STRENGTH AND PERMEABILITY CHARACTERISTICS OF EXPANSIVE SOIL WITH GYPSUM AND RICE HUSK ASH
Keywords:Expansive soil, Roadway construction, CBR, Permeability, Soil stability
The presence of expansive soils in the site poses threats not only for built residential houses and superstructures but also for roadway construction. The shrink-swell behavior of expansive soils creates a continuous strain on the pavements which can result in cracking and settlements. Therefore, there is a need to stabilize such problematic soils. This study aims to establish a more economic and environmental-friendly way of stabilizing clay loam from Kauswagan, Lanao del Norte. Varying combinations of gypsum and rice husk ash (RHA) were used in soil stabilization. Untreated and treated soil specimens were tested for their California Bearing Ratio (CBR) and coefficient of permeability per ASTM Standard D1883 and D2434 respectively. The CBR of the soil slightly increased with the addition of 15% gypsum. While the addition of 10% RHA with the same amount of gypsum dramatically increased the soaked CBR index of the soil. A peak average value of 21.11% was recorded for 15% gypsum + 10% RHA soil specimen. Falling head permeability tests showed that as the amount of gypsum in gypsum + 10% RHA soil specimen increases, the coefficient of permeability of the soil also increases. A direct relationship was then formed between strength and permeability. This can be attributed to the formation of micropores in the soil specimen with the addition of 10% RHA, allowing an easier flow of water through it. The stabilized soil passed the DPWH Standard for the subgrade layer but slightly fell short of the requirement for the subbase layer.
- 2021-12-30 (2)
- 2021-12-30 (1)