Influences of Specimen Geometry and Loading Rate on Compressive Strength of Unstabilized Compacted Earth Block

Abstract

Loading rate and specimen geometry are critical parameters used in simple compressive tests to determine the strength of earth materials. In this study, cubic and cylindrical unstabilized compacted earth block of different sizes were manufactured and tested in unconfined compression to investigate the size and shape effects on the compressive strength of earth materials under different loading rates. e correlation between the compressive strength of earth materials and the geometric parameters of the specimen was determined. e recommended loading rate and sample for testing the compressive strength of earth materials were given. Finally, a constitutive model for describing the stress-strain response of earth materials was proposed. is model modifies the defects of the constitutive equations suggested in previous studies and may be applied to the numerical analysis of earth structure.

Study on Mechanical Properties and Constitutive Equation of Earth Materials under Uniaxial Compression

“…The total amount of clay particles and powder particles is 58% > 50%, which is a fine-grained soil. Figure 4 shows a plastic diagram of the soil used in this test and related literature [1,14,19,23,[26][27][28]. In Figure 4, it can be seen that the soil used in this test has a liquid limit LL = 36.3% < 50% and a plasticity index PI = 12.8 ≥ 11.899, which is a low liquid limit clay [24].…”

“…The basic physical properties, such as maximum dry density and optimum water content, were measured using the light compaction test [22], and the results are shown in Table 2. Figure 3 shows the particle size distribution curves of the earth materials used in this experiment and in the related literature [1,14,19,[23][24][25][26][27][28]. The obtained curves were also compared with the particle size range recommended by CRATerre (Centre de Recherche en Architecture en Terre) [29] for making compacted soil specimens.…”

“…With the improvement of environmental concerns all over the world, sustainable development has attracted much attention in the construction industry. People urgently need a low-cost, reusable, energy-saving, and environment-friendly building material to replace the industrial building materials with high pollution and high energy consumption [1]. Earth as a natural construction material has been widely used throughout the world since ancient times.…”

“…The influence of the inherent inhomogeneity of earth material on the mechanical properties of adobe is emphasized, and finally the constitutive equation describing the strength and deformation characteristics of adobe under uniaxial compression is established. Lan Guanqi et al [1] carried out uniaxial compression tests on earth blocks under different working conditions, put forward the recommended loading rate and standard specimen size for uniaxial compression tests of earth materials, and established the constitutive equation of earth materials. Rodríguez-Mariscal et al [21] carried out uniaxial compression tests on brick, cubic, prismatic, and cylindrical specimens.…”

“…From the above literature, it can be seen that the shape, size, curing age, and loading rate of the specimen are the factors affecting the uniaxial compression performance of earth materials that have been widely studied by scholars because there is no complete consensus on the uniaxial compression test method. Most of the uniaxial compression constitutive equations of earth materials proposed by scholars are based on fitting the test data obtained by themselves [1,[18][19][20][21]. Whether it has wide applicability and statistical significance-based methods for calculating parameters related to constitutive equations has not received attention by scholars.…”