Measurements Of Shrinkage Induced Pressure (Sip) In Unsaturated Expansive Clays

Abstract

Unsaturated expansive soils are located in many regions of the world. Expansive soils can swell more than 100% and shrink more than 50% of its original volume. When these soil movements are totaled, they often result in significant distress to low overburden structures such as pavements and residential buildings. Cracking occurs when the shrinkage or desiccation induced pressure inside the expansive soil matrix exceeds the tensile strength of the same soils. In general, practitioners use soil tests such as linear shrinkage strain and Atterberg limit tests to determine shrinkage strain potentials of soils. However, these tests do not provide shrinkage induced soil pressures generated within the soil. The main objective of this paper is to present a new technique to measure the shrinkage pressure inherently induced inside the matrix of clays. This test termed as Shrinkage Induced Pressure (SIP) is evaluated for providing repeatable and reliable measurements. SIP test results are compared with Indirect Tensile (IDT) strength test results to explain the shrinkage mechanisms in the soils.