GYPSUM: AS AN ADDITIVE FOR STABILIZATION OF SWELLING CLAYS

9th International Multidisciplinary Scientific GeoConference - SGEM2009, www.sgem.org, SGEM2009 Conference Proceedings/ ISBN 10: 954-91818-1-2, June 14-19, 2009, Vol. 1, 245-246 pp

ABSTRACT

Low rise buildings are particularly vulnerable to ground movements sourced from
swelling and shrinking of the expansive clays. Geotechnical engineers have long
recognized that Swelling of expansive clays caused by moisture variation may result in
considerable damage to the overlying structures, and engineers should take them into
the consideration. The literature contains a vast number of stabilizing techniques such as
lime, cement, fly-ash for treatment of expansive clays. However the use of gypsum as a
stabilizing agent is currently not clear. This paper deals with the performance of the
gypsum as an additive for treatment of the expansive clays by means of swell potential
and strength. Optimum water content for the best compaction of the bentonite was first
determined by Standard compaction tests. Different quantities of gypsum such as; 2.5%,
5%, 7.5%, 10% were added to bentonite and compacted in optimum water content
obtained. Atterberg limits, free swell and unconfined compressive strength tests were
performed on treated and untreated samples, after a curing period of 7 days. Obtained
changes in the plasticity, swell percent and strength parameters of treated and untreated
samples indicated that the gypsum can be used as a stabilizing agent for expansive
clays, effectively.

Keywords: Expansive clay; bentonite; gypsum; stabilization; swell; strength.