Building Pathologies: Experimental Campaigns and Numerical Procedures

The moisture transport in brick masonry is an important phenomenon in several deterioration mechanisms. However, is a very complex process and is influenced by many physical phenomena. Investigation of the moisture transfer through a building wall, which in general, consists of multiple layers, presumes knowledge about the continuity between layers. In this study, three types of contact configurations were analysed, as follows: Hydraulic contact, Perfect contact, and Air space. Therefore, to understand the moisture transport in brick masonry the moisture transport through the interface of materials was analyzed. This was done for samples of brick-cement mortar, brick-lime mortar, and air space between brick-layers, as well as for samples with different interface location heights and different mortar thicknesses and air space. Mainly, the present work is concerned to simulate the hygrothermal behaviour across brick–mortar and brick-brick interfaces to compare the results with the laboratory analysis. The numerical simulations of brick–mortar and brick-brick samples were performed with the hygrothermal simulation software WUFI-2D. The data used to run the simulations were taken from the wetting experiments on the samples; the corresponding moisture content profiles were measured using gamma-ray spectrometer. Although the mechanisms of moisture transport in a single building material have been and continue to be extensively studied, the hydraulic characteristics of the interface at different types of contacts between materials are still poorly comprehended and for this reason, the simplified assumption of perfect contact, is widely used in hygrothermal models. In general terms, the assumption of perfect contact implies that the interface will have no effect on moisture transport. In comparison, the imperfect contact assumption implies that the interface between building materials will resist moisture transport. However, comparisons between experimental and numerical results were used to investigate whether the perfect contact assumption is appropriate for real samples.

The drying process depends on internal and external factors such as temperature, relative humidity, the critical water content of the material, and the water transport properties in the liquid and vapor phases. However, the interface phenomena observed in multi-layered building components, as brick–mortar composites, or mortar-brick-insulation-mortar solutions, contribute to obtaining different values that result from the moisture transfer considering different materials/layers separately. The interface phenomena promote a hygric resistance which means that becomes a slowing moisture transport across the material interface. In this work a numerical study was carried out in order to analyse two different ceramic brick blocks with different interfaces, hydraulic contact interface, perfect contact interface, and air space), at different interface heights. The data used to run the simulations were taken from the wetting experiments on the samples; the corresponding moisture content profiles were measured using a gamma-ray spectrometer. Finally, the numerical results were compared with experimental values presented in the literature. The results showed an increase in the drying time constant for the materials with interface compared to monolithic materials. In addition, the farther away the interface is located from the base, the longer the drying time constant.

The work discusses the behaviour of isolated concrete bottle-shaped struts affected by internal expansion reactions (ISR). For that purpose, the numerical modelling of damaged concrete was performed using the Concrete Damaged Plasticity Model (CDPM) implemented in ABAQUS and validated the model through Sankovich’s tests. A procedure to automatically obtain the concrete plasticity and damage parameters, essential for CDPM, was developed in Matlab. The inputs were the characteristic compressive strength of the concrete, the equivalent length of the finite element mesh and the ratio between the plastic and inelastic compressive strains. The results showed that the CDPM could represent the load-bearing mechanisms of isolated concrete bottle-shaped struts for a range of several stress levels to which these elements may be subjected in the panels investigated. The numerical simulations for different expansion levels consistently captured the expected damage profile of the panels and the load corresponding to the formation of the first crack, the estimated crack opening, and the ultimate load. For the panels investigated, the reduction observed in the failure load reached values close to 70%, the increase of the tensile plastic deformation was more than 60%, and the maximum crack opening can reach an increase of 113% when compared with those observed experimentally in panels without internal swelling reactions.

The Basilica of Nossa Senhora da Penha is a building of great historical, cultural and religious importance in the city of Recife. The manuscript presents the main results of the reinforcement and structural restoration project of Basilica of Nossa Senhora da Penha, namely, the results associated with the injection techniques of cement grout, the structural safety research results, and the results of the use of carbon fibers. This work presents and discusses the history, current situation, original techniques and strategies used in the development of structural reinforcement design of both towers of the Basilica of Penha Church. Repair techniques poorly designed, conducted in 1981, along with lack of preventive maintenance, leaks and even the growth of bushes embedded in the masonry led to the instability of the towers of the Basilica of Penha Church. This paper, which combining integrated solutions in a historic monument reinforcement project, was initially challenging and became an important case study, possibly one of the first works using carbon fiber reinforcement in masonry. Another important contribution is the insertion of visitable galvanic protection that enables monitoring and possible replacement of sacrificial anodic inserts, keeping the protection active over time.

This work presents the results of an extensive non-destructive and destructive experimental campaign performed on thirty concrete columns of a 10 multi-storey residential building located in Paraíba, Brazil, built about 30 years ago, to assess the concrete quality to decide the need for retrofitting works. Ultrasound measurements, electrical resistivity, the corrosion potential of the reinforcements, depth of the carbonation front, void index, compressive strength, and capillarity absorption tests were performed. Results indicated the occurrence of corrosion of reinforcement, low concrete compressive strength, unappropriated reinforcement covering, and water absorption level close to 17% void index of about 31%. Tests in drilled concrete cores extracted corroborated the non-destructive test results with average compressive strength significantly low close to 12 MPa, a value significantly lower than the design characteristic strength, i.e., 20 MPa. The joint realization of non-destructive and destructive tests proved to be an efficient strategy for obtaining relevant information for the diagnosis of pathologies in reinforced concrete elements.

Due to the clinkerization process during the Portland cement production, large amounts of CO₂ are emitted, increasing the effects related to climate change, consequently, the seek for alternatives to mitigate these emissions are necessary. The use of supplementary cementitious materials (SCM) to partially replace Portland clinker/cement has been the subject of different research, including the use of LC³ (Limestone Calcined Clay Cements), where up to 50% of Portland clinker can be replaced. However, the cement industry has already used other SCM with pozzolanic activities in commercial cement and the interaction in LC³ still needs contributions. In this sense, this work evaluates the performance of concretes containing LC³ mixtures incorporating different SCM (silica fume, fly ash, sugarcane bagasse ash, and acai stone ash) regarding its durability by volumetric electrical resistivity and accelerated carbonation. The results showed that the presence of SCM in LC³ concretes increases the resistivity to ionic flow probably due to a refinement in the concrete microstructure, whereas, for carbonation, all concrete with LC³ presented higher carbonation fronts in relation to the reference concrete due to the low Portlandite availability to react with the CO₂ that penetrates into the concrete pores.