International Journal of Masonry Research and Innovation (19 papers in press)
Technical viability of construction and demolition waste reuse in paving blocks industrial production: an experimental study
by Cleber E. F. Leal, José C. Marques Neto, Guilherme A. Parsekian, André L. Christoforo, Fernanda G.S. Ferreira
Abstract: This research aimed at evaluating the partial replacement of the regular sand with a recycled sand from concrete and mortar waste to produce concrete paving blocks (CPB), as a strategy to reduce waste disposal and save natural resources. The recycled aggregate was collected at a municipal construction and demolition waste (CDW) recycling plant. Its physical properties were evaluated and compared with those from regular non-recycled aggregates. The units were manufactured in an industry plant, with 0%, 10%, 20% and 30% aggregate replacement ratios and same cement content. Compressive strength, tensile splitting strength, abrasion resistance and water absorption were determined at 7 and 28 days. As result, the statistical analysis showed no differences among mechanical properties from reference mix (0%) and the other replacement ratios. All mixes met abrasion limits and showed satisfactory water absorption. In conclusion, the natural sand replacement up to 30% is technically viable for CPB scale-up production.
Keywords: construction and demolition waste; CDW; recycled aggregate; concrete paving block; CPB; industrial production; physical properties; mechanical properties.
Investigations on eco-friendly masonry structural elements developed using slag-fly ash-glass powder-based alkali activated concrete
by Shriram Marathe, I. Ramesha Mithanthaya
Abstract: The present study attempts a detailed investigation on the strength performances of alkali activated concrete (AAC) mixes incorporating slag, fly ash, and powdered waste glass as binding ingredients for structural masonry applications. All the concrete mixes were prepared by using graded stone crusher dust as fine aggregates. The tests were performed to investigate the mechanical strength performances, and the results were compared with the conventional OPC-based blocks. Tests were also extended to investigate the effect of one type of geogrid reinforcement on the strength performances of AAC masonry blocks. The prism strength and the cost analysis of the conventional and AAC masonry blocks were also carried out. All the test results strongly prove that the alkali-activated masonry blocks are comparatively better than the conventional blocks made up of OPC. Thus, the use of AAC blocks can be highly recommended as a sustainable alternative to traditional OPC structural masonry executions.
Keywords: alkali activation; masonry blocks; strength; geogrid reinforcement; masonry prism strength.
Stimulus on strength and durability of granite powder in the waste-based masonry units with copper slag and crumb rubber as partial substitute of fine aggregate
by S. Praburanganathan, S. Chithra
Abstract: In this research, an extensive experiment was made to utilise industrial waste rejects for the production of bricks by pressing technique in a factory-controlled environment. A total of 650 bricks were cast and each bricks recipe consists of a fixed percentage of primary raw materials akin to lime and gypsum. Along with granite powder as partly substituted for fly ash composed with copper slag and crumb rubber as a partial replacement with stone dust were used in different percentages. A range of mechanical, durability, morphology, FTIR and UPV studies are presented. The investigations reveal that the bricks of a prototype mix design using granite waste and copper slag using an optimum percentage of fly ash and lime-gypsum binder provide better strength and durability. The advantage of the proposed bricks is twofold: having utilised sustainable wastes make an eco-friendly product and the developed product can be used for load-bearing structural elements.
Keywords: brick; granite waste; copper slag; crumb rubber; strength; durability; masonry units; industrial waste rejects; ultrasonic pulse velocity.
Mechanical behaviour of novel earth concrete walls
by Thi-Loan Bui, Minh-Cuong Le, Tien-Dung Nguyen, Xuan-Huy Nguyen, Tan-Trung Bui, Vasillis Sarhosis
Abstract: This paper presents outcomes of an experimental campaign focused on investigating the mechanical behaviour of a novel earth concrete made of raw earth which is quarry waste from washing aggregates at Luong Son quarry (Vietnam). At material scale, it was found that when the raw earth content varies from 10% to 20% and a low cement content of 4-8% used, the strength of the earth concrete ranges from 8 to18 MPa in compression and 1 to 2.5 MPa in splitting tensile strength. In addition, increasing the content of raw earth, reduces the workability of the earth concrete but increases its strength. However, it seems that there is a limit of strength which corresponds to the case where the compaction of aggregate mixture is optimal. At structure scale, four walls with dimensions (1250 x 1160 x 300 mm) were constructed using earth concrete and subjected to in-plane and out-of-plane loading.
Keywords: ‘earth concrete’ material; out-of-plane behaviour; in-plane behaviour; walls.
Present Day Status and Numerical Modeling of Heritage Masonry Bridges of Kalka-Shimla Mountain Railways
by Vinay Shimpi, Madappa V.R. Sivasubramanian, S.B. Singh
Abstract: This study is conducted on two masonry arch skew bridges located on UNESCO recognised Kalka-Shimla Mountain Railways, India, built in the year 1905 with stone masonry located in Seismic zone IV as per Indian Standard Code 1893 (2016). Hence, the present day assessment and seismic performance evaluation of the bridges is necessary for conservation. In this study, field measurement of the bridges is conducted using ambient vibration testing (AVT) and operational modal analysis (OMA) with sensitive accelerometers and data acquisition system. Further, modal parameters have been extracted using frequency spatial domain decomposition (FSDD) technique from recorded data. Furthermore, the measured response of the bridges is compared with the developed initial numerical model to estimate the present day status of the bridges in terms of material degradation. A reliable model is then developed adopting modal updation trial and error procedures. At last, the study is concluded towards understanding status of material degradation and preparation of reliable numerical models of the heritage bridge structures.
Keywords: historical structure; masonry; arch bridges; ambient vibration test; AVT; operational modal analysis; OMA; finite element modelling; finite element modal updation.
Seismic response of plain and timber-laced masonry building models before and after interventions
by Elizabeth Vintzileou, Lucia Karapitta, Chrissy-Elpida Adami, Charalambos Mouzakis
Abstract: Two two-storey stone masonry building models of the same geometry were built at 1:2 scale. In one of the models, masonry was unreinforced, while in the other timber laces were provided at intervals along the height, as it is the case in historical structural systems in several earthquake prone areas. The models were subjected to base excitation tests on the earthquake simulator of the Laboratory for Earthquake Engineering/National Technical University of Athens (NTUA). Each building model was subjected to biaxial seismic tests with the base acceleration increasing stepwise until repairable damages occurred. Afterwards, the building models were repaired (i.e., re-pointing of mortar joints, re-fixing of failed timber connections) and strengthened by: 1) grouting of the three-leaf masonry using a natural hydraulic lime-based grout; 2) enhancing the diaphragm action of the floors and the floor-to-wall connection. Subsequently, the models were re-tested up to severe damage. This paper provides comparison of the response of the two models in their as-built and strengthened state with the purpose of documenting the beneficial effect of the selected strengthening techniques, as well as the beneficial effect of timber laces on the seismic performance of historical masonry buildings.
Keywords: three-leaf stone masonry; timber-laced stone masonry; interventions; diaphragm action; grout injection; seismic response; seismic tests; shaking table.
CO2 capture of concrete units for pavement through accelerated carbonation cure
by Lívia Regueira Fortunato, Guilherme Aris Parsekian, Alex Neves Junior
Abstract: The process of extracting and manufacturing the raw materials needed to obtain concrete emits large amounts of CO2 to the environment. However, recent research has shown that Portland cement-based materials have the ability to store CO2 in the form of CaCO3 through the accelerated carbonation process during the early ages. This technology can be applied to structural elements without reinforcing steel, as concrete used in pavers.
Therefore, the present work performed the CO2 curing in concrete pavers produced on an industrial scale. The samples were placed in a carbonation chamber with 20% of CO2 concentration, the temperature and relative humidity were set in 23 C and 65% respectively and the curing process occurred in 4 and 16 hours. The amount of CO2 absorbed by the samples was determined by the method of mass gain. After the curing process, the mechanical properties were measured. The concrete pavers cured with CO2 reached the highest compressive strength, especially in the first ages (2 days), and the resistance to abrasion and water absorption presented satisfactory values, but there were no variations at 2 and 28 days.
Keywords: CO2 cure; accelerated carbonation; concrete units for pavement; CUP; concrete.
Analysis of the possible geometries of a disappeared Parthian adobe dome: from in-situ tests to finite element macro-modelling
by Daniele Ferretti, Eva Coïsson, Erica Lenticchia, Elena Michelini
Abstract: The work studies - from a structural point of view - the possible geometries of the adobe dome covering the Round Hall building in the archaeological site of Old Nisa (Turkmenistan). Thirteen dome geometries are identified, starting from archaeological reconstructions of the disappeared dome. The dome reconstructions are subsequently modelled through nonlinear finite element analysis in order to check their static behaviour. Concrete damage plasticity model is used to describe the nonlinear behaviour of adobe masonry. To calibrate the material model, the results of an onsite experimental program characterising adobe bricks are used. The analyses show that all the 13 geometries are stable with large safety margins. The results do not allow excluding some geometries, but on the contrary, highlight that the choice of the geometry of the dome was not a critical element. This aspect supports the hypothesis that the round room was actually covered by a dome.
Keywords: adobe; domes; archaeological heritage; Turkmenistan; concrete damage plasticity; FE modelling.
Masonry framing and capacity characterisation
by G.L. Stockdale
Abstract: Masonry framing has a great potential to become a modern construction technique for residential, commercial and infrastructure applications. The focus of this design project was to create a full-scale mechanically controllable masonry arch frame and develop a non-destructive capacity quantification strategy. The blocks were designed and constructed from readily available materials found at most hardware stores. They were also designed to be lightweight and easily manageable. A tilting platform was also created to provide a simple and efficient failure method for establishing a non-destructive capacity quantification approach. The repeated tilting of the constructed arch demonstrated that the design arch frame can be mechanically controlled. Varying the defined mechanism under repeated failure testing also generated a quantification approach that can synchronise theoretical and measured capacities beyond the tested mechanisms under the given loading condition. This project therefore provides the first physical link towards the modernisation of structural masonry framing.
Keywords: masonry arch; masonry framing; kinematic equilibrium; RSBD; masonry as a method; masonry design.
Special Issue on: ArCo2020 New Approaches in Diagnostic and Safety Evaluation of Cultural Heritage
An integrated experimental and numerical approach for preventive Cultural Heritage conservation. The San Marco Museum case study.
by Margherita Vicario, Carla Balocco
Abstract: Microclimate knowledge inside historic buildings is a prerequisite for their preventive conservation and protection. In this research a methodological approach, based on the integration between experimental measurement and numerical simulation by means of CFD environmental control techniques, is provided. This method is aimed at identifying criticalities and risk conditions for the cultural heritage preventive conservation. The San Marco Museum in Florence is the case study. Results show that the proposed method can be a useful tool for guidelines for possible effective interventions, as well as basic rules of correct behaviour.
Keywords: microclimate monitoring; simulation; CFD; cultural heritage; preventive conservation; historical building.
Special Issue on: Latest Developments in Digital Technologies, Experimental Testing and Numerical Simulation of Earthen Constructions
Numerical simulation of shaking table test on an adobe masonry building through nonlinear macro-element analysis
by Luigi Fenu, Valeria Colasanti, Fulvio Parisi
Abstract: Earthen constructions are often built in seismic areas, notwithstanding their vulnerability to even low-intensity earthquakes. Numerical simulations and design methods to predict the seismic response of earthen constructions under future earthquakes and, if any, to design and implement retrofitting systems are hence required. This study aims at evaluating the applicability of the equivalent frame method (EFM) to assess the seismic performance of adobe masonry buildings through nonlinear static analysis, allowing a trade-off between computational efficiency and accuracy in the simulation of earthquake damage. Experimental results of shaking table tests performed on a half-scale adobe building specimen were compared to the output of numerical simulations performed on the prototype building through the EFM. A satisfactory numerical-experimental agreement was found both in terms of seismic capacity features and damage to load-bearing walls. Such results indicate that the EFM can be suitably used also in adobe buildings, hence confirming previous validations on other building typologies.
Keywords: earthen constructions; adobe buildings; shaking table testing; nonlinear static analysis; equivalent frame method.
Study of experimental behaviour of seismically retrofitted earthen structures
by Muhammad Masood Rafi, Muhammad Saad Khan, Shoaib Ahmed, Adnan Rais
Abstract: The details of shake table testing of a seismically retrofitted adobe model have been described in this paper. The retrofitting of the model was carried out using bamboos and steel wire mesh in the vertical and horizontal directions, respectively. The acceleration time history of the 1995 Kobe earthquake was used to apply dynamic forces on the model. Different levels of this ground motion were employed which were scaled appropriately. The damage to the structure was limited to minor hairline cracks till peak ground acceleration (PGA) of 0.790g (in prototype domain). The perforated in-plane (IP) wall was the most severely damaged wall whereas the out-of-plane (OOP) walls suffered least damage. The displacements of the perforated IP and OOP walls were similar which was a result of strong box action developed by the tested model due to the applied retrofit. The behaviour of the perforated IP wall became non-symmetrical at higher levels of applied PGA whereas the OOP wall showed nearly symmetrical behaviour in the positive and negative directions of loading till the end of testing.
Keywords: adobe model; wall stiffness; peak displacement; wall inertia force; seismic retrofitting; fundamental frequency; inclined cracks.
Special Issue on: Simple Mechanical Models for Unreinforced Historic Masonry Constructions
P-Bezier energy optimisation for elastic solutions of masonry-like panels
by Antonio Fortunato, Antonio Gesualdo, Ida Mascolo, Michela Monaco
Abstract: The equilibrium problem for masonry-like materials in the Heyman sense can be formulated looking for a minimum of the complementary energy functional defined in the field of admissible stress tensors, belonging to the class of negative semi-definite tensors. The classical mixed boundary problem for a masonry panel is developed assuming that the stress is uniaxial so it is possible to express the complementary energy as a function of the slope of compressive rays which characterise the uniaxiality of the stress field. In this work, a family of proximity curves defined starting from a Bezier curve with three control points to model the slope function is employed. Two structural cases are solved, pure shear displacements and shear-flexural-tensile ones, showing the usefulness of the method when applied to the analysis of masonry piers.
Keywords: masonry panel; mixed boundary problem; complementary energy; energy optimisation; proximity curves; P-Bézier curves.
Limit analysis based interactive tool for bidimensional studies of complex masonry
by Paul Nougayrede, Thierry Ciblac, François Guéna
Abstract: In a context of growing interest about historic masonry buildings, there is an identified need for a simple and efficient approach for stability studies. An adaptative tool, LITHFI, has been developed as a plugin of Rhinoceros software to interactively analyse the stability of complex bidimensional masonry structures with rectilinear joints. Using the theoretical framework of limit analysis under Jacques Heyman hypothesis with the static theorem and interactive lines of thrust search methods, the main goal is to take into account the diversity of multiple cases and different kinds of needs (various complexity of geometries, topologies and loading, hinges positioning, search for extreme thrusts domains). The algorithmic architecture of the tool and the possible uses in actual case studies are also presented.
Keywords: structural masonry; limit analysis; yield design theory; lower bound theorem; line of thrust; numerical modelling; interactivity; multi-agents programming; genetic algorithm.
A new experimental approach for small-scale dynamic tests on masonry arches aimed at seismic assessment
by Anna Castellano, Isabella Elia, Aguinaldo Fraddosio, Carlo Olivieri, Mario Daniele Piccioni
Abstract: This paper considers the dynamics of stone or brick masonry modeled a la Heyman. Current regulations prescribe for such structures to adopt response spectra based on the identification with a harmonic oscillator. Since 1963, Housner observed that the dynamic of structures behaving unilaterally is more correctly described by the rocking motion. This approach enabled lately other scientists to reconstruct response spectra for arches, portals, and more complex structures. In this light, the present paper focuses on response spectra for masonry arches obtained by performing laboratory tests on a shaking table of scale models produced through 3D printing formworks. The difficulty due to the scaling of friction is overcome by special indents at the interfaces of the blocks enforcing no-sliding conditions. The comparisons with numerical solutions represent the first results, being the final goal to obtain a robust experimental method to test scale models of complex masonry
Keywords: masonry arches; dynamic tests; seismic assessment; scale models; 3D printing.
When cracks are (not) a structural concern: the case of 'Giovanni Vinciguerra' School in Anagni
by Chiara Ferrero, Concetta Cusano, Mehmet Nuri Yavuzer, Yu-Xian Wu, Antonino Iannuzzo
Abstract: This paper presents the structural assessment of a portion of Giovanni Vinciguerra School, located in the municipality of Anagni, Italy. In 2009, the presence of some cracks in the vaults of the basement led the authorities to close the building and declare it not usable. In this work, firstly a proper knowledge of the history, geometry and structural configuration of the school was achieved by means of bibliographic research, laser-scanner survey and visual inspections. During onsite inspections, the damage observed was also surveyed and mapped in detail. Then, structural analysis applying graphic statics and inverse piecewise rigid displacement (PRD) analysis was carried out with the aim to identify the causes of damage and evaluate the residual structural safety of the building. The results obtained allowed to prove that the structure is safe despite the occurrence of some damage in the basement.
Keywords: historic structures; damage assessment; structural analysis; effects of settlement; masonry.
Between stereotomy and mechanics: joints inclination and minimum thickness in frictionless pointed and circular arches
by Danila Aita
Abstract: This research is inspired by an issue strictly linked to the art of stereotomy and rarely tackled in the contributions on the statics of arches and vaults, i.e., the search of the inclination to be assigned to each joint able to ensure the respect of the equilibrium conditions when the friction between the voussoirs is absent, by assuming that the intrados and extrados curves are known. After presenting some brief notes on the state-of-the-art on this subject, both a numerical and an analytical approach, based on the maxima and minima Coulomb method revisited through a re-edition of Durand-Clayes method, is developed in order to determine the inclination of the joints as well as the minimum archs thickness compatible with equilibrium. The analysis is performed for frictionless pointed and circular arches for different values of the embrace angle (i.e., the complement of springing angle).
Keywords: frictionless arches; pointed arches; circular arches; minimum thickness; stereotomy; Coulomb; limit analysis.
Numerical modelling of grouted anchors in masonry walls
by João M. Pereira, Federico Rossetti, Paulo B. Lourenco
Abstract: This work aims to numerically simulate experimental pull-out tests in masonry wall anchors. Advanced finite element (FE) 3D models were built to fully reproduce the loadbearing capacity, the failure mode, the stresses and the force-displacement curve and, in general, all the phenomena involved for both brick and stone specimens. Three different modelling approaches were considered. First, a macro-model was adopted, where both brick and stone masonry were assumed as a homogeneous isotropic material. The steel bar and the grouted mortar of the anchor system were considered linear elastic and the system was placed in the specimen using interfaces. The second approach was a unit model, developed with the aim to reproduce the influence of the unit where the anchoring fastening is located. The last approach studied was a micro-model, where both the units and the mortar are considered. The challenge in modelling these systems is highlighted from the different modelling strategies used and compared.
Keywords: asonry; grouted anchors; numerical modelling; finite element method.
Studying the equilibrium of oval-base pointed masonry domes: the case of Pisa Cathedral
by Francesco Barsi, Riccardo Barsotti, Stefano Bennati
Abstract: This paper addresses the equilibrium problem of an oval-base, pointed masonry dome, that of famous Pisa Cathedral. Set within the framework of the safe theorem of limit analysis, the analysis involves searching for compressive-only statically admissible internal actions for the dome under vertical loads by using the concept of 'thrust surface'. According to Heyman's hypotheses, it is assumed that no in-plane tensile stresses can be transmitted within the thrust surface. The equilibrium problem is tackled by finding an explicit solution for the stresses within a suitable collection of thrust surfaces having the shape of ellipsoids, all contained within the dome thickness. The dome intrados and extrados surfaces have been carefully reconstructed by laser scanner survey and approximated by regular surfaces. The analytical expressions used for both the stress field and the intrados and extrados surfaces have enabled determining estimates of the safety level by means of an expressly developed optimisation procedure.
Keywords: masonry domes; limit analysis; thrust surface.