Influence of number of blows and water content one engineering properties of compacted gypseous soi

الملخص EN

The main problem in laboratory re-molded gypseous soil is that, gypsum material in soil do as bounded material between soil particles which increases soil strength.

But these bounding between soil particles would be broken when attempts to recompact soil and made it difficult to return to its origin state.

As a results, the value of cohesion and angle of internal friction would be changed for samples which that re-compacted using the ordinary compaction method comparing with the field values.

In this study, compaction test was used with different blows number (15, 25, 30) for each layer.

Different value of water content are used for each case to record the effect of numbers of blows and water content on thecohesion and angle of internal friction.

Three different gypsum content samples (18.9% , 32.4% , 60% ) are used in this study which taken from three different locations in Tikrit city - Salah-Aldeen Governorate, in the middle of Iraq.

The results of laboratory tests for re-molded gypseous soil show that increasing number of blows and water content leads to increase cohesion and angle of internal friction.

Also, the optimum blows number per layer was (30) for the three percent of gypsum content.

But the optimum water content increased with increasing gypsum content to (7% , 12% , 15% ) for the three values of gypsum content (18.9% , 32.4% , 60% ) respectively, to obtain laboratory value of cohesion and angle of internal friction close to the field value.

So it could be notice that, changing gypsum content in soil had no effect on the optimum number of blow for laboratory re-molded gypseous soil.

But increasing gypsum content leads to increase optimum water content.