Ground Heave from Caustic Soda Solution Spillage—A Case Study

Abstract

ABSTRACT The present study discusses the cause of ground heave of an inherently non-swelling, kaolinite-rich red soil (from Bangalore, India) due to prolonged spillage of concentrated (40%, weight/weight solution) caustic soda (sodium hydroxide) solution into the sub-soil through cracked drains in an industrial establishment. The heave of the foundation soil caused considerable distress to the industrial building. The proposed remedial measures to chemically stabilize the contaminated foundation soil against future caustic soda solution spillage are also considered. The observed heave of the undisturbed soil sample in the laboratory oedometer test on permeation of 40% caustic soda solution and the significantly reduced pH of the outflowing caustic soda solution (pH = 9.35), suggested that certain chemical reactions occur during the passage of the strong alkali solution through the residual soil that is responsible for the ground heave. It is considered that loss of the cementitious iron oxide coatings coupled with the negative charge imparted to the soil particles by the passage of the caustic soda solution, disperse the soil particles that manifests as ground heave. Treatment of the contaminated ground with 5% ferric chloride solution and simultaneously taking measures to minimize caustic soda solution spillage should stabilize the foundation soil against heave from caustic soda attack for several years.