Francisco Manuel Carvalho Pinto Fernandes

Handmade Clay Bricks: Chemical, Physical and Mechanical Properties

The clay brick masonry that is much used in historical structures often is in a rather poor state of conservation. In order to intervene correctly in these buildings, it is convenient to characterize the old material. For this purpose, a large sample of clay brick specimens from the 12th to 19th centuries were collected from six Portuguese monasteries and were characterized chemically, physically, and mechanically. A large variability of the properties was found. Additionally, a sample of handmade new bricks, which are commonly used as replacing material, was also analysed. The results were compared with the old bricks, and these new bricks could be possibly adequate as substitution bricks. Still, significant differences were found in chemical composition and in water absorption and porosity, which are much lower in modern handmade bricks. With respect to mechanical properties, the range of values found in old bricks was rather high and the degree of deterioration exhibited a large scatter, meaning that a conclusion is hardly possible.

Application of radar techniques to the verification of design plans and the detection of defects in concrete bridges

Non-destructive tests (NDT) are an essential tool used in special inspections to gather detailed information about the condition of a bridge. The inspection of bridge decks is a critical task, and, currently, can be successfully carried out using a wide range of NDT techniques. Nevertheless, some of these techniques are excessively expensive and time consuming. One of these techniques, the ground penetrating radar (GPR), has been used for some decades in the non-destructive inspection and diagnosis of concrete bridges. GPR is useful to find general information about the true position of reinforcement and tendon ducts, and check the quality of the construction and materials. A significant number of reinforced and prestressed concrete bridges are deteriorating at a rapid rate and need to be repaired and strengthened. During these rehabilitation processes, designers are often faced with a lack of original design plans and unawareness of the real position of reinforcement and tendon ducts. In this paper, three case studies of the use of GPR techniques for the inspection of concrete bridges are presented and analysed. The main aim of this research is to show the strong need and usefulness of these techniques, which can provide non-visible information about structural geometry and integrity required for strengthening and rehabilitation purposes.

Ancient Clay Bricks: Manufacture and Properties

Clay brick masonry is one of the oldest and most durable construction techniques used by mankind. Masonry consists of manually built stable stacks of small elements, with or without mortar. It was a fundamental building material in the Mesopotamian, Egyptian and Roman periods. During the Roman period, the use of clay brick increased and became specialized in order to maximize its benefits. Clay brick masonry continued to be used during medieval and modern times. Despite several modifications of the clay brick uses, shape and manufacture along thousands of years of constant evolution, the simplicity that made its success remained.

Practical implications of GPR investigation using 3D data reconstruction and transmission tomography

Non-destructive investigation using ground penetrating radar is becoming more popular in the inspection of civil structures. Currently, traditional 2D imaging is used as a preliminary tool to find possible areas of interest for more detailed inspection, which can be accomplished by more advanced techniques like 3D image reconstruction or tomography. In this paper, a general overview of the work done at University of Minho regarding these techniques is presented, together with their limitations and advantages over typical radargrams, with implications for civil engineering applications. For this purpose, data acquisition on two large masonry walls and one large concrete specimen have been carried out, using reflection mode, 3D reconstruction and transmission tomography. The specimens have been specially built for non-destructive inspection techniques testing, incorporating different materials and internal voids. Radar tomography and 3D image reconstruction techniques provided much more detailed information about structural integrity and shapes and location of the voids, when compared to 2D imaging originally used for potential target identification.

Characterization and Damage of Brick Masonry

Clay brick is among the oldest used masonry materials. Given the technological evolutions since the industrial revolution, old bricks are much different from todays’ bricks. This chapter provides a review on the chemical, physical and mechanical properties of mortar, brick and masonry. In addition, a discussion on the possible causes of damage and the usage of expert systems in building diagnostics is also given.

Luiz Bandeira Bridge: Assessment of a Historical Reinforced Concrete (RC) Bridge

The Luiz Bandeira Bridge is located along the Portuguese national road EN333-3, breaching the valley of the Vouga River, just northeast of the small village Sejães, in the district of Oliveira de Frades. It is considered to be the oldest concrete bridge in use in Portugal, and one of the oldest in Europe. Since this bridge is at risk of disappearing due to a construction of a dam, the Department of Civil Engineering of the University of Minho decided to launch a comprehensive study of Luiz Bandeira Bridge, in an attempt to preserve the memory of the past cataloguing the heritage for future reference. These studies include historical, geometric, and damage surveys; the physical and chemical characterization of existing structural materials; the assessment of the reinforcement detailing; and dynamic characterization by determining the main frequencies and vibration modes and safety level. This work presents a comprehensive overview of the most important results of these studies.

Tube-jack testing: semi-irregular masonry wall testing

The authors would like to acknowledge the Fundacao para a Ciencia e Tecnologia, which supported this research work as a part of the Project “Improved and innovative techniques for the diagnosis and monitoring of historical masonry”, PTDC/ECM/104045/2008. The authors would also like to thank Claudia Almeida for her help with performing the tests.

Evaluation of Structural Intervention in the Quartel das Esquadras, Almeida (Portugal)

ABSTRACT The “Quartel das Esquadras” is an 18th century infantry barrack located within the limits of the bulwarked fortress of Almeida, in Portugal. An ongoing adaptive reuse project of the building aims to recover its full capacity and also its importance, by implementing a variety of new uses. The architectural intervention results in the need of the structure to withstand new and diverse imposed loads. As the current configuration of the structure will be altered, the main objective of this article is to evaluate the suitability of some of the proposed structural interventions. The current condition has been characterized following a multidisciplinary approach comprising historical research, visual inspection, non-destructive testing, and structural analysis to identify the possible sources of major structural problems. A portion of the building particularly affected by the alterations has been selected to carry out structural analysis. A comparative safety assessment of the selected area in both current and altered condition has been done through finite element modelling and nonlinear static analysis, resulting in an identification of the weaker points against the new implemented loads and alterations. Finally, proposals for the implementation of the studied intervention, as well as recommendations for future research and analyses, have been given.

Geometric and Radiometric Analysis of TLS Point Clouds to Diagnose the Conservation State of Historical Constructions. Case of Study in the Master Gate of San Francisco, Almeida, Portugal

This paper summarizes the experimental results obtained after the radiometric and geometric analysis of the 3D point cloud model of one of the most emblematic constructions inside the Fortress of Almeida (Portugal): the Master Gate of San Francisco. The data acquisition was performed with a Faro Focus 120 Terrestrial Laser Scanner previously calibrated. The evaluation of the construction involved the combination of both approaches through the use of K-Means unsupervised classification approach, the Efficient RANSAC Shape Detector and the CANUPO algorithms. As a result, an accurate identification of a wide diversity of indicators of damage (salt crusts, black crusts and deformations, among others) was achieved. The results of the proposed semi-automatic methodology have allowed, in a non-intrusive way, a robust identification of the different degradation mechanisms that are promoting the blistering of that construction’s masonry.

Integrated structural safety analysis of San Francisco Master Gate in the Fortress of Almeida

ABSTRACT After more than 300 years of being exposed to human and nature actions the Master Gate of San Francisco in Almeida, Portugal, has sustained visible extended damage. Although its importance, as a historical monument, is undeniable, no attempts have been done so far to determine its level of safety. In this article, several models are developed in order to achieve this goal. A brief description of the Gate’s history is presented followed by a summary of the inspection and diagnosis procedures employed in this study and the results obtained from them. Later, the type of numerical models selected are discussed as well as the methodologies used to represent damage. Finally results from the numerical models are presented in a first attempt to identify the safety level of this historic construction. Results indicate that although the structure has lost a great percentage of its original capacity is still safe.