Masonry Prisms Research Articles

Influence of strength behavior in brick masonry prism and wallette under compression

For decades, prisms and wallette have been used to explore masonry’s strength and deformation capabilities under uniaxial compression; moreover, the link between these two main test methods needs to be better established. Using standard masonry design expressions and data, the prism or wallette test can determine compression qualities. The researchers compared the standards and came to judgments on their conservatism or lack thereof, independent of how the rules for those design standards were formed. As a result, an attempt was made to link the behaviour of the enormous masonry prism to the wallette pressure behaviour. Prisms and wallette were made and tested by three different types of units and three mortar compositions. According to test results, the compressive strength of prism tests is consistently higher than that of identical wallette samples. It has remained demonstrated that a linear relationship concerning the compressive strengths of prisms and wallette is tolerable. To test data from the prisms and wallette, a simplified analytical model for the deformation properties of masonry is given.

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.

Compressive strength prediction of hollow concrete masonry blocks using artificial intelligence algorithms

In this study, artificial intelligence algorithms are proposed for estimating the compressive strength of hollow concrete block masonry prisms, including neural networks (ANN), combinatorial methods of group data handling (GMDH-Combi), and gene expression programming (GEP). To train and test the proposed models, 102 samples of hollow concrete prisms from previous research works were collected. The height-to-width ratio of hollow concrete prisms and the compressive strength of mortar and concrete blocks were considered as inputs. In order to evaluate the validity and predictability of the proposed models, they were compared with empirical models and models presented in codes and standards. Among the suggested and existing models, the ANN model with an R-value of 0.950 and MAPE error value of 6.921% had the best performance, which with a more complicated equation, can be used in the scientific aspect. In contrast, the other two proposed models (GMDH-Combi and GEP) with acceptable performance and accuracy levels and more simple closed-form equations can be utilized in practical aspects. Based on the parametric analysis, the proposed models were highly efficient and accurate. Moreover, the sensitivity analysis results showed that in all three proposed models of ANN, GMDH-Combi, and GEP, the compressive strength of concrete blocks was the most effective input parameter in the compressive strength estimation of hollow concrete prisms.

Compressive and Shear Behavior of Masonry Reinforced with Ultra-Rapid-Hardening Fiber-Reinforced Mortar (URH-FRM).

Masonry structures are very vulnerable to lateral forces such as earthquakes. In particular, for existing masonry buildings that have not been designed for earthquake resistance, appropriate seismic resistance retrofit is required. In this study, ultra-rapid-hardening fiber-reinforced mortar (URH-FRM), which has a high ductility, with an ultimate tensile strain of about 0.07, and is an economical and easy-to-construct seismic reinforcing material, was developed. Compressive strength and initial shear strength tests were performed on masonry prisms reinforced with the URH-FRM. As an experimental variable, the reinforcement thickness of the URH-FRM was varied from 10 to 30 mm and the structural performance was compared with specimens reinforced with general mortar and specimens without reinforcement. As a result, the beneficial effect of URH-FRM on the in-plane initial shear strength of horizontal bed joints in masonry prisms was confirmed. In addition, the thicker the URH-FRM reinforcement, the clearer the improvement in ductility through strain hardening.

Constitutive behaviour of masonry prisms using a full-field measurement technique

To obtain analytical models for the compressive behaviour of masonry structures, it is crucial to accurately measure the compressive strengths of its constituents, i.e., brick and mortar. The mechanical properties and the stress-strain relationship under uniaxial compression are essential for thoroughly investigating and evaluating masonry structures. The present work aims to validate a non-contact measuring technique for obtaining full-scale strain and failure patterns and investigate joint mortar composition's effect on masonry behaviour. Forty masonry prisms were manufactured in this study using two distinct types of brick and five different types of mortar varying according to cement and lime contents. The results showed that 2D Digital Image Correlation (DIC) could generate full-strain assessments of masonry prisms, resulting in a full-scale stress-strain analysis. It was also found that, in the post-peak region, prisms with lower cement content exhibit a more ductile behaviour with strain localisation at the joint mortar level. Based on current experimental results and data from the literature, new analytical relationships were presented to predict masonry mechanical properties and masonry complete stress-strain compressive behaviour.

Experimental Study on the Compressive Behaviors of Traditional Tibetan Three-Leaf Walls

ABSTRACT Three-leaf stone masonry constitutes a widespread construction typology in historical buildings, but limited reports can be found on its mechanical behaviors. This study intended to understand better the compressive behaviors of traditional Tibetan three-leaf walls (TTTLWs) constructed from stones and mud mortar by a series of laboratory experiments on the constituent materials as well as the masonry prisms and walls. The physical properties of the TTTLWs, e.g. the elastic modulus, crack strength, compressive strength, and damage evolution were investigated. A three-dimensional numerical micro model, validated by the experimental results, was proposed to discuss the compressive behavior of the walls. TTTLWs may be concluded to have medium compressive strength, low elastic modulus compared with other types of three-leaf walls. Large separation between the leaves was observed during the test, and the consequent second-order effect caused the reduction of the compressive performance. The key stones provided a transversal connection between wall leaves, resulting in a limited positive influence on the compressive strength of walls.

A New Proposed Model to Estimate Compressive Strength of Brick Masonry Prisms

This study presents a new model to estimate the compressive strength of masonry prisms considering both crashing and splitting failure mechanisms of the masonry prisms. The model is developed considering a probability of events by defining the resulted failure of the masonry prism as the main event. On the other hand, the different modes of failure including crushing of brick units, crushing of mortar under compression stresses and splitting of the brick units and mortar under bilateral stresses have defined as sub-events of the resulted failure. Eventuaaly, the developed model is verified against extensive results of experimental tests of masonry prisms that published by other researchers. A comparison is conducted between the estimated strength and the experimental results as well as those obtained from several available models in term of statistical measures. Comparison results reveal that the new proposed equation exhibits very good agreement with experimental results and shows the best accurate estimations with less deviations compared with the other available equations. The new proposed equation shows a mean value of the experimental to the estimated compressive strength of masonry equals to 1.01 ± 0.35 and a coefficient of variations equals to 35.12 %.

Closed-form model for curved brittle substrates reinforced with FRP strips

Externally bonded Fiber Reinforced Polymer (FRP) strips have been proved to be effective for strengthening masonry structures. The role played by the bond between composite and substrate is crucial for transferring tensile stresses from masonry to the reinforcing system, thus has become the object of extensive investigation. When the reinforced components are curved, such as arches and vaults, which appear quite commonly in masonry buildings, the influence of the substrate curvature on the bonding cannot be ignored. The debonding mechanism can be studied with a concise model in which the substrate is rigid and the FRP plate is elastic, and the interface where the two are bonded is assumed to lump all the nonlinearities. In this paper, a fully analytical approach for FRP strengthened curved masonry prisms is proposed based on this model, providing closed-form solutions for different geometrical configurations. The interface cohesive law is assumed to be piecewise linear with elastic, softening and residual strength stages. The influence of the normal stress appearing at the interface due to the substrate curvature is considered in the cohesive law for both extrados and intrados strengthening cases. An extensive validation carried out considering both existing experimental results and alternative numerical approaches indicates that the procedure proposed is able to accurately predict the bond strength as well as to reproduce the global bond behavior, requiring few parameters and little calculation effort.

Effect of Structural Bonding Patterns on Mechanical Characteristics of Clay Brick Masonry under Different Loadings Using Digital Image Correlation Technique

This paper assesses the effect of two different structural bonding patterns on the mechanical characteristics of clay brick masonry assemblages under compression, flexure, and shear loading conditions. A 2D digital image correlation technique (DIC) was used to appraise the nonlinear compressive stress-strain characteristics, orthotropic properties, damage, and failure mechanisms of masonry prisms. The experimental investigation ascertained that full-brick thick masonry exhibited reasonably higher capacity and deformation characteristics than half-brick thick masonry under compression, flexure, and diagonal compression loadings, except in bed joint shear strength. The compressive strength and corresponding strain of full-brick thick Flemish bond prisms were higher and had more deformable (maximum strain recorded 2.4 times) behavior than half-brick thick masonry prisms. The failure mechanics of the masonry was quantitatively established by strain analysis obtained from DIC. The rupture modulus of Flemish bond masonry walls was four times higher, and its failure (a combination of tensile splitting of bricks and bed joint failure) was gradual compared to stack bond masonry. The diagonal compression strength of full-brick thick masonry wallettes was about 1.3 times as large as running bond wallettes, as the bond arrangement resisted diagonal cracks propagation. The applicability of the available idealized compressive stress-strain analytical models was evaluated, and a few improvements were recommended. The research study assessed that due attention needs to be given to structural bonding patterns in evaluating the mechanical characteristics of masonry required in the design and analytical modelling of masonry constructions. DIC technique can be conveniently used to capture the nonlinear strain characteristics and can be handy in detecting the damage early.

Characteristics of Masonry Prepared with KM Soil as Fine Aggregate in Cement Mortar and Concrete Block

Manufactured Sand (M Sand) has become a viable alternative for the river sand in the construction industry as a potential fine aggregate. The M Sand poses environmental implications as it is produced by crushing natural resources like stones. The extensive use of M Sand may also lead to a reduction in availability due to the depletion of natural rocks in the days to come. Hence, this study attempts to assess the feasibility of utilizing the clayey soil containing Kaolinite – Montmorillonite (KM) as a predominant clay mineral, as a replacement to the Manufactured sand in the preparation of cement mortar and cement block that are used in masonry construction. In the case of concrete block masonry units, the M Sand is replaced by 25%, 50%, and 100% with KM Soil, and an attempt is also made to produce the mortars by completely replacing the M Sand with KM soil. Further, the properties of the concrete blocks and mortars prepared with KM soil are assessed and compared with the ones prepared with M Sand. Also, the performance of the stack bonded masonry prisms like compressive strength and bond strength in shear is assessed for the various masonry prism prepared with combinations of the Concrete block masonry units and mortars. The results indicate that the stack bonded masonry prism assemblies with KM soil both in cement mortar and concrete block have performed moderately well in compressive strength and shear bond strength in comparison with the one prepared with M Sand.

Out-of-Plane Behavior of Masonry Prisms Retrofitted with Shape Memory Alloy Stripes: Numerical and Parametric Analysis.

This paper provides a novel Finite Element (FE) simulation to estimate the out-of-plane response of masonry prisms retrofitted with Shape Memory Alloy (SMA) stripes. Empirical data were utilized to develop the computational analysis parameters (mechanical parameters for brick, mortar, and SMA materials) as well as the calibration of the computational FE-based models. For this purpose, a complete micro-modeling approach was applied, assuming perfect contact between mortar joints and brick units. A Concrete Damage Plasticity (CDP) model was developed to define the constitutive relation between brick and mortar. SMA stripes were mortar-installed on the surface of the prisms with a perfect connection. The masonry prism’s verified computational model was utilized to generate parametric research to explore the effect of varying SMA stripe thicknesses and different SMA usage (Ni-Ti or Cu-Zn-Al). The FE study findings indicated that, independent of their material type or thickness, using SMA stripes greatly minimizes brick prism deterioration. SMA stripes greatly decreased residual displacement and plastic strains. Parametric tests, however, revealed that employing Ni-Ti SMA and increasing its thickness is more effective with respect to the masonry prism out-of-plane response than Cu-Zn-Al SMA.

Calibration of a total strain crack model for adobe masonry based on compression and diagonal compression tests

Although it has good compressive behavior, adobe masonry is classified as a quasi-brittle material mainly due to its relative low tensile strength and softening behavior after the peak tensile strength. The behavior, plus the high variability in the adobe mechanical properties, makes it difficult to evaluate the performance of entire adobe buildings. For such a purpose, the development of reliable and computationally efficient numerical approaches is required. This work shows a numerical methodology to calibrate the main mechanical parameters to be used in the numerical modeling of adobe samples following the finite element method (FEM) by using the Total-Strain Crack model. The present paper shows that this numerical model is able to represent the nonlinear behavior of the adobe masonry. The calibration process is based on preliminary experimental tests performed on masonry prisms (piles and wallets) subjected to axial compressive and diagonal compression loads, respectively. The main results show that it is possible to model adobe masonry in practice. A consistent reproduction of the cracking pattern from experimental tests is obtained. By using the calibrated properties, this work may be extended to evaluate the seismic vulnerability of complete adobe structures. • A total-strain crack model is calibrated based on experimental tests. • The model captures well the highly non-linear behavior of adobe masonry. • The tensile strength controls the end of the elastic behavior in the model. • The tensile fracture energy controls the nonlinear behavior in the model.

Compressive strength of recron fibred cement mortar by replacement of cement with alccofine

In India, masonry structures are still practiced on major scale. Causalities majorly happens in masonry structures during earthquakes in earthquake prone zones due to less bond strength and non-structured designs. The main aim of afore mentioned paper is to find solution to increase this compressive strength, so that practice of masonry structures in rural area can made safe and economic with respect to strength. This study of bond strength can be carried out by analytic approach as well as experimental approach. In analytic approach, finite element method is used for the study, which requires large numbers of properties to model materials, which are not available in literature for the Indian scenario because literature focuses about results not properties. Hence this compressive strength study is carried out by experimental approach to give it more practical and meaningful direction. In mortar, arbitrarily dispersed fibers and alccofine 1203 are generally used for fortification to resist proliferation of crack and also helps to improve strength and ductility behavior which will help the structure to get less damage and to enhance the performance during earthquakes in earthquake prone zones. This will reduce the causalities. The use of recron 3s fibers is economic and alccofine 1203, easy to practice and effective approach as well. These experimental studies are started by making mortar cubes and ended up with making masonry prism and columns by using recron 3s fibers and alccofine 1203 with different mortar bed thicknesses. The studies on brick masonry prism suggests that use of recron 3s fiber and alccofine 1203 in mortar can increase the compressive strength to enhance the performance of the masonry structure. Use of 8 mm thick mortar bed gives more convincing when compressive strengths of masonry wallets are compared.

Studies on Strength of Hollow concrete Block Masonry Externally Bonded with Textile Reinforced Mortar Composites

The aim of present study is to determine the mechanical properties of hollow concrete block masonry externally bonded with coir and glass textile reinforced mortar composites. The properties of textile composites were determined by testing TRM Coupons. A total number of 39 prisms were cast. The block masonry prisms were externally bonded with coir and glass textile fibre mesh with mortar. The elastic properties of block masonry, shear and flexural strength were determined for both unreinforced and strengthened specimens. The results showed that increasing the number of layers of textile fibers, enhanced the flexural capacity of TRM coupons. The provision of connectors also enhanced flexural strength. The stiffness of unreinforced masonry prisms was found to increase by strengthening with textile reinforcements even though the increase in compressive strength is marginal. There is a significant enhancement in flexural strength and shear bond strength when compared to unreinforced masonry.

An experimental study on the mechanical properties of solid clay brick masonry with traditional mortars

An experimental study is carried out to investigate the mechanical properties of clay brick masonry fabricated using traditional mortars. In this regard, four types of mortar whose frequent uses in Iranian traditional and historical monuments have been reported in the literature are selected. These mortars are gypsum mortar and three types of lime-based mortars including, Sarooj, lime-sand mortar, and lime-cement-sand mortar. In this study, tests on brick units, mortar specimens, masonry prisms and wallettes are conducted. The compressive stress-strain behavior, compressive strength, elastic modulus, and rupture modulus of mortars are determined from the standard tests. Moreover, the compression test of masonry prisms, direct shear test of brick-mortar bond, and diagonal shear test of masonry wallettes are carried out. The compressive stress-strain behavior of masonry and the shear bond strength of brick-mortar interface are determined from the tests on masonry prisms. Furthermore, shear stress-strain behavior of masonry wallettes is evaluated through diagonal shear tests. Some key mechanical properties of masonry wallettes such as modulus of rigidity and Poisson's ratio are also found from the test results. Accordingly, the brick-mortar bond governed the in-plane shear behavior of the masonry wallettes in diagonal shear tests. Furthermore, the highest compressive strength, elastic modulus, and diagonal shear strength belong to the masonry fabricated with gypsum mortar. By using the results of the experimental program, the applicability of some well-known empirical formulations for estimating the compressive strength of masonry prisms as well as the accuracy of idealized stress-strain models proposed for masonry material, are assessed.

Axial performance of grouted C-Shaped concrete block masonry columns jacketed by carbon and glass FRP

To overcome the relatively low ductility and capacity of masonry elements, the confinement technique may be an effective alternative for improving their performance, especially the columns. Fiber Reinforced Polymers (FRP) jacketing is a potential approach has benefits in terms of strength enhancement and gaining ductile behavior. Therefore, in this study, two types of FRP were used to improve column axial capacity and ductility: carbon and glass FRP. The effect of FRP wrapping on the compressive behavior of concrete masonry columns was investigated experimentally. Fully grouted scaled masonry columns constructed using C-shaped concrete blocks were wrapped with FRP jackets and tested under concentric compressive load until failure. For this purpose, 18 half-scale masonry prisms under variations in FRP jacketing and FRP thickness were developed and tested in six sets. The effect of FRP confinement on the unconfined masonry columns was evaluated. The CFRP and GFRP jacketing increased the peak strength and ultimate axial strain. Confinement improves post-peak performance by softening the descending stress–strain relationships. Increasing FRP jacket thickness improved the axial strain, strength, and ductility of masonry columns. The CFRP wrap gives 10 ∼ 16% more strength than GFRP. Ultimate strain enhanced by 76 % and 57 % for CFRP and GFRP respectively.

In-plane behaviour of masonry walls embedding with steel welded wire mesh overlay with mortar

ABSTRACT This paper presents an experimental study of the structural behaviour of masonry walls strengthened with steel-welded wire mesh (WWM) overlay with mortar to improve their in-plane shear strength and deformation capacity. The experimental programme consists a compression testing of masonry prism and a diagonal compression testing of 15 wall specimens made of clay brick strengthened with four different WWM systems: (i) embedding WWM along the bed joint, (ii) embedding WWM along the bed joint and a strip diagonally crossing on wall surface, (iii) WWM alternately embedding along the bed joint and continue to the surface of wall and (iv) WWM fully cover on wall surface. The experimental results show that the adopted WWM-strengthening solutions produce a beneficial increase of compressive strength, shear resistance, ductility and energy dissipation capacity making them suitable for seismic strengthening.

Performance of clay masonry prisms with light weight plaster exposed to standard fire exposure

AbstractClay bricks are one of the most widely used materials in building construction due to their advantages, including local availability, ease of fabrication and cost‐effectiveness. Fire is one of the dangerous hazards that can cause damage the life and property. Lightweight plasters play a vital role in insulating the masonry construction during fire accident. There is only limited data and information available on the fire performance of Clay Brick Masonry (CBM) insulated with lightweight plaster. An extensive investigation was undertaken to evaluate the residual strength properties and physical characteristics of CBM prisms exposed to elevated temperatures. CBM prisms plastered with M‐sand mortar, vermiculite mortar, and perlite mortar were used for the investigation. Protected prisms were exposed to elevated temperatures following the ISO 834 standard fire curve for durations of 30 min (821°C), 60 min (925°C), 90 min (986°C), and 120 min (1029°C). Mechanical properties such as axial load carrying capacity, stress–strain behaviour, elastic modulus, and crack pattern were examined. The mechanical properties of CBM prisms were found to be highly influenced by the type of plastering, intensity, and the duration of heating. The microstructure and image analysis confirmed the effects of temperature exposure on protective plasters. Equations are proposed to determine the residual axial compressive strength and the elastic modulus of CBM. It was found that the specimens plastered with perlite mortar had better fire resistance.

Cyclic in-plane behavior of unreinforced and confined masonry walls retrofitted by shotcrete: Experimental investigation

This study aimed to investigate the efficiency of shotcrete retrofitting method for seismic rehabilitation of conventional unreinforced and confined masonry walls. In this regard, six large-scale masonry walls have been built using fired clay bricks and sand-cement mortar. The specimens were listed as unreinforced and confined masonry walls with vertical concrete ties before and after retrofitting using shotcrete overlay. Moreover, a relatively new approach was adopted for seismic retrofitting of unreinforced masonry (URM) walls as an alternative to vertical concrete ties. Correspondingly, a series of material tests were carried out to obtain the mechanical properties of the masonry, in particular the compression test on masonry prisms, shear triplet, and diagonal compression tests. The masonry walls were tested under simultaneous gravity and reversed cyclic in-plane loading. The dominant failure mode of the URM wall was rocking, while in the case of shotcrete-retrofitted specimens, the failure mechanism was predominantly bed-joint sliding. Besides, the confined masonry walls with vertical ties failed mainly due to diagonal cracking. Evaluation of the cyclic performance of the specimens showed that vertical concrete ties significantly increased the ultimate lateral resistance and the cyclic dissipated energy, though a reduction in the ductility capacity was identified. The specimens retrofitted by shotcrete exhibited a significant enhancement in the lateral strength and a more gradual strength deterioration in the post-peak behavior, even though the shotcrete reinforcing bars were neither anchored to the foundation nor to the concrete ties. Furthermore, the shotcrete-retrofitted specimens exhibited maximum dissipated energy and minimum stiffness degradation among the specimens.

Structural and thermal performance of sustainable interlocking compressed earth blocks masonry units made with produced water from oilfields

There is a growing interest in plausible reuse of wastewater and solid waste materials for compressed earth bricks (CEBs) production due to their sustainability benefits, affordability, and they are considered relatively ubiquitous raw materials. However, a study of the behavior of CEBs produced from soil and injected wastewater from oilfields has not been well documented in the literature. This study aimed at employing an experimental testing program to assess structural and thermal properties of masonry units, mainly prism’s compressive strength, masonry wall’s behavior, and thermal properties of CEBs rooms made with produced water and soil obtained from two oilfields in Oman: namely Marmoul and Nimr oilfields. It was found that prism strength decreases with increasing prism height, with Marmoul CEBs (2.4–3.9 MPa) showing slightly better performance compared to that Nimr (1.8–3.8 MPa). The masonry prism efficiency factor, which was estimated based on the ratio between the prism and block strength, was in the range of 52.3–59% for Marmoul CEBs, whereas for Nimr blocks, it ranged from 39.2% to 57.9%. The results of the masonry wall test showed that the wall reached an ultimate load of 386 kN at a deformation of 8.0 mm and the mode of failure was deformation of the wall due to overall buckling. The CEBs rooms have shown enhanced thermal performance compared to the reference room built with hollow concrete blocks. The CEBs rooms provided 1–7 h of time lags and achieved between 0.15 and 0.23 lower decrement factors than the reference room due to their high thermal mass and thermal resistance, respectively. While the CEBs under this study have shown good structural and thermal insulation potential as a sustainable building material, other factors, including indoor air quality emissions, acoustic properties, seismic resistance, and cost-benefit analysis, need to be considered in future studies.