Ana Sofia Guimarães

Rising Damp in Walls: Evaluation of the Level Achieved by the Damp Front

Treating rising damp in the walls of historical buildings is complex because moisture transfer into the walls of old buildings in direct contact with the ground leads to the migration of soluble salts. This work analyzes rising damp using concepts and methods of unsaturated moisture flow theory, and a numerical validation study. A simple analytical model describes the rising damp front for the simplified situation of a monolithic wall. The influence of wall thickness, boundary conditions, wall composition, and material properties, such as porosity and sorptivity, are analyzed in detail.

Analysis and Monitoring of the Drying Process of a Hygro-Regulated Wall Base Ventilation System Implemented in a Historical Church to Control Rising Damp

Treating rising damp in the walls of historic buildings is a very complex procedure and the traditional techniques currently used to minimize rising damp are not effective or too expensive, in particular when dealing with walls of considerable thickness and heterogeneous materials. This work presents the results of an in situ application of the hygro-regulated wall base ventilation system to control rising damp in a historical church located in northern Portugal. The main purpose is to validate the wall base ventilation technology for treating rising damp in very thick and heterogeneous walls. The analytical model used well describes the observed features of rising damp in building walls, verified by in-field tests, which contributed to simple sizing of the hygro-regulated wall base ventilation system to be implemented in historical buildings.

Salt Damage and Rising Damp Treatment in Building Structures

Salt damage can affect the service life of numerous building structures, both historical and contemporary, in a significant way. In this review, various damage mechanisms to porous building materials induced by salt action are analyzed. The importance of pretreatment investigations is discussed as well; in combination with the knowledge of salt and moisture transport mechanisms they can give useful indications regarding treatment options. The methods of salt damage treatment are assessed then, including both passive techniques based on environmental control, reduction of water transport, or conversion to less soluble salts and active procedures resulting in the removal of salts from deterioration zones. It is concluded that cellulose can still be considered as the favorite material presently used in desalination poultices but hydrophilic mineral wool can serve as its prospective alternative in future applications. Another important cause of building pathologies is the rising damp and, in this phenomenon, it is particularly severe considering the presence of salts in water. The treatment of rising damp in historic building walls is a very complex procedure and at Laboratory of Building Physics (LFC-FEUP) a wall base hygroregulated ventilation system was developed and patented.

Advances in Building Technologies and Construction Materials 2016

CONSTRUCT-LFC, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, -ákurova 7/2077, 166 29 Prague 6, Czech Republic Department of Mechanical Engineering, Federal University of Campina Grande, Av. Apŕıgio Veloso, 882, 58429-900 Campina Grande, PB, Brazil

Treatment of Rising Damp in Historical Buildings

Humidity is one of the main causes of decay in buildings, particularly rising damp, caused by the migration of moisture from the ground through the materials of the walls and floors via capillary action. This water comes from groundwater and surface water. The height that moisture will reach through capillary action depends upon factors such as the quantity of water in contact with the particular part of the building, surface evaporation conditions, wall thickness, building orientation and the presence of salts. In historic buildings, rising damp is particularly difficult to treat, due to the thickness and heterogeneity of the walls. Traditional methods of dealing with this problem (chemical or physical barriers, electro-osmosis, etc.) have proved somewhat ineffective. There is therefore a need to study new systems. In recent years, experimental research into the effectiveness of wall base ventilation systems (natural or hygro-regulated) to reduce the level of rising damp, conducted at the Building Physics Laboratory, Faculty of Engineering, University of Oporto, has yielded interesting results. Numerical simulation studies, using the software WUFI-2D, have given similar findings. This paper describes a new system for treating rising damp in historic buildings based upon a hygro-regulated wall base ventilation system, and analyses the results obtained following implementation of the system in churches in Portugal. It was defined criterions to avoid condensation problems inside the system and crystallizations/dissolutions problems at the walls.

A Wall Base Ventilation System Applied at Different Wall Geometries—Numerical Simulation of the Evaporative Process

This work describes the moisture transfer process between a moving air flux and a saturated cylindrical pillar, in alignment with the direction of flow. Numerical solution of the partial differential equation describing moisture conservation gave the concentration field near the saturated surface and the mass transfer flux was integrated to give values of the Sherwood number as a function of the relevant parameters. An expression is proposed that accurately describes the dependence found numerically between the value of the Sherwood number and the values of Peclet number and aspect ratio, L/d 1, of the cylindrical pillar in contact with a wall base ventilation system, the Humivent device. For large enough cylinder diameter, the problem degenerates into mass transfer from a planar surface and the same equation applies, with L/d 1 = 0. The importance of the equation was demonstrated through the application of a practical example, namely, in the drying process of a porous media.

Characterization of a Hygro-Regulated Wall Base Ventilation System for Treatment of Rising Damp

The treatment of rising damp in the walls of historical buildings is very complex, due to the thickness and heterogeneity of the walls. The techniques traditionally used for dealing with this problem (such as watertight barriers, injection of hydrofuge products, etc.) have sometimes proved ineffective, and that is why it is necessary to find a new approach. In recent years, the Building Physics Laboratory at the Faculty of Engineering, University of Porto has been conducting experimental research on the effectiveness of the wall base ventilation system, using natural or mechanical higro-regulate systems to reduce the level of the damp area. This experimental research and the simulations that were performed, clearly show that wall base ventilation is a system with potential. This paper presents the characterization of the hygro-regulated systems operation based on experimental studies developed in laboratory, which allowed the influence of the velocity of the air, condensation risk and the possibility of salt crystallization.

Development of virtual reality game-based interfaces for civil engineering education

Virtual Reality (VR) is gradually becoming a part of the life of the average person as hard-ware prices become more affordable for the end user. A growing variety of hardware allows users to engage in a series of immersive experiences for ludic, educational or even professional activities. In this regard, the diversity of affordable solutions could provide an alternative to highly immersive, but expensive environments such as, CAVE experiences [1]. The development of VR technologies is starting to spread its influence to the AECO (Architecture, Engineering, Construction and Operations) sector through the creation of new work methodologies and techniques, as well as original interfaces for communication. Creating new tools for the discussion of topics and providing collaborative work among participants with different backgrounds provides opportunities not only for the industry, but also for applications in education. The development of VR applications and its outcomes, regarding the acceptance (or lack of it) from the students will be the focus of this paper. The description of three case studies will be fully detailed, providing data analysis from each one of the tests conducted.

Wall-Base Ventilation System to Control Rising Damp: A Case Study of Vilar de Frades Historical Church in Portugal

Moisture transfer in the walls in direct contact with the ground leads to the migration of soluble salts, which are responsible for many building pathologies. The treatment of rising damp in historical heritage walls is a very complex procedure. The traditional techniques currently used to minimize rising damp are, in most cases, slight effective or too expensive, especially when dealing with walls of considerable thickness and/or heterogeneous materials such as the historical monuments. The main purpose of this work is to present the experimental results of the rising damp treatment conducted, over 3 years, in the Vilar de Frades Church, in northern Portugal, using the wall-base ventilation technology. The results showed that, for this particular climate conditions, the best solution is to operate seasonally, with outside air admitted to the system during summer months and inside air admitted to the system during winter months.

Degradation Control of Walls with Rising Damp Problems

Degradation in walls of Historical Building with rising damp is a complex problem to solve, due to the thickness and heterogeneity of those walls. The traditionally treatment techniques used (such as watertight barriers, injection of hydrofuge products, etc.) show, sometimes, to be ineffective or too expensive, justifying the need to find a new approach. Experimental studies validate the effectiveness of a new treatment technique applied to the walls of old buildings wall base ventilation system. Building Physics Laboratory (LFC) is developing a model of this technique. The sizing of the treatment system is based on knowledge of the characteristics of the wall, of the geometry of the ventilation system and of the building being dealt with. In this work it is described the moisture transfer process between the moving air flux, inside the system, and the wall. Experimental results were used to validate the mathematical solution and the values obtained are very similar.