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The northern coastal strip of Venezuela with a semiarid climate presents conditions for the development of extensive areas with the presence of expansive clays, and, this is the main pathology of its communication routes due to deformation in the surrounding civil works. This contribution characterizes the presence of expansive clays in northern Venezuela in 81 samples distributed in several states of the country. The study included the determination of geomechanical properties through field work and laboratory tests by Atterberg limits, consistency indices and expansion tests as well as the relationship between the indexes and information from edometer tests. The soil grain size is mainly fine (silts and clays), in the Anzoátegui state the average content of fine grains is 86%, while in Falcón and Miranda they are a little lower, 82% and 67%, respectively. In general, the plasticity index (PI) of these expansive clays is high, with an overall average of 23, although the region of Falcón state presented a moderate average (18). The correlations between the expansion pressure and the PI showed a high correlation. These results corroborate that the criterion used to evaluate the Expansion Potential of a clay soil based on the PI proposed by Chen (1988), is a fairly adequate criterion to be used in the study and identification of the expansive behavior of these types of soils. [ABSTRACT FROM AUTHOR]

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Introduction: the following study focuses on the granulometric analysis of soils, using a soil from the town of Cuauhtémoc, Villa Flores, Chiapas, Mexico, to determine its possible use in the elaboration of Compressed Earth Blocks (CEB). The purpose of the study is to achieve adequate mechanical strength without using chemical stabilization Method: the initial characterization procedure of the soil samples was developed by means of granulometric determination and consistency limits, which made it possible to identify the soil by its granulometric curve and resistance to axial compression. The discussion arose from the identification in the existing regulations for CEB in Spain and Mexico that they establish too wide granulometric intervals and do not seem to give importance to achieving an optimal accommodation of the granulometric curve, forcing chemical stabilization. A granulometric range for CEB was idealized by adjusting maximum and minimum limits of the different sizes of particles that make up the samples and the percentage of initial water was established from the plasticity index. Afterwards, 3 series were elaborated with five samples of compressed earth in each configuration, varying the granulometric curve, percentage of water and elaboration pressure to improve their resistance to compression. Results: the results describe a notable improvement in the behavior of the soil as a compressed block when the granulometric adjustment is carried out. The CEB mix design was improved from 32.5 kg / cm² to 54.75 kg / cm² by adjusting the percentage of water and nominal brewing pressure. Conclusion: it is concluded that it is possible to optimize the use of soil for construction by controlling the granulometry, water content and nominal pressure of the raw material, achieving mechanical strengths greater than 50 kg / cm² without using cement, asphalt, or lime as stabilizers. [ABSTRACT FROM AUTHOR]

This paper proposes two models or equations based on the PI (plasticity index) to describe the degradation of normalized shear modulus and damping ratio in volcanic ash soils for the city of Armenia, the equations are derived from the dynamic tests performed at soil samples collected in the microzonation of the city. The first model is associated with ash soils, evidenced through cyclic triaxial testing to measure their dynamic properties at high strain levels. The second model is derived from the resonant column test that measures the dynamic properties of soil with low deformations. It was found that the IP is a fundamental variable in the model describing the dynamic behavior of volcanic ash, where it was shown that the lack of variable effective confinement pressure σ'o in the obtained models, generate a notable difference between the curves obtained with the triaxial test model and the model of resonant column test. [ABSTRACT FROM AUTHOR]