PROJECTS

Analysis of the influence of the support properties on the performance of the rendering mortar, in order to be able to know the characteristics of the mortar after application to the support, from the knowledge of its characteristics determined in the laboratory.

SCOPE

The studies of mortar properties are usually conducted on laboratory specimens with standard dimensions, curing conditions and tests. However, when mortars are applied to the supports, their behaviour will not be exactly the same. What are the parameters that influence this behaviour? Which characteristics have the greatest influence: those of mortars or those of supports? How do these characteristics influence the behaviour of mortars? Will application and curing conditions have an influence on this behaviour? Will the characteristics of mortars change over time differently depending on the type of support? These are some of the questions that have not yet been answered rigorously and that are addressed in this project.

MAIN OBJETIVES

The main objective of this project is to analyse the influence of the support properties, namely the porous structure, behaviour in the presence of water/water vapour and mechanical performance, on the characteristics of the rendering mortar.

Another objective is to be able to know the characteristics of a mortar after application to the support, from the knowledge of its characteristics determined in the laboratory and which are usually provided in the technical specifications of manufacturers.

As a final objective to be achieved, it is intended to develop mathematical expressions that allow, from the values of the characterization parameters determined in the laboratory, to estimate these same parameters for mortars after application to the supports.

PROJECT ACTIVITIES AND EXPECTED RESULTS

The IF MORTAR project is organized into six distinct activities. These activities and their expected results are described below.

Activity 1 – Start-up and literature review
Initially, a literature review will be conducted. The types of mortars and supports to be analysed will also be selected, taking into account the materials most commonly used in new construction and old buildings in Portugal. Since it is also intended to analyse mortars for smoothing and finishing, mortars with aggregates with various particle sizes will be considered.

Activity 2 – Characterization of the mortars in the moulds
Mortars will be characterized in the laboratory according to existing standards. The characterization of mortars will begin with the characterization of their constituents, namely sands, binders and possibly some additives. The physical, hygrothermal and mechanical characterization of the mortars will be conducted in several phases: after normalized cure, after 120 and 365 days. Some test pieces will be subject to "accelerated aging" in climate chambers, according to EN 1015-21.

Activity 3 – Characterization of the mortars applied to the supports
The activity will begin with the characterization of all the supports. This characterization will include the determination of density, open porosity, capillary water absorption and water vapour permeability. Porosimetry will also be determined. After this characterization, one layer of each type of mortar will be applied to each type of support. The specimens will remain in the same conditions as those established for the laboratory specimens, i.e. 28/60 days, 120 days and 365 days. These specimens will also be subjected to accelerated aging. After the curing times, the mortars will be detached from the supports and the same properties indicated for the mortars hardened in the laboratory moulds will be determined.

Activity 4 – Interface analysis
In the context of this task, it is intended to evaluate the type of structures and compounds formed at the mortar-support interface. The bond that is created between the supports, with different porous structures, and the reactive components of mortars will be evaluated using a methodology that involves several advanced experimental techniques. The results obtained will be correlated with the performance results obtained in the previous tasks, in order to establish the best operative and mortar formulation practices in real application contexts.

Activity 5 – In-situ applications
Mortars will be applied to large supports subjected to real weather conditions (outdoor walls). To this end, only a few mortars and supports will be selected. The tests to be performed on the mortars thus exposed will be similar to those described for mortars applied to the supports in the laboratory. In addition, more specific tests will also be performed, indicated for in-situ application. The results obtained will be compared with those determined for the mortars hardened in the moulds and for the mortars applied in the laboratory to small supports.

Activity 6 – Development of final mathematical formulations
The objective of this task is to develop mathematical expressions that estimate the characteristics of mortars after application to the supports, from the values of these characteristics determined in the laboratory for standardized specimens. The fundamental characteristics for which mathematical expressions will be developed are those which are usually referenced in the technical specifications of pre-dosed mortars and which are normally required for CE marking. Using these expressions, it will be possible to choose, in a more adequate and rigorous way, mortars that will have the intended characteristics after application.

MAIN RESULTS

Activity 1 – Start-up and literature review
A literature review was carried out, including new scientific developments relevant to the project, especially on the mechanisms involved in the interfaces of multiphase systems.

The mortars and supports to be studied were selected, namely: i) cement, hydraulic lime and air lime mortars (traditional and industrial); ii) hollow ceramic brick, solid ceramic brick, concrete slab, lightweight concrete block, concrete block and natural stone supports.

Activity 2 – Characterization of the mortars in the moulds and Activity 3 – Characterization of the mortars applied to the supports
The selected mortars were prepared and prismatic and cylindrical specimens were made, according to the applicable standards, for the initial characterization of mortars. The mortars were also applied on the supports. The mortars hardened in the moulds (prismatic and cylindrical specimens) and the mortars hardened on the supports were subjected to similar curing conditions, according to the applicable standards. Some mortars were subjected to accelerated ageing or to a greater curing time (365 days).

After curing, the mortars hardened in the moulds and the mortars detached from the supports were characterized. Tests were also conducted to characterize the supports.

The characteristics of the mortars hardened on the supports were compared with those of the mortars hardened in the moulds. With the results obtained it was possible to verify how different supports influence the behaviour of different mortars. It was found that different porous structures of the support, namely different pore diameter distributions, influence differently the characteristics of the mortars. For example, ceramic supports, which have more capillary pores than concrete supports, tend to lead to greater compactness of the applied mortar.

Activity 4 – Interface analysis
Some specimens similar to those tested in the scope of previous activities were made for microstructural analysis. These specimens were subjected to X-ray computed microtomography (micro-CT), X-ray diffraction (XRD) and scanning electron microscope (SEM) tests. Both the mortars applied on the supports and the mortars hardened in the standard moulds were tested.

The porous and solid structures of the mortars were examined, particularly at the interface with the support, and the correlation between the microstructural and macrostructural properties of the mortars was analysed. Some determining parameters for the adhesive strength, in the interface zone, were identified, namely: mortar/support contact area, porosity (type, size and distribution of pores), surface regularity and binder compactness in the contact region. It was also concluded that a thinner and more compact mortar layer is formed at the interface and that there is an increase in porosity as the distance from the interface increases. It was also possible to notice the formation of smaller and irregularly shaped pores when comparing the applied mortar with the reference mortar.

Activity 5 – In-situ applications
Some of the specimens composed by pre-dosed cement mortar applied to the different supports were placed outdoors, under real weather conditions, until completing 300 days.

Mortar specimens were detached from the supports and the same tests conducted on the specimens subjected to normal curing and accelerated aging were conducted on these specimens. Mortars applied on the supports were subjected to the ultrasonic pulse velocity test and water absorption under low pressure test (with Karsten tubes).

The results obtained were compared with those of the mortar hardened in the moulds and of the mortar applied on the supports and subjected to normal curing and accelerated aging. It was possible to conclude that the mortar exposed to the weather became more porous, more permeable to water vapor, with higher capillary water absorption and lower compressive strength.

Activity 6 – Development of final mathematical formulations
Machine learning algorithms were used to predict the characteristics of the support that lead to the performance of applied mortar.

For this, a database with experimental results obtained for 410 samples of the pre-dosed cement mortar applied to five the different supports was generated. These samples were subjected to tests (conducted in the scope of Activities 2 and 3) which evaluated the following characteristics: bulk density, open porosity, capillary water absorption coefficient, drying index, and compressive strength. This database fed machine learning algorithms (random forest, artificial neural network and support vector machine) to predict the characteristics of supports in classification and regression mode. It was concluded that, for each characteristic evaluated, there is an algorithm with better performance and it was found that the characteristics of the “ideal” support for this mortar (the support on which the mortar presents better performance) are similar to those of the concrete support

COMMUNICATIONS LIST

Torres I, Flores-Colen I. 2018. Estudo experimental e numérico da interface argamassa-suporte. 3º Simpósio de Argamassas e Soluções Térmicas de Revestimento, 11-12 October 2018, Itecons, Coimbra.

Torres I, Matias G, Paulo D. 2018. Influência da presença de chapisco nas características das argamassas aplicadas. 3º Simpósio de Argamassas e Soluções Térmicas de Revestimento, 11‑12 October 2018, Itecons, Coimbra.

Torres I, Flores-Colen I, Silveira D. 2019. Discussão de métodos de avaliação da interface de argamassas e suportes. XIII SBTA – Simpósio Brasileiro de Tecnologia das Argamassas, 11-13 June 2019, Goiânia.

Silveira D, Torres I, Flores-Colen I, Travincas R, Matias G. 2019. Interface argamassa-suporte: Análise das características físicas. XIII SBTA – Simpósio Brasileiro de Tecnologia das Argamassas, 11-13 de junho de 2019, Goiânia.

Torres I, Silveira D, Flores-Colen I, Pinto R, Matias G. 2019. Influence of the support on the mechanical characteristics of the applied mortars. 5th Historic Mortars Conference, 19-21 June 2019, Pamplona.

Travincas R, Flores-Colen I, Pereira M, Maurício A, Torres I. 2019. Microstructural analysis of cement-based mortars combining X-Ray Microtomography, XRD and FTIR. Ball, R., Dams, B., Ferrandiz-Mas, V., Ke, X., Paine, K., Tyrer, M. & Walker, P. (eds) 2019, 39th Cement and Concrete Science Conference 2019, University of Bath, Bath, UK.

Travincas R, Pereira M, Flores-Colen I, Maurício A, Torres I. 2020. Study of the mortar-support interface by advanced characterization techniques. REHABEND, 24-27 March 2020, Granada.

Travincas R, Silveira D, Flores-Colen I, Torres I, Matias G. 2020. A influência do suporte em tijolo cerâmico na resistência à água das argamassas aplicadas. V Congresso Internacional na “Recuperação, Manutenção e Restauração de Edifícios”: CIRMARE 2020, 08-10 September 2020, Rio de Janeiro.

Torres I, Flores-Colen I, Silveira D, Travincas R. 2020. Influence of grid presence in the characteristics of applied mortars. DBMC 2020: XV International Conference on Durability of Building Materials and Components, 20-23 October 2020, Barcelona.

Silveira D, Torres I, Flores-Colen I, Travincas R. 2020. Influence of lightweight concrete block support on physical and mechanical characteristics of applied mortars, DBMC 2020, XV International Conference on Durability of Building Materials and Components, 20-23 October 2020, Barcelona.

Pereira M, Flores-Colen I, Travincas R, Maurício A, Torres I. 2020. Micro-CT no estudo da interface argamassa-suporte de tijolo cerâmico, placa de betão e bloco de betão leve. ENCORE 2020 – 4º Encontro de Conservação e Reabilitação de Edifícios, 3-6 November 2020, Lisbon.

Torres I, Flores-Colen I, Braz J. 2020. Comportamento de argamassas de cal aplicadas sobre tijolo maciço e pedra calcária. ENCORE 2020 – 4º encontro de conservação e reabilitação de edifícios, 3-6 November 2020, Lisbon.

Torres I, Flores-Colen I, Silveira D, Travincas R, Matias G. 2020. Interface argamassa-suporte: análise das características físicas com base em várias campanhas experimentais. Ambiente Construído, 20(3), 331-342.

Torres I, Matias G, Faria P. 2020. Natural hydraulic lime mortars - The effect of ceramic residues on physical and mechanical behaviour. Journal of Building Engineering, 32, 101747.

Torres I. 2020. Argamassas laboratoriais versus argamassas aplicadas. Revista Materiais de Construção, 191, 66-67.

Torres I, Flores-Colen I, Braz J, Bellei P. 2021. Análise do comportamento de argamassas de cal aérea aplicadas em suportes de tijolo maciço e pedra calcária. CONREA’21, 30 June - 1 July 2021.

Silveira D, Soares K, Torres I, Flores-Colen I, Travincas R. 2021. Performance of hydraulic lime mortars applied on a traditional substrate. CEES 2021: 1st International Conference on Construction, Energy, Environment and Sustainability. 12-15 October 2021.

Matias G, Torres I, Bellei P, Flores-Colen I, Silveira D, Travincas R. 2021. Influence of the substrate in the porosimetry of hardened mortars. CEES 2021: 1st International Conference on Construction, Energy, Environment and Sustainability. 12-15 October 2021.

Torres I, Travincas R, Flores-Colen I, Belei P. 2021. The influence of ceramic brick support on water properties of applied industrial mortars. CEES 2021: 1st International Conference on Construction, Energy, Environment and Sustainability. 12-15 October 2021.

Bellei P, Torres I, Flores-Colen I, Travincas R, Silveira D. 2021. Study of cement mortars with different particle size sands after application to ceramic brick substrate. CEES 2021: 1st International Conference on Construction, Energy, Environment and Sustainability. 12-15 October 2021.

Travincas R, Torres I, Flores-Colen I, Mendes M, Silveira D. 2021. Machine learning applied to mortars: a discussion on possible applications. CEES 2021: 1st International Conference on Construction, Energy, Environment and Sustainability. 12-15 October 2021.

Travincas R, Pereira M, Torres I, Maurício A, Bellei P. 2021. Microtomografia de Raios X aplicada a argamassas. 5CNEND - 5ª Conferência Nacional em Ensaios Não Destrutivos, 16-17 December 2021, Coimbra.

Silveira D, Gonçalves A, Flores-Colen I, Veiga R, Torres I, Travincas R. 2021. Evaluation of in-service performance factors of renders based on in-situ testing techniques. Journal of Building Engineering, 34, 101806.

Moura R, Bellei P, Torres I. 2021. Production of Mortar Blocks with Translucent Potential using Optical Fiber in Civil Construction. IOSR Journal of Mechanical and Civil Engineering, 18(1), 12-17.

Belei P, Arromba P, Flores-Colen I, Veiga R, Torres I. 2021. Influence of brick and concrete substrates on the performance of renders using in-situ testing techniques. Journal of Building Engineering, 43, 102871.

Torres I, Flores-Colen I, Braz J, Bellei P. 2021. Análise do comportamento de argamassas de cal aérea aplicadas em suportes de tijolo maciço e pedra calcária. Revista Pedra & Cal, No. 70, January /June 2021.

Soares K, Torres I, Flores-Colen I. 2021. Argamassas de cal aplicadas em suportes tradicionais. Revista Construção Magazine, Noº 106, November/December 2021, 08-13.

Torres I, Flores-Colen I. 2022. Argamassas produzidas em moldes versus argamassas aplicadas sobre suportes. IV Simpósio de Argamassas e Soluções Térmicas de Revestimento. 10-11 March 2022, Coimbra.

Travincas R, Bellei P, Torres I, Flores-Colen I. 2022. Avaliação da porosidade e permeabilidade ao vapor de água de argamassas de revestimento. IV Simpósio de Argamassas e Soluções Térmicas de Revestimento. 10-11 March 2022, Coimbra.

Soares K, Torres I, Flores-Colen I. 2022. Argamassas de cal aplicadas em suportes tradicionais. IV Simpósio de Argamassas e Soluções Térmicas de Revestimento. 10-11 March 2022, Coimbra.

Bellei P, Filho F, Flores-Colen I, Torres I. 2022. Avaliação da adesão de revestimentos de argamassa estabilizada em obra. 10-11 March 2022, Coimbra.

Travincas R, Mendes M, Flores-Colen I, Torres I, Bellei P. 2022. Previsão da porosidade aberta do suporte em função das características da argamassa aplicada. 3º Congresso de Ensaios e Experimentação em Engenharia Civil – Tecnologias Inteligentes, 21-23 February 2022, Caparica.

Travincas R, Bellei P, Torres I, Flores-Colen I, Matias G, Silveira D. 2022. The Use of Fibreglass Mesh in the Experimental Characterisation of Applied Coating Mortars. Coatings, 12, 1091.

Torres I, Flores-Colen. 2022. IF Mortar. Argamassas laboratoriais versus argamassas em serviço. Revista Pedra & Cal, Nº72, January/June 2022, 46-48.

Travincas R, Pereira M, Torres I, Maurício A, Silveira D, Flores-Colen I. 2023. X-ray microtomography applied to mortars: Review of microstructural visualization and parameterization. Micron, 164, 103375.