. Drawbacks such as the influence of the carbonate media and the tendency of the gel to crack during the drying-shri...

The paper presents a study on the mechanical characterization of eight rubble stone masonry walls from different structures of a Portuguese monument and on the assessment of their quality using the Masonry Quality Index (MQI) and the Italian Building Code Commentary (IBCC 2019). Rebound hammer tests were used to evaluate the quality of stone units...

Marbles are widely present in noteworthy constructions but are prone to decay due to the anisotropic thermal behavior of constituent minerals. In this paper, fine to coarse sound marbles possessing diverse technical properties were subjected to different artificial heating protocols to simulate varied degradation scenarios. The ultrasonic pulse vel...

This work explores the short- and long-term effects of admixtures typically used to improve durability on air lime mortars. With that purpose, two air-entraining admixtures (AEA), based on sodium alpha olefin sulfonate (AOS) and sodium dodecyl sulfate (SDS), and a water-repellent admixture (WRA) based on alkylsilicone resin were studied. The AEAs p...

The work explores the use of admixtures as a way to improve the freeze-thaw resistance of lime mortars. For that, different types of admixtures (water-reducers, viscosity-modifiers, air-entrainers and water-repellents) were added to air lime mortars and several properties on the hardened state were determined before, during and after subjecting the...

The paper compares the behaviour of three types of integral water-repellents (WRs) on air lime mortars. These were based on sodium oleate, silane and silicone resin. Results demonstrated that sodium oleate was the most effective in reducing water absorption without compromising water vapour permeability, but decreased mechanical strength. Conversel...

The relevant role of mortars for the structural behavior of historical rubble stone masonry and the scarce information available justifies the research on these materials. Mortars collected from several masonry structures of the National Palace of Sintra (Portugal), built across different centuries, were examined in situ and in laboratory. The infl...

The paper examines the suitability of three different surfactants as air-entraining admixtures (AEAs) for air lime mortars. The substances tested were based on sodium dodecyl sulfate (SDS), sodium alfa olefin sulfonate (AOS) and cocamidopropyl betaine (CAPB). Results showed that CAPB had the highest air-entraining action of the three, due to its am...

The present research addresses the compositional and textural properties of bedding mortars from rubble stone masonries of a historic construction, built between 13th and 17th centuries and during different constructive periods (National Palace of Sintra, Portugal). The characterization of mortars established the basis for the formulation of compat...

Salt weathering is one of the main damaging factors that affects old renders, much owed to their particular characteristics and to the diversity of salt sources available. Salt tests are usually used to experimentally study this topic. They enable to predict the susceptibility of repair or replacement materials and, hence, to improve the durability...

Viscosity-modifying admixtures are frequently used to ease the application of mortars, especially in ready-mixed products, with consequences on the hardened material. However, the knowledge on the influence of these admixtures on lime mortars is still incipient. In this context, this paper intends to analyse the impact of a viscosity-modifying admi...

Water-reducing admixtures have the potential to minimize the disadvantages that typically discourage the use of lime in restoration works. However, the knowledge on the effect of these admixtures on the properties of lime mortars is not as consolidated as it is for cement-based materials. Therefore, this paper aims at studying the influence of two...

Investigations on materials used in historical monuments are of great importance to support studies on archaeology , history and conservation sciences. Most of these investigations focus the characterization, evaluation of the state of conservation and provenance of ornamental stones and mortars but little attention is given to stones in rubble sto...

The consolidation of soft limestones has since long been practiced by using various products applied by different procedures, both for laboratory conditions and as real conservation actions. However, the actual performances of these consolidants have always left doubts, mostly as regards to their long-term – and, in some situations, short-term – be...

The characterization of historic mortars applied in construction is required in many situations, namely for their conservation. In this sense, the drilling resistance test has been being explored by the scientific community, since it has the unique feature of assessing the material strength in depth with very low intrusion. However, the drilling pr...

Solvent nature plays an important role on sol-gel routes of alkoxysilane-based sols and therefore it is predictable that this variable also affects their performance as stone consolidants. In this work, three alkoxysilane-based sols were prepared by using different solvents (white spirit, isopropanol and ethanol). The applicability and initial effi...

Traditional lime-based plasters and renders are complex multilayer systems composed of various mortars; they exhibit behavior affected by their own properties, mutual interaction, interaction with the substrate and by external conditions (e.g. environment). A full understanding of the many mechanisms which impact on system performance is essential...

The lack of relevant chemical bond between carbonate minerals and TEOS-based consolidants was addressed by using a fine-grain porous carbonate stone to investigate alternative single treatments and functionalization pre-treatments for a commercial TEOS-based product (BS) (combined treatments). Solutions of tartaric (T) and citric (C) acids with dif...

Two lime mortars were treated under laboratory conditions to assess the potential effectiveness of three consolidation treatments performed with: an ethyl silicate, a nanolime and a solution of barium hydroxide. The consolidation products were applied by direct contact capillarity. The duration and number of applications were adapted to the specifi...

The drilling resistance is very useful for the in situ characterization of renders as it provides the strength profile in depth with very little intrusion. Its use is widespread in soft homogeneous materials, like carbonate stones. However, in heterogeneous materials, it yields very irregular profiles, difficult to interpret. Low-strength mortars,...

Aerial lime mortars have been increasingly used in restoration interventions due to their compatibility with old materials. However, they present disadvantages such as low mechanical strength at early ages, high drying shrinkage and high porosity and permeability to water. In this context, water-reducing admixtures can be particularly useful for re...

The majority of aerial lime mortars currently made lack the desirable durability. In this context, chemical admixtures can improve some characteristics of aerial lime mortars, without making them incompatible with ancient materials. However, and even though the use of modern chemical admixtures is frequent on the formulation of cement based materia...

Efforts have been made to create new procedures based on Electrochemical Impedance Spectroscopy (EIS) to study several characteristics of cementitious materials with practical interest. Similar approaches can be followed to study other materials, in which the comprehension of their physical, transport-related and durability properties are also need...

Unsatisfactory behaviors of consolidation treatments applied to porous carbonate stones in the field are frequent, although they had revealed promising performances when applied to sound stones in laboratory. Thus, accurate assessment of the potential efficacy of consolidation treatments in laboratory conditions is of outmost importance to support...

ResumoOs calcários muito porosos estão presentes em muitos objectos e construções de valor cultural e os problemas que frequentemente apresentam são de muito difícil resolução. O artigo faz uma breve resenha sobre os problemas e sobre os principais métodos que têm sido propostos para repor a coesão em zonas muito afectadas pela deterioração. A cons...

A degradação em elementos pétreos no património edificado sob a forma de perda de coesão requer que a consolidação seja uma das hipóteses consideradas na conservação. Muito embora os produtos comerciais mais utilizados na consolidação sejam baseados em silicato de etilo, têm vindo a ser identificadas diversas limitações, especialmente na consolidaç...

The paper analyses the influence of different paint finishes on the water transport properties of rendering mortars for old masonry walls. For that, a variety of tests were performed on painted and unpainted mortar specimens, using five different paint finishes: a limewash, a modified limewash with synthetic resin, two silicate paints and an acryli...

This paper investigates some consolidation treatments applied in multilayer renders aiming at improving the conditions for the consolidation practice in the ancient renders. The experimental work comprised the application of an ethyl silicate by poulticing and brushing in prismatic specimens and renders of one and two coats. Two lime mortars with c...

The paper intends to evaluate the behaviour of different paint coatings when applied on renders based on natural hydraulic lime and, thus, to aid in the selection of adequate paint solutions to be used in conservation interventions. For that, tests were performed on painted and unpainted specimens of hydraulic lime mortar and of blended lime putty-...

Os rebocos antigos são tipicamente compostos por argamassas à base de cal aplicadas em várias camadas. As práticas associadas à execução destes rebocos eram suportadas num conhecimento empírico que praticamente desapareceu com a industrialização da construção e o advento do cimento Portland. Esse conhecimento é valioso, quer enquanto testemunho his...

O presente artigo apresenta a caracterização de um reboco antigo através do ensaio da resistência à furação. Este método é usado na caracterização in situ de materiais porosos, tais como pedras ou argamassas, permitindo obter a resistência mecânica do material em profundidade com muito pouca intrusão. O método tem sido escassamente usado na caracte...

This paper presents some examples of recent experiences carried out with a portable instrument, the DRMS device (Drilling Resistance Measurement System), for the assessment of consolidation performance. This method has been utilized successfully on the study of consolidation effect of some commercial products when applied on carbonate stones and wa...

The paper focuses on the study of barium hydroxide applied to two high porosity limestones from Portugal (Ançã stone, with 27% porosity) and Italy (Lecce stone, with 37% porosity), both in the laboratory and on site. The results show that barium hydroxide acts both through carbonation with atmospheric CO2 and by replacing calcium for barium in the...

The paper analyses the potential of blended lime-cement mortars to substitute blended lime-natural hydraulic lime mortars as repair mortars in restoration works, since the availability of natural hydraulic lime is reduced in many countries, unlike cement. The study focuses on the pore structure of both types of blended mortars and its implications...

Os rebocos antigos são compostos por várias camadas de argamassa de composições distintas, adaptadas às funções específicas de cada camada. O ligante adotado era habitualmente a cal aérea. Estes rebocos registam com frequência problemas de perda de coesão das argamassas, que, em algumas situações, podem ser mitigados através de tratamentos de conso...

Blended mortars are commonly used in conservation practices with the purpose of reducing the disadvantages presented by both lime-based and cement-based mortars. However, there is a lack of knowledge concerning the behaviour of such mortars. This paper evaluates the influence of hydraulic lime content on the properties of blended lime-hydraulic lim...

The drilling resistance method provides the material strength profile in depth. Its use is widespread for soft homogeneous materials, like carbonate stones. The application in heterogeneous materials, like low-strength mortars, is not so well established due to the irregularity of the drilling profiles yielded. This paper demonstrates the viability...

Two carbonate stones and one granite in two alteration stages were treated with silanes and polysiloxanes to study the influence of the support, the relevance of the amount of product applied and the stability in time of the initial water repellent effect. This study shows that the support and the amount of product applied influence the initial eff...

This paper proposes the contact sponge method for assessing water absorption of mortars in renders: the moist sponge is placed against the material surface during a predefined period, at constant pressure. The mass difference of the sponge, before and after the test provides information on the water absorption characteristics of materials. The meth...

The drilling resistance test is a valuable tool, suitable for in situ characterization, as it provides the material strength profile in depth, with little intrusion. This unique feature enables assessing the strength and thickness of the layers in multilayer renders. Additionally, information about the bond quality between layers and between the wh...

The aim of this research work was to test the influence of stone properties, consolidation product, and application procedure on the potential harmfulness of consolidation on carbonate stones as assessed 1 through the impacts on colour and water absorption kinetics. This article contributes to understanding the immediate and delayed impacts of cons...

Fire safety is an important issue of buildings safety, especially when their fire load contents enhance the risks of fire deflagration. When existing timber structures are involved, the most usual way to improve its reaction to fire is to treat wood with fire retardants. This study focuses on the surface protection of existing timber roof structure...

The application of the drilling test on the characterisation of homogeneous stones is widely used, mainly on carbonate stones that are softer. The drilling revolution and penetration speed are important test parameters that are defined by the operator according to the hardness of the testing material. When in presence of heterogeneous materials com...

In the domain of heritage buildings conservation, interventions must be designed, whenever possible, to maintain existing materials instead of their replacement by new ones. The cohesion loss is a common problem of ancient mortars due to their characteristics (low mechanical resistance and high porosity) and to the exposure to deterioration agents....

O património construído deve ser preservado respeitando a sua autenticidade. Tendo esse princípio como orientação, as intervenções de conservação devem privilegiar, sempre que possível, a manutenção em obra dos materiais existentes em detrimento da sua substituição por novos materiais. Em termos práticos, e no caso concreto dos rebocos antigos, res...

Artificial salt crystallization tests are frequently used as a research tool estimator of the porous materials durability and susceptibility because salt weathering is one of the most important deterioration mechanisms that building materials undergo in a wide range of environments [1, 2]. Pressures created by salt crystallization in pores weaken t...

Compressive strength, porosity and two “in situ” techniques (ultrasonic velocity and rebound hardness test) are used for the characterisation of several aerial, hydraulic lime-based and cement-based mortars. Prismatic specimens and mortars applied as a brick render are used for the characterisation. A comparative analysis of the “in situ” test resu...

This article demonstrates the importance of treatment application procedures on the consolidation effectiveness obtained by comparison of the results obtained using three different consolidants on four carbonate stone types, and proposes a general methodology for assessing the potential effectiveness of consolidants in laboratory conditions. It str...

Consolidation of limestones with organic based products, including ethyl silicate, is still an uncertain operation and very few alternatives appear as promising. Inorganic products have been used in the consolidation of decayed marble surfaces, but their action in decayed porous limestones still remains to be demonstrated. The paper presents some p...

SUMMARY: In the framework of the Eu-Artech project a research study was carried out, aiming at developing “good conservation practices” based on inorganic products. Barium hydroxide and ammonium oxalate were studied and compared with ethyl silicate as a reference. Both treatments were applied on Gioia marble and in a porous limestone (Ançã stone) t...

SUMMARY: In the framework of the Eu-Artech project the action of an organoalkoxysilane coupling agent (aminopropyltriethoxysilane) was studied when applied as an integral blend in a solution of ethyl silicate on limestones and marble. Ançã and Lecce highly porous limestones and Carrara marble (Gioia type) were used as substrates. The consolidation...

Four types of carbonate stones and three consolidation products were used in a systematic study to assess the influence of the application procedures on the amount of product applied, as a primary step to evaluate consolidation treatments. Microdrilling, ultrasonic velocity and flexural resistance were used as performance indicators. The amount of...

Abstract The Renaissance portal in the Old Cathedral of Coimbra is built of limestones, some of them containing relevant amounts of clay minerals. The degradation state was very severe and the abandonment it suffered for decades has left it virtually crumbling in pieces. The study here presented is part of a broader study carried out in this portal...

The recent development of a new drilling machine in the framework of the EU project HARDROCK brought some interesting perspectives for the characterisation of decay profiles, for tracing old consolidating treatments and for evaluating new consolidants. The equipment executes a drill hole, typically 5 mm in diameter, down to 5 cm, under precisely de...

During the exterior conservation project of the Tower of Belem, Lisbon, it was noticed that although most of the Lioz limestone used in its construction was in good condition, some specific areas presented severe powdering and flaking deterioration patterns. These are mainly due to the effect of natural weathering, including anthropogenic air-pollu...

It studies the behaviour 4 water repellents applied in granite substrates and submitted to ageing tests. Contact angle, microdrops absorption time, water absorption, weight loss, and colour change were used as monitoring parameters.

It presents the assessment of effectiveness and harmfulness of 4 water repellents applied in granite substrates. Contact angle, microdrops absorption time, water absorption, water vapour permeability, and colour were used in the assessment.