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The paper presents a novel experimental investigation, comprising material tests and column tests, focusing on the effect of concentric axial loading and slenderness on the capacity reduction factors of cement stabilized rammed earth (CSRE) columns of rectangular (R) cross sections. The study also attempted to calculate the ultimate compressive str...
Contexts in source publication
Context 1
... results of wallettes are summarized in Table 2. Wallettes failed by vertical cracking followed by shearing of the material along the full height of each specimen. ...
Context 2
... study deals with three slenderness ratios (i.e., effective height to thickness ratios) of 6, 8 and 10 with zero eccentricity were investigated ( Table 2). The maximum average compressive strength measuring 3.03 MPa was obtained for R900 (i.e., least slender), followed by 2.83 MPa and 2.64 MPa for R1200 and R1500 columns respectively. ...
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Citations
... Walker and Morris [32] conducted the same tests on panel walls following standard NZS 4297: 1998. Silva et al. [33] analyzed the behavior of unprotected soil [34] (Fig. 4). ...
... Walker and Maniatidis [13] performed tests on square rammed earth columns with side lengths of 300 mm and a height of 48-300 mm. Tripura and Singh [34] fabricated a rectangular column using cement stabilized soil and applied a compressive load to examine the column strength and sliming. They also studied the slimming and ultimate stress of circular columns with dense soil under areal loads (Fig. 5). ...
Rammed earth structures consist of soil piers, natural materials, and water, which are hammered in thin layers in a container. Rammed earth walls are the primary elements of rammed earth structures and offer high-quality insulation properties as well as recyclability. Unfortunately, only minimal information is available regarding rammed earth structures, especially in new material areas such as nanomaterials and finite element modeling. In this context, this paper reviews the factors that can be used to identify the environmental impacts of rammed earth walls and demonstrates the need for using new materials in rammed earth structures. Several previous experimental and numerical studies are discussed to establish a framework for better understanding the history and future of rammed earth structures.
The goal of this study is to provide first-hand knowledge to the industrial community on the mechanical properties of structurally graded materials (polylactic acid/ceramic-reinforced polylactic acid) wall fabricated through fused filament fabrication. Structurally graded materials are inhomogeneous materials that consist of two or more materials to produce a final structure with distinctive material properties. Because of their specific gradient, structurally graded materials are commonly used in various applications such as aerospace, medicine, optoelectronics, biotechnology, etc. These applications have certain requirements and significant properties such as thermo-mechanical resistance and chemical stability. Filaments of polylactic acid were deposited over ceramic-reinforced polylactic acid to fabricate structurally graded material walls. Coupon studies revealed that structurally graded materials exhibited mechanical properties (tensile strength: 19.1 ± 0.3 MPa, flexural strength: 100.1 ± 0.23 MPa, compressive strength: 64.6 ± 2.35 MPa, impact energy: 1.32 ± 0.038 J, and hardness: 81.5 Shore-D) that are better than polylactic acid. It is revealed that structurally graded materials possess better mechanical properties than polylactic acid and exhibit behavior similar to ceramic-reinforced polylactic acid. Fracture morphology indicates the occurrence of brittle fracture in tensile sample.
The aim of this study is to provide first-hand knowledge on additively manufactured structurally graded material (SGM) (polylactic acid / wood-fiber polymer composites) wall. Polylactic acid or polylactide is most effectively used in manufacturing plastic films, bottles, biodegradable medical devices, textile, and agricultural goods. Wood-fiber polymer composites are essentially used in furniture, particleboard, oriented strand board, medium-density fibreboard, plywood, and constructions. SGM is characterized through the change in material composition that is applicable to specific functions. Fabricated SGM exhibited mechanical property such as tensile strength (15.78 ± 0.05 MPa), compressive strength (46.8 ± 2.7 MPa), flexural strength (88.2 ± 0.15 MPa), and impact energy (1.64 ± 0.07 J). Hardness value of SGM is 74.5 shore-D. The coupon studies revealed that SGM possesses better mechanical characteristics than wood-fiber polymer composites and is on par with polylactic acid. The observed morphologies on fracture surface indicate the brittle nature of fracture. This SGM come under advanced materials that are utilized in biomedical, defence, energy, aviation, and nuclear sector, for integrated structural and thermal application.
This paper deals with the validation of cob sample production technique that replicates the on-site wall construction method. Cob cubes were prepared under confined and unconfined conditions with varying drop heights (0.50 m, 0.75 m and 1.0 m) and moulding water content (25.7% to 39.7%) by mass of soil. Prior to mass production of samples, a trial test was performed at a constant drop height of 0.75 m and varying water content. Based on the trial test results, other two drop heights of 0.50 m and 1.0 m were adopted for further validation. The effect of confinement, drop heights and moulding water content on compressive strength and density of cubes were studied. Test result shows maximum compressive strength and density ranging from 1.22 MPa to 1.31 MPa and 1.65 g/cc to 1.70 g/cc respectively at 33.7% water content and 0.75 m drop height with confined specimen being the highest. The strength and density values obtained satisfy the guidelines prescribed by some of the standards. Thus, the proposed technique for cob production may be adopted to achieve the desirable compressive strength and density for the particular soil used in the present study.
Among many alternative building materials, soil in the form of rammed Earth is the most ancient construction material and technology. Large-scale application of the rammed Earth technology in the construction industry requires the assessment of its strength and failure behaviour. Therefore, this study focused on performing a nonlinear stability analysis of cement-stabilized rammed Earth (CSRE) specimens having a height-to-thickness (H/T) ratios—3 and 4 and loaded under varying degrees of eccentricities 0, 1/3, 1/6, and 1/12. The maximum compressive strength and the stress-strain behaviour of the CSRE specimens were determined through finite element (FE) modeling. The experimental results of the cement-stabilized rammed Earth (CSRE) have been obtained from literature for validation by FE simulation. As the H/T ratio was increased from 3 to 4, the load-bearing capacity of the CSRE specimens increased by 2.91% under concentric loading condition; however, when the eccentricity of load application was swapped from 0 to 1/12, 1/6, and 1/3, the load-bearing capacity decreased incrementally. The results of the FE analysis of the specimens showed that the compressive strength and elastic properties of the CSRE specimens did not differ significantly. The stress-strain relationships were nonlinear and elastic properties were affected by soil textural composition and density.
Present study investigates the flexural strength of cob wallettes strengthened with bamboo and steel
mesh reinforcement under lateral load. Soil, coconut coir, paddy straw, cement, bamboo and steel bars
are the main ingredients for preparation of test wallettes. About 5% fibre and 10% cement (by mass of
dry soil) was used to reinforced and stabilise soil for production of cob wallettes. Three major categories
of samples were prepared. First category comprises: unstabilized-unreinforced cob wallettes (USURCW),
cement stabilized cob wallettes (CSCW), coir fibre reinforced cob wallettes (CFRCW) and straw fibre reinforced
cob wallettes (SFRCW). In second category similar samples shown in first category were reinforced
with bamboo mesh and likewise in third category samples were reinforced with steel mesh. Test results
shows that bamboo-fibre and steel-fibre reinforcement enhances the ductility property of wallettes,
while bamboo and steel reinforced cement stabilized wallettes possess the maximum flexural strength.
Only bamboo-fibre reinforced, steel-fibre reinforced and cement-stabilized bamboo and steel reinforced
wallettes satisfies the minimum flexural strength (0.1 MPa) criteria specified in NZS 4297. The proposed
scheme in the current study can be used for strengthening single leaf internal and external load bearing
walls of single or two storey houses considering design seismic loads.
Rammed earth wall load-bearing dwellings are widely distributed in western China. Rammed earth has the advantages of warm in winter and cool in summer, and it is a kind of sustainable construction material. In recent years, in previous earthquakes, the collapse of rammed earth buildings is serious, resulting in huge losses of personnel and property. To improve the seismic performance of rammed earth buildings and retain the characteristics of local buildings, a reinforcement measure with additional structural columns is proposed in this article. Three kinds of structural columns are designed, which are cast-in-place concrete, square steel tube, and concrete-filled square steel tube core column. Through the quasi-static experimental study on the rammed earth wall, the effects of different structural columns on the failure shape, bearing capacity, deformation capacity, and energy dissipation capacity of the wall are compared. The test results show that adding structural columns on both sides of the wall can effectively restrain the rammed earth wall, restrain its brittle failure, significantly improve the energy dissipation capacity of the wall, and obviously improve the seismic performance of the wall. This measure is applicable to rammed earth buildings and provides theoretical support for improving the seismic performance of traditional dwellings.
