Investigation on dry shrinkage and wet expansion of solidified saline soil containing different salts

Dry shrinkage and wet expansion characteristics of saline soils containing rich chlorine and sulfate,solidified by three sorts of soil stabilizers were investigated.It was shown that dry shrinkage and shrinkage coefficient of specimens decreased if partial cement was replaced by fly ash and slag,and then further by more fly ash.Compared with cement,the chemical activity of fly ash-slag stabilizer was lower and thereby less reaction products were produced.Furthermore,less calcium ions were provided so that the promoting effect of chlorine and sulfate on chemical reaction in soil was weakened,resulting in the differences of chemical reaction degree and therefore the transform from free water to bound water and also the pore characteristics between the specimens with salt and those without salt were reduced.So the difference caused by salts in dry shrinkage and shrinkage coefficient of specimens was also reduced.The positive effect of sodium sulfate on the increase of dry shrinkage and shrinkage coefficient was stronger than that of sodium chloride.In low calcium system,physical effect of chlorine was more obvious than its chemical effect.In moist environment,moisture absorption of the specimens with chlorine was obvious but without huge expansion.However,much rudimental sodium sulfate in soil might cause serious cracks in specimens by huge expansion.