Types Of Mortars Research Articles

In-plane shear strengthening of traditional unreinforced masonry walls with near surface mounted GFRP bars

In this study, the effectiveness of Near Surface Mounted (NSM) method, for in-plane shear strengthening of traditional and historical Unreinforced Masonry (URM) walls, is investigated through a comprehensive experimental study. For this purpose, square solid clay brick masonry wallettes (42 samples) with three different types of traditional mortars including gypsum mortar, lime-cement-sand mortar and lime-sand mortar are prepared and retrofitted with NSM Glass Fiber Reinforced Polymer (GFRP) bars. Then, diagonal shear tests are conducted to evaluate the in-plane shear behavior of the masonry wallettes. The effects of some key variables such as wall thickness, the retrofitted face of the wall, reinforcement ratio, and the type of paste for mounting the reinforcing bars, on the effectiveness of the retrofitting method are investigated. The results of the tests are presented in terms of the failure modes and the lateral shear stress-drift curves of the test specimens. Accordingly, the retrofitting method can enhance the in-plane shear strength, and the ultimate lateral drift capacity of the URM wallettes. According to the test results, the type of filler paste and reinforcement ratio influence the strength enhancement of the test specimens. Furthermore, in specimens retrofitted with the one-side retrofitting scheme, due to the asymmetry of walls under in-plane loads, an unexpected out-of-plane deformation is induced in the walls under in-plane load which adversely affects its global behavior.

Physico-Antibacterial Feature and SEM Morphology of Bio-Hydraulic Lime Mortars Incorporating Nano-Graphene Oxide and Binary Combination of Nano-Graphene Oxide with Nano Silver, Fly Ash, Zinc, and Titanium Powders

The study evaluated the impact of graphene powders used as additives in the recipe of the experimental lime mortar to a mixture ratio of 1:2.5 of NHL3.5 hydraulic lime:fine sand. The content of binder, aggregate and water was kept constant, varying only the amount and the type of the added additives in relation to the amount of natural hydraulic lime NHL3.5. The following five types of experimental mortars were prepared as follows: reference mortar (without additive); mortars containing 1 wt.% GO and 5 wt.% GO powder; mortar with the following GO powders mixture: GO powder functionalized with silver nanoparticles and with fly ash (GO-Ag + GO-fly ash); mortar with the following GO powders mixture: GO with zinc oxide and with titanium oxide (GO-ZnO + GO-TiO2). The influence of the GO-based additive addition on the porosity, surface microstructure, and water sorption coefficient of the mortar samples was evaluated. The antibacterial effect of the mortar samples against three bacterial strains was also investigated. The best results were obtained for the experimental mortar containing GO-ZnO -TiO2, which showed improved experimental properties that potentially allow its use for the rehabilitation of heritage buildings.

The technology of ancient lime mortars from the Żejtun Roman Villa (Malta)

Studies on original mortars can greatly assist archaeological interpretations, as elucidating the composition of such mortars gives clues on the origin of raw materials, manufacturing technology, and the construction phases of a site. This article presents the multi-analytical characterisation of 24 mortars and plasters from the Żejtun Roman Villa, Malta, to support archaeological hypotheses on the history of the construction of the site. The samples, belonging to at least three distinct phases included in the stratigraphy of the Żejtun archaeological site, were analysed using polarised light microscopy (PLM), scanning electron microscopy (SEM–EDS), X-ray diffraction (XRD), thermogravimetry (TGA/DSC), X-ray fluorescence (XRF), ion chromatography (IC), and stable isotope analysis (13C and 18O). The assessment of the results through correlations with archaeological evidence identifies five types of mortars with varying degrees of hydraulicity. These are associated with different development phases of the site and distinctive uses and were mainly produced using local resources, except in the Early Roman period when natural pozzolanic raw materials started being used. As there are no natural pozzolans on the Maltese Islands, it is hypothesised that the pozzolanic materials used as aggregate in the mortars were imported to the Islands from neighbouring volcanic regions. This volcanic aggregate was especially abundant in one of the mortar types, which was used mainly as a bedding mortar for floors.

The impact of mortar thickness and strength on the brick masonry prism: An investigation

Brick masonry is the oldest type of building construction, and despite advances in technology, it is still widely used worldwide. The quality of resources adopted in the erection, thickness, and the kind of masonry bond all impact the mechanical characteristics of the prisms. The investigation is intended to examine the mechanical features of masonry that are affected by the joint thickness and mortar type. Cement mortar and hydrated lime mortar are combined with the same kind of brick throughout the experimental work. For evaluation, 5 layers of bricks are used to prepare a masonry prism prototype. The thicknesses used in the study are 13 ± 3 mm, 20 ± 3 mm, and 27 ± 3 mm with cement mortar and lime mortar. Results reveal that the properties of the mortars impact the failure mechanisms of the prisms. Crushing brick units showed masonry failure with 13 mm of mortar thickness, and 27 mm of mortar thickness showed the shearing failure of brick-and-mortar units. A joint thickness of about 20 mm is advised during the construction of standard masonry walls to sustain the loading.

Self-healing of cement mortars based on fly ash and crystalline admixture

The actual study has followed the effect of fly ash and crystalline admixture on cement mortars' mechanical and self-healing properties. Three types of cementitious mortars composed of (i) 16 wt.% fly ash, (ii) crystalline admixture, and (iii) 16 wt.% fly ash and crystalline admixture were compared to the standard mortar (in compliance with EN 196-1). The capillary water absorption determined the sealing efficiency of the cracks over a period of time. The experimental results showed that by autogenous self-healing the standard mortar has a sealing efficiency of 40% after 28 days of treatment and 70% after 6 months of treatment, but the addition of fly ash and crystalline admixtures stimulated the autogenous self-healing. The best results showed the mortar (iii) containing 16 wt.% fly ash and crystalline admixture, where the sealing efficiency achieved 79% after 28 days of treatment and 98% after 6 months.

Experimental investigation on tensile and shear bond behaviour of Basalt-FRCM composites for strengthening calcarenite masonry elements

The use of Fabric Reinforced Cementitious Matrix (FRCM) composites for structural retrofit has seen an increased interest among the scientific community, during the last decade. Various studies have revealed their effectiveness as external retrofitting technique of masonry elements, offering numerous advantages respect to the well know Fibre Reinforced Polymer (FRP) in terms of compatibility with masonry support, reversibility of intervention and sustainability. Despite the growing use, the characterization of FRCM mechanical behaviour is still an open issue, due to numerous uncertainties involved in test set-up adopted and fibre-mortar combination. The proposed experimental study aims to investigate the tensile and shear bond behaviour of Basalt-FRCM for strengthening calcarenite masonry elements. Calcarenite is a natural stone with sedimentary origin and it is widely present in existing buildings of the Mediterranean areas. Direct tensile tests are performed on two types of Basalt-FRCM coupons, with cement-based and lime-based mortar, adopting two different test-set-up based on clamping and clevis grip methods. Moreover, double shear bond tests are carried out to evaluate the adhesion properties of the two types of Basalt-FRCM with calcarenite support. Experimental outcomes are compared in terms of stress-strain curves, evaluating the influence of mortar grade and test set-up on the mechanical performances of Basalt-FRCM composites. The comparisons provide information about the mechanical stress transfer phenomena that occur at the fibre-to-matrix and FRCM-to-substrate interface level and the failure modes.

The influence of different types of mortar on the compressive strength of masonry

In the investigation of typical masonry buildings in villages of China, it was found that the number of masonry structures accounted for more than 90% of buildings (Wang et al., 2022). The mortars used in masonry structures in villages of China have developed rapidly from mud to while clay mortar/slag mortar and to cement mortar. In this article, it is found that there is a difference of the compressive strength between the result calculated by the Chinese standard code and the experimental result. The test of the compressive strength of masonry columns with different types of mortars is carried out for modifying the equations. The research is carried out from the perspectives of stress-strain curve, elastic modulus, Poisson's ratio, compressive strength of masonry columns. The results show that the compressive strength of the masonry increases with the increase of the compressive strength of the mortar. The compressive strength of the experimental values is 1.2 times more than the calculated value of the specification. Therefore, the study puts forward the revised equation for masonry in terms of stress-strain relationship, elastic modulus, Poisson's ratio, and compressive strength of masonry.

Producing a gypsum-based self-leveling mortar for subfloor modified by polycarboxylate admixture (PCE)

Self-leveling mortar is a layer applied on a surface without the need for thickening. This type of mortar has large fluidity and is often cement-based, with low productivity. The production of a self-leveling gypsum-based mortar provides shorter execution times, as well as better thermal and acoustic properties and eliminates the need for expansion joints in large areas. This article aims to develop a gypsum-based mortar with self-leveling properties for application in the subfloor layer. In this sense, water/gypsum ratios of 0.45, 0.475, and 0.5 were used, in addition to plaster/sand ratios of 1:1 and 1:0.5 for each consistency. The content of superplasticizer additive (PCE) was adjusted to consistency suitable for self-leveling through the fluidity test. The set of mortars were characterized by considering tests of fluidity, enthalpy of hydration, setting times, compressive and flexural strength, and experiments of scanning electron microscopy (SEM). The results revealed that the PCE increased the setting times, reduced the water content, and modified the crystalline structure of the dihydrate. Finally, the mortar with water/gypsum ratio of 0.5, gypsum/sand ratio 1: 0.5 and 1% PCE presented satisfactory properties, with the exception of setting times.

Design and preparation of high-performance polymer mortars based on performance prediction model

This article had presented a systematic and adjustable method to forecast the performance of certain type of polymer mortars, most of all, using the performance prediction model to accurately control the dosages of water reducing agent (D WR ), cellulose (D C ), polypropylene fiber (D F ), expansion agent (D EA ), redispersible emulsion powder (D REP ), and cement content (C C ), according to the changes of properties of polymer mortars. The article had given a full verification supported by a series of orthogonal experiment results to demonstrate the effectiveness and the feedback loop between raw materials and properties of polymer mortars, which had revealed a big practical value and convenience for rapid construction in the job sites, especially for researchers and engineers in the field. Its effort to avoid, or at least control the damage of polymer powders to compressive strength of cement mortars. The mix proportion of high-performance polymer mortars (HPMs) was determined as follows, considering the working and mechanical properties: D WR was 0.85 g, D C was 1.05 g, D F was 1.15 g, C C was 42%, D EA was 10 g, and D REP was 20 g. Successfully created HPMs with pumping resistance of just 61.6N, compressive strength of 68.5MPa at 28d.

Behaviour of masonry lateral loaded walls made with sediment-based bricks from the Usumacinta river (Mexico)

A feasibility study on Usumacinta River sediment-based bricks for resilient housing adapted to both climate change and seismic risks is performed on laterally loaded reduced-scale walls. Mortar formulations with different volume ratios of lime and sand (2/1, 1/2, 1/4, 1/6) are prepared while different types of sediment-based bricks are thoroughly investigated, manufactured and strength characterized. Commercial fired bricks as reference bricks completed the set of bricks tested (FRS: Fired River Sediment-based brick (at 850 °C); LRS: Lime treated River Sediment-based unfired brick (1.5% of lime addition); NRS: Natural fiber Reinforced river Sediment-based unfired brick and FR: commercial Fired Reference brick made without sediment). Walls of different sizes were built with these types of bricks and mortars. Tests under lateral in-plane loads of walls i.e. pushover tests , were conducted. The most significant results are as follows:(1) the addition of lime increases the strength of the mortar; (2) the wall size effect is observed for wall built with reference bricks (FR) and mortar ratio (1/2), where, large walls (LW), intermediate walls (IW) and small walls (SW) exhibiting maximum load of about 1200 N, 440 N and 260 N respectively. Rocking failure mode is the most observed unlike shear and sliding mode which are rarer. (3) maximum load measured during a pushover test performed on walls with sediment-based bricks provides a satisfactory average of 130 N, which exceeds the strength recommended for light buildings; The failure mode is sliding for fired bricks and rocking for unfired bricks. (4) the sediment-based bricks walls give an interesting ductility to pushover test while (2.6–40). These results show promising perspectives on the possibility of using the Usumacinta River sediment-based bricks in walls for light constructions under seismic loading. • The use of Usumacinta River sediment-based bricks is suitable in light buildings (80). • Fired, unfired: lime treated and fibered sediment-based bricks are used for wall tests (86). • The sediment-based brick wall gives satisfactory pushover resistance (68). • The ductility of the walls demonstrates significant seismic resistance (69).

The Effectiveness of a Simulation Model of Thermal Insulation in Building Materials Using Cellulose Extracted from Agricultural Waste in Baghdad

This study found that one of the constructive, necessary, beneficial, most effective, and cost-effective ways to meet the great challenge of rising energy prices is to develop and improve energy quality and efficiency. The process of improving the quality of energy and its means has been carried out in many buildings and around the world. It was found that the thermal insulation process in buildings and educational facilities has become the primary tool for improving energy efficiency, enabling us to improve and develop the internal thermal environment quality processes recommended for users (student - teacher). An excellent and essential empirical study has been conducted to calculate the fundamental values ​​of thermal conductivity coefficient for different types of cement mortar, including the different concentrations of cellulosic fibers. And in our study, those cellulosic fibers obtained from sugarcane and sugarcane residues (agricultural waste materials) were used. The percentage is 10%; 20% and 30% of cellulose fibers were added to the cement mixtures. Then the differences are measured, specifically in the physical properties (heat capacity, density, and thermal conductivity coefficient) for 28 days. The Design-Builder program also implemented a precise simulation of the thermal loads of the external envelope of the educational building that is exposed to direct sunlight before and after the insulation process. It was found that with the use of thermal insulation material (meaning the cellulosic fiber technology) mixed with the cement mortar layer of the educational building, the given value of the heat transfer coefficient W/m2 Kelvin decreased by 47.2%. Accordingly, this contributed significantly to a significant and very significant saving in the values ​​of electrical energy consumption by 11.9% for cooling and heating operations and to reducing dangerous carbon dioxide emissions by 52.2%. The simulation has shown that applying thermal insulation techniques to all buildings and educational facilities is highly recommended to save a large consumption in the value of electrical energy and the costs of waste materials and to ensure integrated protection for the ecosystem.

Archaeometric Surveys of the Artifacts from the Archaeological Site of Baro Zavelea, Comacchio (Ferrara, Italy)

This work is part of a project of the Superintendence of Archaeology, Fine Arts, and Landscape for the enhancement of the widespread archaeological heritage of the Po delta area. Excavation activities, carried out in 2015, allowed the sampling of the stratigraphic elements and artifacts of the archaeological site of the lighthouse tower of Baro Zavelea, municipality of Comacchio (Ferrara, northeast Italy). In this work, the geochemical characterization of sediments and building materials was conducted using granulometric analyses, X-ray fluorescence analysis, and calcimetry on different types of samples, including sands, clays, mortars, and bricks, with the scope to better characterize all of the different types of sediments collected. This multidisciplinary approach allowed the diagnostic and evaluation of the state of conservation of Baro Zavalea. Granulometric analyses highlighted the fact that depositional environments were of very different natures: fluvial environments and paleo–alveo environments. In addition, XRF analysis allowed the discrimination of different clay samples, some from basins poor in carbonates, while, for the construction of the bricks of the second wall structure, clays rich in carbonate were chosen to add lightness to the structure.

Assessment of the Applicability of Selected Data Mining Techniques for the Classification of Mortars Containing Recycled Aggregate.

The article contains the results of selected tests of physical and mechanical properties of mortars differentiated in terms of the binder used: cement, epoxy, epoxy modified with PET waste glycolysate and polyester. Each type of mortar was modified by partial (0-20% vol.) substitution of sand with an agglomerate made from waste polyethylene. The obtained results were used to build a database of mortar properties, which was then analyzed with the use of three different techniques of knowledge extraction from databases, i.e., cluster analysis, decision trees and discriminant analysis. The average results of the properties tested were compared, taking into account the type of mortar, indicating those with the most favorable parameters. The possibilities and correctness of mortar classification with the use of the indicated "data mining" methods were compared. The results obtained confirmed that it is possible to successfully apply these methods to the classification of construction mortars and then to propose mortars with such a composition that will guarantee that the composite will have the expected properties. Both the presented method of plastic waste management and the proposed statistical approach are in line with the assumptions of the currently important concept of sustainable development in construction.

Material behaviour of unstabilised earth block masonry and its components under compression at varying relative humidity

In this study, the material behaviour of unstabilised earth block masonry consisting of different block and mortar types is analysed with particular regard to the influence of varying relative humidity. The uniaxial compressive strength and deformation characteristics of unstabilised earth blocks and mortars as well as of unstabilised earth block masonry are studied in detail and compared to conventional masonry to evaluate whether the structural design can be made accordingly. An increase of 30 % points in relative humidity leads to a reduction of the masonry´s compressive strength between 33 % and 35 % whereas the Young´s modulus is reduced by 24–29 %. However, the ratio between the Young´s modulus and the characteristic compressive strength of earth block masonry ranges between E33/fk = 283–583 but is largely independent of the relative humidity. The results show that the mechanical properties of the investigated unstabilised earth block masonry are sufficient for load-bearing structures, yielding a masonry compressive strength between 2.3 MPa and 3.7 MPa throughout the range of moisture contents investigated. In general, the design concept of conventional masonry can be adapted for unstabilised earth masonry provided that the rather low Young´s modulus as well as the moisture dependence of both, compressive strength and Young´s modulus, are sufficiently taken into account.

Ketahanan Mortar Ringan Campuran Gula Aren dan Ragi pada Suhu Tinggi: Narrative Review

Lightweight mortar is a specific type of mortar that is made by adding a foaming agent. A lightweight mortar has a lot of pores or cavities filled with air, which reduces the mortar’s weight. The lightweight mortar has better heat insulation than an ordinary mortar with its high porosity. There has been much research and application of lightweight mortar in the last few years. This review focuses on lightweight mortar made with a natural additive that has good high-temperature resistance. Many additives can be used, such as yeast and palm sugar. Yeast is a microorganism that can be used as a foaming agent because it can produce carbon dioxide (CO2) that creates a lot of pores in the mortar through the glycolysis process. Palm sugar is a disaccharide groups sugar, and sucrose, consisting of glucose and fructose. Glucose can reduce gypsum consumption in mortar and ettringite formation. Besides, sugar contains lignin, which can increase the bonding strength of mortar components. This study proves that the innovation of lightweight mortar with organic additives has a long-term potency with its durability at high temperatures.

Experimental study on the strength and durability-related properties of ordinary Portland and rapid hardening Portland cement mortar containing polyurethane binder

The durability of cement-based materials plays a significant role in controlling their life cycle. Bio-based polyurethane (Castor oil) was used to improve the durability and mechanical properties of two types of cement mortar, namely: Ordinary Portland cement (PCM-mortar) and rapid hardening Portland cement (RHPC-mortar). To investigate the effects of polyurethane (PU) binder; therefore, experimental tests, including flowability, rate of water absorption, early and dry restrained shrinkage properties, compressive strength, and flexural strength, were performed on the two mortar types. Moreover, the shrinkage properties were estimated using a restrained shrinkage eccentric ring device (RSERD) to improve cracks observation. The PU binder was added to the mortar mixture at 0 %, 15 %, and 25 % by cement weight. The result indicates that the optimum PU binder content (15 %) improves the flexural strength of PCM-mortar at 3 d, 7 d, and 28 d by 10.1 %, 0.93 %, and 10.62 %, respectively, and the flexural strength of RHPC-mortar at 3 d, 7 d, and 28 d was increased by 6.93 %, 1.78 %, and 1.74 %. However, a reduction in the compressive strength was observed. The workability of PU-cement mortar reduced with optimum PU binder content and increased with higher PU binder. The flow-ability percentage drop index revealed that PU-cement mortars containing 25 %PU from the PCM and RHPC- mortars showed lower FPI values of −3.57 % and −8.69 %, respectively. The RSERD mortar specimen controls the cracks propagation as expected crack occurred only on the eccentric side. None of the PU-cement mortar exhibited crack propagation for 182 d. The cracking time of PCM-PU0 and RHPC-PU0 are 104 h and 87.2 h, respectively. The water absorption capacity of PCM and RHPC-mortar was reduced by 67.97 % and 23.46 %, respectively. The PU could be regarded as a suitable candidate for improving cracking resistance and reducing the water absorption rate of cement-based composites.

Experimental study on preparation and properties of low content rubberized geopolymer mortar

• Different blending ratios of raw materials have a great influence on the properties of geopolymer. • Effects of rubber particle size on the working and mechanical properties of RGRM has been studied. • Long term high temperature curing will reduce the compressive and flexural strength of RGRM. • The morphology of rubber particles in RGRM is characterized by XRD and SEM. • The developed rubber geopolymer repair mortar has good economic and environmental evaluation. With the continuous increase of infrastructure construction, the supply of river sand is becoming increasingly scarce in recent years. Partially replacing river sand with waste rubber as fine aggregate has attracted extensive attention. Many studies were involved in the physical and mechanical properties of rubber mixed in ordinary mortar. However, there are few studies on the property changes of rubber blended into geopolymer mortar. In this study, a new type of rubberized geopolymer mortar (RGM) using rubber as fine aggregate replacement of 5 % river sand was investigated. Four kinds of rubber particle sizes are 4 mm, 1.7 mm, 0.83 mm and 0.27 mm respectively. The fluidity, compressive strength, flexural strength and microstructure of these RGMs were tested and analyzed in detail. Results show that the addition of rubber particles slightly reduces the fluidity of the corresponding geopolymer mortar (i.e., 22.4 cm), the fluidity of studied RGMs are within 17.6–21.5 cm. The compressive and flexural strength of RGMs also decrease with an increase of rubber particle size. However, RGMs have relatively high early strength, and their highest 1-d compressive and flexural strength can reach 47.2 MPa and 7.2 MPa, as well as 51.3 MPa and 8.2 MPa, respectively, at curing temperatures of 25 °C and 80 °C, implying that high-temperature curing can improve their early strengths. It is also found that the compressive and flexural strength of RGMs decline when these RGMs are cured at relatively high temperature for a long time.

Evolution of the Hierarchical Molecular Structures of Tectonically Deformed Coals: Insights from First-Order Raman Spectra.

The dynamic metamorphism of tectonically deformed coals (TDCs) is closely correlated with the occurrence of coalbed methane. Here, a Raman detection technique was used to characterize two primary coals and 14 TDCs sampled from the Huaibei coalfield, allowing for profound insight into the dynamic metamorphism caused by tectonic stress in coals. A nine-peak curve fitting method was applied to deconvolute the first-order Raman spectra, and six structural parameters were used to characterize the hierarchical evolution of TDC molecules. The lower AS/ATotal and AS/AD ratios in TDCs indicate that the cross-links in secondary and aggregated (outer) structures are cleaved by tectonic stress. Once the aromatic structures are released through the cleavage of cross-links, the outer structures can be rearranged into a more ordered configuration, as indicated by the higher IG/IA2 ratio in TDCs. Additionally, the basic structural units (including aromatic structures and side chains) in TDC are also altered by stress. The increasing values of AD/AG and A(D+A1+A2)/ADs illustrate that the size of aromatic structures and the ratio of small aromatic structures both increase with increasing coal deformation intensity. The value of AC/ATotal decreases with increasing deformation intensity, indicating that oxygen functional groups are disassociated by tectonic stress. However, as the basic structural units are commonly rigid and cannot be altered as readily as the outer structures, the evolution of basic structural units is not always obvious in weakly deformed coals (such as cataclastic, mortar, and schistose types) but is more significant in strongly deformed coals (such as granulitic, scaly, and wrinkle types).

Efficacy of pond ash (PA) combined with ground granulated blast furnace slag (GGBFS) in producing cement-less mortar

In this research, an attempt has been made to produce cementless construction materials utilizing industrial wastes, e.g., pond ash (PA) and ground granulated blast furnace slag (GGBFS) as binder materials, followed by alkali activation using a mixture of sodium hydroxide (NaOH) and sodium metasilicate (Na2SiO3) solution. In this study, two types of samples, i.e., alkali-activated paste (AAP) and alkali-activated mortar (AAM) were prepared. The AAP samples were prepared to evaluate the setting times, hydration behavior (by monitoring hydration temperature as the function of time), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Analyzing the results, it is revealed that AAP samples sets within the standard time range (initial and final setting times are 55 and 105 min, respectively). The compressive strength analysis of the AAM sample (prepared using the same binder composition with a binder to fine aggregate ratio = 1: 3) is measured to be ∼12 MPa after 28 days of ambient curing. The setting and the hardening ability of AAP and AAM samples appear to be due to the pozzolanic reaction of PA and GGBFS with alkali activators, which is verified by the formation of hydrated products as demonstrated by the FTIR, XRD, and SEM analysis. Finally, a comparative study has been done to assess the reduction of CO2 emission for the use of PA-GGBFS binary mixture in the construction sector replacing the cement.

Experimental Research and Numerical Analysis of CFRP Retrofitted Masonry Triplets under Shear Loading.

This paper presents an experimental and numerical study into the shear response of brick masonry triplet prisms under different levels of precompression, as well as samples reinforced with carbon fiber-reinforced polymer (CFRP) strips. Masonry triplets were constructed with two different mortar mix ratios (1:1:3 and 1:1:5). In this study, finite element models for the analysis of shear triplets are developed using detailed micro-modelling (DMM) approach and validated with the experimental data. The failure mechanisms observed in the masonry triplets were simulated using a coupled XFEM-cohesive behaviour approach in ABAQUS finite element software. The nonlinear behaviour of mortar and brick was simulated using the concrete damaged plasticity (CDP) constitutive laws. The cohesive element with zero thicknesses was employed to simulate the behaviour of the unit–mortar interfaces. The extended finite element method (XFEM) was employed to simulate the crack propagation in the mortar layer without an initial definition of crack location. CFRP strips were simulated by 3D shell elements and connected to masonry elements by an interface model. The changes in failure mechanism and shear strength are calculated for varying types of mortar and fiber orientation of CFRP composite. Based on this study, it was concluded that the ultimate shear strength of masonry triplets is increased due to the external bonding of CFRP strips. The performance of masonry specimens strengthened with CFRP strips is assessed in terms of gain in shear strength and post-peak behaviour for all configurations and types of mortar considered. The comparison of FE and experimental results proved that the models have the potential to be used in practice to accurately predict the shear strength and reflect damage progression in unreinforced and CFRP-reinforced masonry triplets under in-plane loading, including the debonding of the CFRP reinforcement. Additionally, XFEM was found to be a powerful technique to be used for the location of crack initiation and crack propagation in the mortar layer.