EFFECT OF RICE HUSK ASH AND RBI GRADE 81 ON GEOTECHNICAL PROPERTIES OF CLAYEY SOIL

Abstract

Highlights  The combination of clayey soil, RHA and stabilizer reduces the water absorption, optimum mix identified as 86%clay, 10%RHA and 4% stabilizer (RBI Grade 81)  The combination of clay with RHA and stabilizer increases the compressive strength with the age  The relation establishes between modulus of elasticity and unconfined compressive strength, í µí°¸=µí°¸= 0.038í µí±ží µí±¢ + 0.033  The SEM images indicates the formation of CSH and CAH gel, which helps to increase the strength and reduce the compressibility of clayey soil. Abstract Rice husk ash (RHA), RBI Grade 81 (stabilizer), and their combinations are used variously as stabilizers in different proportions maximum up to 20%, to understand and evaluate stabilized clayey soils.The effect of rice husk ash and dosage of stabilizer on fresh and mechanical properties are evaluated through consistency limits, light compaction test, unconfined compressive strength (UCS), modulus of elasticity and California bearing ratio (CBR) test. The chemical reaction identification tests like scanning electron microscopy (SEM) and Energy dispersive spectrum(EDS) are conducted on pure clay and optimum mix of clay, RHA and stabilizer. Optimum mix obtained from the Atterberg's limits tests is 86:10:04(Clay: RHA: RBI grade 81). UCS and CBR tests were conducted on the optimum mixfor 3, 7 and 28 days curing periods. Comparatively with clay optimum mix shows increased in percentage i.e. 782% and 166% in UCS and CBR respectively. Correlation between strength, modulus of elasticity, and CBR test are also established. The SEM and EDS images show that formation of impermeable CSH and CAH gel which fills the void spaces and due to that reduction in the compressibilityof clayey soils. The optimum mix which was developed stabilized soil has shown satisfactory strength and durability characteristics and can be used for rural and low cost construction road infrastructures.