Extracting cores with diameters of 100 to 150 mm from masonry structures has emerged as a novel, less destructive method for assessing the mechanical properties of masonry units, particularly their compressive strength. Unlike traditional methods, such as using larger wallets, this approach requires less material and causes minimal damage to the original structure, which is critical when dealing with historical buildings. However, to obtain consistent and reliable results, certain parameters, specifically the dimensions of the core cap, must be carefully defined, as they significantly influence the overall behaviour of the samples. The study employs a detailed block-based modelling approach, incorporating zero-thickness cohesive elements at the brick-mortar interfaces. Additionally, tangential and normal contact interactions were defined between the cap and core components. The concrete damage plasticity (CDP) model, implemented in ABAQUS, has been adopted as the constitutive model to account for the nonlinear behaviour of brick, mortar, and cap. The results indicate that the length of the cap has a more pronounced effect on the sample’s mechanical behaviour than its height. Additionally, the study investigates the mechanical properties of the interface between the cap and the core, identifying friction and normal stiffness as critical factors. These findings provide valuable insights for optimizing the core capping process and improving the reliability of masonry mechanical property assessments, particularly in the preservation of historical structures.

Anatolia has been home to various long-standing civilizations, many of which have left historical monuments for future generations. The Cappadocia area, which covers over 5000 km² in Central Anatolia, Turkey, is home to several rock-cut constructions and masonry buildings built of tuff stone. Preserving these monuments, listed as UNESCO World Heritage sites, is critical for the region. This study focuses on the in-plane behavior of walls constructed of tuff stone and alkali-activated waste earth mortar, which is typical in the Cappadocia region. First, an experimental investigation is described. Second, a simplified block-based modeling technique is used to perform 3D nonlinear finite element analysis, which replicates the experimental results. The findings of the numerical modeling approach were then compared to experimental data, emphasizing the lateral load-displacement response of masonry tuff stone walls. There was good agreement between the experimental and numerical results.

This paper presents the results of an experimental campaign carried out to characterise the mechanical properties of multi-wythe masonry infrastructure in the city of Amsterdam. Samples were extracted from a 1.2 m thick bridge’s pillar constructed in 1882. For the characterisation of shear and compressive properties of masonry, tests on cores with a 100 mm diameter were performed at the Stevinlaboratorium of Delft University of Technology. Samples were extracted along different locations in the wall thickness to evaluate the effect of exposure to environment conditions. Overall, the study provides a first insight on the mechanical properties of multi-wythe masonry city infrastructure and knowledge regarding the sampling and testing strategy for these structures. In turn, this will increase the knowledge on multi-wythe masonry, which is limited in literature, and will support the assessment of many infrastructures in typical Dutch canal cities.

Cracks are one of the most common expressions of damage in masonry structures. Aside from aesthetic issues, they can compromise the overall behaviour of the structure; therefore, they are undesirable and need to be repaired. The repointing technique is traditionally implemented in this context, especially in historical masonry. Nevertheless, future damage is not prevented and may arise again, thus requiring renewed repointing interventions. The paper describes a preliminary study conducted at Delft University of Technology to investigate the applicability of the innovative self-healing technology to enable an automatic repair of masonry cracks. A bacteria-based self-healing mortar, developed to repair existing concrete structures, was implemented to explore the capacity of couplets to recover their original strength and aesthetic aspect after multiple damaging events. Specimens built with calcium-silicate and clay bricks were subjected to subsequent cracking cycles using a crack-mouth-opening-displacement controlled bond-wrench test. Experimental results showed that self-repair, in terms of strength restoration and aesthetic filling of cracks, occurs even after multiple cracking cycles when the self-healing mortar is used with both types of bricks, optimizing the autogenous healing of cement-based mortars. In this context, the healing effectiveness tended to decrease as the crack width and the number of cycles increased. The effectiveness varied also according to the types of brick and healing environment used, e.g. under humid conditions (RH ~ 95%), 50% vs 80% of the original capacity was regained in fully separated couplets made respectively with clay and calcium-silicate bricks. This outcome provides the ground to delineate the remaining testing campaign.

The brick-to-mortar bond often represents the weakest link leading to cracking and failure of masonry structures. For this reason, the in-situ characterization of masonry’s flexural bond behaviour (here defined as flexural bond strength and flexural bond fracture energy), is essential for the assessment of existing buildings. Among masonry bond properties, the flexural bond strength is commonly determined on-site, given the minimal invasiveness of the so-called bond wrench test. However, often the reliability of the results is questioned inputting their large variability to the operator. The present study discharges this assumption by comparing the accuracy of various testing set-ups (manually-operated vs computer-controlled set-ups). Additionally, the influence of the specimen’s type (with/without head joints and couplets vs wallet) on the flexural bond strength assessment is studied providing preliminary correlation factors that can be of help for the in-situ measurement on single-wythe masonry. In addition, to obtain a complete description of the bond behaviour, a new test set-up able to determine the post-peak response is presented. Considerations regarding the dissipated bond fracture energy and its relation to the tensile fracture energy are provided with the support of literature data.

The present work aims at providing insights on the material characterization of multi-wythe masonry infrastructure, in particular exploring a through-thickness effect of mechanical properties and benchmarking the core testing as an efficient slightly-destructive testing method. An experimental campaign was carried out to characterize shear, compressive and bond properties of a 1.2-m thick bridge's pillar constructed in 1882 in the city of Amsterdam (the Netherlands). Both cores and rectangular samples (e.g. prisms, triplets, couplets) were extracted across different locations in the wall thickness to evaluate the effect of exposure to environment conditions and to verify the capability of core testing methods. Results show that the masonry close to the water side (external) showed higher values of elastic modulus and lower values of flexural bond properties with respect to masonry inside the pillar. As for the capability of core testing on multi-wythe masonry, generally cores would present similar compressive/shear properties compared with rectangular samples. Besides, bond patterns and dimensions of cores showed negligible effect on compressive properties; However, this needs to be extensively verified by considering other masonry typologies. Overall, the study provides a first insight on the mechanical properties of multi-wythe masonry urban infrastructure and knowledge regarding the sampling and testing strategy for these structures. In turn, this will increase the knowledge on multi-wythe masonry, which is limited in literature, and will support the assessment of many infrastructure in typical Dutch canal cities by providing input for calculation methods.

Bed joint reinforced repointing is a retrofitting technique for unreinforced masonry structures that is commonly applied in the Netherlands to repair settlement-induced damage. Using this technique, the bed joints of masonry walls are reinforced with steel rebars that are embedded in a high strength repair mortar. Due to the increase of induced seismic events in the northern part of the Netherlands, an experimental study was carried out at Delft University of Technology to investigate the performance of this retrofitting technique for combined settlement and seismic loading. This paper aims to simulate the experimental results, with a focus on the comparison of different finite element modelling approaches for studying both un-strengthened and strengthened full-scale tested walls. To that end, three different models are investigated – comprising both macro (continuum) and simplified and detailed micro (brick-to-brick) modelling approaches. The bricks and mortar joints are modelled as one homogenous continuum in the macro model, whereas in the two brick-to-brick models these structural components are modelled separately, with the detailed model including interface elements to simulate the brick–mortar bonds. Nonlinear pushover analyses are subsequently carried out using all three modelling approaches, for both monotonic and cyclic loading cases. Based on these analyses, the detailed brick-to-brick model was found unsuitable to simulate the strengthened wall because cracks in the model mainly occur in the form of opening of the brick–mortar bond interfaces, while smeared cracking in the plane stress elements of the mortar joints is very limited. Similarly, the continuum damage model was found to be inaccurate when pre-existing damage in the experiment needed to be taken into account. The continuum damage model also showed lower axial stresses in the rebars, compared with the simplified brick-to-brick model, as the former does not allow for the direct assignment of material properties for the high strength repair mortar in the strengthened joints.

To date, several different structural representations of masonry are available for use in the numerical and analytical assessment methods, each calling for a distinct level of refinement regarding the material input. To determine material properties, in terms of strength, stiffness, and toughness under compression, bending, and shear loading, extensive experimental research is necessary. To minimise the burden associated with performing complex and invasive experimental studies, this paper investigated the possible correlations between different material properties, particularly toughness, which received limited attention in past research. The correlation study was mainly conducted on the rich database established from tests on laboratory-made as well as specimens extracted from unreinforced masonry structures built between 1910 and 2010 in the Netherlands. Considering the outcomes of the correlation study, this paper puts forward recommendations to indirectly derive elastic and toughness properties as a function of strength properties. In this way, a complete picture of material properties can be obtained, while minimising the number of experiments and the extent of their invasiveness.