Abstract:
The pavement performance is determined by the behaviour of the subgrade soil and its
bearing capacity. Expansive subgrade soil is problematic to the pavement and other types of
construction activities due to its excessive swelling and shrinkage, necessitating stability with
various materials. Soil stabilization using different chemicals have been used to improve the
soil property to make them suitable for the desired engineering purpose. Expansive subgrade
can be stabilized using alkali activated slag, fly ash and other waste materials and this also
helps in solving disposal difficulties. The purpose of the current work is to strengthen Black
Cotton Soil (BCS) with alkali activated Rice Husk Ash (RHA) and to design flexible
pavement using IITPAVE software (based on IRC 37-2018). This research explains the
behaviour of the modified expansive soil for highway subgrade with liquid alkaline activator
stabilizer and RHA. A combination of sodium hydroxide and sodium silicate was utilized as
the liquid alkaline activators. Sodium oxide (Na2O) and silica modulus (Ms) are the activator
parameters selected for the investigation and were varied in different proportions.
Unconfined Compression Strength test and Durability test were used to study the effect of
different proportions of alkali activated RHA and activator parameters at different curing
durations. CBR test, Swelling test and Flexural strength test were done on samples that have
passed the Durability test and Unconfined Compressive Strength (UCS) with the highest
compressive strength. This soil treatment enhanced the CBR, UCS, durability and flexural
strength of the BCS. The swelling was also significantly reduced.
