Abstract This research work examines the utilization of cement in order to improve low plasticity clay soil. The soil samples treated with 2, 4 and 6% cement percents and cured for different curing times extended to 90 days. Laboratory investigations include unconfined compression, indirect tensile, gas permeability and microstructural tests, which were conducted on the tested samples. The soil-water retention behavior has been also investigated. The test results showed that the cement addition improved both the compressive and tensile strength properties of soil specimens. These strength properties were also increased with curing times. pH and electrical conductivity values were good indicators for the enhancement in the strengths properties. The results of micro structural tests illustrated that the natural soil specimens contain voids and the open structure. Further, these tests showed the cementation of soil grains and filling the voids among soil grains with cementing compounds. Gas permeability and soil-water retention behavior of soil specimens are strongly related to the variations in the soil structures. Further examination illustrated that in the case of low cement content, the pore size distribution (PSD) and the efficiency of gas permeability are more sensitive to curing times.

RESUMEN Este artículo buscó investigar el uso de desechos espirálicos de aluminio de fresado de control numérico por computador (CNC-W) en la construcción de subrasantes de pavimento de carretera. La tierra (CL) fue mezclada con espirales de CNC-W con proporciones entre 0% y 20%, e incrementos del 5% por peso seco con contenidos diferentes de agua. Se efectuaron las pruebas California Bearing Ratio (CBR), Resistencia a la Compresión Uniaxial (UCS), y de consolidación. Los resultados experimentales indicaron que la inclusión de espirales de CNC-W incrementaba el valor CBR de la arcilla hasta el 15 % de proporción en la mezcla y después lo disminuía. Similarmente, el valor UCS de la arcilla se incrementó con las mismas proporciones, mientras que la USC no se pudo determinar debido a la falla de todos los especímenes con una proporción de mezcla más alta que el 15 %. Se definieron los valores de permeabilidad e hinchazón, así como las características de consolidación de las mezclas. Los porcentajes de hinchazón disminuyeron de 1,15 cm/sec a 0,81 cm/sec, con un incremento en el contenido de espirales de CNC-W. se observe una reducción en los valores del coeficiente de permeabilidad (k) con una proporción de mezcla de hasta el 15 %, mientras que estos permanecieron constantes con el cambio en el contenido de espirales de CNC-W con 20 % de proporción en la mezcla. El coeficiente de consolidación demostró un patrón similar de comportamiento a los cambios de permeabilidad.

ABSTRACT This paper aims to investigate the use of spiral aluminum computer numerical control milling waste (CNC-W) in the construction of road pavement subgrade. The soil (CL) was mixed with CNC-W spirals with ratios of between 0% and 20%, and 5 percent increments by dry weight with different water contents. California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS), and consolidation tests were conducted. The experimental results indicated that the inclusion of CNC-W spirals increased the CBR value of clay up to the 15% mixture ratio, then decreased it. Similarly, the UCS value of clay was increased to the same ratio, whilst the UCS was not able to be determined due to the failing of all specimens with a mixture ratio higher than 15%. The permeability and swelling values, as well as the consolidation characteristics of the mixtures, were defined. The swelling percentages decreased from 1,15 cm/sec to 0,81 cm/sec with an increment in the CNC-W spiral content. A reduction was observed in the coefficient of permeability (k) values up to 15% mixture ratio, whilst it remained constant with change in CNC-W spiral content with a 20% mixture ratio. Coefficient of consolidation demonstrated a similar pattern of behavior to the permeability changes.