Study On The Influence Of Gangue Desulfurization Slag On The Performance Of Cement-soil Engineering

Soil that does not meet construction requirements is often referred to as inferior materials.They are often likely to exhibit poor engineering behavior,such as potentially high expansion properties and high shrinkage,high moisture sensitivity and low load carrying capacity.Engineering can usually choose to replace the original soil with better soil or try to improve the engineering properties of the soil through suitable soil stabilization techniques.Given the availability of materials,transport distances and economic issues,stabilizing existing soil is often the preferred option for construction.Cement stabilized soil technology is often used to improve the mechanical properties of soil（such as strength and stiffness）,compared with other methods have the advantages of low cost,high construction efficiency,and obvious results.In order to study the effects of circulating fluidized bed（CFB）coal gangue desulfurization slag on the mechanical properties and failure modes of cement soil and the modification effect of desulfurization slag on cement.In this project,unconfined compressive strength tests were carried out on specimens with 15%,20%,25% and 30% binder（cement and desulfurized slag）and different proportion of desulfurized slag and cement under the same amount of cementitious materials.The stress-strain characteristics of the specimen、the relationship between the elastic modulus and the compressive strength were studied by compressive strength test.Some specimens of different proportions were selected to carry out swelling and dry shrinkage tests,standard consistency water consumption,and condensation time tests and microscopic tests（SEM and XRD）.The main results are as follows:（1）The compressive strength of the cement soil specimen gradually increases with the increase of cement,and the increase in compressive strength gradually decreases,and the cement dosage increases the most from 15% to 20%,followed by 20% to 25%,and the minimum from 25% to 30%,with an increase of 5.3MPa,0.4MPa and 0.1MPa,respectively.（2）The content of binder and the curing time have an impact on the strength of cement-soil and cement-soil mixed with desulfurization slag,and the compressive strength of the specimen increases with the increase of the curing time,and the compressive strength of the curing time for 28 days reaches more than 90% of the compressive strength of 60 days.（3）With the increase of the curing time,the damage of the specimen changes from plastic to brittle damage,and the peak strain is reduced.The stress-strain curve of the specimen can be divided into three parts: linear growth stage,pressing stage and strength growth stage.（4）The expansion characteristics of the desulfurization slag will cause volume deformation of the specimen,and the expansion will stabilize during the curing time of14-25 days.The dry shrinkage test showed that the shrinkage rate of the cement soil specimen with desulfurization slag addition was significantly smaller than that of the specimen without desulfurization slag addition.（5）The setting time of the cement stabilized soil with desulfurization slag is mainly affected by the desulfurization slag-cement system,and the addition of desulfurization slag to the cement can reduce the standard consistency water consumption of the system and shorten the setting time,but with the increase of the amount of desulfurization slag,the standard consistency water consumption also increases.