Three-dimensional printing with cement-based materials is a promising manufacturing technique for civil engineering applications that already allows for the design and the construction of complex and highly customized structures using a layer-by-layer deposition approach. The extrusion mechanism is one of the most expensive parts of the 3D printer. Also, for low-scale 3D printers, based on the shape of the extruder and the geometry limitation of the mixing blade, the 3D mixture is often limited to a narrow range of materials due to the risk of layer splitting or blockage. Therefore, there is a need to develop affordable and feasible alternatives to the current design–fabrication–application approach of 3D printers. In this paper, various newly designed mixtures of fiber-reinforced mortars that can be 3D printed using only a commercially available screw pump are analyzed based on their fresh properties and mechanical characteristics. The results, in terms of extrudability, buildability, flowability, and flexural and compressive strengths, highlight the potential of using this technology for constructing complex structures with high strength and durability. Also, the reduced facility requirements of this approach enable 3D printing to be made more available for civil engineering applications. With further innovations to come in the future, this method and these mixtures can be extended for the sustainable and economically feasible printing of single-family housing units.

This study provides insight into the structural assessment, diagnosis, and strengthening of the medieval church of Tazlău Monastery in Piatra Neamț, Romania. The first part of the paper briefly presents the wider context of strengthening and preserving heritage churches and monastic buildings and describes the architectural setting and the structural features of the traditional Romanian Orthodox churches. The second part of the paper is a case study related to the rehabilitation of a medieval heritage church, which is the paramount building of a larger monastic complex. Erected in 1496, the church of the Nativity of the Blessed Virgin Mary closely follows the medieval traditional Orthodox patterns from both architectural and structural points of view. Structural assessment and diagnosis revealed that degradations were induced and developed throughout the life of the structure due to approximately 24 earthquakes (estimated at over 6.0 magnitude) having endangered the structural safety of the building and the mural iconography. After the structural diagnosis, a combined and complex method of strengthening consisting of both grouting and introducing steel rods in vertically drilled galleries along the entire height of the walls was selected. The main advantage of applying this combined strengthening strategy was a remarkable enhancement of the structural seismic performance of the church building.

Cultural and religious heritage assessments and restorations are considered to be a fundamental requirement of any modern society because these constructions represent one of the most meaningful and tangible connections to our past. With rare exceptions, heritage buildings were built with materials and systems that could bear gravitational loads but not bending and shearing resulting from seismic loading. Thus, in many cases, earthquake ground motions have led to severe degradation and even the collapse of various parts of these structural systems. In order to address these issues, repair and replacement techniques are applied as common parts of restoration work. In the peculiar case of stone masonry structures, a standalone macroscopic examination is not self-assured and, most often, can lead to an inadequate selection of a replacement material. Therefore, a knowledge of mesoscopic, petrographic, physical and mechanical properties is compulsory in the design, planning and execution of restoration work. From this perspective, the present research has taken, as a case of study, the Frumoasa monastic complex from Iași, Romania, introducing microscopic, XRF (X-ray fluorescence) spectroscopy and petrographically based approaches, comparing three limestone samples with a sample dislodged from the original wall. The physical properties (bulk and real densities, open porosity and capillary water absorption coefficient) and the mechanical properties (compressive and tensile strengths) were also experimentally determined. The samples were extracted from stone quarries located on the territories that were part of the same historical region as the Frumoasa monastic complex. Based on the outcomes of this study, suitable criteria for the stone replacement—consisting of identifying the main structure, quarry rock petrographical parameters and physical and mechanical characteristics—were determined and applied.

This paper presents the set-up needed for an experimental study regarding the in-plane shear behaviour of stone masonry panels, strengthened with a prototype hemp reinforced mortar. Seven stone masonry panels will be designed and manufactured for this purpose: one unreinforced, three plastered on both sides and three plastered on a single side. The aim of this experimental study is to evaluate the effectiveness of the prototype hemp reinforced mortar in enhancing the shear strength and the displacement capacity of the stone masonry walls. In addition, the design and the manufacturing stages of the prototype hemp reinforced mortar have been carefully described, thus allowing an easy application of this TRM system on a large scale. Crucial aspects regarding the shear behaviour of stone masonry unstrengthen/strengthened walls, such as the quantification of the ultimate forces and displacements, the description of the dominant failure modes, and the characterization of the stress-strain state may be analysed by performing the envisaged experimental study based on the proposed set up.

3D printing with cement-based materials is a promising manufacturing technique for civil engineering applications that already allows for the design and the construction of complex and highly customized structures using a layer-by-layer deposition approach. Usually, in this type of additive manufacturing, a mixture of cement, water, aggregate and additives is extruded through a specific print head and deposited in successive layers to form the desired shape. The extrusion mechanism is one of the most expensive parts of the 3D printer. Also, for low scale 3D printers, based on the shape of the extruder and the geometry limitation of the mixing blade, the 3D mixture is often limited to a narrow range of materials due to the risk of layer splitting or blockage. Therefore, there is a need to develop affordable and feasible alternatives to the current design-fabrication-application approach of 3D printers. In this paper, various new designed mixtures of fiber reinforced mortars that can be 3D printed using only a commercially available screw pump are analyzed based on their fresh properties and mechanical characteristics. The reduced facility requirements in this approach allow 3D-printing to be more available for civil engineering applications. With further innovation in the future, this method and mixtures can be extended for sustainable and economically feasible printing of single-family housing units.