The Effect of Curing Period on Strength Behaviour of Sand Bentonite Mixes

A landfill is a secured engineered pit in the ground into which the wastes are dumped. Proper landfill liners need to be used to avoid any hydraulic connections between waste and surrounding environment. These liners can be created of different materials of which sand-bentonite mixtures are attracting greater attention. The sand bentonite mixture is a mixture of two different materials in terms of their particle size and chemical activity to produce a material with low hydraulic conductivity, low compressibility and sufficient strength. Low hydraulic conductivity of the mixture is due to the ability of bentonite particles to swell and fill the voids between the sand particles and whereas sand framework provides low compressibility. In this work, 80% sand and 20% bentonite were taken for the sand-bentonite mixture, on which various preliminary tests and secondary tests were carried out to study the properties of the mixture. The Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) were determined by Standard Proctor Test. Variation of unconfined compressive strength with curing period as well as with the water content on sand-bentonite mixture were obtained from the results of the tests performed in order to get the optimum curing period and water content. Hence, a suggestion can be made as to when the maximum Unconfined Compressive Strength (UCS) will occur at a particular curing period.