Earth Block Masonry Research Articles

Shear capacity of interlocking compressed stabilized earth block masonry panels

An experimental study was conducted to investigate the shear performance of reinforced and unreinforced interlocking compressed stabilized earth block (ICSEB) masonry wall panels. Forty-eight wall panels were fabricated using Auram 295 blocks and subjected to diagonal-compression. The influence of coir fibres, channel block, type of reinforcement (steel and bamboo) and arrangement (mesh and vertical) on wall shear behavior were studied. Cracking patterns, failure modes, load-deformation response and shear capacity were analyzed and discussed. The feasibility of using conventional masonry analytical equations in estimating the shear load capacity of wall panels was also evaluated. The test results demonstrated that wall panels without bamboo/steel reinforcement failed suddenly in a brittle manner and split into two parts, whilst bamboo/steel reinforced grouted wall panels behaved in a more ductile manner and remained intact after the failure, irrespective of presence of fibres. The incorporation of fibres effectively increased the shear load and deformation ability of wall panels, irrespective of the variables examined. The panels reinforced with steel/bamboo showed a significant improvement in shear load capacity of about 20.33% to 162.94% and in deformation capacity of around 48.47% to 258.29% when compared to the panels without reinforcement. The adopted analytical equations inaccurately predicted the shear capacity of wall panels.

Material evaluation of earth block masonry in the context of Belgium: a survey

Material evaluation of earth block masonry in the context of Belgium: a survey

Axial load behavior of unreinforced and reinforced hollow interlocking compressed stabilized earth block masonry walls

This study investigates the axial load behavior of unreinforced and reinforced hollow interlocking compressed stabilized earth block masonry walls. Sixty walls were constructed and tested under axial compression. The variables include block type (unreinforced and coir fibre reinforced), grout condition (ungrouted and grouted), channel blocks, reinforcement type (steel bars and bamboo splints) and configuration (vertical and mesh type). The results show that addition of coir fibres significantly increase the axial load capacity and ductility of walls, regardless of all other variables considered. Grouting of masonry cores increases the load capacity of unreinforced and fibre-reinforced walls (without bamboo/steel reinforcement), however slightly affecting the deflection capacity. The channel block had a detrimental effect on the load and deflection capacity of both unreinforced and reinforced walls. Bamboo/steel reinforced vertically significantly contributed to the axial load and deformability of walls, despite the presence or absence of channel blocks. Both bamboo and steel reinforced walls behaved in a similar manner; yet bamboo splints showing slightly lesser load and deflection capacity than steel. The axial load and deflection capacity of bamboo reinforced grouted walls are about 78.54% to 90.00% and 79.50% to 94.60% respectively as compared to steel reinforced counterparts. Bamboo/steel mesh reinforced walls with channel blocks exhibited better performance compared to corresponding specimens with only vertical reinforcement. However, the improvement was marginal, due to larger spacing between the horizontal reinforcement. Nevertheless, the presence of horizontal reinforcement greatly improved the failure behavior by restraining the buckling of vertical reinforcement. Overall, fibre and vertical steel reinforced grouted wall specimens without channel blocks (FSVRGMW) showed the best performance in terms of compressive strength. The design equations in MSJC-11 predicted the load capacity of unreinforced and reinforced masonry walls more conservatively. Finally, it can be stated that MSJC-11 recommendation of internally reinforced grouted walls must be treated as unreinforced walls, if no horizontal reinforcements was provided, is not reasonable.

Finite Element Detailed Micromodeling of Unreinforced Earth Block Masonry

Finite Element Detailed Micromodeling of Unreinforced Earth Block Masonry

Challenges to upscale earth block masonry in Western Europe from a life cycle perspective

Earth block masonry (EBM) has the potential to be reintegrated as an environmentally sound alternative to conventional masonry systems. However, applications with EBM are rare in highly industrialised contexts. Therefore, overcoming the obstacles impeding its entrance into mainstream construction is critical to enable upscaling. This study aims to identify the priority challenges of EBM in Western Europe. Literature on the barriers to upscale earth construction and EBM was reviewed and verified by interviewing earth block manufacturers in Belgium, France, Germany, and Switzerland. The challenges were grouped into six categories: technical, environmental, economic, sociological, political, and organisational. The data were analysed from a life cycle perspective in light of the transition to a circular built environment. The results show a discrepancy between research and practice to meet the current needs and ambitions of the manufacturers. Despite being largely unexplored, knowledge of end-of-life (EOL) scenarios may catalyse the upscaling of EBM. This outcome implies the importance of integrating the EOL phase in future studies on the barriers of EBM and matching research topics with the demands from practice following a multidisciplinary approach.

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.

Performance evaluation of confined dry-stacked block masonry against blast loading

The ascendancy of the current spate of home-grown and international terrorism increased the awareness of the possibility of cowardice terrorist attacks in Pakistan. Many buildings in Pakistan and other affected countries in the world, are at continuous risk of terrorist attacks including the buildings of Law Enforcing Agencies (LEA), education and health sectors. The revolution in masonry units has been extended from ordinary masonry units to mortarless interlocking blocks. Keeping in view, the astounding energy-dissipating capacity of dry-stacked block masonry, it was decided to explore the behavior of Interlocking Compressed Earth Block (ICEB) masonry against blast loading. Four confined masonry walls and a typical full-scale structure were subjected to blast load at different scale distances. The pressure sensors data, high-speed video, and post-testing inspection of the test’s specimens were assessed for the evaluation of structural performance against shock waves. It has been concluded that the ICEB has sufficient out-of-plane shear capacity against blast loading and the reinforcement detailing of the confining elements plays a vital role in the overall performance of the confined dry-stacked masonry.

Experimental and numerical evaluation of a stackable compressed earth block masonry system: Characterization at cyclic shear loads

Soil is a traditional construction material that is currently experiencing a new boom as an eco-sustainable alternative for housing. In this article, a structural system made up of compressed earth blocks is analyzed as a construction alternative for seismic countries. This study evaluated the physical properties of base soil as well as an optimization process for the chemical stabilization of the mixture using cement and lime. The mechanical characterization of the blocks and of a masonry system designed to be stackable and dry joint was also performed, including the evaluation of its seismic response to cyclic shear wall tests. Results indicate that it is possible to improve the workability of the stabilized soil mixtures and the mechanical behavior of blocks in compression and tension, by using cement-lime additives in a ratio of 1:3 with respect to the dry weight of the materials. In addition, it was found that it is feasible to produce a stackable masonry system that has the capacity to dissipate energy due to friction between blocks. The parametric analysis and the calibration process of numerical models performed for the cyclic shear tests highlight the importance of using a micro-modeling approach to obtain representative models that correctly predict the experimental capacity curve in both maximum load and ductility. The use of those models in the present study allowed to adequately replicate the concentration of damage in the joints between blocks, corroborating what was observed through experimental testing.

Flexural behavior of hollow interlocking compressed stabilized earth-block masonry walls under out-of-plane loading

The present study aims to investigate the out-of-plane flexural behavior of hollow interlocking compressed stabilized earth block (ICSEB) masonry walls reinforced with bamboo and steel bars. The effect of grouting, channel block and reinforcement layout (vertical and mesh type) was assessed. A total of thirty masonry walls were fabricated using fibre reinforced blocks and categorized into five groups: two groups of ungrouted and grouted (without bamboo or steel reinforcement) masonry wall specimens and three groups of grouted masonry wall specimens reinforced with bamboo splints and steel bars. All the specimens were subjected to a constant pre-compression load while lateral load parallel to bed joints was gradually applied until failure. In addition, the experimental moment capacity of reinforced masonry walls was compared with the MSJC-11 formulations to assess the applicability. A statistical regression analysis was then performed on the test results to predict the ultimate moment and deformation capacity of all wall specimens. Test results suggest that grout alone has significantly contributed to the load carrying capacity of wall specimens but with a marginal improvement in deformability. While, channel blocks has no significant effect on load carrying capacity of reinforced grouted masonry wall specimens. Bamboo splints and steel bars as internal reinforcements are very effective in preventing the sudden failure and also enhancing the flexural resistance of masonry walls. Steel mesh showed the highest load carrying capacity, lateral deformation and energy absorption capacity. The addition of bamboo or steel reinforcement combined with grout improved the ultimate load carrying, deformation capacity and energy absorption of walls by 114.88%–260.55%, 19%–35.52% and 168.25%–489.28% respectively.The MSJC-11 code overestimated the moment capacity of reinforced masonry walls; whereas the regression models developed accurately predicted the moment capacity and lateral deformation of the masonry walls.

Thermal comfort analysis of fired-clay brick, cement-sand block and cement stabilized earth block masonry house models

Thermal comfort analysis of fired-clay brick, cement-sand block and cement stabilized earth block masonry house models

Study of compressive strength test methods for earth block masonry—Capping method and loading mode

Earth blocks are different from sintered bricks and concrete blocks, and earth block masonry (EBM) is built chiefly with slurry, which shows evident plasticity and water absorption softening characteristics. The compressive strength test method for conventional masonry cannot be applied to EBM. Therefore, establishing a compressive strength test method for EBM is essential in researching and applying this green building material. The capping method and loading mode are two key factors affecting masonry compressive strength testing. This study involved a series of uniaxial compression tests of masonry to analyze the influence of the capping method and loading mode on EBM compression performance. The optimal capping method and loading mode were determined based on the Analytic Hierarchy Process. Fast-hardening self-leveling plaster combined with plastic film isolation simultaneously eliminated moisture erosion in the slurry in an earth block and ensured close contact between the masonry top surface and loading plate. This combination capping effectively improved the stability of the test data, such that it should be used as the standard leveling method for compressive strength testing of EBM. The proposed loading mode can improve the operability and effectively avoid impact load in the loading process. The stress state of a specimen under this loading mode was close to the actual working state, specimen deformation fully developed, and, thus, it should be used as the standard loading mode for compressive strength testing of EBM. • A series of uniaxial compression tests of earth block masonry were conducted. • The influence of the capping method and loading mode on the compression performance of earth block masonry was studied. • The optimum capping method of earth block masonry for compressive strength test is fast hardening plaster self-leveling. • The optimum loading mode of earth block masonry for compressive strength test is improved Chinese loading method.

Shear test method analysis of earth block masonry mortar joints

A series of triplet shear strength tests and numerical simulations were conducted in this study to secure a suitable shear test method for earth block masonry mortar joints. The effects of the block type, horizontal mortar joint, loading location, mortar material, specimen form, block dimensions, and elasticity modulus on the shear performance on the masonry joints were analyzed. The optimal test method was determined based on comprehensive evaluation via Analytic Hierarchy Process (AHP). The shear test method significantly affects the shear performance along the mortar joint of earth block masonry; the shear strength of specimens with horizontal mortar joints is generally higher than that without a horizontal mortar joint. The loading location affects the shear strength of the 6-block specimen, and the shear strength of the specimen loaded at the half-block is higher than that of specimen loaded at the whole block in most cases. The distribution of the shear stress along the height of the mortar joint varies unevenly by specimen form. The stress distribution at the mortar joint tends toward uniformity as the block’s elasticity modulus increases. The 4-block specimen showed favorable test operability and stress state in addition to the highest comprehensive AHP value, 0.322. The 4-block triplet shear strength test is recommended as the standard assessment for earth block masonry.

Stability coefficient of interlocking compressed earth block masonry under axial compression

To investigate the effects of the height–thickness ratio (β) on the mechanical properties and stability coefficients ([Formula: see text]) of interlocking compressed earth block (ICEB) masonry members under axial compression, four groups of specimens with different β of 3.75, 6.75, 11.25, and 14.25 were tested, thereby assessing their stress process, failure mode, compressive strength, and in- and out-of-plane deformations. All the specimens underwent brittle failure under axial compression: the compressive strength was found to decrease in a range from 5.6% to 43% with increasing β, whereas the initial stacking defects and the in- and out-of-plane deformations increased. The specimens became less stable, and we noticed that the overall damage was caused by strength failure and not instability failures. Because the stability coefficient of ICEB-based masonry components cannot be calculated as those of more conventional brickwork, we combined our results with well-established masonry design guidelines and derived an interlocking improvement coefficient. Finally, we proposed a formula for calculating the axial compression stability coefficient of ICEB masonry that can provide a useful reference for subsequent research on ICEB walls.

Experimental study of the mechanical behaviour of a new extruded earth block masonry

The aim of this research is to investigate, through the Digital Image Correlation (DIC) technique, the mechanical performance of a new type of earth masonry, built with extruded blocks and characterized by dovetail horizontally staggered bed joints. The experimental program consists of two levels of investigations: (i) preliminary phase on components, (ii) compression, diagonal compression and combined shear-compression tests on 12 wallettes. Regarding the components, results showed that the mean compressive strength of the earth block was low (3.5 MPa) with respect to traditional bricks and similar to adobe blocks. The dovetail joints were effective in their joining role showing a rather good strength (2.4 MPa) when tested in triplet configuration. Regarding the wallettes, the DIC highlighted failure modes complying with the ones of a traditional masonry under shear, while it showed a “column behaviour” with vertical sliding under compressive tests. Fragile failures occurred during the diagonal compression test. DIC revealed to be a promising technique to recover the full-field strain and crack maps.

Compressive strength of earth block masonry: Estimation based on neural networks and adaptive network-based fuzzy inference system

Estimating the compressive strength of earth block masonry is an essential aspect of structural design. Artificial neural networks and an adaptive network-based fuzzy inference system were utilized in this study to predict the compressive strength of earth block masonry per three parameters: height-to-thickness ratio, and compressive strength of blocks, and compressive strength of mortars. Seventy-two datasets were collected from experiments and references to train and test two respective models. The prediction results are compared against empirical calculation results to validate the proposed technique for determining earth block masonry compressive strength.

Behaviour of Compressed Stabilised Earth Block Masonry under Compressive Loading

Behaviour of Compressed Stabilised Earth Block Masonry under Compressive Loading

Prediction of Compressive Strength of Stabilized Earth Block Masonry

The present study investigates the compressive strength of cement‐stabilized earth block masonry prisms with a number of masonry units and joint layer mortar combinations. The compressive strength of masonry was determined to be performed by uniaxial tests on 144 masonry prisms. The simple relationship has been identified for obtaining the compressive strength of stabilized earth block masonry from their corresponding block and mortar compressive strength. The predicted compressive strength of masonry prisms using the proposed expression is compared with 14 empirical equations and experimental data of past research available in the published literature. The compressive strength predicted by the expression proposed in the present study was found to be in good agreement with corresponding experimental data compared with other empirical equations available in the published literature.

Long-term monitoring of an earth-masonry shell house in Johannesburg, South Africa: thermal performance

Earth has been used as a building material for millennia, and several structures built in antiquity still exist today. Recently, there has been renewed interest in earth-block masonry as it offers some benefits over more traditional materials, including sustainability, low embodied carbon dioxide and energy, good thermal performance and affordability. Additional benefits may be achieved by utilising shells for roof or structure. Of particular focus in this paper is a shell house built in Johannesburg, South Africa. It is a double-storey house, comprising interlocking masonry walls, earth-block vaults and a rib and block slab. This paper presents some in situ experimental results from a long-term thermal evaluation of the prototype house. The effectiveness of several passive design strategies was also examined. Natural ventilation and painting external surfaces white were especially effective at reducing late afternoon and evening temperatures during summer. Another important finding was that the shading of the shell's surface resulted in a significant reduction of indoor temperatures during the winter months. Specifically, the temperature within the north vault was regularly 3–5°C warmer than in the partially shaded south vault between 5.00 p.m. and 9.00 p.m. Several performance recommendations are presented for unreinforced earth-masonry shells.

What are the barriers affecting the use of earth as a modern construction material in the context of circular economy?

One path to decrease the impacts of construction is to switch from the current take-make-dispose extractive industrial model, to a circular economy scheme. Building with prime materials and especially with earth (locally available soils containing clay), is a way to foster the circularity of the materials because the unstabilised earth is 100% infinitely reusable. Earth architecture involves different modern and ancient techniques of construction like rammed earth or compressed earth block masonry. However, the development of new earth building is still limited to a niche in spite of its high circularity potential in a modern context. We have performed a review of the barriers that may affect the uptake of the earth as a building material. We have studied journal papers and some findings are based on the experience of the authors as practitioners and researchers. The identified barriers can be classified in Steering mechanisms, Process, Economics, Client understanding and Underpinning knowledge. We have discussed the barriers and reviewed some possible paths to smooth the existing obstacles to the development of earth architecture.

Thermal performance assessment of masonry made of ICEB’s stabilised with alkali-activated fly ash

Despite being a material used over time, soil has lost its space as a building material with the appearance of the most diverse materials and techniques that today are considered traditional. However, with the latest environmental and energetic concerns, earth construction techniques appear revitalized. Recently, the Interlocking Compressed Earth Block (ICEBs) masonry system has experienced considerable development. Some studies prove the potential of new stabilization techniques, such as alkaline activation, to improve the mechanical performance and the durability of the blocks, allowing the incorporation of industrial by-products. The high-energy consumption for buildings acclimatization has been another aspect of high discussion. Many times, buildings constructed with earth are referred as an example with respect to the thermal performance. In this sense, an assessment of the heat transfer coefficient of the ICEBs was carried out. The results show that the ICEBs system performs poorly when compared to other current construction materials regarding the heat transfer coefficient, but presents an improvement when stabilization is done with alkali activated fly ash compared to other earth based materials.