Concrete Masonry Research Articles

Numerical simulation of autoclaved aerated concrete masonry wall subjected to close-in explosion and the structural damage assessment

In this study, we investigated the destructive effect of autoclaved aerated concrete (AAC) masonry walls subjected to close-in explosions. First, full-size refined finite-element models of the AAC masonry wall were established, and the accuracy of the models was verified by comparison with the test results. The destruction pattern and damage characteristics of the AAC wall were studied, and the effects of block size, wall thickness, mortar compressive strength, and explosion distance on the destruction degree of the AAC masonry walls were analyzed. The results showed that the destruction pattern of the AAC masonry wall subjected to close-in explosion manifested as punching damage in the middle of the wall. When the scaled distance remained unchanged, the punching damage area of the AAC masonry wall was positively correlated with the block size and negatively correlated with the wall thickness and mortar compressive strength. When the explosive equivalent remained unchanged and the explosion distance increased, the punching damage area first increased and then decreased. According to the damage mechanism of the AAC masonry wall, a calculation method for predicting the punching damage area of the AAC masonry wall was established, and the accuracy of this method was verified by comparing it with the numerical results. In addition, the damage criterion based on the punching damage area was established to determine the destruction levels of AAC masonry walls.

Structural, acoustical, and thermal evaluation of an experimental house built with reinforced/hollow interlocking compressed stabilized earth brick-masonry

With the increasing demand on affordable construction that addresses the global challenges of the modern world, earthen construction is being reintroduced and investigated as a potential sustainable and affordable building method. Compressed stabilized earth blocks (CSEBs) are a common form of enhanced earthen building materials. Previous studies focused on the structural performance of CSEB walls and prisms consisting of one type of bricks with the same mixture, analyzed their thermal and acoustic properties as units only, or evaluated the thermal performance of solid unreinforced CSEB masonry.The present research is the first complete structural, acoustical, and thermal investigation of an experimental house built with a novel reinforced/hollow interlocking compressed stabilized earth brick-masonry (ICSEB) using varying stabilizer contents, compliant with the Egyptian code for building with stabilized soil—Part One: Building with compressed stabilized soil units (EG-SE2016). Methods depend on experimental testing, codified theoretical calculations, finite element analysis, and live measurements. According to the structural experimental testing program, reinforcement was found to triple the load bearing capacity of ICSEB columns and, although minimal rebars were used in the ICSEB walls, it has improved their load bearing capacity by 23% for single walls (125 mm) and 58% for double walls (250 mm). In addition, doubling the thickness of the unreinforced ICSEB walls increased the load bearing capability by 164%, while raising the thickness of the reinforced wall from 125 mm to 250 mm increased the load bearing capacity by more than threefold (3.38). Based on the codified theoretical calculations and findings of the finite element analysis, it is safe to recommend reinforced double ICSEB walls as a reliable construction for a two-story residential building. Acoustically, double ICSEB walls attained the noise reduction index value of 40 dB, which is required by the Egyptian code for acoustic insulation and noise control in residential buildings, to protect against the average outdoor noise levels of 65–70dBA. Thermally, reinforced double ICSEB walls kept the indoor air temperature and relative humidity values within the thermal comfort zone, 23.9–25.7 °C and 28–36%, respectively, despite the fluctuating outdoor temperatures and relative humidities (16–37 °C and 7–88%, respectively). Indoor air temperatures were 1.5–2 °C lower than those of concrete masonry walls. Additional research is required to evaluate resistance to environmental aspects, such as exposure to water, wind, and corrosion, and to further investigate their thermal and acoustical properties.

Reinforced concrete block masonry walls under eccentric compression: Assessment using experimental and numerical data

This paper presents the outcome of a research study carried out to assess the eccentric compression behaviour of reinforced concrete block masonry (RM) walls. The design provisions pertaining to axial compression capacity of RM walls are overly conservative, especially where slender walls are to be designed. To verify the relevancy of the design provisions outlined in the Australian masonry standards (AS 3700), an experimental database of RM walls tested under eccentric compression was created by gathering data from the past studies. In total, 76 partially grouted (PG) and 18 fully grouted (FG) RM wall test data were gathered. The established database revealed that the performance of fully grouted (FG-RM) walls are generally overlooked. To fill this gap, a finite element (FE) based numerical modelling procedure was established to understand the performance of FG-RM walls under eccentric compression. The established FE modelling procedure was validated with a set of experimental results and the validated modelling procedure was then used to parametrically analyse the eccentric compression behaviour of FG-RM walls. In total, 72 FG-RM wall cases were numerically simulated under eccentric compression, varying slenderness ratios (15, 21, 26, 32, 37, and 42), grout strengths (20 MPa, 30 MPa and 40 MPa) and boundary conditions (pinned-pinned and fixed-fixed). The analysed numerical data along with the experimental database were then used to verify the design provisions outlined in previous version of AS 3700 (2011) and current version of AS 3700 (2018). It was found that the provisions specified in AS 3700 (2011) were overly conservative than the AS 3700 (2018), justifying the need of deliberate revisions in terms of the treatment of slenderness, eccentricity and grout strength for designing the RM walls under compression.

Unreinforced concrete masonry for circular construction

This paper proposes an effective approach to realise circular construction with concrete, and shows Unreinforced Masonry as a foundational building block for it.The paper outlines the importance of circularity in building structures. It specifically focuses on the impact of circular construction with concrete on improving the sustainability of the built environment in a rapidly urbanising world economy. Subsequently, the relevance of principles of structural design and construction of unreinforced masonry to achieve circularity is articulated. Furthermore, the paper presents and summarises recent developments in the field of Unreinforced Concrete Masonry (URCM) including digital design tools to synthesise structurally efficient shapes, and low-waste digital fabrication techniques using lower-embodied-emission materials to realise the designed shapes. The paper exemplifies these using two physically realised, full-scale URCM footbridge prototypes and a commercially available, mass-customisable building floor element, called the Rippmann Floor System (RFS).The paper also outlines the benefits of mainstream, industrial-scale adoption of the design and construction technologies for URCM, including accelerating the pathway to decarbonise the concrete industry. In summary, the paper argues that URCM provides a solution to significantly mitigate the carbon emissions associated with concrete and reduce the use of virgin resources whilst retaining its benefits such as widespread and cheap availability, endurance, fire safety, low maintenance requirements and recyclability.

Evaluating the axial compression behaviour of hollow concrete block masonry walls with small-size openings: Various opening positions and their influence on experimental results

Openings such as windows or channels for ventilation and heating systems are commonly encountered in masonry buildings to meet with functional needs. Although these openings are known to reduce the strength and stiffness of masonry walls, however, the relationship between the position of openings and load bearing capacity of masonry walls is not well understood. Therefore, the primary aim of this study is to investigate the effect of double opening positions on the axial compressive behaviour of masonry walls constructed with hollow concrete block units. Seven one-half scale walls with different double opening positions were constructed using hollow concrete block units and subjected to a uniformly distributed axial load. The compressive performance such as the strength, stiffness, load-deformation behaviour, stress-strain response, cracking pattern and failure behaviour of the walls have been reported. The results indicate that the 50% reduction in sectional area ratio caused by introducing two small openings in the walls reduced the load bearing capacity by 36 to 50%. Measured ultimate strain values ranges between 5.5 to 38.8% reduction in walls with openings compared with the wall without opening. Vertical cracking, face spalling, and block rupture were the dominant failure modes for walls with double openings, in contrast to mainly vertical cracks observed in the solid wall. This research provides valuable insights into how the positions of double openings influence the performance and overall structural response of hollow concrete block masonry walls under compression load.

Comparative life cycle assessment of light frame timber and reinforced concrete masonry structural systems for single-family houses in Luxembourg

The building sector's significant greenhouse gas emissions and energy consumption present added challenges to meeting European climate commitments amidst rapid population growth. In Luxembourg, single-family houses dominate the residential buildings, noticeably contributing to construction waste and CO2 emissions. This study compares the environmental impacts of a three-story reinforced concrete masonry single-family house and an identical timber building in Luxembourg, emphasizing greenhouse gas emissions and embodied energy. A cradle-to-grave life cycle assessment was conducted using Building Information Modelling (BIM) models to analyze the global warming potential and primary energy requirements. Environmental product declarations from the producers and the ÖKOBAUDAT German database were used to determine the environmental impacts of the materials. The results show that the timber building outperforms the concrete building with a 43.5% lower global warming potential, while the concrete building demonstrates a 15.6% reduction in primary energy demand. This aligns with the average outcomes of seven similar studies discussed in this paper, at 33.2% and 4.7%, respectively. Moreover, the timber building is 78.6% lighter than the concrete one. When evaluating benefits and loads beyond the system boundary, the timber building provides 3.6 and 4 times greater advantages in terms of global warming potential and primary energy, respectively, compared to the reinforced concrete masonry building. Additionally, the study explores the impact of reusing the floors in the timber building. The cradle-to-grave LCA reveals that reusing the timber slabs improves the building's global warming potential and primary energy by 2.4% and 1.2%, respectively. However, when considering the benefits and loads beyond the system boundary, floor system reuse exhibits a 38.9% surge in global warming advantages while reducing primary energy benefits by 28.1%. The findings advocate for a policy promoting timber construction and reuse in Luxembourg, aiming to achieve the net-zero emission target by 2050.

An Investigative Study for the Seismic Performance of Composite-Reinforced Masonry Wall with Prestressing Technology

Prestressing technology is an effective way to improve the seismic performance of masonry structures such as concrete masonry wall. Therefore, bonded prestressing technology applied to integrated concrete masonry wall (ICMW) was proposed in this study, and a cyclic loading test on specimens with different section types was conducted. It was found that the prestressing technology rendered thinner and denser cracks on the load-bearing component of the specimens, while the failure mode remained unchanged. The prestressing technology increased the initial stiffness of the specimens and accelerated their stiffness degradation. Although the prestressing technology advanced the yield displacement of the specimens, it had a positive influence on the displacement ductility of the specimens. Additionally, the energy dissipation of the specimens increased with the deepening of the damage state, while the influence of the prestressing on the energy dissipation of the specimens decreased with an increased in the drift ratio. Furthermore, the equivalent viscous damping of the specimens with a rectangular and T-shaped section finally converged at 8% and 14%, respectively. Overall, the aforementioned findings indicate that the prestressing technology proposed in this study is a useful method for improving the damage propagation and seismic performance of ICMW, which could be used to construct low-rise masonry structures in the future.

Failure mode dependent shear strength of unreinforced concrete brick masonry wall panels

This study conducted diagonal compression tests to propose the failure mode dependent shear strength for unreinforced concrete brick wall panels. The test variable was the bed-joint mortar mixing ratio. Six brick wall panels were manufactured for each variable, and finally thirty specimens were tested. The test results showed five failure modes in the unreinforced masonry wall panels: diagonal tension, combined, bed-joint sliding, toe crushing, and non-diagonal failure. Furthermore, the shear strength of unreinforced brick wall panels was highly dependent on the failure mode. Based on the test results, the shear strength is suggested according to each failure mode. Additionally, the shear modulus of concrete brick wall panels was suggested as half of the value presented in the current codes for masonry structures.

Flatjack application on existing hollow concrete block masonry

This work aims to validate new flatjack in evaluating existing hollow concrete block masonry. The flatjack method is used as a non-destructive on-site test in masonry structures to obtain the actual stress-strain curve of masonry and estimate its strength. This method is already internationally standardized by ASTM and RILEM standard codes. However, most of the studies, standards, and available jacks refer to masonry with solid units, such as bricks and stones. The research adapted the deformability test performed on hollow block walls with the double flatjack to estimate the elasticity module and the masonry compressive strength, validating this technique as non-destructive. Experimental test using the newly developed equipment was performed in existing masonry buildings. The estimated strength results were compared to test results provided by the company responsible for the construction. The methodology using the new equipment proved good results. The adapted deformability test can be carried out on-site elements to estimate the properties of masonry made with hollow concrete blocks.

Modelos de estimativas de resistência à compressão de prismas a partir de componentes da alvenaria estrutural

Abstract This work proposes models to estimate the resistance of hollow and grouted concrete blocks prisms based on the compressive strength of their components. A database composed of 27,426 tests results on hollow and grouted prisms, mortar, grout and concrete blocks was assessed, grouped into 875 samples. Different statistical analysis models were proposed, and the best model was selected for each predetermined block resistance range. The blocks strength r ranges are Range 1 (up to 8 MPa), Range 2 (from 8 to 18 MPa) and Range 3 (above of 18 MPa). An adjustment factor of 95% confidence was calculated for each model. When comparing the results of the models with the results estimated by the design codes, it was observed that, in general, the estimates of the models of hollow and grouted prisms were similar to those of prism resistance of ABNT NBR 16868-1 (2020), except for the Range 3 resistance, in which the code is more conservative, and the proposed model with the intrinsic adjustment factor estimated values lower than those proposed by the norm. Regarding the international standards, AS-3700 (2017), TMS 602 (2021) and CSA S304 (2014) presented more conservative estimates, while Eurocode 6 (2020) adapted better to the results of the proposed models. Models considered as safe are proposed, based on the hundreds of analyzed samples, allowing estimating the hollow and grouted prism strength from their components strengths for concrete blocks structural masonry.

Development of Non-Load Bearing Three-Core Stretcher Concrete Masonry Unit With Polyethylene Terephthalate Waste

Persistent problems stem from factors such as the difficulty of waste recycling wherein plastics are substantial contributors having strong environmental impact. To mitigate this dilemma, reengineered plastics are emerging as reforms in solving solid waste management issues. This study aimed to investigate the effects of utilizing Polyethylene terephthalate (PET) as an admixture in a non-load-bearing concrete masonry unit. Moreover, it sought to limit the amount of environmental degradation and prevent ecological and environmental strains caused by plastic. This study used the experimental method which involved compressive strength testing, unit weight, and unit cost analysis. In addition to this, the properties of the materials were studied to arrive at the optimum percent composition to generate the highest efficiency. Five treatments were utilized including the control (0%), 1.5%, 2.0%, 2.5%, and 3.0% PET waste admixture. In the findings, both the control CMU and the 1.5% PET waste admixture have qualified on the standard specification, ASTM C129, for CMU compressive strength. The unit weight decreases as the amount of admixture increases. In terms of unit cost, the sample with the highest percentage of PET waste has the lowest unit cost but with the lowest compressive strength. However, between the control CMU and the 1.5% PET waste admixture, the latter has a lower unit cost. Therefore, it can be inferred that adapting the use of PET wastes as admixture at 1.5% showed the most competence proving to reduce plastic waste environmental issues while gaining higher possible profit when introduced into the commercial industry of construction supplies. For future studies, a Comparative Analysis of walls made with plain and PET waste concrete masonry units may be conducted to improve the application of the material.

Self-sensing concrete masonry structures with intrinsic abilities of strain monitoring and damage detection

Self-sensing cementitious materials are emerging technologies for Structural Health Monitoring (SHM) of civil structures. Their application for SHM of concrete masonry elements was not investigated in previous studies. The effects of triaxial strain/stress states of masonry joints and units on their self-sensing response are still unknown. Therefore, this work aimed to investigate mechanical and self-sensing properties of masonry elements produced with self-sensing mortar joints, solid concrete bricks and/or hollow concrete blocks fabricated with carbon black nanoparticles. The intrinsic abilities of strain monitoring and damage detection were evaluated in piezoresistive tests of masonry prisms, based on variations in the type of unit, mortar bedding approach, bonding arrangement, relative strength of mortar and units, joint thickness and location of self-sensing regions. These variations did not affect significantly the gauge factor of cementitious sensors embedded into the prism units. In contrast, the gauge factor of self-sensing horizontal or vertical joints was statistically affected by most of these variations. Stages of balance and abrupt increases in fractional changes in electrical resistivity (FCRs) during the plastic regime of the prisms provided an anticipated warming associated with the propagation of vertical and diagonal cracks associated with tensile splitting and crushing failure of units. The strong non-linearity on the electrical output of self-sensing joints provided an evidence of the mortar pore collapse. In conclusion, the self-sensing units and mortar joints were found to be promising alternatives for strain monitoring and damage detection in smart concrete masonry structures.

Stress-strain characteristics of autoclaved aerated concrete masonry under varying displacement rates

Comprehending the impact of displacement rate on the mechanical properties of autoclaved aerated concrete (AAC) masonry is critical for predicting the response of structures to seismic and other natural dynamic loads. This study investigates the effect of varying displacement rates (0.1 mm/min, 1 mm/min, and 10 mm/min) on the mechanical properties of AAC masonry under uniaxial compression through systematic laboratory tests. Results indicate a substantial increase in elastic modulus (100 %) and compressive strength (200 %) as displacement rates rise from 0.1 mm/min to 10 mm/min. Finite element analysis using a micro-modelling strategy in Abaqus corroborates experimental findings, simulating crack propagation and identifying stress and strain distribution. The outcomes of this study would facilitate the accurate design and analysis of framed buildings infilled with AAC block masonry, especially under dynamic loading. These findings are expected to significantly contribute to the enhancement of structural engineering practices, enhancing the reliability and effectiveness of AAC block masonry for constructing resilient buildings.

Experimental assessment of concrete masonry units integrated with insulation and phase change material: A wall-pattern study

The installation of functional materials, including thermal insulation materials (TIMs) and phase change materials (PCMs), in concrete masonry unit (CMU) block (brick) walls is expected to obtain high thermal performance. However, since the apparent thermal capacity of PCMs is affected by a variety of factors, how to use PCMs rationally becomes a complex and systematic issue. At the same time, how to combine PCMs with TIMs in building envelope to achieve high stationary and transient thermal performances simultaneously is also an important issue that arises with the application of PCMs. The quantitative impact of the key factors, including the underlying patterns of the functional materials themselves, as well as others such as wall pattern, the location, quantity, and handling of the functional materials, is still not clear. In this study, a wall pattern analysis is experimentally performed for the integration of TIM and PCM in CMU-block walls. Walls equipped with various volumes of the two functional materials in eight placement modes under three representative thermal conditions are measured and discussed. The performance associated with the wall modes is completely analyzed. Thermal bridging is found to be a key factor in weakening the effect of the functional materials filled in wall cavities. In addition, the optimal locations and volumes of the functional materials are obtained. This study thermally reveals and gathers effect laws and applied principles, and provides data reference for the proper use of TIM and PCM outfitted building envelopes.

Experimental investigation of the influence of head joints and grouting conditions on the shear strength of concrete block masonry

The nonlinear composite nature of masonry has limited theoretical understanding of material shear strength – especially with concrete block, where minimal experimentation has rendered the influences of two important variables (head joints, presence of grout) unknown. The effects of these variables were investigated experimentally on non-precompressed triplet specimens. Head joints did not influence shear strength statistically significantly: the proportion of grouted cores linearly increased shear strength. The provisions in the Canadian standard lacked accuracy when predicting partially grouted specimen strengths (overestimating up to 135%). Units from tested triplet specimens were also found to have similar compressive strengths to undisturbed units.

Examining Mechanical Properties of Strengthened Aerated Concrete Masonry Walls

Masonry structures primarily rely on their walls as the principal load-bearing components. The walls are brittle materials such as natural stone, sandstone and brick. The walls of masonry structures have lack of the deformation capacity and to resist the tensile stresses caused by earthquake forces, settlement of foundation, and so on. To avoid loss in bearing capacity or to have more strength against lateral loads, during the production or after some precautions can be taken. The aim of this study is to investigate the behavior of strengthened aerated concrete walls by clamps. Six samples were tested under diagonal compression. All tested samples were knitted with mortar advised by the aerated concrete producer. The left five samples were knitted using different orientation of clamps and anchors made out of Ø12 deformed bars and welded plates. According to the experimental test results, it was observed that the interconnection of aerated concrete blocks with different combinations had increased stiffness, energy consumption capacity, and load bearing capacity of the walls. In addition to the brittle behavior of the reference specimen, the strengthened wall specimens have exhibited more ductile behavior.

Life cycle assessment and life cycle cost analysis of different walling materials with an environmental approach (comparison between earth-based vs. conventional construction techniques in Iran)

PurposeClimate change, environmental concerns, and economic problems pose challenges to the construction sector in Iran, which must provide affordable solutions while addressing environmental issues. Hence, natural earthen building materials are critically needed to reduce energy-intensive and costly construction practices dramatically. The purpose of this paper is to provide a framework for comparing life cycle assessments (LCA) and life cycle costs (LCC), for load-bearing walls of an single-family affordable housing unit in a desert part of Iran, Ardakan City.MethodsTo do so, both LCA and LCC for the unit were performed, considering a cradle-to-site perspective. For this purpose, 22 load bearing wall systems are assessed, including 18 stabilized and unstabilized earthen construction techniques, such as adobe, rammed earth (RE), and compressed earth block (CEB), in addition to four conventional wall assemblies of fired brick (FB), autoclaved aerated concrete block (AAC), ceramic block (CB), and concrete masonry unit (CMU). As well as assessing the environmental impact and life cycle costs associated with the life cycle of each wall, the optimal assembly of the wall is also examined.ResultsResults show that unstabilized earthen walling alternatives have significantly lower environmental impacts than conventional materials.ConclusionsSensitivity analysis indicates that by utilizing local materials to the maximum extent possible, impacts can be further minimized. Considering the results, transportation may even account for a greater proportion of EI than wall components.

A case study on performance of structures during Turkey-Syria multiple earthquakes occurred on February 6, 2023

Buildings are an important components of both urban and rural infrastructure, and it is crucial that they perform well during a seismic event. The earthquakes occurred on February 6, 2023 in Kahramanmaras, Turkey, which also had an impact on eleven other locations surrounding it. Turkey has suffered significantly from fatalities as well as damage to structures and other facilities. The area was severely damaged by two earthquakes, Mw7.7 and Mw7.6, which occurred within a time window of roughly 9 hours on February 6, 2023 in Turkey. Seismic regulations only take into account the design of structures during a single earthquake; multiple earthquake occurrences are not taken into account. The performance of reinforced concrete buildings, masonry buildings, and precast buildings damaged during seismic sequences are discussed in this case study. From this study it is observed that, buildings that are subject to multiple earthquakes often collapse because of damage by previous earthquake, weak foundations, detailing errors at site, the use of poor materials, and inadequate craftsmanship. Multiple earthquakes should be considered during the analysis and design phase of structures, and seismic code regulations should be adjusted to allow for multiple earthquakes.

Perbandingan Tingkat Pelaksanaan Praktik Kerja Industri SMKN 2 Purwodadi dan SMK Pembangunan Nasional di Purwodadi

The purpose of this research was to describe the process of the implementation of student state Vocational School Prakerin in Purwodadi and test the difference Prakerin in state Vocational School and private Vocational Schools in Purwodadi. This research uses research survey that is descriptive. The population of this research is the grade I Concrete Masonry Construction Engineering (TKBB) of state Vocational School and private vocational schools in Purwodadi. The Sampling technique used was Simple Random Sampling. The results of the research implementation process of state Vocational School that is as much as 10 students (21.74%) stated the very high category, 31 students (67.39%) including the categories high, by as much as 5 students (10.87%) stated the categories and score an average of 141.26. Results of the study in private vocational schools show that as many as 8 students (17.39%) including the very high category, 14 students (30.43%) said the high category, as many as 14 students (30.43%) including categories and score an average of 134.37. The results of calculation using SPSS t-Test of can to score t of extent and significance is 3.794 0.000 < 0.05 so the hypothesis described there are differences in the implementation process state Vocational School and private Vocational Schools in Purwodadi was supported by the data. Implementation of students state Vocational School Prakerin including categories higher and private Vocational Schools categories include enough.

Effect of boundary element detailing on the seismic performance of reinforced concrete masonry shear walls

Laboratory tests demonstrated that reinforced masonry shear walls (RMSWs) can provide sufficient strength and ductility to be considered an efficient seismic force resisting system (SFRS) for mid-rise buildings. The ductility and overall seismic performance of shear walls were increased by providing confinement to the end zones of the walls to form boundary elements (BEs)., which enhanced the ultimate masonry compressive strain and curvature ductility of the walls. Regular stretcher blocks are commonly used in the construction of masonry boundary elements; however, they impose some constraints due to their geometrical characteristics. This study investigated the construction and testing of three half scale specimens of reinforced masonry shear walls with boundary elements (RMSWs+BEs) that were characterized by flexural dominance under reversed cyclic moment and lateral loading. In the lower story panel of a 12-story RMSW building, these walls constitute the plastic hinge zone, which is represented by a plastic hinge wall. In this study, C-shaped masonry units were used instead of stretcher units to construct BEs with different sizes and vertical reinforcement ratios. The findings of this work revealed that employing C-shaped masonry units to construct the BEs was effective in overcoming the construction limits imposed by stretcher units. Additionally, the results of this study demonstrated that when RMSWs+BEs are subjected to quasi-static reversed cyclic loading, they are capable of providing a high level of ductility with minimal loss of strength.